Does the sun's rising/setting angle change every few months?

Question: When I lived in Darwin, Australia, I noticed that the Sun set in a slightly different direction to the West. In the evenings, I used to sit on a couch and watch TV. There was a huge window to my right and the setting sun would always shine bright into my face. So I moved a single vertical blind to block it out just about right. In the months of October/November I started noticing the sun shining into my eyes again. Neither the couch nor the blind had moved. After moving the blind again to block the sun, in a few months I would have to move the blind again. I was living alone and there is no way the blind or the couch would move.
When I lived in Canberra, Australia, I had the habit of stepping out of my house early in the morning. I would face the sun as soon as I stepped outside because it was too cold and I wanted the warmth of the sun on my eyes/face. I noticed again in October/November that my usual position of facing the sun was wrong. The sun would rise from a slightly different angle. So if earlier the sun was rising at 130 degrees from my door, it would now be rising at 110 degrees. The door faced the southeast, and because of the very narrow path and vegetation from my door I am very certain of my positioning.
I really don't know what this phenomenon is called. When I lived for so many years in other countries, I never noticed this. Am I just being silly or does the Sun rise/set differently every so many months?
Comment: [Manhattanhenge](https://en.wikipedia.org/wiki/Manhattanhenge) is a more well-known example of this.
Comment: MIT students celebrate this phenomenon, on days when the setting Sun shines down the axis of the longest corridors in the core campus buildings. [Coming up next week!](http://web.mit.edu/planning/www/mithenge.html)
Comment: Legend says that the sun rise shines through the Box rail tunnel, near Bath, UK, on Brunel's birthday
[Box Tunnel Legend](https://www.networkrail.co.uk/who-we-are/our-history/iconic-infrastructure/the-history-of-box-tunnel-wiltshire/#:~:text=Legend%20has%20it%20that%20the,April%20and%20again%20in%20September)
Comment: The term _solstice_ literally means "sun stop" and indicates the point at which the sun's path has reached its limit and starts moving back the other direction.
Comment: Coastal Californians that go to the same beach regularly to watch the sunset can easily tell that it moves
Comment: @JohnDoty - well, logically, if the corridors in that building are, in fact, parallel, then it is clearly impossible for the sun to shine down *all* of them AT THE SAME TIME, as only ONE of them can be pointing directly at the sun at any given moment, unless - and you'll no doubt find this funny - unless - and I am of course pointing out the logical impossibility of this situation - unless - are you ready for this one? - unless - hah-hah, this is REALLY funny! - UNLESS the sun was ACTUALLY LARGER THAN THE BUILDING!!!! Ridiculous, I know, but there you are...
Comment: Related question: https://astronomy.stackexchange.com/q/6546/189
Answer: The Sun rises and sets at a different point on the horizon every day. The change is small, so without careful observations, it may take several days or weeks to be fully aware of the change. Mathematically, the position of rising/setting can be found from the following formula:
$$\cos(\theta) = -\frac{\sin(declination)}{\cos(latitude)}$$
where

$\theta$ is the angle measured from due south to the point on the horizon where the object rises. (The angle is the same for rising and setting, if you ignore the change in the Sun's declination during the day.)
declination changes from approximately +23.5 and -23.5 degrees for the Sun during 6 months (southern hemisphere winter to summer) and then from -23.5 to +23.5 during the next 6 months. The reason the declination changes is because the Earth's north pole is tilted 23.5 degrees toward the Sun at the June solstice (making the Sun's declination +23.5), the north pole is tipped 23.5 degrees away from the Sun at the December solstice (Sun's declination -23.5) and changes each day in between the solstices.
latitude is the observer's latitude.

From 35° S latitude (latitude = -35), the winter Sun would rise at $\theta=119$ from due south (or 61° from due north, approximately ENE). The summer Sun would rise at $\theta=61$ from due south (or 119° from due north, approximately ESE). The range is 119-61=58° along the horizon.
At latitudes closer to the equator (0° latitude), the difference is smaller. The range is approximately 47° along the horizon when at the equator. At latitudes closer to the poles, the range becomes larger. At the Arctic and Antarctic Circles, the range is the largest that it can be: 180° (at least mathematically). At these high latitudes, the apparent diameter of the Sun and refraction become important to calculate the precise location of rising.
Comment: I love the math. But, based on the text of the question (and more specifically, how the question sounds), I'm not sure you've made it easily and explicitly clear that the sun rises and sets at a different point because of the combination of the earth's tilt and the position of the earth along the sun's orbit. You kind of just dove right in to the details, but the details might not make sense to someone who hasn't made the high-level connection yet. It kind of seems like most of the answers so far suffer from this.
Comment: It's interesting that this formula directly shows that on the equinoxes the sun sets due west everywhere on earth, except at the poles, where it doesn't set—the formula is undefined.
Comment: Indeed. As far as I can tell, this is just a conversion between equatorial and altazimuth coordinates. One way to visualize it is to launch Stellarium and to enable the equatorial grid. It's easy to see where +23.5 and -23.5 intersect the horizon. By playing with the latitude of the obverver, we see how the equatorial grid rotates relative to the horizon, and how the intersections gets further apart when close to the poles.
Comment: I noticed this at my old house, where the front window pointed due east.  You couldn't watch TV during the day at some times of the year without closing the blinds.
Answer: You're not silly1, it certainly swings back and forth (North and South) one full cycle every year. It's directly related to why days are longer in the summer and shorter in the winter.
I am no expert, but some say that Stonehenge and other ancient "observatories" are supposedly set up to do exactly what it is you do, except much more carefully and quantitatively, to time things like crop plantings.
For more on that see Wikipedia's List of archaeoastronomical sites by country
One example in Australia is Wurdi Youang, and the drawing below nicely highlights exactly what you are describing!

Wurdi Youang: An Australian Aboriginal Stone Arrangement with Possible Solar Indications Rock Art Research 2013 - Volume 30, Number 1, pp. 55-65. R. P. NORRIS et al.

 Source

1at least in this regard :-)
Comment: And your ancient temple builder didn't start making observations because they needed them to build their idea of a whatever-pointing temple; they built the temple that way because they *already* knew the directions involved.
Comment: @happybuddha why would they get it wrong? They had plenty of time to look at the stars in order to orient themselves. And if it takes multiple year to build a temple, it's no big deal to wait for the equinoxes to perfectly align E-W.
Comment: A few more exapmples.
At sunset on the winter solace, the Sun shines directly into  [Maes Howe](https://en.wikipedia.org/wiki/Maeshowe). Around 30 May and 12 June, the Sun will sun shine directly along (Manhatten's streets)[https://en.wikipedia.org/wiki/Manhattanhenge]
Comment: @happybuddha each Stack Exchange site has a different "culture", it's a little bit like going from one country to another. In Engineering SE they will want to see an engineering problem explained clearly, ideally in engineering terms. Maybe *focus less on* the religious aspects and details, and add more about the exact mechanical behavior you need. Right now I can't figure out what you are describing there.
Comment: @EricDuminil The equinoxes can align - but the Idol isn't necessarily facing the rising sun *all* the time - which I think is necessary. I have asked this question else where too : https://engineering.stackexchange.com/q/38529/29293
Comment: @uhoh Thanks mate. I have made it more pointed and engineering specific.
Comment: @happybuddha looks much better, thanks!
Comment: I wonder how temples and mosques were built back in the day? Indian temples are all meant to face East and the mosques are all meant to face E/W (wherever Mecca is, relatively) - did the people of the yore get it all wrong?
Comment: @happybuddha The various archaeoastronomical sites are evidence that people have been able to do this kind of thing for a *long* time. By the time of the Ancient Egyptians, they were *very* good at aligning buildings to the Sun on a particular day. And that means they knew how to calculate this stuff. Sure, they didn't have calculators, or modern trigonometry, but they could measure angles, and they knew about the properties of similar triangles, and could draw accurate scale diagrams.
Answer: This answer is a supplement to the existing answers.
I looked around for nice graphs showing the sunrise azimuth over the year for various latitudes, but I couldn't find anything suitable. So I just wrote a couple of small Python scripts, using Sage / Matplotlib to do the plotting.
Sunrise azimuths for various latitudes

Sunrise times for various latitudes

That graph is for apparent solar time (i.e., sundial time). Here's one for mean solar time (clock time).

You can play with the azimuth plotting script on the SageMathCell server here.
The script is actually encoded in the URL. It's a bit cryptic & terse to save space. Just type a comma-separated list of latitudes into the box & it'll plot the corresponding curves.
Hopefully, I haven't made any coding or algebra errors. ;) I used the azimuth formula given in John Holtz's answer, and I got the declination equation from Wikipedia's article on the Position of the Sun, modified to use slightly more accurate values for the obliquity of the ecliptic and the Earth's orbital eccentricity. In the script,

dpy is days per year
sinOE is the sine of the obliquity of the
ecliptic
ecc2 is twice the eccentricity
mam is the mean orbital motion
n is the day number, with 0 = midnight on New Years Day
lat is the latitude
sindecl calculates the sine of the declination
sraz calculates the sunrise azimuth

Here's a simpler version, which just plots a single curve.
Here's the script that plots apparent sunrise times.
This script's for the mean sunrise times. And here's one for the Equation of Time, the previous script uses the formula from this one to convert apparent time to mean time.

Those curves are calculated for an observer at longitude 0° (pretty much), but they're accurate for any longitude. (At any given longitude there's a small displacement that's almost constant over the year, apart from effects due to the variations in the Sun's speed along the ecliptic, aka the Equation of Time). They do not account for the observer's height above sea level (and hence the distance to the horizon) or the angular size of the sun, or atmospheric refraction: I just wanted to show the general trend. But as John Holtz notes, refraction does have a noticeable affect on sunrise time and the Sun's apparent altitude, especially at higher latitudes, where the Sun makes a lower angle to the horizon.
If you ask those scripts to plot curves for latitudes in the Arctic or Antarctic circles, they will do their best, but will print error messages warning that they couldn't plot some points. I didn't want to waste space in the scripts handling days when the Sun doesn't rise. ;)
Comment: Thanks, @Jonathan! Yes, this question is about azimuth, not altitude, so your graphs would be a bit off-topic (but maybe you can ask a self-answered question, or find an old relevant question that could do with some graphs). FWIW, Sage does have some animation capabilities. I made a version with a slider for the latitude, but unfortunately the slider doesn't work too well on touchscreen devices: you can click the slider to a new position, but you can't grab it & slide it.  And the clicking doesn't give you much precision. Very frustrating!
Comment: These are nice! I'm almost tempted to post my Desmos interactive graphs simulating the suns elevation over the day where you can vary the latitude and day of year. But they're not quite on subject for the question. I guess I'll have to wait.
Comment: That's good to know (about Sage). Desmos has very nice, smooth, and precise sliders, but the syntax for entering formulas is a real pain and pretty limited.
Comment: I couldn't decide which year length I ought to use for `dpy` (days per year). Wikipedia isn't consistent: some formulae use 365.25, some 365.24. So I originally went with the Gregorian length, 365.2425. However, I used the anomalistic year in the Equation of Time & mean sunrise time scripts. Another reasonable option is the mean tropical year. OTOH, I guess it's hardly relevant in calculations that completely ignore years. ;)
Answer: The Sun does indeed drift across the sky throughout the year, not only rising higher in the summer and lower in the winter, but also varying along an east-west axis. This can be shown by observing the Sun at the same time each day throughout the year, and seeing that it changes position. This shape is called an analemma, and is a result of the earth's axial tilt and orbital eccentricity around the Sun.
Here's a diagram showing the position of the Sun at noon throughout the year, as observed from the Royal Observatory in Greenwich. Most people are aware of the change in altitude between summer and winter, but the fact that the angle of the sun varies side-to-side may be less well-known.

Now, this figure shows the position of the sun at a fixed time of day over the course of the year. But the question relates to the position of the sun at sunrise, which is clearly not fixed throughout the year. To answer the original question of if the sunrise "moves", you can imagine drawing an analemma for any time of day - let's pick a time that's before sunrise for part of the year, and after sunrise for another part of the year (let's say 6am). In this case, the whole curve shifts downward, and the bottom part of the analemma drops below the horizon, showing that indeed, for some parts of the year, the sun will be visible at 6am, but at other parts of the year, the sun will not be visible at 6am. Furthermore, we see the curve drop below the horizon at two different spots - this shows that there are two dates at which sunrise is at (approximately) 6am, and that the sun will rise at different azimuth on those days.
It's a little more complicated if we want to draw the "sunrise analemmas" over time, since we'll have a figure-8 shape that drifts upward as sunrise becomes earlier, following the position of the sun as it moves across the sky. It's not as easy to visualize, but that series of analemmas will drop below the horizon at different points, showing that the sunrise does move throughout the year. This shape, which is traced out by the intersection of a series of analemmas with the horizon, is not an analemma itself. The example of two dates with the same sunrise time is much easier to visualize with a single analemma.
Comment: OP was only concerned about the position of the sun during sunrise and sunset. By definition, it only happens when the sun elevation is 0, and the time is not relevant at all for the azimuth. The azimuth at sunrise only depends on the declination, which is independent of the sun azimuth at noon. The question can be perfectly answered without analemma or sunrise time (see others answers, e.g. from PM2Ring or JohnHoltz), and adding those concepts doesn't help at all and only obfuscates the situation. Sorry for the harsh feedback.
Comment: @RBarryYoung The OP is asking about the Sun's azimuth at sunrise, not its azimuth at mean noon. The info in this answer *is* important, though. The Sun crosses the meridian (the north-south line) every day at local solar noon (aka "high noon"), but that's not equal to mean solar noon, due to the Equation of Time. And then there's a further adjustment if you aren't located at the meridian of your time zone (plus a possible adjustment for Daylight Saving). I discuss the details of this issue in [this Physics.SE answer](https://physics.stackexchange.com/a/469884/123208).
Comment: I'm not convinced that the analemma plays any role for this question. It is about the azimuth of sunrise and sunset, not their times. For a given latitude, only the sun declination plays a role. For the above question, only the vertical motion is relevant in the analemma and you can ignore the horizontal motion.
Comment: I calculated the azimuth of sunrise for each day, at my location. I also calculated the sun position at noon for each day. Here's a plot of sunrise azimuth vs elevation at noon : https://i.stack.imgur.com/Jwlrc.png There's no analemma anymore, and the equation of time doesn't have any influence on sunrise azimuth. I'm not sure how you could correct your answer, since it appears to be based on a false premise. Sorry to rain on your parade!
Comment: @Eric I get what you're saying (& agree that the analemma is irrelevant here because we want the Sun's azimuth direction at sunrise time, not some particular clock time). We do need the eccentricity to get the Sun's declination (or ecliptic longitude) for the day, because the eccentricity causes the Sun's ecliptic speed to vary. (And then the obliquity causes the Sun's equatorial speed to vary, and the Equation of Time shows both effects). But once we have the declination, the sunrise azimuth is a simple function of the declination and the observer's latitude.
Comment: Nicely answers the questions that were actually asked by the OP.
Comment: @PM2Ring Good point, I had a little trouble trying to visualize it with analemmas, since we'd be talking about multiple analemmas that describe different times of day for different sunrises. But I think I found a good example showing that two different dates with the same sunrise time will have those sunrises at different azimuth.
Comment: One simple way to check : during the equinoxes, sunrise and sunset will be exactly at 90° and 270°. On your diagram the equinoxes are wide apart. Same goes for the first week of November and February: they will have very similar sunrise and sunset azimuths. Sorry, the analemma is a cool diagram but it's not relevant here, and it needlessly complicates the explanation.
Comment: @EricDuminil I agree the analemma doesn't show the path of the sun at sunrise each day, but I do think it's relevant - it clearly illustrates that at some particular time of day, the sun will be in different positions throughout the year. If we set that time to sunrise on any day that's not a solstice, the fact that the analemma crosses the horizon in two points is sufficient to show that the sunrise's location is not constant. On two days with identical sunrise times, the azimuth will be different, which can be observed with the analemma only.
Comment: Agree that knowing that the sun traces an analemma is *sufficient* knowledge (although not *necessary*) to infer that the sunrise moves.
Comment: FWIW, the analemma is a relatively recent innovation. Before the development of accurate mechanical clocks, which led to the use of mean solar time, local apparent solar time was the usual way to keep time in most parts of the world. There were various systems of hours in use, but *everyone* agreed that noon is when the Sun crosses the meridian, i.e., when its azimuth is 180°. Ancient timekeepers were aware that the Sun's speed along the ecliptic varies throughout the year, but they didn't have the modern notion that all hours ought to have the same duration.
Comment: (cont) That's basically an artifact of the mechanical clock. It was hard enough for early clockmakers to make a device that kept consistent time. Few attempted to make a clock that could track sundial time. So the old systems of variable hours died out, and were replaced with rigid systems based on mean solar time.
Comment: @NuclearHoagie: Sorry to insist. Analemma is completely unneeded, and tangential to the question. To explain the shift in sunrise azimuth, all you need to know is that the Earth axis is tilted by 23.5° in comparison to the plane of its orbit. That's it. It explains the seasons, and it explains the variation in sunrise azimuth. You don't need any eccentricity, you don't need any equation of time, you don't need any analemma. As you said, "the fact that the angle of the sun varies side-to-side may be less well-known", but it's also irrelevant for OP's question.
Comment: @PM2Ring: Thanks for the comment. As far as I can tell, we don't need the eccentricity to explain why the sunrise azimuth varies. By only taking the obliquity of the ecliptic into account, it's possible to plot a curve which is *very* similar to yours. It's possible to add more details to get a more accurate model, but your diagram doesn't change much if you set ecc2 to 0. It becomes kinda boring if you set sinOE to 0, though. :)
Comment: @Eric That's true: changing the eccentricity won't affect the size of the maximum or minimum azimuth, it just shifts the time a bit. FWIW, I originally made a typo in my script & used 0.167 for the eccentricity instead of 0.0167. But you can't see the difference unless you look very carefully. ;)
Answer: I hope someone can come along and make this more precise, but I'm pretty sure the effect is greater the further you move away from the equator. So it would be more noticeable in Canberra (35° S) than in Darwin (12° S). Do you know the latitudes of the previous places you lived?
Answer: To augment many of the good answers already:  A great way to view and record this effect is called a Solarigraph.  (Often also referred to as a solargraph, solargraphy, or solarigraphy).
This is a pinhole camera, usually just a soda can with a hole poked in it, and a piece of photographic paper left out for a long period of time.  Usually at least 1 day, and most often from one solstice to the next solstice.  The Sun is bright enough to form an image directly on the paper, so there is no development process needed.
When left out from solstice to solstice, lines are formed on the photo paper for each day.  The lines tend to run together near the solstices, and are farthest apart near the equinoxes.  Breaks in the lines are caused by clouds.  Most long exposures will show some form of water damage, as moisture exposure is part of the image forming process.  When left out spanning a solstice, the lines often overlap.
Below are a few examples, but an image search will reveal many, many more.
Solargraph from Sashegy - Budapest, 2014.01.01 - 2014.12.31 (1).jpg
Original image link

A 7 day solarigraph near the winter solstice

A three day solarigraph near the equinox.  The lines that look like contrails are reflections due to the use of glossy photo paper.


Contract Design: Interfaces

Question: Why use interfaces? I've heard this allows for easier bug fixes down the road, but with or without an interface, wouldn't you have have to scrap the bugged contract entirely?
Answer: Interfaces are a good way to let people understand how to use a contract.
On a purely utilitarian view, if you keep your contracts into different files, interfaces allow you to avoid cross-reference compilation errors:
I.sol:

contract I {
    function deployB();
    function doSomething();
}

J.sol:

contract J {
    function doOnI(address i);
}

A.sol:

import "J.sol";
import "B.sol";
contract A is I {
    function deployB() {
        new B();
    }
    function doSomething() {}
}

B.sol:

import "I.sol";
import "J.sol";
// You would not be able to import A.
contract B is J {
    function doOnI(address i) {
        I(i).doSomething();
    }
}
Comment: So if "A" creates a contract "B" which wants to use a function defined in "A", contract "B" must use the interface of  "A"?
Comment: Yes, that is always true as the Solidity compiler will replace `A`'s function calls with their equivalent in bytecode. However, here, because of the `import` cyclicality, we need to use interfaces.
Comment: Ok great, so there is no security benefit to using interfaces?
Comment: Not that I know of. After all, a Solidity contract is compiled into bytecode, which has no concept of interface. If your bytecode is there and can be called, it does not matter whether you used interfaces.

Contract Design: Interfaces


In an Apache + lighttpd setup, who should be the proxy?

Question: In a setup where you use Apache for PHP / Python scripts and lighttpd for static files, but only one listens on the outside IP address and acts as a proxy to the other listening on the loopback interface, which should be which, why, and does it matter?
Answer: The lighter of the two (lighttp) should be the proxy, only bothering the heavier Apache for action when a script needs running.
Unleas of course requests for static files are rare, but in that case you don't want to split the jobs between too servers anyway as you are overcomplicating things.
As an alternative have you considered running lighttp only with php and python running as FastCGI processes? While PHP as a module can be a little quicker than FCGI the difference may not be worth the hassle of running two servers and may be negated completely anyway by the proxy arrangement.
Another alternative is to have the static content served from another IP address if the server can have a second assigned, then neither set of requests need be run through a proxy. You could use a different port on the same address too, though there is a chance some of your viewers might have trouble there if they are behind very strict firewalls that won't allow the non-port-80 traffic through.
Comment: +1  i'd just replace lighttpd with nginx for greater performance and stability. also, nginx is first a loadbalancer, and only second a (wicked fast) http server.
Answer: If this is on the same server, you should not install more then one HTTP server. You just enable the Apache server to listen on the outside IP adress :-)
Installing two HTTP servers on one machine is pretty pointless. If this were a two server setup, then it would be a good idea so that the backend machine is less vulnerable to attacks from the Internet.
Comment: I beg to differ.  I admin a machine with Varnish (a reverse caching proxy) as the front end.  I also have pound handling https requests (since they can't be cached anyway) so apache doesn't need to worry about encryption.

On the back end, I have apache and nginx for the static content (any URL not involving a PHP script).  Both listen to non-standard ports and only allow connections from the IP of the server itself, so nobody can bypass the proxy.

(I'd normally bind apache and nginx to locahost, but they reside in a FreeBSD jail which doesn't support localhost.)

It really works quite well.
Comment: The scenario I'm outlining seems to be quite a typical way to improve scalbility. It makes a lot of sense to me, because you assign different tasks (dynamic and static content) to different programs who are especially good at it.
Comment: Answer couldn't be more wrong. Running Apache behind nginx/lighttpd and proxying to it for dynamic content is becoming a popular way of getting significantly better performance out of a single server.


Upgraded to 13.10 and my airtel connection manager does not detect Huawei E398 4g LTE modem

Question: I was using the Airtel 4G LTE modem (Huawei E398) with the Airtel connection manager successfully in Ubuntu 12.10 (in one partition, have Ubuntu 13.04 in another partition). Upgraded to Ubuntu 13.10 2 days back and since then I couldn't get connected. The Airtel connection manager would start but not detect the modem. I tried adding a connection manually but that did not work either. Any insight would be helpful.
Answer: After looking at various daunting options, I realised that the connection manager's configuration could have been replaced during the upgrade. So, I uninstalled the connection manager (uninstallation steps from here)
<code> cd /usr/local/airtel
 sudo ./UninstallMobilePartner
</code>
As soon as I uninstalled the Airtel connection manager, the modem was detected in the Ubuntu network-manager and I was able to create the connection manually, which is working now. Also, I want to inform that 13.10 has an exhaustive list of Indian operators and modems in the network manager.


What is a symbol table?

Question: Can someone describe what a symbol table is within the context of C and C++?
Answer: There are two common and related meaning of symbol tables here.
First, there's the symbol table in your object files.  Usually, a C or C++ compiler compiles a single source file into an object file with a .obj or .o extension.  This contains a collection of executable code and data that the linker can process into a working application or shared library.  The object file has a data structure called a symbol table in it that maps the different items in the object file to names that the linker can understand.  If you call a function from your code, the compiler doesn't put the final address of the routine in the object file.  Instead, it puts a placeholder value into the code and adds a note that tells the linker to look up the reference in the various symbol tables from all the object files it's processing and stick the final location there.
Second, there's also the symbol table in a shared library or DLL.  This is produced by the linker and serves to name all the functions and data items that are visible to users of the library.  This allows the system to do run-time linking, resolving open references to those names to the location where the library is loaded in memory.
If you want to learn more, I suggest John Levine's excellent book Linkers and Loaders.
Comment: Hi Ben, in the second case, are you referring to the export table? That is, is the export table a special case of the symbol table? Or are these unrelated concepts?
Comment: Hi. I believe it's not in any object file but referred from them. Secondly, could you please explain a bit more what you meant by "final location"? Physical address or finalized relative address in the source code.
Comment: Don't executables or shared libraries also have symbol tables? Can you explain why you didn't include them?
Answer: Briefly, it is the mapping of the name you assign a variable to its address in memory, including metadata like type, scope, and size. It is used by the compiler.
That's in general, not just C[++]*. Technically, it doesn't always include direct memory address. It depends on what language, platform, etc. the compiler is targeting.
Comment: I think, it was very important you to mention the content of the address by saying "it doesn't always include direct memory address".
Comment: I think it is important to note what it is mapping of the name you assign a variable and **function** to its address (not only variable)
Comment: How does the compiler know where the variable is located iif the symbol table doesn't include the direct memory address?
Answer: In Linux, you can use command:

nm [object file]

to list the symbol table of that object file. From this printout, you may then decipher the in-use linker symbols from their mangled names.
Answer: The symbol table is the list of "symbols" in a program/unit.  Symbols are most often the names of variables or functions.  The symbol table can be used to determine where in memory variables or functions will be located.
Answer: Check out the Symbol Table wikipedia entry:

data structure used by a language translator such as a compiler or interpreter, where each identifier (or symbol), constant, procedure and function in a program's source code is associated with information relating to its declaration or appearance in the source.
Answer: Symbol table is an important data structure created and maintained by compilers in order to store information about the occurrence of various entities such as variable names, function names, objects, classes, interfaces, etc.
Comment: Linkers and assemblers also deal with symbol tables (often simpler than the compiler ones).
Answer: From the "Computer Systems A Programmer's Perspective" book, Ch 7 Linking. "Symbols and Symbol Tables":

Symbol table is information about functions and global variables that
are defined and referenced in the program

And important note (form the same chapter):

It is important to realize that local linker symbols are not the same
as local program variables. The symbol table does not contain any
symbols that correspond to local nonstatic program variables. These
are managed at run time on the stack and are not of interest to the
linker

What is a symbol table?


Riding mower start issues

Question: Wheel Horse 314 has no response to turning ignition key when temp is below 40 degrees otherwise it start fine. New starter and relay.
Answer: I had a similar problem with my John Deere rider. When I inspected the battery cables at starter and battery, they were visually clean and shiny, but I cleaned them all anyways. (Battery terminals, posts, relay connections, starter connection and ground). After that she cranked every time. If this doesn't help, get your battery tested. For some reason they only put nominal battery sizes on these things and battery life isn't usually pristine.

Riding mower start issues


Possible to mine on nvidia Pascal (10xx) GPUs?

Question: I haven't found a miner that works yet on 1070s. Does anyone know if this is possible? If so, could you share how you've done it?
Comment: Can you give more details on what you have tried?
Answer: My EVGA 1070 Founders Edition maxes at 470 h/s with Tsiv's CCMiner pool software, though its possible I'm missing some settings that could help it hash higher. Pretty stinky scores. This is worse than many older cards. Basically, there is not yet good public mining software for the newer cards.
Source code found here: https://github.com/tsiv/ccminer-cryptonight/
Compiled Windows binaries are under "releases".
Instructions for compiling on Ubuntu 16.04 here: https://steemit.com/monero/@mobidick/how-to-mine-monero-on-ubuntu-16-04-using-ccminer-cryptonight
Comment: Newer version here, supports mining against the daemon https://github.com/hyc/ccminer-cryptonight
Comment: Hi, any ideas if there is a 64 bit version of this? I have ubuntu 16.04 (64 bit) and it seems it doesn't build there for me. I get "configure: error: C compiler cannot create executables" and this looks like a 32 bit problem, not sure thou...
Comment: I don't ever build from source. I just use the precompiled binaries.
Answer: My GTX 1080 is maxing out at around 537 H/s. This is also using tsiv's ccminer, which XMR_Eric linked in his answer. I've found the best settings for the card to be 80 blocks of 12 threads. Default settings yield around 200 H/s I think. You can set 12x80 by appending --launch=12x80 to the end of the command when running it.


i need a Windows UWP library to convert Youtube videos to mp3

Question: I'm looking for a library that I can use for my Windows 10 UWP app. I just want to convert Youtube videos to mp3 and save in my PC. Everything in the best possible quality. I know videoLibrary but it is more for downloading videos. Thank you
Comment: Avidemux and Virtualdub has command line options.
Answer: Because YouTube video and audio are in separate streams, the easiest way to download a YouTube file is to stream it and use ffmpeg to write the stream to disk. VLC can serve as a GUI for ffmpeg to do that. Commercial software downloads the two streams separately and merges them using ffmpeg.
Answer: You can use the python library & program youtube-dl to do this. You will either need python installed available for most platforms and then you can pip install youtube-dl to install it or you can download an exe and put it somewhere on your path.
You can then tell it that you only want to download the mp3 format (if available) with the command line option -f mp3 or, provided you also have FFMPEG installed and on your path,
you can convert whatever is available to mp3 after download with:
youtube-dl -x URL --audio-format mp3


Why whenever I repeat an algorithm on Rubik's cube 3 times the orientation of all corners remains the same?

Question: I don't get why whenever I repeat an algorithm 3 times the orientation of all the corners magically returns back to normal. Here is where my confusion comes.
Let's say that some algorithm rotates the corner A clockwise. Now obviously if the corner is rotated in place, meaning the corner is not moved to another position, it's obvious that after another 2 repeats it will return back to normal.
Bit what if the algorithm also permutes the corner. Let's say that corner B goes to A. Would it not be the case that the rotation of A is dependent on the rotation of B? Can it not be the case that on the first repeat we receive a corner rotated twice for example, meaning the total rotation in A changes. Now in such a chaotic system how can we be sure that 3 repeats always return to normal? My head hurts thinking about and I know I miss something but I can't figure it out...
Answer: I assume you are only talking about cube permutations that when repeated three times will return the corners to their original locations.
Your observation is not universally true. For example, take the following algorithm:
F2 L2 F' R' F L2 R' B' R F' R' B R2 F'

It twists the URF corner in place clockwise, cycles the other three U corners and twists one of them anti-clockwise. If you perform this three times, URF becomes solved again, but the three other U corners have each undergone one anti-clockwise twist.

You could also construct a corner permutation consisting of two 3-cycles, with one corner twist in each, but as this involves 6 corners it would not be something you would use while solving the cube. This would leave 6 twisted corners when performed three times.
If however you take any corner 3-cycle where the corners outside the 3-cycle are not twisted, then your observation holds. The twist constraint of the cube means that the three corners either all get twisted the same direction, or two of the three corners get twisted in opposite directions. In the first case performing it three times will twist each corner three times, while in the second case each corner undergoes opposing twists that cancel out.
Comment: Thanks for the answer, but I still do not understand something. When we compute the cycle length of an algorithm the maximum multiplier that the orientation of the corners can add is 3. Why is that the case? Does that not mean that the orientation is a 3-cycle?
Comment: For example when we calculate the cycle length of R U. We have a 5 cycle of edges, a 7 cycle of corners. The order of the algorithm is 5*3*7, because the orientation of the corners is a 3-cycle.
Comment: @TeodorDyakov The sequence `R U` affects 6 corners. The URF corner stays in place but twists clockwise, and the other corners move in a 5-cycle with some twists that added together are an anti-clockwise twist. That single twist of the URF corner means that the sequence will have to be done a multiple of 3 times before that corner is solved.


Suggested way to backup Google Cloud Storage

Question: I have an appengine application using gcs storing a lot of images and serving them thru blobstore.
So what's the suggested way to backup gcs?
One problem is that for each image in gcs, I'm storing the blobkey in db, which means if I copy the image, the blobkey is different. In worst case, I've got to write the backup and restore program, but I'm wondering if there're any existing solutions.
Answer: I am not aware of an existing solution, but I would suggest the following solution.
For a true backup, you probably want to be outside of GCS. You can create a bucket in Amazon's S3 service, which is very similar to GCS. First, you save an image to a bucket in GCS. Then, you save the same file to a bucket in S3 using the same key/object name that you used for GCS.
In your code, you can add simple logic to serve a file from GCS first, but if it fails, to serve it from S3. The only difference is a path to the file.
If you prefer to stay within GCS, you can have two buckets - production and backup, and set up a cron job to periodically sync them. Again, you can use the same object name as object names have to be unique within a bucket. If a file has a unique object name in production bucket, it is guaranteed to be unique in backup bucket as well.


Why would you use MVC over Web Forms?

Question: Recently an architect described our company as offering a Rolls-Royce solution (MVC) when all he needed was a Toyota (Web Forms).
I'm curious to find out what you think about web forms vs MVC as an architectural choice.
Comment: I think that the architect doesn't have a very good understanding of ASP.NET MVC.
Comment: @Chris Webforms is not a subset of MVC. Both work completely independently of one another. Also webforms is old and probably not getting maintained much longer. Also, to front-end web/UI devs it is the anti-christ.
Comment: Ask the architect what year his car was built, and which safety standard it follows. His analogy is so flawed it might as well be a shoe fishing for baby carrots.
Answer: The Rolls-Royce/Toyota analogy is terribly flawed and misleading. One (ASP.NET MVC) is not simply a fancier or more expensive version of the other (ASP.NET WebForms). They are vastly different approaches to building web applications using ASP.NET.
To me, the biggest architectural difference between MVC and WebForms is how they work with the stateless environment of the web: WebForms works hard to build a set of abstractions that hide the stateless nature of web programming, whereas MVC embraces the stateless environment and works with it.
Each approach has its benefits and detriments, but I really enjoy how building web sites with MVC feels much more natural than WebForms (with its layer upon layer of leaky abstractions).
Comment: those lewky abstraction are very problematic. Learning Asp .Net MVC opens your eyes on http protocol
Answer: Old question but it deserves a more detailed answer just in case anybody else out there is still actually having a dilemma over it.
Ultimately, webforms is a thin-client solution by which it's meant that you press a bunch of pretty buttons and the front end (client) stuff is built for you. If you have people who know how to crank it out in webforms and there are absolutely no maintainability/modifiability concerns and the site is completely short term and disposable, there is nothing at all wrong with this approach. It is possible to learn how to do your own stuff but in this case it would require knowing both the web stuff webforms tries to protect .NET app developers from and all the webforms stuff that makes most client-side web devs want to murder the Microsoft engineers responsible.
In the 99.5% of all other use-case scenarios, we've stopped trying to hide the web from app developers because really, if you want to write web apps you're much better off actually learning how the web works. The irony of thick vs thin client solutions is that inevitably the thin-client approach inevitably bloats the crap out of your front end and is anything but performant. More importantly, these solutions have always made things inflexible as all Hell for people who actually know what they're doing and don't want to be constrained by the framework in effect.
There is nothing quite so pointless as taking somebody who knows everything about CSS, JavaScript, HTML, XHR and making them completely useless by roadblocking them every step of the way with a framework that...

Clears out all 'unneeded' script tags in the head tags to keep you from screwing up on script dependencies. (better to let a 'script manager' handle that for you) Granted, nobody puts 'em up there nowadays if they know what they're doing but that's just messed up.
Insists you wrap all of the HTML in one ginormous form tag. HTML doesn't allow forms inside forms so you do forms the webforms way or no way at all.
Creates like an 18-step "life-cycle" for what really should boil down to reacting to UI events by interacting with the browser to send messages to the server and then react when the server responds. Abstracting that process with a big giant pile of garbage never needed to happen (and to be fair, MS isn't the only jackass who's tried to do this).
Actually does everything it possibly can to get in the way of using non-webforms solutions to problems. Example: When I was a more junior client side dev I spent an entire day finding a way to make a submit button at the top of the page trigger a submit button at the bottom of a page (I assume due to that one-big-giant-form thing). Normally this would take 5 minutes but after quite a few hours reverse engineering the webforms JavaScript responsible, I discovered that they were among other things setting a property I didn't even know about at the time that tells you what the last form element to have focus was so that when a submit button was clicked, only the official Microsoft Submit(tm) button would work in regards to the activation of an official Microsoft Submit(tm) handler.

So no, Rolls-Royce vs Toyota, is completely unreasonable. I would say more, a perfectly reasonable Hyundai that you pay way too much for vs. a Microsoft engineered Pinto with an onboard system that automatically makes sharp 90 degree turns when it discovers you bought gas or oil from somebody other than Microsoft and it's detected a convenient wall to slam into. An ideal car for the suicidally-brand-loyal driver who knows nothing about the web and wants to swear life-long loyalty to Microsoft.
All .NET MVC really is, is simple and reasonable, and it doesn't reinvent its own layer to slap on top of the web. It just works with what's there to help knock out some boilerplate for you. There's better/cheaper/free-er frameworks available but if you've already locked yourself into the .NET thing, you could do much worse.
But seriously, stay the !@#$ away from webforms. It's almost dead now. Let it go. Tell your clients you'll do it for three times the money if they also promise you an exclusive and lucrative by-the-hour support contract for when they actually want to do something new or different or when crap starts breaking because not even MS could be bothered to continue adding to that behemoth of a 10,000 line ajax.js file they pull out of their DLL ass where you can't touch it.
Comment: Hi Erik loved you reponse, so you got my upvot. Just learning HTML 5 and CSS so your post was very informative.
Comment: **+1** Very nice answer! I've been avoiding MVC for years because I thought it would just be a more complicated approach to web-forms. Sounds like in reality it would make what I try to do with web-forms easier (e.g. I always try to avoid all of the Microsoft B.S. like the Script Manager).
Answer: An ASP.NET MVC solution doesn't have to be any more complicated than a WebForms solution. Personally, I find ASP.NET MVC to actually be a lot simpler than WebForms, and it definitely seems to be inherently cleaner.
From my experience, a lot of the MVC frameworks (ASP.NET, Rails, CodeIgniter, etc.) have much of the same core functionality and conventions. WebForms is really the odd duck from a web perspective. My guess is most web programmers would be much faster at picking up ASP.NET MVC than WebForms.
Answer: The top reason you would use ASP.NET MVC over ASP.NET WebForms is testability. Sure you can kind of unit test WebForms but this requires mocking frameworks and a lot pain. The second reason is MVC does make it a bit easier to separate concerns.  This can provide a great deal of code reuse and make your code loosely coupled.  This does not mean it's impossible to do the same in ASP.NET with patterns like MVP.
The downside of MVC is that you lose a lot of the functionality and that has been built into WebForms over the past decade (well almost).  MVC has come a long way since its inception to provided similiar features.
As far as performance, does anyone have proof one way or another of which tech is "faster"?
I don't think one is better than the other. I do really like the MVC framework and have used it with great success but I always make sure that I choose the tech that matches the project.

Why would you use MVC over Web Forms?


What does a Trolloc 'scythe-sword' look like?

Question: In one of his interpretations of the Wheel of Time's Trollocs, artist Wayne Barlowe drew the monster holding a blade that looks like a giant sickle, with the concave edge being the sharpened one- is that anything like how Robert Jordan envisioned the sword looking like?
Comment: I cannot see, broadly speaking, any other specifically meaningful interpretation of "scythe-sword."  It's not like a scythe without a curved blade, and if the convex side of the curved blade is the striking side, it's a scimitar or cutlass.
Answer: I think the closest we can get is the official cover art.  The Fires of Heaven back cover shows a handful of Trollocs stalking our Heroes:

and they are shown with something like a scimitar, a curved blade but with the convex edge being sharpened.
This cover art is one of the covers reproduced in the companion book, The World of Robert Jordan's The Wheel of Time, so clearly it had some level of blessing by RJ.
Comment: @PastychomperthanksMonica just for completeness, [the thing held by the guy in the green coat](https://wot.fandom.com/wiki/Ashandarei) is supposed to be even more alien - it was given to him by another species, only properly identified by a person who could remember centuries' worth of lifetimes, and (I think) was unique in the entire series.
Comment: Speculation: RJ might have based it on real-world scythe weapons, that I gather were common at one time. A peasant heading to war would re-position the blade on his scythe so instead of sitting at 90° for mowing, it was at 180° like the thing held by the guy in the green coat in the picture. Fitting it on a shorter handle would give him something like the Trollocs are holding - but in each case only the concave edge would be sharpened.
Comment: I will say, based on my experience with pocket knives, that a concave blade is the last thing you want to take into battle.  When you pull it to get it out of whoever you sunk it into, then it will dig itself deeper rather than come loose - as Neal Stephenson pointed out, leaving you with your blade all hung up while its victim's best buddy comes running up to you for revenge.
Answer: There are forward-curved blades which have been called scythe-swords. He could have taken inspiration from an ancient dacian falx or modified medieval falchion (specifically an Elmslie type 2a). Never mind non-european cultures, like the Nepali Kukuri or Egyptian khopesh, which could have been an inspiration. (It could have been as simple as: "Dude, imagine a long kukuri but the edge is on the other side! That's going in!")
As an important note, european weapons suffer from evolving and varying names in both their native tongues as well as through time. This makes it really hard to pin down what someone is thinking of through the medium of writing. This may be a contributing factor for the descriptions of weapons in literature. Additionally, so many names for swords are just "sword" or "knife" in that language, like spatha, spadone, Messer, etc. so using a descriptive but informal name may be just as effective.
Comment: OP isn't asking what they *might* look like. They're after a description from the books (or supplementary materials)
Answer: Based on the descriptions in the books the closest real world weapon would be giant sword sized karambit knife. They're described as scythe like and curved. Scimitars and  kopesh curve backwards. These are specifically compared scythes sickles which curve forward, possibly reflecting a claw. I've also noticed that they're frequently used to try to decapitate people, something a scythe or sickle like design would be exceptionally good at.
Comment: What descriptions in the books? All I could find was that the swords were huge, large, curved and scythe-like


How to get back in workplace after a long absence

Question: I've been out of the workplace for 3 years due to some severe health problems (8 surgeries within 2.5 years). The surgeries are finally behind me, but I don't know how I can re-enter the workforce with such a gaping hole in my resume. I know I'll be able to explain the absence and assuage an employer's concerns if I can get in front of someone, but how do I get to the point where I'm offered an interview? Thanks in advance for your advice!
Comment: As usual, which country ? What is your age ? In which field ? Try to be as precise as you can. :)
Comment: Found [this](http://www.monster.com/career-advice/article/job-hunting-after-medical-absence) article to help you ! :D
Comment: Sorry, it's my first time on here. USA and I'm looking for writing and editing positions, preferably within a non-profit organization.
Answer: Given you know that you have a gap on your resume and you also know you are fully able to explain that gap at interview, your question appears to be asking how to get to interview.
The classic, but rather obvious, methods apply- find jobs and apply for them.
If you are worried that the gap on your resume means you will not be invited to interview in the first place, then don't leave a gap. Instead of a role put something like:

[start date] - [end date] : Health related sabbatical

Or even just "Sabbatical", which can then be explained face to face.
Comment: I remember a document, which stated that you don't have to say anything about health related issue in your CV. Is a white lie not a problem about sincerity ?
Comment: @GautierC, Not in the US. In the US and in large companies, many HR departments would actually black out anything you say about your health in your cover letter, or in your resume, before it even gets to the hiring manager.
Answer: The best way to deal with that is to bypass the screening of random resumes process. Start networking with people. Get involved in a professional organization related to your field. Start reaching out to old coworkers. Attend job fairs. Work with a recruiter. Basically anything that can lead to bypassing the typical random resume filtering process is going to be a good thing. These are all good things in general but are even more relevant when you've got "issues" that can lead to easy disqualification of your resume.
You can put something on your resume so there isn't a gap and employers aren't left wondering but that can be as much of a problem as a gap.
Are your health issues really behind you?
Are you really ready to be back to work?
Are your skills still up to date?
etc...
It will take a bit more effort to get back to work most likely but should get much easier once you get that first job back.


Why are legal journal articles so long-winded?

Question: Having read and skimmed several articles in legal journals, but not being a lawyer myself, my impression is that many law review articles are long-winded, using many words and sentences when fewer could convey the same information. Do lawyers and legal scholars feel this way as well? If so, what reasons do they give to explain this situation?
Answer: Law doesn't have a monopoly on bad writing.
Steven Pinker, in "Sense of Style" and other articles, says that the kind of poor writing you mention is a symptom of the "curse of knowledge".
Justice Kagan believes that good legal writing needs to at least be good writing, and law schools aren't doing enough to teach that. All the other Justices expressed similar opinions to that in interviews with Bryan Garner.
Comment: In fact, poor writing is actively encouraged- having recently watched my wife complete a Masters of Nursing Research she was constantly required to make her writing style more *academic*: that is, more opaque and long winded, substituting three words for one at every opportunity.
Answer: I think the underlying reason is the requirement (somewhat shared with philosophy) to be exhaustive, i.e. cover all perspectives on a question and all relevant facts. Short articles narrowly focused on hair-splitting minutia might cover all of the case law and legal literature within a few pages, but anything that takes on a massive topic like "what does 'literal truth' mean in perjury case law?" will have to cover very many cases. One of the reasons is that while Bronston v. US is the "leading" case on that topic, it is not the last word, and there have been some interesting subtle developments after that. Gathering up that case law in one place is thus very useful.
Answer: At least in common law jurisdictions, where judicial precedent forms a large part of the way the law works, the authors of academic or review articles are often at pains to avoid appearing to prejudge any issue, while at the same time seeking to get their own interpretation of the ramifications of some quirk or novelty of the law across to a wider readership. It is important for several reasons that this is the case: firstly, that authority in law belongs to the legislature and to the judiciary and not to academic writers, on whom it is impressed throughout their training that the word of the judge is final and that judges are to be persuaded and not to be told what to do; secondly, that because of this academic writers tread a narrow line where their opinion must be clearly based upon the known precedented facts of the law as it is known and understood to stand while simultaneously expressing a didactic opinion that may at the time have little or no legislative or judicial support and indeed lack any evidentiary basis, for which they depend on fully-explored hypotheticals which usually take some explaining and hedging and qualifying; thirdly that every academic hopes that someday their work will be quoted approvingly in court, which is unlikely to happen unless it is couched in language that the court will find acceptable.
More briefly: an academic writer is neither a judge nor an advocate. They can't lay down the law or be seen to be trying to do so. So they wrap up detailed arguments in ifs, buts and maybes, partly through training and partly through traditional deferral to the judiciary as the real arbiters of the law.
It's quite instructive to read different things written by the same writer, you'll find they are much more prolix in academia, and much more succinct when arguing before a court (which is a situation where they are both allowed and expected to express robust opinions)
Answer: The customary length of a law review article is to a great extent a matter of tradition and historical issues like length limitations.
There are many people who believe that law review articles are too long, and indeed, law review articles are quite rarely cited by courts or lawyers, although they are fairly often used to locate cases on points relevant to the article. There is a weak movement in the legal academy to change this trend, but tradition is a powerful force and there is a strong normative belief in the legal academy that a law review article should be exhaustively complete and definitive.
One of the most famous examples of the sparring between the judiciary and the legal academy involve a hypothetical law review article mentioned by Chief Justice Roberts and the law professor who retroactively wrote it (incidentally, the law professor was himself quite conservative as law professors go, this wasn't simply a matter of partisanship). The abstract of the rebuttal article (which is contrary to tradition and precedent just three pages long) is as follows:

In 2011, Chief Justice Roberts commented that if you "pick up a copy
  of any law review that you see," "the first article is likely to be,
  you know, the influence of Immanuel Kant on evidentiary approaches in
  18th-century Bulgaria, or something, which I'm sure was of great
  interest to the academic that wrote it, but isn't of much help to the
  bar." No such article exists, of course -- until now. This short essay
  explains why, in all likelihood, Kant's influence on evidentiary
  approaches in 18th-century Bulgaria was none.

Orin S. Kerr, "The Influence of Immanuel Kant on Evidentiary Approaches in Eighteenth Century Bulgaria" (March 28, 2015)


Taylor series for $f(x) = cos (x)$

Question: For the function $f(x) = cos(x)$ I want a taylor series approximation accurate to within 0.1 of the actual function on an interval $-5\le x \le 5$. How would I determine the number of terms necessary to do this?
Comment: @JQQ It's Taylor power-series expansion is an alternating series. (Of course only on the even indices. On the odd it is 0)
Comment: Look up remainder of alternating series on google
Comment: @qbert I was under the impression that cos (x) was not an alternating series, despite having positive and negative values, because it does not alternate between them?
Answer: The Lauren remainder in Lagrange form is $$R_n(x) = \frac {f^{(n+1)}(c)} {(n+1)!}x^{n+1}$$ for some point $c$.
So seeking for an $n$ for which $|R_n(x)| \lt 0.1$ means:
$|\frac {{cos}^{(n+1)}(c)} {(n+1)!} x^{n+1}| \le | \frac {x^{n+1}} {(n+1)!}| \lt \frac {5^{n+1}} {(n+1)!} \lt 0.1$ first for $n=13$ (check that), so $n=13$ is guaranteed to work.

Taylor series for $f(x) = cos (x)$


Error:R cannot be resolved - Android - A check list

Question: This would serve the purpose as a check list, when someone encounter this basic error on android.
Please add interesting points you have come across.
Refer links
Description: R.java is a generated class. In a Android Development Tools (ADT) environment it is generated whenever the project is built. This class holds all the references of your android project in integer values. whenever you reference a R. something that means you refer to one of this integer value.
Cause: This Error may happen when the R.java is not properly generated.
Errors: There are several reasons which prevent this R.java from generated automatically which will be detailed below by our fellows.
Thank you.
Comment: Clean your project and remove line import com.android.R if you have it. Also make sure you dont have errors in classes and XML files because R.java is not regenerated in this case.
Comment: check for errors in your resource files
Answer: Make sure that AndroidBuildTools are installed and your views are correct.
Sometimes needs to import .R;


What will the data type in Java be, when Schema fields type is Component Link in Tridion

Question: Can you please provide some examples for mapping of Component Link Schema fields in Java.
Comment: This is very open ended question. I would recommend try something and let us know what have you tried and what was the output? That way it will be easier to understand what you are trying to do
Answer: Component Link fields can be mapped to different View Model property types:

String - represents the resolved Page URL for the linked Component.
Link - represents the resolved Page URL for the linked Component.
A subclass of AbstractEntityModel - represents the linked Component itself
A subclass of MediaItem - in case of a Multimedia Component; represents the linked Component's Binary content.
Answer: As Rick mentions Component Links are flexible in how they are mapped.
You can use the code on Github as a reference guide
See Teaser's link, of type Link.
It shows a simple example using Link that exposes url, text and alternate text


SharePoint List Connected to PowerApps

Question: I have a PowerApps canvas app that I created and within that app, it connects to a SharePoint list.  But when I click on New or Edit in the SharePoint list, it still uses the out of the box SharePoint form.  I see an "Integrate with PowerApps" option on my SharePoint list, but I already built the PowerApps form and don't want to recreate.  How can I have the New and Edit command connect to that PowerApps form?
Answer: I don't think you can import already created Power Apps Forms (even connected to a list) into a SharePoint list. SPO Custom forms are embedded in the list/library itself.
For more info on this consult, MS Document (Q&A) here

Create Custom List/Library Forms by using the link in the menu bar as shown below

And then update "Form Settings" of the list/library
Answer: According to my research and testing, Canvas Power Apps cannot be integrated with the SharePoint list as a custom form.
Canvas Power App:
Pros:

Design for Desktop, Mobile, or both using Responsive configuration
Full screen display mode
Native mobile integration using Power App phone app

Cons:

Unable to use SharePoint Integration object (list actions) to interact with form
Forced to open form in new tab

SharePoint list form Power App
Pros:

Use SharePoint Integration object (list actions) to interact with form
Open form in 'Panel' mode without leaving page

Cons:

No full screen mode
Awkward interface for mobile device

If you want to customize forms, you can do it through the SharePoint list form Power App.

SharePoint List Connected to PowerApps


Lightroom adjustment brush settings or shortcuts

Question: Working in Lightroom and suddenly my 'adjustment brush' tool is auto masking the entire photo I am editing. I must have hit a key on the keyboard. The 'auto mask' box is unchecked (I tried checking the box as well and it does the same thing), 'range mask' is off (I do not think I use this option), and I have restarted the program with no change.
Upon further inspection I tried editing a different photo and the brush did not act the same, I went forward two photos and the brush again acted normal. I removed the photo with the brush issue and re-imported back in. The brush works normally again. What happened?
Is there a keyboard shortcut that I have accidentally turned on this auto-masking?
Answer: The auto of the brush tool does not seem to be in relation with the problem described as it is a setting to activate automatic mask border in course of brushing.
As you  indicate, most likely, is that you have activated a shortcut, and we will probably never know what it is.
Well, with everything back to normal, it's not too bad.
However, if it happens again, you should try to see if it's a brush mask, or as I think a gradient mask.
Answer: This week it has happened twice this week. I tried re-starting Lightroom and the computer. Previously this issue was only happening in one image. Now its happening in multiple. I had an idea it was a glitch in one of my brushes, I deleted the suspecting brush and tried another. I cannot figure out this problem.
I only use brushes, I do not use gradients. Auto mask is turned off.
Comment: Just to check a fool idea, what is the size of your brush ?
Comment: As it seems reprodyctible, can you describe exactly when this happens ?
Start with a non edited file.


greece schengen visa going to germany?

Question: If I get a schengen visa issued from greece embassy, and it was the first visa on my passport, can I enter germany without any problem as a first entry?
Answer: You are supposed to get the Schengen visa from the main destination of your trip, not from the first destination. You can then travel through the other Schengen states on the way. That's what the Schengen area is all about. One could, say, drive a car from France through Belgium to the Netherlands without ever stopping the car in Belgium or talking to a Belgian official.
However, you probably submitted an itinerary with your visa application. If there is a substantial change in your travel plans, the entry may be refused. For example, if you wrote that you want to see Italy and Greece and you show up in Iceland instead, there will be questions.

greece schengen visa going to germany?


I have lost my blockchain password and recovery phrase, how can I recover my wallet?

Question: I forgot my blockchain password and recovery phrase because it was saved in my phone— and i have lost my phone.
please help me if there are any chances for recover my funds that was in blockchain
Answer: Please note, you are probably refering to the blockchain.info wallet service. Not the blockchain itself.
I don't think it is possible to recover your funds if you lost your password and your recovery phrase.
You should have secured your recovery phrase somewhere where it can't get lost or destroyed. A phone isn't a good place for that.
Read here more for detail: https://blog.blockchain.com/2016/04/20/support-team-tips-why-your-wallet-recovery-phrase-is-so-important/
Next time, write it down on paper or store it encrypted on a cloud service where nobody other than you can access it.
You can try and contact support on blockchain.info, but I don't think they can help you as your private keys will probably be encrypted with your password and can be recovered with you recovery phrase. But as you don't have any of them, I think recovery of your funds is not possible.
For more on this, read here: https://support.blockchain.com/hc/en-us/articles/211205343-I-forgot-my-password-What-can-you-do-to-help-
It may be a bit salty, but learn how to deal with security and secure your passwords, use 2FA and save your recovery phrases and anything else in a secure place. This should be done for everything, not only the blockchain.info service.
COMMENT: Yes you can recover your funds without the password and wallet ID.
You can do that by requesting your wallet ID as a first step using your e-mail at this link https://login.blockchain.com/#/reminder, second step is to download the wallet.aes.json file and then its possible to brute force the password. A possible script for doing that can be found here: https://bitcoin.stackexchange.com/a/3037/46677


Magento 2.2.4 - Order header status is different than detail section

Question: I'm getting a weird error in one of my orders where the header status is processing but order details are all cancel. Can anyone give me a SQL command that I can use to update the table status for the orders tables?
Answer: You can use this one:
UPDATE sales_order SET status = 'your status' WHERE increment_id = '000000670' ;

Comment: Thank you very much for your input. My problem was way beyond what I thought as it was created by the payment gateway plugin which made a mess of the status in various tables. Anyway all is fine now. Thanks for you help.
Comment: you're welcome!
Answer: You should update the tables sales_order and sales_order_grid as Amit Bera said.
In sales_order you need to update the state column too in order to have consistent data.
So the correct SQL statement for updating the sales_order table is (assuming you want to cancel the order):
UPDATE sales_order SET status = 'canceled', state = 'canceled' WHERE increment_id = '{ORDER_INCREMENT_ID}';

You should check before if the related data in sales_order_item table is consitent (i.e. qty_canceled is set)
Answer: There are main two tables where Magento store order status.

sales_order
sales_order_grid

So, you have to two queries for an orders

UPDATE sales_order SET status = {ORDER_STATUS_CODE} WHERE increment_id = '{ORDER_INCREMENT_ID} ';
UPDATE sales_order_grid SET status = {ORDER_STATUS_CODE} WHERE increment_id = '{ORDER_INCREMENT_ID}' ;

{ORDER_INCREMENT_ID}  means 000001,00000670.
Comment: Thank you. I'm making progress buy now I'm left with the order items showing it's canceled. :(
Comment: Alex Lim, this query is not proper for all case, Magento different logic   on  order process. Cancel and complete and close is not support for this query,
Comment: Thanks Amit. I jumped into CPanel and used phpMyAdmin to dissect the structure myself. It looks like there is more than meets the eye.

In sales_order table, there are 2 columns which are state and status as well as sales_order_grid table which has a status plus sales_order_items which has qty_canceled too.

Managed to edit the records and get everything fine now. Your post is of great help to get me started.


How do I make a game that can transition from 2D to 3D?

Question: My plan is to start from an really old game and build my way up to todays graphics and games. So for example start with Pong and then go to Space Invaders, then go to Zelda and Super Mario. But then I need to make the first 2D games change into 3D games. How do I do that?
Comment: I believe you mean a game similar to [Evoland](http://evoland.shirogames.com/)?
Comment: This question is very broad, and obvious. All you need to do is transition between the different "games" that have different graphics. Your plan seems okay to me... Also, this really isn't an appropriate question, what are you asking?
Comment: I voted to close because you asked about which tech to use.  But I think you have a salvageable question here; please modify it to ask about the process of rendering in both formats.  And as always: be specific and mention what you've already tried.  You should also change your question title to reflect the question itself, rather than the context you are interested in.
Comment: I think he's asking how to make a game that _plays 2D_, suddenly start playing in _3D_.
Answer: That's easy.  Just program your game with the z-axis aligned to to the camera forward direction.  Set z=0.  Everything appears flat, or 2D.

Skew the axis a bit to reveal the world is actually 3d

So in short, to make a 2D game appear 3D, it has to be 3D in the first place.  You cleverly draw the 3D scene to make it appear 2D.  Then later you can change the camera angles to show it is really 3D.
Comment: Thank you for your help i will try to do this and see how it goes
Comment: Basically what I am asking is how to make lets say a cutscene between one game and another.
The game before the cutscene is 2d and the game afterwards is 3d. How can i do this and what is the best way to do this.
Comment: It sounds like you would essentially need to make two different games. That or you could create your game in 3D then force the camera to render orthographically and restrict game movement in the x and y plane. There isn't exactly an easy way to change a game from being 2D to 3D since both perspectives require radically different design and control.
Answer: I have messed a bit with Unity and XNA both of which force you to develop in a 3D environment, even when making 2D games. In order to do this you need to ignore the 'Z' axis and just focus on 'X' and 'Y'. If you're looking on how to make a 2D game, there are several tutorials out there that aren't hard to find.
To transition from a 2D to a 3D game could mean several different things. You could go from traditional 2D side scroller (original mario) to 3D adventure (super mario 64) to 3D side scroller (splosion man) (its more like a 2D sidescroller with 3D textures) so you need to know what kind of 3D game you want to make.
If you want to make a 3D side scroller then just change objects from 2D objects to 3D and TADAA you're pretty much done. However, if you are wanting to go from 2D to 3D adventure, I would suggest the advice of @bobobobo (Master of Fist of the Nose Hair).
I would definitely learn how to make 2D and 3D games separately first THEN learn how to transition since you would know more about both.
Comment: Check out a game that was made called  ["Fez"](http://en.wikipedia.org/wiki/Fez_%28video_game%29) Its not exactly what you want but it has similar elements. If you watch some of the videos on YouTube you can get a visual representation of what @bobobobo was saying. It should just be a camera trick. hope this helps!
Comment: I know how to make both 2D and 3D games and i will definitely try what @bobobobo said. What i want is to go from classic Super Mario to Super mario 64
Answer: I'm not a 3d dev, but I think that all you have to do is make scenes for each game,3d or 2d, then swap them
Comment: This does not provide an answer to the question. Once you have sufficient [reputation](https://gamedev.stackexchange.com/help/whats-reputation) you will be able to [comment on any post](https://gamedev.stackexchange.com/help/privileges/comment); instead, [provide answers that don't require clarification from the asker](https://meta.stackexchange.com/questions/214173/why-do-i-need-50-reputation-to-comment-what-can-i-do-instead). - [From Review](/review/late-answers/104915)


Positivity of certain Fourier transform

Question: Is the Fourier transform of the function
$$ f(\xi) = e^{-t|\xi|^{2m}}$$
positive for $t>0$ and $m \in \mathbb{N}_0$?
Comment: I love it when simple questions like this one generate such wonderful answers
Comment: See also this question: https://mathoverflow.net/questions/228462/is-the-fourier-transform-of-e-xn-positive. Note that the linked question is different to the one above, but the top-voted answer to the linked question does not answer the linked question, but instead the question asked above!
Answer: A simple argument that the Fourier transform cannot be nonnegative for any $m>1$, integer or not, is given in my 1991 paper with Odlyzko and Rush:

Noam D. Elkies, Andrew M. Odlyzko, and Jason A. Rush: On the packing densities of superballs and other bodies, Invent. Math. 105 (1991), 613-639.

The Fourier transform $f$ of a nonnegative even function must satisfy
$4f(\xi) \leq 3 f(0) + f(2\xi)$ for all $\xi$.  This fails for any $m>1$ once $\xi$ is close enough to (but not equal) zero.
Postscripts:
0) The inequality $4f(\xi) \leq 3 f(0) + f(2\xi)$ holds because
the difference is $\int_{-\infty}^\infty \hat f(\eta) \, w(\eta) \, d\eta$
with $w(\eta) \geq 0$ for all $\eta$ because
$3 - 4\cos \theta + \cos 2\theta = 8 \sin^4 (\theta/2) \geq 0$.
1) The nonnegativity of $3 - 4\cos \theta + \cos 2\theta$
is also a key ingredient in the proof of thenonvanishing of the Riemann zeta function $\zeta(s)$ on the edge
$s = 1+it$ of the critical strip, and thus of the Prime Number Theorem.
See the last exercise of
this chapter
my notes on analytic number theory.
2) Sergei noted that it is also known that for $0 < m \leq 1$
the Fourier transform is positive.  As I wrote earlier this year
on Math Stackexchange,
the same paper with Odlyzko and Rush also proves that fact as follows,
crediting the argument to B.F. Logan (see Lemma 5 on page 626).
We first prove this for $m=1$, then reduce $0<m<1$ to this case.
For $m=1$, the function $\exp(-t|\xi|^{2m})$ is a Gaussian,
and thus so is its Fourier transform; Gaussians are positive everywhere,
so the case $m=1$ is done.  For $0<m<1$, the function
$\exp(-t|\xi|^{2m})$ is a nonnegative mixture of Gaussians $\exp(-c\xi^2)$ by
Bernstein's theorem.
Therefore the Fourier transform is also a nonnegative mixture of Gaussians,
so again positive everywhere.  QED
Answer: it is positive for $m=1$, but not for $m=2$, see this Mathematica output:
Comment: Sorry, I should have done this myself. Thought too abstractly about it -.-
Answer: I think the result goes back to Polya, see "Some theorems on stable processes" by Blumenthal and Getoor. Another reference is Paul Lévy "Sur une application de la dérivée d'ordre non entier au calcul des probabilités" page 1118 of CRAS 1923.
It might be good to also give the gist of Levy's very simple argument: if the Fourier transform was positive then the exponent would be the log-moment generating function of a random variable $X$. But if $m>1$, the second derivative at the origin vanishes and thus also the variance of $X$. The positive function would be a delta function which is a contradiction.
Comment: Due to information in 2013 V.P.Zastavny thesis a problem was first in more general form formulated in Schoenberg,1938,Tran.AMS 44. Interesting generalizations are in Zastavnyi V. P. Positive definite functions depending on the norm / V. P.
Zastavnyi // Russian J. Math. Physics. – 1993. – Vol. 1,ð4. – P. 511–
522. and Koldobskii : http://www.mathnet.ru/php/archive.phtml?wshow=paper&jrnid=aa&paperid=255&option_lang=eng
Comment: @Sergei: thanks for pointing out the work of Zastavnyi. However, the latter seems to consider the (more difficult) case where the norm involved is $L^p$ with $p>2$ on $\mathbb{R}^n$, $n\ge 2$.
Answer: This is a well-known problem, solved recently in dissertation of Zastavny based on some inequalities for p.d.f.
More: it is a Schonberg problem, positive for $0<m\leq1$, not positive otherwise.

Positivity of certain Fourier transform


List all calendar events on iPhone

Question: How can I see the list of all my events on my iPhone 4s? Not just the ones for that day or by searching with an alphabet letter.
Answer: This is really a bit tricky on iOS. If you are in Calender view, there are three icons on the right side. The third from the right is the list icon. But there are two types of that list icon: one only shows three lines, the other shows two lines and a square.
The mode you are talking about must be the one with the two lines and the square. So you see the calender view on top ("the square") and a list of events for that ("the two lines").
Press this button so it is not selected any longer. Now you see the calender view without the list. Now press the "Today" button in the lower left corner. The view will switch to show you the timeline of the day, and also the third icon from the right switched to the one with the three lines. Pressing this "three lines" button will show up the event list you are searching for.
Comment: my feeling was that the first answer didn't get the point at all. Hitting the today button several time did not help anything, it's important to see the difference between the two modes of the button, as described in my answer.
Comment: How is this answer substantially different from the answer already provided?  If just a few details need to change, don't add a new answer just edit and update the answer already there.
Comment: despite 6 years of iOS updates, this still works on iOS 15.7 as of Oct/2022
Answer: I agree this is non obvious and takes a few try
Click on the menu icon so it is not highlighted (the third from left in the top row)
Then keep hitting today at the bottom left hand corner until the calendar disappears.
You then have a list of events
Comment: That did not work on my 4s.  The calendar never disappeared just the date highlighted and blinked. I did not get the list of all the events I put in.
Comment: I see no menu icon on my calendar page.
Comment: I hate icons as you can't tell people about them - it is the 3rd one from the right
Comment: The only items above the calendar is  from Left to right: date then the list icon then the magnifying glass icon then the + sign.  The List Icon just puts up the list for that day and hitting today when it is highlighted does nothing.  I might go by a apple store and see what they say.  Hour away so rather find a way to see all of them listed by asking someone who knows how to do it on my phone.
Comment: I mean the list icon as I said icons are not easy to read
Answer: Completely non-intuitive, and it works differently on iPad vs iPhone.
On iPhone, from any view, click on the magnifying glass. Type in a '?'. This will show all events on all your calendars in an agenda format.
On iPad, select the magnifying glass. iPad by default will list all events in an agenda view, flowing under the Search box. The '?' trick still works, but there really is no need for it.

List all calendar events on iPhone


how do i migrate Azure storage account from classic to ARM

Question: i have created a storage account and have a few VM's and blobs. It is supposed to be a classic account.
i want to migrate or convert the storage account to ARM or new version. what is the process to do so?
i have tried to move the contents of one resource manager to a different one, but i didn't get the option to move from classic to ARM

thanks
Comment: please if one of the answers solved the problem for you, don't forget to accept it as an answer
Answer: The whole process of moving ASM to ARM resources can be found here.
Migrate IaaS resources from classic to Azure Resource Manager by using Azure PowerShell
To migrate a Storage Account, all you need is to execute the following PS Cmdlets:
ps:> $storageAccountName = "myStorageAccount"
ps:> Move-AzureStorageAccount -Validate -StorageAccountName $storageAccountName
ps:> Move-AzureStorageAccount -Prepare -StorageAccountName $storageAccountName
ps:> Move-AzureStorageAccount -Commit -StorageAccountName $storageAccountName

If you want to abort the process (before commit), just use:
Move-AzureStorageAccount -Abort -StorageAccountName $storageAccountName

Comment: This was the shortest explanation on the nest for this, thank you!
Answer:
i want to migrate or convert the storage account to ARM or new
  version.

In Azure, we can't convert the storage account from ASM to ARM, but we can migrate it.
Are you want to move VMs and storage account to ARM module? If yes, we can use follow script to move those:
move VMs to ARM module(this VM create without network, behind cloud service):
Login-AzureRmAccount  #login Azure Account ARM module
Get-AzureRMSubscription | Sort SubscriptionName | Select SubscriptionName
Select-AzureRmSubscription –SubscriptionName "My Azure Subscription"
Register-AzureRmResourceProvider -ProviderNamespace Microsoft.ClassicInfrastructureMigrate
Get-AzureRmResourceProvider -ProviderNamespace Microsoft.ClassicInfrastructureMigrate

Add-AzureAccount     #login Azure Account ASM module
Get-AzureSubscription | Sort SubscriptionName | Select SubscriptionName
Select-AzureSubscription –SubscriptionName "My Azure Subscription"
Get-AzureService | ft Servicename
$serviceName = "jasonvm333"
$deployment = Get-AzureDeployment -ServiceName $serviceName
$deploymentName = $deployment.DeploymentName

$validate = Move-AzureService -Validate -ServiceName $serviceName -DeploymentName $deploymentName -CreateNewVirtualNetwork
$validate.ValidationMessages

Move-AzureService -Prepare -ServiceName $serviceName -DeploymentName $deploymentName -CreateNewVirtualNetwork
Move-AzureService -Commit -ServiceName $serviceName -DeploymentName $deploymentName

After VMs move complete, then use PowerShell to move Storage Account to ARM module:
$storageAccountName = "jasontest333"
Move-AzureStorageAccount -Prepare -StorageAccountName $storageAccountName
Move-AzureStorageAccount -Commit -StorageAccountName $storageAccountName

More information about move IaaS resources to ARM module, like migrate the VMs to a platform-created virtual network or migrate to an existing virtual network in the Resource Manager deployment model, please refer to this link.
Comment: For now, we can't use azure portal to move classic to ARM, we can use Azure PowerShell to achieve this. Please let me know if you would like further assistance.
Answer: Indeed @Stevie W is correct, there is an option in the Storage Account (Classic) blade that offers Migrate to ARM. Clicking it offers buttons for Validation, Prepare, and Commit.
Answer: I know this is a late reply, however this thread comes up when searching for migrating classic storage to ARM so thought I'd provide an update.
Since the last comment on here, the Azure Portal has been update to allow running the migration process within the blades.   This has worked for a test account, and seems to just apply the 3 powershell commands that have already been noted by Bruno
Azure Storage Blade - "Migrate To ARM" option


Input impedance is higher in Common-Emitter than Common-Base?

Question: Why is input impedance is higher in Common-Emitter configuration as compared to Common-Base configuration  as signal is applied on Base-Emitter junction in both Amplifiers. Not in both configurations the resistances r'e and r'b will be considered?
Answer: Although in both the common base amplifier and in the common emitter amplifier (non-swamped: with a nonexistent or bypassed emitter resistor), the signal appears to be coupled to ground only across the BE diode. So intuitively, you might expect the same low impedance in both.
However, in the common base amplifier, there is a dynamic action going on which lowers the input impedance.
The  action in the common base amplifier can be understood like this. Suppose that the input AC signal swings a little bit low. This increases the \$V_{BE}\$ voltage. The collector-emitter current is very sensitive to \$V_{BE}\$ so a small increase \$V_{BE}\$ causes a large increase in the current.  But in this common base amplifier, the collector-emitter current goes through the input. So, the input pulls down the voltage slightly, and a lot more current pours out!
Since the current flowing out of the emitter reacts sensitively to the input, it means that the input stage behaves rather like a voltage source. The opposite (a current source) would not react to voltage changes at all: the same current would flow regardless of our attempts to shake the voltage this way and that.
And, of course, voltage sources are what? Low impedances!
So in summary, the common base amplifier has a kind of active voltage source behavior, according to how the collector-emitter current responds to changes in the applied input voltage, and this gives it a lower impedance than you would expect just from looking at it statically.
This behavior is absent in the common emitter, because the input interacts with the base current, not the collector emitter current. In the common emitter, we even get feedback-driven impedance raising action if we add an unbypassed emitter resistor.
Comment: "The collector-emitter current is very sensitive to VBE so a small increase VBE causes a large increase in the current." Upvoting because of THIS sentence.
Answer: In common emitter, the current flowing into the base is \$(\beta+1)\$ times smaller than the current flowing into the emitter in the common base. If the voltage amplitude is identical, but the current is lower, then the resistance is higher with the same factor \$(\beta+1)\$. This is derived from \$i_e=i_c+i_b\$ and \$i_c = \beta \cdot i_b\$

simulate this circuit – Schematic created using CircuitLab
Comment: How can we show it using h-parameters of Bjt transistor?
Comment: You can replace \$\beta\$ with \$h_{fe}\$. It's been too long since I used them to be of more use at this moment.
Comment: The input resistance at the base node (emitter grounded) is r,in=hie and at the emitter node (base grounded) r,in=1/gm=hie/hfe (gm:transconductance).
Answer: Another way of thinking about it:
Common-base
The "input" is connected to the emitter and, the "input" has to supply the signal current that goes through the collector load. Let's say collector signal is 5mA peak to peak.
Common emitter
The input supplies a fraction of the collector's 5mA peak to peak because BJTs have current gain in this configuration - typically in the order of 100 but can be as low as 5 and as high as 500.
If you looked at the signal current flowing in the base when it is a common base configuration you will see 5mAp-p/100 = 50uAp-p
Comment: @ Andy can you more elaborate on your answer?
Comment: @AliKhan I think I've said enough that needs to be said without repeating. Is there one particular area you don't understand?
Comment: Can you define it in h-parametrs?
Comment: @AliKhan - your question asked about input impedance being higher in common emitter and I have answered the question by stating that the current taken from the input in common-base is higher. Ohms law therefore tells us that Zin is lower on common-base.
Comment: But you did't define it convincingly. I am asking the reason to prove.
Comment: @AliKhan My reasoning is correct and i have also used references to Hfe (current gain) to give a numerical answer that is typical for most BJT transistors.


Can my proprietary program use a GPLv3 binary?

Question: I want to use in my program (closed source code) binary (GPL v3) which is used by execute it with parameters and read output/log of this execution. Can I do it? If yes, what information should I include to my software if I have to? Of course my software will distributed with included binary (GPL v3)
Comment: "Executing with parameters and reading output/log" is "at arm's length" according to the FSF
Answer: It depends a bit on how your program and the GPL program communicate with each other, but most likely you can do what you want.
The FSF uses the concept of communication "at arm's length" and when two programs communicate at arm's length with each other, then they are considered independent programs whose copyright licenses don't affect each other. Two programs communicate at arm's length if they use a communication mechanism that is typical for communicating between independently running programs (commandline arguments and stdin/stdout are examples of that) and if the two programs don't communicate complex data structures. It is that latter part which I can't tell from the question, but it is a-typical to communicate complex data structures over stdin/stdout.
Also, it must really be two programs, which means that the end-user must be able to replace the GPL program with a different version after the package has been installed on their system.
As for the information you need to include, you must include a copy of the GPLv3 license that comes with the GPL program and you must tell your users how/where they can obtain a copy of the GPL source code. For the GPLv3, that could be a link to the project/repository where you obtained the binary from.
Comment: @needprayfornotaxes, no that doesn't change the situation
Comment: Thank you for your comprehensive comment. Does the situation change if the program asks the user to download the binary (GPL v3) during installation or startup? In this case, the binary is downloaded by the user and the program is not distributed with my software, it is only somewhat dependent, and it is the user who decides whether he wants to download this software.


Why might a cross currency swap from EUR into USD have higher CVA than a cross currency swap from USD into EUR?

Question: I was having a discussion with a colleague in the industry, who mentioned in passing that CVA on a cross currency swap from EUR into USD (pay EUR) is always higher than if paying USD and receiving EUR... why?
Answer: The CVA on a cross currency swap comes mostly from the final exchange (being the biggest flow).  If you as an end user are paying the EUR, then the bank is receiving the EUR a d paying the USD.  They will see that this position is a net receivable, because EUR is more valuable on a forward basis than spot.  Receivables attract a higher CVA than payables.  (The reason EUR is valued more highly on forward dates is due to the interest rate differential between EUR and USD.  See covered interest rate parity ).
Answer: If by paying EUR you mean on the initial exchange you are short USD vs long EUR i.e. you're short USD forward, then a simple explanation might be the higher CVA is coming from the fact that the EUR/USD basis is generally negative (i.e. USD demand exceeds EUR demand). Hence the expected exposure is more material to the short USD position on notional exchange (offsetting any effect of the higher rate payer's position).
Answer: It will also depend on the kind of CSA. For example if does it allow posting of collateral in EUR?


What kind of matza should I buy?

Question: So many different kinds of matza, what should I buy?
Answer: Matza with a certification you consider reliable which is marked Kosher for Passover.
Comment: Good point!  I forgot to mention: ALWAYS CHECK THE PACKAGE!  They make "not for Passover" matza too, so watch out!
Answer: Firstly: ALWAYS DOUBLE-CHECK THE PACKAGE for Passover certification.  They make "not for Passover" matza, too.  So watch out!
If you have gluten intolerance, spelt or (if that's also a problem) oat matza.
For the seders, "shmurah matzah."  If your ancestral customs are German, or if you have a connection with the old-time Jews of Jerusalem, get machine shmurah matzah.  If you're Hassidic, get hand-made shmurah matzah.  (To the very best of my knowledge, all commercially available hand-made matza happens to be shmurah anyhow.)  If you're anything else, ask your local rabbi what's preferable between the two.  (R' Ovadya Yosef shlit'a expresses mild preference for hand-made.)  If you want whole wheat, I don't think it's available in machine shmurah, so get hand-made.
For the rest of yomtov, if you have a custom to only consume shmurah, then shmurah.  (Here Rabbi Yosef allows machine shmurah as well, but if you're Hassidic, stick with hand matza.)
Otherwise, non-shmurah is okay too (and available in machine whole wheat, or a whole wheat / rye blend for extra fiber).
My family serves hand matza with meat meals (including the seders), machine matza with dairy meals (e.g. breakfast).  That way you don't have confusion as to which matza is "meaty" or "milky."
Egg matza can't be used for seders.  For the rest of the holiday, it's not recommended for Ashkenazic Jews (unless someone's ill or the like -- ask your rabbi).
I'm told that some Sephardic Jews make soft (almost pita-like) matza.  If that's your custom, and you can find it, go for it.  I assume it's only available handmade; don't know if it comes in whole wheat.  If it's not your custom, ask your rabbi first.  Rabbi Hershel Schachter thinks it's okay for Ashkenazic Jews too.
Comment: I believe the Germans eat machine, too, don't they?
Comment: Yes that sounds right; I added it in.  Thanks.
Comment: Rav Aviner also thinks it's fine for ashkenazim. See HaRav Asher Weiss's opinion differs a little.
Answer: The NY Post did a taste test last year and recommended Pupa-Tzelim Matza as number 1. As someone that has been using their Matzos for years I agree.
http://www.nypost.com/p/news/local/brooklyn/but_which_matzoh_is_best_T48ht2PKbTbjBtRidPzueL
Answer: Go with whole wheat Shemurah - it's delicious!
Comment: JewishJon, Welcome to mi.yodeya, and thanks very much for sharing your opinion! Please consider clicking "register," above, to create an account. This will give you access to all of mi.yodeya's features, and will allow you to take full credit for your contributions.
Comment: i agree. whole wheat matza is great. but, note that it is often thicker, so if you use a matza chart, you should adjust your measurements accordingly.

What kind of matza should I buy?


How to show a teaser of the next node?

Question: At the bottom of each blog post I need to show a teaser for the next blog post. I know there is module to add links to next/prev blog. But I need to show more than a link. I need to show the title and summary. Could someone please suggest a way to achieve this?
Comment: Assuming you want the next blog in date created order. That could easily be done with a little bit of custom code in a block. You could get the created date of the current node and then do an entityquery/database query to return 1 node of type blog with a created date greater than the current blogs created date and then sorted by created ASC
Answer: I was able to achieve it by using the helper service defined in https://www.drupal.org/project/prev_next.

How to show a teaser of the next node?