Shooting film with a camera that doesn't have a ISO meter

Question: So got a yashica J that doesn't have an iso dial or meter and I was wondering does that mean my camera is only limited to a set of film iso or that I can't push or pull the film
Comment: Do you have a Yashica J rangefinder or a Yashica Penta J SLR?
Comment: Just in case the answers below don't make it clear: You need to use a separate _[light meter](https://en.wikipedia.org/wiki/Light_meter)_ to get the best results with that camera.
Answer: With a manual camera (assumed, as the Yashica Model J isn't familiar to me), pushing and pulling are just a matter of setting your external meter (hand held meter, smart phone app, or Sunny 16 rule) to a different Exposure Index (EI) than the ISO speed of the film that's loaded in the camera.
So, you've loaded Tri-X, ISO 400, but you're shooting in a bar late at night, and it's pretty dark, so you decide you need to push to EI 3200 in order to get hand held shutter speeds.  All you do is set your aperture and shutter as if you had 3200 speed film, and then mark the cassette after shooting to remind yourself to process with a three stop push.
Bottom line, the camera itself has nothing to do with "pushing" or "pulling" film, it's the metering.  In some cases, the camera has a meter, which you can set (or which sets itself, by reading the DX code on the film cassette), and changing this setting will, for automatic cameras, cause them to treat the film as faster or slower than its box speed.  But for cameras without internal meters, it's up to the photographer to set whatever metering device is used.
Answer: As far as I can tell, there is no built-in light meter in the Yashica J rangefinder. You should purchase an external light meter or use the "Sunny 16" rule.
There is no ISO setting because ISO is determined by the film you select. Exposure is further defined by the aperture, and shutter speed you select.  To push or pull, change the shutter speed or aperture appropriately.
See YouTube: Yashica J Overview and Features
Answer: Most of us with white (or none) hair, started our photography journey with cameras that did not have light meters. We consulted charts or used a hand-held meter or made guesstimates. Thanks to what is called "film latitude" most times we got acceptable results.
First, you should know, we set these cameras manually. This means there is not built-in automation so we must do the mechanical settings  which involve setting the subject distance (focusing), setting lens f-number (aperture), setting shutter speed plus choosing a film with appropriate sensitivity (ISO).

We often set the exposure using what is known as the "sunny 16 rule". On bright sunny days, we set the camera lens aperture to f/16. We choose a moderate speed film, likely 100 ISO. We set the shutter to a value that borders the film's ISO. Likely 1/125 second for a 100 speed film.  Summation – set shutter 1 over ISO. For 200 ISO set shutter to 1/200 of a second or as close to this value as possible. Lastly, for bright sunlight vista set lens to f/16.
There are other ways – use a hand-held light meter.  Use a modern camera, set to the same ISO as the film you are using, compose the shot and jot down the shutter speed and aperture settings it's logic chose. Transfer these setting to your manual setting camera.
Also you can consult a chart that likely comes with the film or one that you Googled as attached for 100 ISO film.
Answer: If your camera has no light meter, there's no need for the camera to know what speed film is loaded. It would make absolutely no difference if it did know. All of the variables are controlled by the photographer.
You can use whatever speed film you wish in your camera, assuming your camera is capable an exposure time and aperture combination that will give you the exposure you want. If you try to use ISO 1600 film on a bright sunny day, you may find that the camera's shortest available exposure time and narrowest available aperture might still leave your exposure too bright. Or, even more likely, you might find yourself in a lower light situation where ISO 25 film shot at your lens' widest available aperture requires a longer exposure than is practical if you need to handhold the camera, or if your subjects are not totally motionless, etc.
To select a proper exposure time ("shutter speed") and aperture to get an acceptable exposure for any specific scene under any specific lighting condition with any particular speed film, you'll need to rely on something other than the camera to guide you.

Use known rules of thumb, such as the "Sunny 16" rule. This works well on a sunny day with no clouds. It doesn't help at all in many other lighting conditions, particularly in artificial ambient lighting.
Take a wild guess. The success of this method depends on your knowledge and experience.
Shoot in very low ambient light and use artificial lighting that provides known brightness. With strobe flashes you'll need to calculate the aperture needed based on the distance of each light source from your subject as well as your film's sensitivity. With constant lighting you'll also need to include the exposure time in your calculation.
Use an external light meter.

In the latter case, you'll need to tell the light meter what speed the film in your camera is or, if you're going to "push" the film, what speed you wish to use for the film in your camera. How you do that depends on the specific light meter.
For more about calculating exposure without a light meter, please see:
How did people calculate exposure in the pre-light meter era?
What is the EV scale?


SVN Server Not Responding to Write Requests

Question: I am in the process of trying to set up an SVN repo using an apache web server. I was able to get the repo created and configured without too many problems. I can reach the repo via the browser, so I think the apache configuration is correct. The problem comes when I try to do the initial commit. When I run the commit command in the terminal, it hangs for several minutes before returning svn: E175012: Connection timed out. The initial commit is a single file, less than 100kb. Even more strange, after the command times out, it seems to create an HTTPd process on my system that uses 90% of the CPU.
I did some research to see if I could solve the problem myself, but so far nothing has worked. I was able to use Charles Proxy to monitor the HTTP requests and it looks like the svn client is sending the POST but it is never receiving a response from the server. After the default timeout (10 minutes) the client gives up and displays the timeout error.
I also tried setting up the repo using SvnServe instead of apache. I was able to read and write to the repo using svn://. However, the code I am working on expects to communicate with the repo over HTTP, so I still need to figure out what the problem is with apache.
Does anyone know what could be causing this issue? Are there any other steps I can take to troubleshoot the problem for myself?
[Update]
I checked the logs for my apache server. Here is what I'm seeing when I run the commit:
_myip_ - - [28/Feb/2017:10:04:04 -0500] "OPTIONS /my/repo HTTP/1.1" 200 190 "-" "SVN/1.9.5 (x86_64-apple-darwin16.1.0) serf/1.3.9"
_myip_ - - [28/Feb/2017:10:04:04 -0500] "OPTIONS /my/repo HTTP/1.1" 200 97 "-" "SVN/1.9.5 (x86_64-apple-darwin16.1.0) serf/1.3.9"
[Update 2]
In an attempt to further narrow down the cause of this issue, I tried setting up a different apache server in a Linux virtual machine. That server worked perfectly, and I was even able to read/write to it from osx. So it would seem that the issue is something specific to the apache server on OSX.
Answer: Please try this.

$ sudo chmod -R 775 /var/lib/svn

Reference URL-: https://gotechnies.com/setup-svn-server-ubuntu/
Comment: Please consider adding some context to your link (i.e. quoting the relevant part of the article). http://stackoverflow.com/help/how-to-answer
Comment: As I mentioned in the post, it works fine in a linux system. It's on OSX where I'm having issues.


At what stage of computer science PhD should you start looking for post-doc?

Question: I am exactly mid-way in my PhD in computer science. Is this the right time to start looking for a post doc?
Comment: I deleted the second part of your question, because it did not seem to have a direct connection with the main part of your question. If they are connected perhaps edit to make the link clearer or ask separate question about the funding aspect.
Answer: Around your last year.
So much of this comes from networking though, so it is important to be meeting people at conferences long before you are about to graduate.
In the US, many postdoc positions are filled quite late (often after faculty offers have gone out, so mid to late Spring, maybe even early Summer) but you should start talking to potential postdoc advisors maybe a year before your graduation to put a bug in their ear.


Linux Deploy on Android 5.0 (Nexus 5): "Configuration file not found!"

Question: I used Linux Deploy on Kitkat before and it worked. Now that I updated my Nexus 5 to Lollipop (Chainfire-rooted the device), I installed Linux Deploy again, but whenever I would like to create the disk image or virtually do anything else, I obtain Configuration file not found! or Updating configuration file... fail. I tried various settings, also enabled Wi-Fi while the application is running... no success. Has anyone been able to run Linux Deploy on Android 5.0 or know how I can get the configuration file?
Answer: You need to install Busybox to be able to update the configuration file. However, on my Nexus 5, I haven't been able to get past "Updating configuration file ... done" after the fact. It could be incompatibility or some settings need to be tweaked first. I'll report back if I fix it.
Comment: Thanks, now I experience the same as you. Enabling debug info, I obtain: `[22:44:34] tmp-mksh: [1]: /data/data/ru.meefik.linuxdeploy/linux/bin/linuxdeploy: No such file or directory` How can one fix that?
Comment: I tried to play with the permissions (as this seems to be the problem as the file does exist), but wasn't successful yet.
Answer: Quick Answer: Verify the path/file really exists, using a "terminal emulator" or an ssh connection to your Android (not a graphical file browser).
First thing (as Marius Hofert suggest) is to enable "debug info". You will see the full message of the issue.
While installing I saw many "No such file or directory"
Someone suggested to change the directory and after many changes I got it installed & running.
But something changed and I couldn't run the installed OS anymore after shutdown (same messages).
I installed an SSH Server and started checking permissions and files, and guess what, the folder does not exist indeed.
The default configuration (on my phone) has
/storage/emulated/0/linux.img
but (on my phone) the file is in
/storage/emulated/legacy/linux.img
(to be honest it is in /storage/emulated/legacy/linux/linux.img but the example above seems closer to what most people may find).
But that's not all.
Using a graphical file explorer, I DO can see
/storage/emulated/0/
/storage/emulated/legacy/
but the first (/0/) looks different, like if it were a symlink (symbolic link).
Maybe "Linux Deploy" is getting lost because of that, so better use clear, reliable paths.
Again, I did my verifications using a ssh connection.
I hope it helps others.
I provided the troubleshooting so others can help themselves too.


Learning electronic circuit design

Question: Is there a good website or book to learn electronic circuit design from the beginning.
I would like to learn more about basic electronic elements and how to use transistors appropriately in my circuit designs and learn more about popular IC s and their applications.
Comment: thread on [Basic Electronics Books](http://electronics.stackexchange.com/questions/616/basic-electronics-book)
Comment: In addition to answers posted below, also try searching this site using keyword "learning" for a bunch of other probably useful suggestions. Videos. Simulation software. Particular focused application areas that might appeal to you and add motivation.
Comment: Please search for a good book on electronics. look for ISBN-10: 0521370957
Answer: Art of Electronics by Horowitz and Hill: not very new but is well loved for its excellent practical approach to teaching fundamentals.
Comment: Horowitz and Hill
Answer: Start developing small embedded projects.
Read good embedded system magazines, example, circuit cellar and elektor.
Comment: Check out free video lectures and tutorials from top universities at http://freevideolectures.com/

Learning electronic circuit design


Adding disk to windows-7 RAID-5

Question: If I have a 3-disk RAID 5, and I want to add a 4th disk to the RAID, can this be done without moving all the data out of the existing raid array and rebuilding it as a 4 disk raid-5 array?
Answer: It depends a lot on who makes the RAID controller and what the model is, but I would be surprised if it didn't let you.
Note that if you add a disk to a RAID5 array, it must be equal or bigger in size than the smallest drive currently in the array.
You also need a free SATA port, but presumably, if you're asking about RAID, you know that already.
Comment: Hi, i am asking about windows (software) based RAID. I am familiar with how to set it up and the necessary software.

Adding disk to windows-7 RAID-5


disabling color correction in quartz 2d

Question: Ok, I know that it's not possible to actually disable color correction in quartz. What I'm looking for is a device-independent color space setting that dosn't change the RGB values I draw in a CGLayer.
I tried all the ICC profiles from the system library, they all shift the colors.
This is the best result I got:
const CGFloat whitePoint[] = {0.95047, 1.0, 1.08883};
const CGFloat blackPoint[] = {0, 0, 0};
const CGFloat gamma[] = {1, 1, 1};
const CGFloat matrix[] = {0.449695, 0.244634, 0.0251829, 0.316251, 0.672034, 0.141184, 0.18452, 0.0833318, 0.922602 };
CGColorSpaceRef colorSpace = CGColorSpaceCreateCalibratedRGB(whitePoint, blackPoint, gamma, matrix);

This uses Apple RGB's color conversion matrix and D65 white point.
The colors still shift a bit, although I'm a lot happier with this than with the device dependent settings.
Here's how I write the CGLayer to a TIFF:
CIImage *image = [CIImage imageWithCGLayer:cgLayer];
NSBitmapImageRep *bitmapImage = [[NSBitmapImageRep alloc] initWithCIImage:image];
[[bitmapImage TIFFRepresentation] writeToFile:fileName atomically:YES];

Any help would be greatly appreciated.
Answer: Why not declare your colours to be part of the same colour space as your destination CGLayer?
The doco for CGColorSpaceCreateDeviceRGBseems to be saying just that:
CGColorSpaceCreateDeviceRGB

disabling color correction in quartz 2d


USB Power Adapter gets really hot?

Question: Is it okay if your power adapter gets hot, because mine gets really really hot, it's kinda burning to the touch and I'm really worried, especially because my Iphone is brand new and i don't live in US, but that is where i got it from, and there aren't any apple stores in my country so i can go and ask for help. If anyone knows any solution, i would be really grateful. Thank you.
Answer: Mmm I think it all depends on how much you use it and for how long you've been having it.
Though if you use it for several hours straight it may start getting a little bit hot (or even worse sometimes), it's common.

But if you think it's way out the normal, you may want to consider about purchasing a new one maybe?
You can either purchase the official one from the Apple Online Store.
Or on Amazon (thus today only 12/07/2016 is the Prime Day!) take a look!

USB Power Adapter gets really hot?


How to acknowledge a retired professor?

Question: I want to acknowledge a retired professor. How do I specify his name? With just Prof. or something particular?
Comment: This will probably depend on your field, and even the specific journal/venue, some of which may have already been addressed in other Q&A's.  We'll need those details.
Answer: I usually see acknowledgements in papers with just the full name of the person, regardless of their degrees or academic status.  No "Prof." or other honorific would be used at all.  "We would like to thank Jane Doe for helpful advice regarding our data analysis."
Comment: @hhh If you must, write Dr. Doe, but it would seem weird to me. In an international journal, I'd write "according to private discussion with Jane Doe, ...". Of course, it would be totally different issue when writing for a national journal because then local customs have to be considered.
Comment: What about when I refer to them in the text: `according to private discussion with Prof. (ret.), the domain was earlier called ...`? So then I use the titles but no titles in the acknowledgements?
Answer: Where a person who previously held rank or position has now left through retiring from the position (as opposed to resignation or termination), it is not uncommon to see them listed as Rank (ret.) Person Name.
For a professor, this would be Prof. (ret.) Person Name.
Comment: In academia titles, latin is usually preferred. On the faculty list you often see Prof. (emer.) which is used for Professors in https://en.wikipedia.org/wiki/Emeritus status.
Comment: @Anony-Mousse But of course emeritus and retired are two different things.
Answer: In USA, a retired professor is not probably called a professor. A retired professor with doctorate can continued to be called as Dr. and identified in bio or intorduction as a former professor.

How to acknowledge a retired professor?


StarterSTS issue additional claims

Question: Does anyone know how to issue additional claims from StarterSTS by Dominic (Codeplex). I currently am getting only Login Time Instance and the Authentication Type which is password. Is there some config file i can edit or Code i need to insert to provide additional claims to the user ?
Answer: I'm not sure if you can in StarterSTS, but if you note on the project it says:-

IMPORTANT
  StarterSTS has been discontinued. The sources will stay up here for educational purposes. Please use my new project IdentityServer (http://identityserver.codeplex.com) from now on.

IdentityServer does support additional claims. You add the claims using the user profile - it's very easy to do so I would recommend you upgrade to this if possible.
I can't see the source for starterSTS so I'm not sure if it supports this feature. You can find Identity Server V2 here
Comment: It sure does support, but has to be coded here is the link https://github.com/thinktecture/Thinktecture.IdentityServer.v2/issues/84

StarterSTS issue additional claims


Standardizing skewed distributions for visualisation alongside others

Question: It's common for QC purposes, when there's a suite of measurements in different units and with different distributions, to normalise their display such that each value is shown as a deviation from a chosen central tendency (mean, etc), scaled according to its dispersion (sd, interquartile, etc). [I believe this is generally known as standardization, but am not a statistician]. Particularly when displayed alongside the same for a large number of samples, this can be an effective way to spot "defects" worth investigation.
How is this process best refined when it comes to skewed distributions, particularly when related to dispersion? I understand the common options for central tendency choice when it comes to skewness (and outliers, etc), but don't know anything similar to "x standard deviations" when a distribution is very skewed.
The skew on the data I'm concerned about is not pathological in any mathematical sense: usually it is just something which "looks" more like $xe^{-x^2}$ than $e^{-x^2}$, and restricted to positive $x$.
The best I've come up with so far is to scale each side of (whatever) chosen central tendency individually, but the discontinuity at the centre is troubling me. (For example, if above a mean to show a line of length scaled by the 2-3 quartile range but if below scaled to the 1-2 quartile range).
Are there better ways? Does going any further absolutely require a thorough knowledge of the nature of the underlying distribution in a situation like this? (Because we don't have it!) The data is only used for initial, rapid visualisation of a large number of samples side-by-side, for investigative purposes.
Answer: It may help if you can provide examples of what you've got and what you're going for.
For unknown distributions, it's hard to beat box plots. Not that they're perfect, but they are well known by technical audiences and able to show skewness and outliers. Here's an example with 20 mostly skewed distributions of 1000 data points each, standardized to mean = 0 and std = 1.

It sounds like your distributions may be log normal (like 11-14 in the plot). If you find that or another distribution that fits well, you could fit the parameters and plot only those.


Who is the counterparty when buying shares through a broker

Question: If I buy shares of a company through a broker, who is my counter-party? The company or the broker? i.e Do I face counter-party risk twice over(if company goes bankrupt and also if broker goes bankrupt)?
Comment: The counterpart is either another individual, an institution or a market maker, (ie: whoever is selling the shares).
Answer: If one is using a broker to trade equities then the equities are held in "street name"; in other words, in the brokerage's name at the equity's transfer agent on behalf of the client.  A client can request that they be held in the client's name, but it will then be out of the broker's fiduciary so will be almost impossible to trade unless if the client can find someone to buy directly.
All shares are settled and cleared ultimately through a registrar, but many shares are netted between brokerages who mostly clear for themselves.
The counterparty risk for a brokerage client is the brokerage; however, many insure their accounts.
The ultimate counterparty risk for a shareholder is the registrar.  Restrictions in the contract between corporation and registrar usually prohibit lending the shares and anything else that would place the shares at risk.


Trying to connect my SNES to new TV using RF cable - can't get it to auto tune or manual tune

Question: Whenever I select auto tune it just goes through 0% - 100% and finishes saying it didn't detect anything and to check the antenna connection. With manual tune, there is 'DTV' or 'TV'. In DTV, I have the option to change UHF CH. and there is an indicator (of signal strength I guess?) which is labelled 'Bad' 'Normal' 'Good' and then 'Add' 'Close' below it. 'Add' is greyed out on UHF CH. I try so I guess it doesn't detect anything?
On 'TV' there is 'Storage'  'System' 'Band' 'Channel' 'Search' 'Name' 'Store' and 'Close'. I'm guessing the answer is somewhere in 'TV'? Anyone know how to tune this? The alternative is that the cartidge isn't working (tried cleaning it) or the console is broken. Or the RF just won't work on my TV, I haven't got AV cables but I'll get them if none of you can help. Thanks
Comment: Got a VCR? And it is under Analog not digital(T.V not DTV).
Comment: RF switches use channels 3 or 4, which are VHF not UHF.
Answer: You have to tune it manually to Chanel 3 or 4


No module named PiCamera

Question: Trying to run a python program in a vm (virtual environment) with the picamera module, i'm running it in the vm because i have other modules there like OpenCV.
When running the program i get the error:
   " ImportError: No module named 'picamera' "
Does anyone know where the picamera module is installed or the location, so i can move it.
Btw, the module imports correctly when i run the program outside of the vm. And i can't run outside of the vm, i HAVE to find a way to get the picamera module to work in the vm.
Comment: this is really a python question, not an RPi question.   ..... this may help ... https://packaging.python.org/tutorials/installing-packages/#creating-virtual-environments
Answer: Once you've activated your vm, install picamera in the usual way. It should work - let us see what you're doing (commands, etc), and we'll try to help.

No module named PiCamera


Helmholtz Free Energy at Equilibrium

Question: Can somebody point me towards a derivation using statistical physics for the fact that the Helmholtz free energy $F$ is minimised at equilibrium for a canonical system at constant temperature and volume?
Comment: Related: General thermodynamic (not stat. mech.) idea for the minimization of free energy is here: https://physics.stackexchange.com/a/369412/226902
Answer: I'll sketch the derivation in a classical setting. Let's say we have a system with $N$ degrees of freedom, with $N$ large (disclaimer: I won't discuss the limit properly).
The partition function at temperature $T=1/(k_B\beta)$ is given by the sum over all the configurations $C$ of the system
$$
Z = \sum_C \mathrm{e}^{-\beta E_C} = \int\mathrm{d}E\;
\mathrm{e}^{-\beta E} \sum_C \delta(E-E_C) = \int\mathrm{d}E\; \mathcal{N}_E\mathrm{e}^{-\beta E},
$$
where $\mathcal{N}_E$ is the number of states at energy $E$.
The entropy is defined as $S=-k_B \ln \mathcal{N}_E$, and I will assume that energy and entropy are extensive, so that the densities $\varepsilon = E/N$, $s=S/N$ are well defined in the thermodynamic limit. We can rewrite the partition function as
$$
Z = \int\mathrm{d}E\; \mathrm{e}^{-\beta E+\ln\mathcal{N}_E}
= \int \mathrm{d}\varepsilon N \mathrm{e}^{-\beta N (\varepsilon-T s)}\ .
$$
For large $N$ we can evaluate the integral by Laplace's method, to obtain
the free energy minimisation principle
$$
f = -\lim_{N\to \infty}\frac{1}{\beta N} \ln Z
= -\lim_{N\to \infty}\frac{1}{\beta N} \max_\varepsilon[-\beta N(\varepsilon-T s)]
= \min_\varepsilon (\varepsilon-Ts).
$$
Comment: I am not quite familiar with the definition of free energy as  the limit over N tending to infinity. Could you tell me where that comes from?

Helmholtz Free Energy at Equilibrium


Notation in propositional logic

Question: If in propositional logic one is trying to simplify a formula by evaluating its subformula, would it be considered an abuse of notation to actually substitute the bits $\{0,1\}$ in for the formula, to say something like "$0\wedge 1\equiv 0$" or "$0\wedge 1=0$".
Comment: If you're working in a setting in which truth values are $0$ and $1$, and the connectives have been defined as operations on $\{0,1\}$, then such a calculation would be fine.
Comment: I'm not entirely sure what you have in mind; could you give an actual example?
Comment: @BrianM.Scott Say A and B have truth value $1$ and I want to evaluate $\neg (A\wedge B)$, then I could say $\neg(A\wedge B)\equiv \neg( 1\wedge 1)\equiv \neg 1 \equiv 0$. This way I am consistently aware of the truth values of the formula A and B, with out having to look back to what there truth values are.
Answer: Judging by the comments it seems that what you are trying to do is fine. I think that it would be slightly clearer to use some predetermined symbols for "True" and "False", e.g. $\top$ and $\perp$ or $\Bbb T$ and $\Bbb F$.
This makes it easier to understand that you're talking about truth values.
Of course, if the context is clear that $0$ and $1$ are truth values, then writing those is fine as well.
Let me add my usual advice, be sure to write something like this at the start:

Given a proposition $A$ and an assignment $\sigma$, we shall write $1$ if $A$ is true in that assignment, and $0$ otherwise.

This way you can hint the reader how you are going to abuse them. Or the notation.
Comment: Or use the words 'true' and 'false' (as in $\;A \land \lnot A \equiv \textrm{false}\;$), as Dijkstra c.s. do.

Notation in propositional logic


Who is responsible if a customer does not specify location to taxi driver?

Question: At an airport a family decides to take a taxi and tells the driver they want to go to a particular road and the taxi driver tells them they know that road and feeds it into the GPS. Everything seems fine when midway the passengers realize that the driver is going the wrong way because a road of the same name is in multiple cities, causing several hours to be wasted. Is it automatically the driver's fault? Does it matter  whether the driver is employed by a company as in this case or is self-employed? Is it correct that even if a driver is self employed they owe a certain standard of care to customers?
Comment: I found a plausible example for those wondering "how could this happen". 1600 Pennsylvania Ave., *Washington, DC* is well-known as the address of the White House. If someone landed at [BWI](https://en.wikipedia.org/wiki/Baltimore/Washington_International_Airport) and said "Take me to 1600 Pennsylvania Ave.", many taxi drivers would assume "visiting the White House" but there is a 1600 Pennsylvania Ave. in *Baltimore*. 12 miles to Baltimore, 36 miles to the White House. Wants to go to Baltimore, could easily end up with an extra hour or more of driving depending on when the problem was noticed.
Comment: Was the street the taxi driver navigated to the closest street with the requested name? (Also, how does this waste _several hours_?)
Comment: @marcelm No, actually the street's name was not the same but sounded very similar to a street the taxi driver was familiar with, which was in a different city from the city the airport was located in, which is where the road that the passengers wanted to go to was located.
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](https://chat.stackexchange.com/rooms/133879/discussion-on-question-by-user389532-who-is-responsible-if-a-customer-does-not-s).
Answer: It could be the passenger's problem or the taxi's problem
When these sorts of breakdowns in communications happen in specifying contract terms then either or both parties can be at fault.
If the passenger specified the wrong address then it is clearly the passenger at fault. Similarly, if the driver drove to a different address from what the passenger said, it would clearly be the driver at fault.
However, if the passenger was imprecise and the driver made an assumption then who bears responsibility depends on whether that assumption is reasonable or not.
For example, the main street in the Sydney, Australia CBD is George Street. Even though George Street is an extremely common name with literally dozens in the Greater Sydney area, a taxi driver would reasonably assume that a passenger at the airport asking for "George Street" means the one in the city, not any of the others. In such a circumstance, the onus is on the passenger to specify exactly where they want to go.
Whether the driver is an employee or a contractor is irrelevant - they are the representative of the organisation with whom the passenger has a contract.
Comment: On the other hand, the taxi driver knows that there are more than one street named George Street, whereas the passenger from the airport could be a tourist who doesn't even know that "Greater Sydney" is not all in Sydney.
Answer: It would very much depend on jurisdiction. In most municipalities in the US, taxis are highly regulated, see Ch. 6.310 of the Seattle Municipal Code for an example. The rate charged is automatically computed by a sealed meter which tracks mileage, and starting at 6.310.460 there are various rules related to rates, for example

E: A for-hire driver shall not ask, demand or collect any rate or fare
other than as specified on the meter, required by ordinance, or
pursuant to special rates or contract rates on file with the Director

and 6.310.465

K: A for-hire driver shall not make any discriminatory charges to any
person, or make any rebate or in any manner reduce the charge to any
person unless such is in conformity with the discounts or surcharges
contained in the filed rates

Since the charge is exactly computed by a sealed machine, there is no provision under the law to dispute the charge.
Under the provisions of 6.310.465 G

A for-hire driver shall use the most direct available route on all
trips unless the passenger specifically requests to change the route

A passenger might therefore file a complaint, based on a purported violation of this regulation. This does not affect the charge to the passenger, but might result in an Class A administrative sanction (fine) against the driver if the administrator who deals with the case finds that the facts support imposing a fine, but such findings are highly discretionary, and the municipal code does not say what level of proof is required to support a finding that a person did not use the most direct route to a mistaken destination where the driven is not clearly at fault for mistaking the destination.
Comment: I don't see anything in these regulations that addresses the driver going to the wrong destination.
Comment: In this case it appears the driver probably was using the most direct route -- to the wrong location. I don't see how this answers the question.
Comment: Correct: there are no such regulations. It would have to fall under the "direct route" regulation and the administrator's interpretation of it.


When do people actually use the maximum entropy distribution?

Question: One of the standard problems in convex optimization is the calculation of the maximum entropy distribution that satisfies some set of criteria.  For example, if $\mathbf{x} \in \mathbb R^n$ is an unknown vector of probabilities, one might solve a problem like $$\mathrm{maximize}_\mathbf{x\geq0} -\sum_{i=1}^n x_i \log x_i ~~~s.t. \\ A\mathbf{x}\leq \mathbf b \\ \sum_{i=1}^n x_i = 1~,$$which would of course find the probability distribution that satisfies a certain set of inequalities whose entropy is as large as possible.  My question is:  where do people actually use this (maybe not just using inequality constraints, other kinds of constraints would be possible as well of course)?  I see problems of this kind arising in textbooks very often, but I don't see research papers in which one really makes use of these distributions to some specific aim.
Comment: I am amazed that nobody noticed the wrong sign. The entropy is $-\sum x_i\log x_i$. As a matter of fact, one usually maximize concave functions and minimize convex functions, and $x\mapsto x\log x$ is convex.
Answer: Many classically important probability distributions are maximum entropy distributions for suitable constraints, including the normal distribution, exponential distribution, and Poisson distribution. Viewing them as maximum entropy distributions gives a unified viewpoint for why such distributions occur often in practice.
Comment: In addition to the book I mention in my answer, I have found KConrad's notes on this topic useful as well: http://www.math.uconn.edu/~kconrad/blurbs/analysis/entropypost.pdf
Comment: @J.FabianMeier, see http://arxiv.org/pdf/math/0603647v2.pdf, especially Definition 2.4 and Theorem 2.5.
Comment: Under which conditions does the Poisson distribution arise as maximum entropy distribution?
Answer: In finance, finding risk neutral probabilities can be done via max-entropy methods.
In short, you observe prices $p_i$ of a finite number of instruments $\phi_i$, and you seek a probability measure $P$ such that $p_i = \int\phi_i\,\mathrm{d}P$. There is in general no uniqueness of $P$, and finding such a $P$ can be challenging. Finding $P$ by a max-entropy method is one very practical way to do this.
There are quite a lot of papers which do exactly this, to name only two:
http://papers.ssrn.com/sol3/papers.cfm?abstract_id=648
http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1968344
Comment: @weakstar: One either maximizes the entropy, or minimizes the Kullback-Leibler divergence. The former is the opposite of the latter.
Comment: Although don't they try to minimize entropy?  With the understanding that finding a low entropy Radon-Nikodym derivative is equivalent to finding a martingale measure that deviates as little as possible from the physical probability measure.
Answer: I have found this book a useful reference:
Maximum-entropy Models in Science and Engineering
It may contain some pointers to applied work that you will find convincing (I don't have it on me right now) if you can get a copy.
Answer: The physicist E. T. Jaynes recommended using maximum entropy distributions as priors in Bayesian statistics. The most basic example of this is the (highly highly controversial) principle of indifference, which states that if you know nothing about a quantity, you should assume it is uniformly distributed.
A more general and wider-reaching version of the Principle of Indifference is the Principle of Maximum Entropy. (http://en.wikipedia.org/wiki/Principle_of_maximum_entropy)
Answer: Thermodynamics can be derived from this principle:
\begin{align*}
  0 &\overset!=\delta \Big[\underbrace{-k_B\langle\ln p\rangle}_{S} + \alpha\Big(\langle1\rangle - 1\Big) + \beta\Big(\langle E\rangle - U\Big) + \mu\Big(\langle N\rangle - N\Big)\Big]
\\\text{where}\ \langle x\rangle :&= \sum_i p_i x_i \ \text{denotes the expectation value of $x$}
\end{align*}
$k_B$ is the Boltzmann constant, which makes the entropy $S$ equivalent to the physical one, while the Lagrangian multiplicators $\beta$ and $\mu$ which conserve (internal) energy and particle count respectively turn out to be equivalent to the thermodynamical quantities $\beta^{-1}=k_B T$ (i.e. $\propto$ inverse temperature) and chemical potential $\mu$.
For the canonical ensemble (i.e. no particle exchange, $N_i\equiv N$) this yields the Boltzmann distribution
$$p_i = \frac{e^{-\beta E_i}}{\sum\limits_j e^{-\beta E_j}}.$$
Comment: Since the Boltzmann constant was mentioned here, I feel compelled to mention that this number is not a physical constant, but rather a unit conversion factor. When temperature was first discovered, people didn't realize that it had units of inverse energy, so they made up a new unit for it. As a result, many expressions in statistical mechanics are traditionally written with some variables in units of temperature and others in units of energy, and we have to use a conversion factor to translate between them.
Comment: @Vectornaut Excellent point, that's why I prefer [natural units](http://en.m.wikipedia.org/wiki/Natural_units#.22Natural_units.22_.28particle_physics_and_cosmology.29) :-)
Answer: One way that maximum-entropy distributions (and, more generally, minimum-relative-entropy distributions) arise is as conditional frequency distributions of long sequences of IID random variables. Here's a sketch.
Say you have a sequence of IID random variables $X_1, \ldots, X_N$ taking values in a finite set $S$, with distribution $\vec{p}$. Measuring the frequency of each element of $S$ in this sequence gives a new random variable $\vec{F}$ taking values in the frequency simplex with $|S|$ corners. As $N$ grows, it becomes increasingly likely that $\vec{F}$ will be close to $\vec{p}$; in fact, the probability that $\vec{F}$ falls outside any neighborhood of this point approaches zero. This is the weak law of large numbers.
Suppose you learn that $\vec{F}$ lies in a certain open subset $Q$ of the frequency simplex, and you condition on this knowledge. Where is $\vec{F}$ likely to fall now? As $N$ grows, it becomes increasingly likely that $\vec{F}$ will be close to the points in $\overline{Q}$ that minimize the relative entropy $K(\vec{F}\|\vec{p})$; in fact, the probability that $\vec{F}$ falls outside any neighborhood of these points approaches zero. In other words, as $N$ grows, you become certain that $\vec{F}$ is close to to a minimum-relative-entropy distribution.

The result above can be generalized to cover multiple IID sequences, with different distributions, whose sizes are growing at roughly proportional rates. This generalization should have a neat application to random walks, although I haven't checked the details carefully.
Say a random walker departs from the point $a \in \mathbb{R}^n$, taking steps of uniform length along the cardinal directions. Suppose you learn that the walker ends up near point $b$ after $N$ steps, and you condition on this knowledge. Using the aforementioned generalization, you should be able to show that as the number of steps in the walk grows (with the length of each step shrinking proportionally), you become certain that the walker's path is close to the straight, constant-velocity path from $a$ to $b$.

The kind of reasoning used here is a baby example of large deviations theory. If you look there, you might find more maximum-entropy-type results.
Answer: The current best approximation algorithm for ATSP (the Asymmetric Traveling Salesman Problem) heavily leverages maximum-entropy distributions. The paper may be found here:
http://epubs.siam.org/doi/pdf/10.1137/1.9781611973075.32
A recent paper by Singh and Vishnoi generalizes the approach of the above to that the algorithmic problem of approximate counting (e.g. counting the number of spanning trees in a graph) is in a strong sense equivalent to computing max-entropy distributions.
http://arxiv.org/abs/1304.8108
Answer: The Bingham distribution is derived as the maximum entropy distribution on the hypersphere which matches the sample inertia matrix. This distribution have been used in a new algorithm to identify an object's orientation using far fewer data points than previous computer vision algorithms required.


Death of a US citizen father of a US citizen child with a non-citizen wife

Question: Bob is a US citizen married to Lily a non-US resident.  They live together in Europe with their US citizen daughter (born abroad).   If Bob was to pass away, would his wife Lily be eligible to live in the US with their minor daughter?
Answer: If Bob were to pass away, Lily can self-petition to immigrate to the US as a widow(er) of a US citizen within 2 years of Bob's death. (If Bob had filed a petition for Lily before his death, but she had not immigrated yet, it would automatically convert to a widow(er) petition; if no petition had been filed yet, then she has to file a new petition within 2 years of his death.)
If she misses the 2 years, then she can no longer has any path to immigrate to the US through Bob; she could see if her daughter will petition her when the daughter turns 21.
Answer: No. He would have to sponsor her green card before passing away. He can do this now even if they are not currently residing in the U.S. Otherwise she will not have any special entitlement to reside in the U.S. with their daughter until the daughter is able to sponsor the parent upon reaching the age of 21.
Comment: Not unless the rules have changed (which they might have). My wife was able to get a green card despite us not living in the U.S. We explained that we had plans to move (which at the time, we did). We never made that move, and she held that green card for two years before finally relinquishing it. I think it depends on your intentions. If I remember correctly, once you are approved, you have to enter the country within a certain  time period, and must reside in the country atleast six months of the year afterwords.
Comment: Filing a sponsorship application wouldn't be sufficient, would it? Wouldn't the wife also need to immigrate to the US before the husband dies?
Comment: Right, but for the purpose of immigration law, entering the country within a certain time period after the approval of the immigrant visa constitutes immigrating, and residing in the country at least six months of the year constitutes maintaining residence there. Regardless of the label applied to these requirements, however, they are certainly additional requirements beyond simply "sponsoring her green card before passing away."
Comment: I'm assuming the OP's intention are to actually move permanently to the United States. Obviously if that is not the OP's intention, then my answer is not relevant. Also, I do believe that the immigration officers will have to be convinced of the OP's intentions. For my wife's that wasn't so difficult as I was worked for a U.S. employer. The OP's circumstances may not support her application.
Comment: I on the other hand assume that the couple plan to move the child to the US at some point in the future and are concerned about the effect on those plans of the US citizen parent's death.
Comment: Fair enough, I've upvoted user102008's answer as that is quite relevant to the OP's situation and your understanding. I'll let my answer stand just in case I'm not too far off (or their plans change).


1991 (I think) Trek 850 MTB bottom bracket replacement. Maybe similar to 830?

Question: I have a Trek 850 MTB that needs the bottom bracket replaced. Is there a standard size to order? If I take off the bike will there be a number that will help me order a new one or do I measure somehow? Thank you.
Answer: Bicycle blue book says the 850 came with a BB-Lp26 bottom bracket, which was 68mm wide, 110mm spindle length, square taper. There are some new (old stock) on ebay, but I don't see why a newer BB-UN26 couldn't also be used (or any other standard ISO bottom bracket made for a 68mm wide shell, with a 110mm spindle).
I'd measure the BB shell and spindle width, just to make sure. Shell width is self-explanatory. You'll need to pull cranks to accurately measure the spindle width, and a caliper would be best. If you pull the BB, this info might be legible somewhere on the BB. I'd try pulling it before ordering a new one. Remember that the drive side has reverse thread, so clockwise to take it off. If it's from 1991, it may be seized pretty well. You may need to clamp a BB tool into a vise and use the entire bike frame as leverage to get it loose. I've had to do this in the past.
Comment: Thank you, will try and take it apart and see. Have tried some other rigid fork bikes and keep coming back to this one.
Comment: Shimano cartridge bearing bottom brackets---and the handful of other company's copy-cats I've seen--have the model number, shell width and spindle length printed on a sticker in the middle of the cartridge.
Comment: Also note the offset of the spindle can vary, so the same length spindle may move  the chainline a few mm.One option is buy a BB from a LBS that allows you to return it for an different length spindle (or get a shop to do it). A few mm chain line change will make no difference, if anything go a bit longer rather than shorted spindle to ensure the chain clears the frame.


OS bootstraping process

Question: I try to understand os bootstraping process. Some questions are not clear to me.
One of them is :
How does bootstrap code in Volume boot record know about absolute LBA address of 0 sector of patition where Volume boot record resides?
Comment: Is there anything that http://en.wikipedia.org/wiki/Master_boot_record does not explain satisfactorily? Perhaps you could be more specific?
Comment: Do you mean 'Master boot record know about absolute LBA address of 0 sector of partition where Volume boot record resides'?
Comment: EFraim, I knew that MBR code searches in partition table LBA address of 0 sector of bootable partition and load and run Volume Boot Record code. But volume boot record code must to find osloader file in root directory of volume filesystem. But to load file in memory and run it you must know absolute LBA address. FAT BPB store only number of sectors, and all structures have relative addresses, as I know.
Answer: Within the VBR is a structure called a BIOS Parameter Block, named after the BIOS, the bottom-half of the traditional MS-DOS kernel structure.  Within the BIOS Parameter Block is a field denoting the number of hidden sectors between the partition and the (MBR-style) partition table entry that encloses it.  The VBR code simply reads that field out of itself and adds it to the Volume-relative Block Address to produce the LBA to read from the disc.
This is why it is impossible to boot operating systems such as Windows NT, MS/PC/DR-DOS, and OS/2 from secondary partitions directly, without assistance.  In primary partitions, the BPB field is simply the start LBA of the start of the volume, because the partition table that it is relative to is the primary MBR in block #0 of the disc, and everything works.  In secondary partitions, because of a quirk of MS-DOS version 3 that everyone has had to remain compatible with ever since, the BPB field is only the offset of the "logical drive" within the "extended partition" containing it, and the boot code doesn't work because it looks for the rest of the boot volume in completely the wrong place on the disc.
Boot managers provide assistance by fixing up the BPB on the fly.  The VBR code of course reads the in-memory copy of itself, not the on-disc copy.  So boot managers simply adjust the field of the BPB for secondary partitions to the correct absolute value, as they are loading the VBR into memory.  Then everything works.

OS bootstraping process


What is the life expectancy of a Mustache Parakeet?

Question: My daughter got Sam when he was less than a year old and he is now 38 years old.  My wife and I have been taking care of him for the last 30 years and we are wondering how much longer it's going to go on. Not that we don't like him, but how long will this go on? Does anyone with a Mustache Parakeet have any experience that can help us?
Comment: Lovely bird. Congratulations for looking after him so well.
Comment: I ask everyone if they want a bird and never had a taker.  We are just trying to outlive him.
Answer: This bird has had a good life and has lived longer than expected. The normal lifespan for this type of bird is about 25 years; some longer like yours and some shorter.
It can possibly keep going for another year or two but this is impossible to say for sure. One day you will find it dead in the cage and this will probably be unexpectedly hard for you.
Here is some information about the bird:
https://www.thespruce.com/moustached-parakeets-as-pets-390268


How to find out if a binary number is zero

Question: I was implementing the ALU from the specs given in my The Elements of Computing systems book. I am stuck on only one problem. How do I find if a given number is zero or not. One thing I can do is or every bit in the bus, and then apply a not gate on that. But there has to be some other elegant solution.
Comment: it doesn't sound like you're stuck really - more like you're unsatisfied :)
Comment: a X input NOR _is_ the elegant solution. In order to determine if the register contains zero, every bit must be examined to see if it contains a logical 0. You specified that you need a single bit output. Therefore you need some function with X inputs, and one output, like a NOR.
Comment: If speed is of little concern you could use a shift register, an or gate and a flip-flop and use a serial operation. The same logic could be used to add etc. Some 8-bit processors actually did this.
Answer: There's simply no way around ORing all the bits, as unsatisfying as that may seem. However, you are not restricted to two input gates in silicon either. You can build a 4-input NOR gate in CMOS logic by putting 4 series p-type transistors in the pullup network and 4 parallel n-type transistors in the pulldown network. That reduces the depth of your tree topology and therefore your propagation delay. You can only take that theory so far though before the cumulative voltage drop across the series transistors makes the pull-up not pull-up enough to be a "1"... four is a good rule of thumb if I remember correctly.
Comment: For a larger number of bits would using alternating NOR and NAND gates make sense? E.g., with fan-in of 4 gates, a 64-bit zero test could use 16 NOR gates feeding a result of 1 if the 4 bits are zero to 4 NAND gates which feed a result of 0 if all 4 bits are 1 (all 16 original bits were 0), these four results would then be sent to a final NOR gate. (I am not an EE, but that would seem to be better than using intermediate inverters—to get the all-zero result back to 0—and using only NOR gates.)
Comment: There might also be ways to partially fold the latency of zero detection into the addition latency.
Comment: What about using NMOS:  One pull-up resistor and X transistors to bring the level down to 0 if any input is 1?
Answer: The logic function is the NOR gate. That is the simplest logic function that exists.
Answer: The typical solution with 8 bit machines was that the ALU would produce a number of 'flag' bits that would represent the outcome of the most recent operation. While it would be possible to have any number of flag bits around (i.e., you could have a 'Z' flag for every register in your CPU), it's usually the thing you've just computed that you're most interesting in, so it makes a certain degree of sense to do it that way.
Some of those old CPUs would automatically set flag bits for almost every data move, while others would require you to stick a specific 'compare' instruction in your code if you just suddenly need to know if a certain register was zero. And whether you provide a zero check for every register or just for what's just been computed, there really is no simpler way to check for "is this word zero" than to just OR all the bits together.
Comment: This is also typical of the 32-bit ARM chips, and may be typical of most architectures. For the ARM, the APSR (Application Program Status Register) holds N, Z, C, V and Q bits (Negative, Zero, Carry, oVerflow, saturateQ) bits to provide other functions in addition to the zero bit you're looking for. These may or may not be useful to your machine.
Comment: I got the or solution alright, but it bugs me I have to use so much of logic to get just one bit. There has to be some elegant solution.
Comment: @Rick_2047 - you didn't mention what you're implementing this with, but I'm guessing an FPGA? It would bug me too, to have to tie up whatever number of logic blocks just to do a high fan-in gate. That's a good reason to only put in only one of them.
Comment: not exactly an FPGA but an HDL and hardware simulator.
Answer: Some CPUs, MIPS for example, have a register that always contains zero, making testing another register for zero very fast.
Comment: a comparator... which degenerates to a glorified NOR gate...
Comment: How do I check the number if I have a register containing zero? Also I want to generate just one bit which is true or false depending upon if the bus of 16 bits is zero or not
Comment: He might gain something this way if the registers are cheap (they are in an SRAM block in an FPGA) and he needs a register compare instruction for other reasons anyway.
Comment: @vicatu - actually if you want to compare two N bit numbers, you'd need N 2-input XOR gates. The OR/NOR thing is only good for zero tests.
Comment: but ultimately i would need to use as many gates as I have input bits or at least as many transistors.
Answer: I am a big fan of or_reduce - most synthesis tools will optimize it to the best implementation since they know exactly what you are doing.
Answer: I found this post for the same reason as the OP - trying to implement zr for the ALU in The Elements of Computing course.
zr is 1 if the ALU output is 0, 0 otherwise
The course provides a hardware simulator and a range of built-in predefined chips.
One of the built-in chips is an 8-way OR gate. An 8-way NOR gate is not provided. The ALU is 16-bit. I split the 16-bit signal into two 8-bit buses using a multiplexer. Each of these go to a separate 8-way Or gate. The outputs from each of the 8-way Or gates goes to a separate Not gate. The outputs from the two Not gates goes to an And gate. The output of the And gate is the function zr.
I tested this using the course Hardware Simulator v2.5.
Answer: We need to check if our output Array contains only 0 bits. If number that Array is representing is 0 then it's not Negative nor Positive in a math sense. So you can check last bit of output Array if it's equal to 0. Because in 2's compliment all negative numbers will have 1 as a last MSB  if MSB==0 then it's not negative.
To check if it's not positive either we can NEGATE output Array and ADD it to itself that will get us array full of 1's. Now we will add output Array to this full of 1's array. If output Array did contain any 1 bit it will generate carry that eventually will cause overflow and set MSB of the result to 0. If output Array did contain only 0's result will remain array full of 1's. And MSB will remain 1 too.
So now we
AND
(NOT(output Array[MSB]),
ADD[MSB](output Array, ADD(output Array,NEGATE(output Array)))
Do that to check if number represented by output Array is nor positive nor negative. Mb tho to use multiway OR for all 16 bits is easier and better.
Comment: What is the sign of a two's-complement zero if "it's not Negative nor Positive"? What does "Mb tho to or all" mean?
Comment: @ElliotAlderson I thought that 0 is unsigned, because positive and negative numbers are defined in relation to 0.

 To OR all - I mean to apply multiway OR gate to whole **output Array** so it will return 1 if at least one bit in the array is 1 - that would mean that it is not zero. As the marked as right answer suggests. It may be less costly because all this adding and negation that I did propose is not free after all.

  I'm going trough the same course as OP -The Elements of Computing systems book. That was my solution. It works but I don't know what is the most efficient yet.
Comment: Numbers are defined to be unsigned or signed regardless of their value. If you use a typical processor then the conditional branching operations will consider zero to be positive. In 2's-complement arithmetic, "positive" means greater than **or equal to** zero. On the other hand, floating-point numbers and sign-magnitude representations have both positive zero **and** negative zero.
Comment: @ElliotAlderson Thank you for explanation! I've edited my answer hope it looks better now.


What is difference between parallel compression and dry/wet knob on compressor?

Question: as I understand parallel compression works by sending some track to compressor with some settings, and then turning send knob how much you want. Doing this, you will get some of the unprocessed signal and also processed. But could you do the same with dry/wet knob on compressor itself? I just don't really understand the concept of this :)
Answer: In theory there is no difference. In practice, using parallel compression gives you more control over how the sound is processed going in and coming out. For example,you could process just the low end of a drum loop to add more power to the the kick. Also, since it uses bussing you could send the output of multiple tracks to a single parallel compressor and then mix in to taste.
Comment: What do you mean by saying that you could process just the low end of a drum loop ? I just thought that you could make 4 sends, each for different bands of frequencies and adjust knobs on your channels. Do I understand right ?
Comment: Well basically you could put a low-pass filter on the parallel channel before the compress. That would only let the low freq. pass through therefore allow you to compress only the lower freq. bands.
Comment: Be sure to use a phase-constant filter/EQ for this kind of stuff, otherwise you'll get funny phasing artifacts.
Answer: The dry/wet knob does the same as mixing between two separate channels with "dry" and "wet" signals.
It's generally easier to set up a compressor channel with 100% wet signal though, because by doing that you can a) mix with the faders (and do it so that raising/lowering the other doesn't affect the other as it does with the dry/wet knob) and b) can decide on the channel routing (what to send and how much) easily.
Answer: I'd say it's a personal work flow thing more than anything. Sometimes it's just easier and quicker to use that dry/wet knob than routing things about, depending on the DAW and the plugins in question. Most times I would route for the reasons mentioned above especially if the sound is a main part of what your working on. However if I'm in a hurry and want quick easy and good parallel compression I will use the dry wet on something like the NI compressors.


Can we measure "wavefunction" of quantum particles?

Question: We know that there is uncertainty principle, so question: can we ever measure wavefunction of particles? I do not think this is possible, but I am not sure. I guess that everything is probabilistic. (that's why, I believe, we have sigma level when we say we discovered some particles...)
Comment: Duplicate of http://physics.stackexchange.com/questions/10240/is-the-wave-function-objective-or-subjective?
Comment: The wavefunction itself is not physical, its modulus squared is (as a probability density function). So we cannot measure the wavefunction directly. And to be clear: the level of confidence we have in the discovery of new particles is not related to the uncertainty principle or the wavefunction of the particle, it is a purely statistical notion about the experiment.
Comment: For a photon, the wavefunction is simply the electromagnetic field, which is measurable.
Comment: There has been some interesting recent developments in this question, which are summarized in this article:

http://physicsworld.com/cws/article/news/2011/jun/15/catching-sight-of-the-elusive-wavefunction

To be clear, in this experiment you still need many copies of the system to gather statistics, but the observables directly correspond to the real and imaginary parts of the wavefunction.
Answer: If you are able to produce multiple copies of the same pure quantum state, then it is possible to reconstruct the wavefunction. In that case, you need a relatively precise experiment, as just measuring the position and building a histogram will only give you the mod-squared of the wavefunction. To get some information of the phase, you might try measuring the momentum distribution, which tells you about the mod-squared of the wavefunction's Fourier transform, but that comes up a bit short; to get the full quantum state you need to perform a state tomography protocol.
If you only have a single particle, getting the quantum state is impossible, because it contains more information than you can get in any one measurement and that one measurement will destroy the state. Even for a qubit, where only two states (and coherent superpositions of them) are allowed, any tomography protocol needs at least two measurements, with a large number of repetitions determined by the required precision.
Now, as to whether you can "measure" the "wavefunction", it is still a complicated open problem in quantum foundations. Operationally, in a tomographical protocol what you're doing is essentially diagnosing your preparation procedure, and there's no one right now that even pretends to know for sure whether the quantum state is in fact a physical quantity, or whether it is an epistemic thing related to our statistical knowledge of quantum systems.
Comment: The no-cloning theorem prohibits the copying of an unknown quantum state. Making multiple copies of the same state is required for many experimental systems. If I want a spin-up particle, and I build a system that always generates spin-up particles, then I have made multiple copies of the same state.
Comment: "If you are able to produce multiple copies of the same pure quantum state..." How do you do that without violating the no-cloning theorem?
Comment: ... which is why, operationally, tomography should really be seen as a diagnosis of the preparation procedure you use to prepare multiple particles in the same state.
Comment: Another example: You could start out with N copies of a known state and time-evolve each under the same unknown Hamiltonian. That would give you N copies of the same _unknown_ state. You could then proceed to measure the heck out of that ensemble and try to estimate the Hamiltonian.
Answer: According to this paper, an experiment was performed that measured the single electron's physical wave function by causing it to interfere with itself.  The interference pattern matched the predictions of the Schrodinger equation.  So, apparently this was a direct measurement of an electron's wave.
Hydrogen Atoms under Magnification: Direct Observation of the Nodal Structure of Stark States
A. S. Stodolna, A. Rouzée, F. Lépine, S. Cohen, F. Robicheaux, A. Gijsbertsen, J. H. Jungmann, C. Bordas, and M. J. J. Vrakking
Phys. Rev. Lett. 110, 213001 (2013)
Published May 20, 2013
I also believe that Bose Einstein Condensates are examples of macroscopic quantum wave functions.  Since it occurs when the wave functions of individual atoms "overlap" thus forming a single matter wave which evolves according to Schrodinger's equation.
However, I believe this begs the question as to what is actually occurring.  If the wave function is physical real but only collapses when there is some "decoherence", then physics needs to explain this mechanism of wave function collapse.  Furthermore, tests of BEC's show that the matter waves behave both classically and quantum mechanically based on whether all of the atoms in the condensates are accounted for by the experiment.(http://www.lkb.ens.fr/IMG/pdf/Toulouse-Leggett_April2012-2.pdf)
Answer: You can measure the amplitude squared of the wave function if you have many copies of the system. You can then make a histogram of the recorded observations of the systems. This histogram will tend to the amplitude squared of the wave function as the number of copies tends to infinity.
Comment: It is still a measurement of the wave function, it is just not a complete measurement as the phase is lost.
Comment: The downvote wasn't mine, but this only says how to measure the square of the wavefunction, not the wavefunction itself.
Comment: Just to add, by measuring in a different basis you can also measure the phase. However, of course with one measurement you can determine almost nothing about ψ at all.


Why would shapeshifters choose to keep an original form?

Question: In any modern story nowadays, shapeshifters always have an original form; Andalites from Animorphs or Mystique from X-men to name a few. It raises the question of why something that can change forms would even bother with an original form. Ignoring the unrealism of a creature evolving the ability to shapeshift, why would a shapeshifter bother having an original form?
Comment: From what I remember, the Andalites did not evolve the ability to shapeshift. They invented technology that gave the power to shapeshift to normal living organisms. That is why the human Animorphs were able to shapeshift just as well as the alien Andalites.
Comment: Note that some shapeshifters do _not_ have an original or default form, at least not one that is known. https://en.wikipedia.org/wiki/Nyarlathotep
Comment: Note that the Andalites can't stay shifted for more than two hours, and the technology requires them to shift back to Andalite before they can shift to something else.
Comment: I was just wondering, why didn't you choose T.J.L.'s answer to accept? It is a lot more true that Cort Ammon's. The reason a shapeshifter has a true from is because it had to be born. It didn't hatch/come out of the womb/whatever shifting between shapes, it was something. Cort just adressed how it's shape can affect its identity.
Comment: @XandarTheZenon I find that while yes T.J.L's answer applies to shapeshifters that gain their abilities, Cort's answer works for both people who gained and evolved the ability
Comment: Well, I take my opinions and beat them over the head of others to see which one breaks first. Then I go with the one that stands longest. Don't get me wrong, though. @CortAmmon gave a nice answer.
Comment: @TrEs-2b That's ridiculous. While someone may have a form they remain in most of the time, TJL actually talks about their true form. Something your born as.
Comment: It's been bothering me. You're born as. You are. You're
Comment: @XandarTheZenon You make a compelling argument, Xander
Comment: I always assumed shapeshifts revert to their original form for the same reason people don't wear clothes all the time.  It's nice to get back to your original state.
Comment: It might cost them energy to maintain a different form than they were born as.
Answer: A shapeshifter doesn't "choose" an original form. A shapeshifter's "original" is whatever form it started as - that's what "original" means. That form is whatever it was in before it gained/learned/discovered its ability to shapeshift.
In cases where maintaining a shape requires concentration and effort (Odo in Star Trek: Deep Space Nine), has a maximum time limit, or is triggered by an outside influence or external catalyst (classic werewolves), a shapeshifer may have a default form that they revert to when resting (Odo turns to a liquid) or in absence of the catalyst (werewolves become human).
Shapeshifters without such a restriction (Mystique from X-Men) or with a default form not conducive to interaction (Odo, again) may have a preferred form. As Cort explains, having such a form helps such an entity reinforce its sense of self. Sentient beings in most stories want to have some way to be relateable to other sentient beings; a preferred form helps you maintain those relationships, too.
Comment: Out-of-universe, it's because they want one version of the shapeshifter that the audience can recognize as being the "real deal".  Rebecca Romijn, Robert Patrick, Rene Auberjonois, etc. are starring roles in their respective franchises, and the audience needs to recognize them.  (Why do so many changeling roles star actors with 'R' names?  Hmm...)  In other cases, where the director wants to keep the audience guessing, there will be no default actor.  This happens more often in horror movies (e.g. The Thing), so that any person can suddenly be the villain, and thus you can never trust anyone.
Comment: Another nice example of a shapeshifter with a (probably) non-default preferred form is Nymphadora Tonks (the metamorphmagus from the Harry Potter series). I doubt she was born with purple hair.
Comment: IIRC in Animorphs they can only stay in that form for an hour, after which they can't shape-shift back.
Comment: @BlueRaja-DannyPflughoeft Two hours, but yes. One of the characters loses their ability to transform and gets stuck as an animal due to this, in the first book.
Comment: Mystique also has to concentrate not to shift back, compare to the moment, when she is training, and Magneto drops the bar on her (X-Men: First Class)
Comment: The Zygons from Doctor Who can only change into creatures that they have captured. The Clawdite species in the Star Wars universe can turn into any humanoid creature, but it requires concentration to retain such form.
Answer: In many stories, shapeshifters have a lot of difficult with their sense of self.  In a world where a physical shape is often associated with an identity, they would continually be bombarded with interactions from everyone based on their physical appearance.
Retaining an original form would be one way to make sure you have an identity that you don't lose over the years.  It's something solid and stable. (except for those rare circumstances where one shapeshifter emulates another, but its rare to find stories where they try to rob another shapeshifter's identity).
Comment: I have a species in one of my stories that can change its appearance at will. They typically incorporate a bauble, piece of jewelry, or symbol into all of their forms so friends can recognize them. Many are nicknamed after the feature they choose. I think it's a good compromise between recognizability and not wanting to be tied down to a given form. As an aside, assuming that a shapeshifting species would experience a loss of self from exercising a natural ability seems human-biased.
Answer: Reasons for why a shapeshifter would return to its original form:

A shapeshifter cannot remain in a new form forever and must return to its original form in order to survive.
Staying in another form requires a large amount of energy or concentration.
A shapeshifter must stay in his original form in order to have access to the benefits of his identity, such as his bank account for example.
A shapeshifter chooses to stay in its original form when it's around its childhood friends, to prevent confusion.
The shapeshifter feels sentimental about its original body the way we feel sentimental about our childhood home or our favorite movie.
Comment: For 2, even a mild amount of concentration or effort would make it annoying.  Imagine having to keep your pinky bent at all times, or to keep the beat of a particular song in your head constantly: wouldn't it be nice to relax sometimes?
Answer: As a metaphor, I will use online screen names.
A person can potentially have as many screen names as they like, with a different one on every site, and potentially several for the same site (discouraged as this might be).  So why is it that most people like to use the same screen name in multiple places?
People like to have an identity, something that others will recognize immediately.  While there are exceptions, it is human nature to want a symbol to identify themselves, taking on other forms mainly for practical purposes.
Unless a shapeshifter is particularly antisocial, it stands to reason that they might feel the same way.  This is also why a shapeshifter who does enjoy mixing it up somewhat might have a common 'mark' possessed by all their forms (for example, all of their forms have the same color skin or fur) so that they can be immediately recognized.
An antisocial shapeshifter will probably be different; in their case their shapeshifting may be an acquired power and they must expend energy to sustain an altered form.  Shapeshifting species are prone to defaulting to an amorphous 'blob' form when resting because this shape takes the least amount of energy to maintain.  Alternatively, they may have a form that they have more experience with and will generally stick to that one when another isn't more practical, simply because the familiar is comfortable.
Antisocial shapeshifters with capricious personalities and without physical limitations are the least likely to have an 'original' form.  Bartimaeus from the Bartimaeus trilogy is a good example, although even he has a common thread between his many forms (he prefers to take the shape of desert animals when possible).
Answer: Supposing you had a shapeshifter for which any form would be equally fitting (ie. we are talking about preferred forms, not original ones), and living in a non-shapeshifter society, I see several reasons for them to have such identities:

Keeping the face people is used to. This is specially important when dealing with people unaware of your shapeshifting abilities, but it is still appropriate in general that people is able to associate your body with your identity.
Bureaucracy. Generating a background takes time and effort. Even though as a shapshifter you can change your appearance as much as you wish, you will probably have only a few identities with a driving license. Similarly for other tasks, such as opening a bank account or renting a house. You may be good at creating fake documents, but some will still require a more careful creation. And they won't be as as shape.
Related to the previous reasons, some identities will require a more detailed crafting: name, job, marital status, studies… Some identities will need the shapeshifter to remember lots of information not to contradict himself. Thus these can be considered as "permanent" identities even if only presented to a few people.
Sentimental reasons: Martian Manhunter adopted the identities of dead people (often killed) as a tribute to them.
Answer:
Ignoring the unrealism of a creature evolving the ability to shapeshift,

Chameleons can change their skin color. Not shapeshifting, but a first step to that direction.
As a sidenote : they have a default/resting/original color that is different for each chameleon species but mostly green or brown.

why would a shapeshifter bother having an original form?

Assuming that the shapeshifter species developed this ability during their evolution, the "original form" is something they inherited from their ancestors.
Comment: Welcome to Worldbuilding Vandor76, can you please extend your explanation on why they would keep the original form? Because the first part of your answer is a comment rather than an answer to the problem, so apart from the citations, only the last sentence is the part that contains the actual answer. Without further explanation, is not clear to me, why a shapeshifter would keep this form and how this differs to [this](http://worldbuilding.stackexchange.com/a/41055/13987) answer: *"That form is whatever it was in before it gained/learned/discovered its ability to shapeshift."*
Answer: I think it depends on how the actual shapeshifting works.
In engineering there are three type of deformation:
Elastic Deformation, Plastic Deformation, and Fracture. I won't consider fracture.
In elastic deformation you apply force to an object to get it into a shape. Once the force is gone it will revert to its' original shape. Think about an elastic band. If your shapeshifter is an elastic deformer, then reverting to a natural form is what happens when you stop using the force keeping you in a particular form.
Keeping up the shapeshift costs energy so to stop draining that they will revert. That's why they prefer their original form.
In plastic deformation you apply force to an object to permanently change its' shape. Think about: clay.
If your shapeshifter is a plastic deformer, it probably won't revert to a natural state. Because keeping up the current form doesn't cost extra energy but the act of shapeshifting can cost a lot of energy. That's why they don't prefer an original form.
Answer: Speaking as a shapeshifter irl ( ͡° ͜ʖ ͡°) It is because we can't stay in the same form for too long. you can change your main form, but it is very hard as doing this would take a lot of energy, eating a lot of junk food for 5 weeks strait should do the trick tho
Comment: i'm also bad at spelling as i just did this and am posting as a rabbit.
Answer: Rejection of their powers. If they don't like or want to have powers, they could just stay in their original form and pretend that the powers don't exist.


How to Create Flowchart from java source code in Eclipse

Question: I would like to create the flowchart or sequence diagram from my java source code.
Is there any plug-in which can help me do that?
Comment: This question is FINE!
Comment: Are you trying to represent your source flow as sequence diagrams(check StarUML) or actually building a tool which will create sequence diagram using some data?
Comment: I have my full project source code in Eclipse. I just want to understand the flowchart of the whole project. something like call hierarchy or sequence diagram.
Comment: possible duplicate of [Eclipse plugin or a Open source tool to reverse engineer java code for sequence diagram](http://stackoverflow.com/questions/2972706/eclipse-plugin-or-a-open-source-tool-to-reverse-engineer-java-code-for-sequence-d)
Answer: ObjectAid is a free UML tool which can creates sequence diagrams. Another commercial tool to create sequence diagrams from existing code is Architexa. I use Architexa very often at my daily work.
Comment: Just fyi, Architexa has also just recently released a free edition.
Answer: Our tool, Code Rocket for Eclipse can produce both pseudocode and flowcharts from Java (and C/C++ code). The design views can be edited and any changes forward engineered into the code. It is not a free tool,  but there is a free 30-day trial. Also it is only for Eclipse 32-bit.
Comment: Just a quick update, Code Rocket for Eclipse now supports 64-bit versions of Eclipse.
Comment: update, it is an exe file and supports only windows
Answer: Is this post meant for flow chart?
Do You mean Sequence Diagram or Class Diagram
eUML is a good tool to create Class Diagram or Sequence Diagram
You can find it at http://www.soyatec.com/main.php
Answer: I am not sure if there is a plugin for this but there are certainly techniques for doing this. If there is no plugin available, theoretically, one could follow the approach of such techniques to build one. One such technique that comes to mind is contained in the paper Object naming analysis for reverse-engineered sequence diagrams by Atanas Rountev and Beth Harkness Connell.
Here's the abstract:

UML sequence diagrams are commonly used to represent object interactions in software systems. This work considers the problem of extracting UML sequence diagrams from existing code for the purposes of software understanding and testing. A static analysis for such reverse engineering needs to map the interacting objects from the code to sequence diagram objects. We propose an interprocedural dataflow analysis algorithm that determines precisely which objects are the receivers of certain messages, and assigns the appropriate diagram objects to represent them. Our experiments indicate that the majority of message receivers can be determined exactly, resulting in highly-precise object naming for reverse-engineered sequence diagrams.
Comment: Probably two far removed from a useful implementation, but nonetheless an interesting reference!
Answer: I found this Eclipse plugin Flowchart4j V 2.0.0 et
http://www.codeswat.com/
You can use it for flowchart or sequence diagram and export it to MS Visio.
It has only one disadvantage. You have to pay for it.
Comment: I wrote it. But works great :-)


What was the role of the bear in Norse mythology? (Are there bears in Asgard?)

Question: The Norse æsir gods had animal helpers, but did anyone of them have a bear? Have bears been found in graves, like dogs and horses et cetera? Are there Norse illustration of bears?
Some Norse warriors were called berserks because they wore the fur of bears. And fur from bears was an important export good.
Is it lost in the tradition because there never were any bears on Iceland?
And absent from archaeology because one couldn't sacrifice a wild animal that one doesn't own.
But while the wolf was an as dangerous animal, it was semi-domesticated and Odin owned wolves. Am I just missing alot of references to bears in Asgard, or did the bear have a different kind of role to play than other animals?
Comment: I remember a myth about the origin of iron and steel: one of both came from the paw prints of a bear and the other from the prints of a wolf. I can't seem to find it anymore though. If anybody has a tip about this it would be much appreciated.
Comment: It is proposed by some authors that the berserkers drew their power from the bear and were devoted to the bear cult, which was once widespread across the northern hemisphere.[6][9]  Wikipedia entry https://en.m.wikipedia.org/wiki/Berserker
Comment: The bear is depicted in the Beowulf story. Some version describe the Grendel with a bear head and the cult of the Grendel's mother dress as bears. Maybe the bear is considered an evil totem of sorts.
Comment: Wikipedia entry https://en.m.wikipedia.org/wiki/Berserker
Answer: You raise a really good point. It is strange that there are no bears in Norse myth. The wolf seems to have really engaged them, perhaps because of the duality of wolf/dog, tame and wild, while the bear to them was totally wild.
I wonder if @LocalFluff isn't on to something, because berserks were seen as totally outside society, too unpredicatable and dangerous to have around. (In Egils saga Skallgrim kills a servant when the berserker rage descends on him, and nearly kills his son.) A wolf could become a dog, but you can't tame a bear and put it to use or have it as a pet.
By the way there were a kind of berserkers, ulfhednar, who turned into wolves, although you don't hear so much about them.
PS - The Lewis chessmen include berserks, biting their shields.
Comment: Yes, there might be something here: the lynx and wolverine are also absent, and the boar has only one representative, and that is a construct rather than a "natural" animal. However, there are deers, grazing the leaves of Yggdrasil. Also, while you can make a pet out of a wolf, doing so is much harder than raising a dog. And you can actually tame bears: dancing bears were once common, and there is a nice short saga about and icelander who brings a tame polar bear to the court of king Sven of Denmark.
Comment: @andejons The alternative cost of domesticating a bear (or an elk) is to eat its meat and use or sell its hide. The meat and skin of a wolf is not as competitive, so it is relatively more economical to domesticate them. Maybe the myths of the animals had to do with the relationship between human and animal. Bears are not social animals and they have no other predator than post-stone age humans.
Comment: You need to have a wolf pup be less than three weeks to be able to tame it with any reliability, and even then it will not be as reliable as a dog would. See https://en.wikipedia.org/wiki/Wolves_as_pets_and_working_animals If you want a pet wolf, you pretty much has to deliberately go about getting one.
Comment: This is really interesting. What's the name of the saga about the Icelander with the polar bear? I think the fact that bears aren't social and not particularly economic explains a lot. I never thought about lynx and wolverine, but it's true that the other larger predators don't feature in Norse myth either.
Comment: @solsdottir It's a tattr, Auðunar þáttr vestfirzka.
Answer: Bears do not feature much in Norse mythology, at least when it comes to the stories involving the gods. The one story I can think of which even mentions them is how Gleipnir, the chain that fettered Fenrir, was made: one ingredient was the "sinews of a bear", together with several more fantastic items, such as the breath of a fish.
However, they do appear in other stories: in the story of Hrólf Kraki, the hero Bödvar Bjarki (the norse version of Beowulf) is asleep during a great battle, but it turns out that there is a great bear fighting in his stead. When he is woken up, the bear disappears. This is told in the Bjarkamál.
As for art, the only thing I can think of is some Vendel era metalwork, which contains what looks like a bear-man:
Comment: The elk (or moose) is also absent, isn't it? As opposed to reindeers which were nomadically domesticated (by the sami people in the far north and by not vikings AFAIK). I wonder if it has to do with elks and bears being undomesticated large mammal as the reason for why they aren't present in connection with the norse gods. And if it says something about the function of animals in their mythology. Those are the two largest animals in Scandinavia and they get alot of attention still today.
Comment: The bear man is probably depicting a berserker. If memory serves berserker literally means bear cape.


Correct meditation Technique

Question: I am subject to thoughts containing anger, hatred, resentment etc. which causes me lower back pain.
I am using medicines but useless because the relief is temporary.
I am a meditator but I watch breath at nose tip, which causes me more
tension after the session is over by 2 -3 hours.
I have read somewhere that watching breath at belly i.e. Dantian is also
recommended.
I have tried it once and found it more relaxing.
What should I do? Watch breath at nose tip or belly button?
I have been doing nose tip meditation for six months which took me sometimes to thoughtless awareness - but did not solve my problems of physical pain and irritability
Answer: Wise-reflection (yoniso-manasikara) is generally recommended as a preliminary practice to formal (anapanasati) meditation.
Here, the practitioner reflects/thinks thoroughly with reason & wisdom on the harm & dangers of anger, hatred, etc, in a manner conducive to give them up.
The Dvedhāvitakka Sutta describes the Buddha-To-be doing this practice before his enlightenment.
Answer: I'd suggest to leave anapanasati behind, do low-concentration ("dry") vipassana which will make you face and learn to face the anger (you will learn how to not attach to it, let it come & go, not judge yourself for it, not analyze and not make theories about the pain it causes), dtto for the back pain. There is nothing wrong with anger, it is your teacher just like pain; the attachment and unskillful dealing is the problem; by observing the pain or anger, you will get insight into yourself, and will learn to accept anger and pain as a part of you being human, and integrate it into your life skillfully, without (progressively) harming yourself and others.
(Explanation:) The reason for this is that people tend to use concentration (including anapanasati or brahmaviharas) to run away from conditions, instead of dealing with them. Those practices can be beneficial, but they have also their blind spots, and the best is to have a long-term teacher who can guide you here. Otherwise it  likely that the ego will use metta-practice to re-affirm itself, such as persuading you about being loving and caring when you're perhaps full of anger and hate. I've seen on a few occasions people developing metta-crust on the top of stuff they never dealt with; which means (a) they learn to live with lie (delusion) instead of being in the present and in the truth (b) in more difficult situations, the crust breaks and I was very surprised how quickly the seemingly loving person turned into almost a hate monster; they regretted that themselves later, but did not understand what happened.
Answer: If you are having pent-up anger, hatred and resentment, then  the maithri bhavana (loving kindness meditation) is what you should practice morning noon and night. It is not easy for everyone to properly do Anapanasati , and it is wrong advice to watch breath at belly. So if you have difficulty in watching the breath,  first practice Asubha Bhavana and Dhathu/indriya Bhavana. You should not mix one meditation with another. You should get out of one type of meditation to get into another. Anytime when there is wandering thought, the concentration is not there. The appearing of a nimitta is a sign of concentration. When you develop an anapanasati nimitta, and practice it further, then you need a good knowledge of teachings (suttas) for you to overcome obstacles that you face.
Answer: If you are having trouble with anger, hatred, resentment etc. then there is a couple of methods I could suggest. Sakyamuni Buddha taught the four brahmavihara (love, sympathy, joy, equanimity) for countering the type of thoughts you are having. This is good for whatever type of Buddhism you follow.
Personally, I am a Pureland Buddhist and we chant the nembutsu in faith of Amitabha Buddha. By faith I mean trusting in the Buddha's power, and don't worry about things outside of yourself. I have found that this inward reflection on Buddha's power makes me more loving and compassionate to others.
Answer: Certainly a variation of meditative techniques may be effective, but modern science has shown that massage therapy effectively reduces aggression (see http://www.ncbi.nlm.nih.gov/pubmed/12458696).
I've found that monitoring bodily feelings helps you trace the root of the negative thoughts. So try monitoring your negative bodily feelings then massaging that area, it seems to work well temporarily (not but permanently).
I've attempted to trace where my negative bodily feelings come from (which causes me have negative thoughts, say negative things, and take negative actions) and I've traced it to early negative childhood experiences (from around age 5 or earlier). It seems that these early negative memories stay inside of us unconsciously, unknowingly until death unless we do something about it.
In order to permanently end the pains you have to deal with the negative memories associated with those bodily feelings which is more complicated.

Correct meditation Technique


How can I solve the problem of optimisation the quantum computer?

Question: I am trying to solve the problem of optimization (VRP) with genetic algorithm and quantum computing in the platform IBM Q Experience.
But I am unable to advance on this. How can I do it?
According to my understanding of quantum computing, we cannot apply the two processes of crossover and mutation in their classic sense.
Comment: Hi Aicha! Is there a paper you're referencing? Most likely the experiments you want to run will be difficult given the available hardware, but some may be feasible
Comment: D-Wave's hardware is better for VRP optimization problems, than IBM's. Many people already have done similar optimization problems on the D-Wave hardware, including Volkswagen. Please look into it.
Answer: Please have a look at this paper: Ising formulations of many NP problems. It deals with binary optimization on quantum annealers (e.g. D-Wave). As mentioned in comments, quantum annealers are more suitable for optimization tasks in comparison with gate-based universal quantum computers like IBM Q.
Here you can find something more about D-Wave, how it works and how it can be programmed.


How to export a polygon based on elevations using a DTM or a DEM

Question: I have a LiDAR generated DTM and a DEM (accurate to 10x10 feet). I am trying to export a polygon within a boundary which includes all elevations below a specific number. Seems like this should be simple but I am having a hard time. Ideally, I would like this to be accurate to 0.5 ft.
Also, I no longer have a 3D analyst license. If that is the only way to deal with the DTM, I may procure a new license. I'm using ArcMap 10.2.2.
Answer: Note that both methods below will export non smoothed polygons boundaries. You may have to resample your DEM file to get smoother lines or use further smoothing techniques.
Step 1: Spatial Analyst (Classification)
You could use Spatial Analyst to classify your data in 2 classes:
1 = data within the boundary values (example : elevation < X meter)
0 = other data
Step 1 (alternative): Spatial Analyst (Conditional tool)
You could also use the Con Tool (Conditional)
Step 2: Spatial Analyst (Raster to polygon)
You will then have an integer raster you can convert to polygon with the Raster to Polygon Tool.

Step 1: QGIS (Classification)
If you cannot have ESRI's extension, you can alternatively do a classification opération with a formula in QGIS:

Load your raster layer
Click on the Raster menu/Raster Calculator
Type in the following formula replacing MyRaster by your data and ElevationMax by the maximum value):
(MyRaster@1 < ElevationMax ) * 1 + (MyRaster@1 >= ElevationMax )*0

This codes allow you to create a new raster with 2 values (0/1).
Step 2:  QGIS (Raster to polygon)
With that, you can convert it to polygon by going in the Processing panel:

Click on GDAL/OGR, then Conversion, and use the Polygonize (raster to vector) tool.

Convex HULL
Last method I can suggest :

Filter your source LIDAR file to keep only points of interest.
Create a Convex Hull for the remaining points (lastools, 3D analyst LIDAR tools, etc)
Answer: f I understand correctly you only want to create polygon boundary that surrounds elevations that are below a certain value...
Assuming you also have 3D analyst/ Spatial Analyst extensions, there are probably several different ways to do this.  Here is the Cut/Fill Tool technique but it involves several steps: I
(The Cut Fill tool but this requires raster as input and also outputs raster.)

Create a raster with a constant elevation of your desired "below"
Run the Cut Fill tool
Convert resulting raster to polygons
Net Gain (Fill) is your polygons "below" and Net Loss (Cut) is your polygons "above"
Clip Fill polygons with your boundary.


Is there a way to grab both keyframes and markers in blender?

Question: I have lots of camera animation binded to markers to switch between the cameras.
I can grab and scale keyframes, and the same goes for markers, but I cannot grab them together. Every time I need to move keyframes and markers I have to do it separately and this is annoying.
Is there a way to move them together?
Answer: Dopesheet's View / Sync markers.
Comment: This option has moved.  I'm using v3.4.1 and it's now in Dope Sheet > Marker > Sync Markers
Comment: Lol. It';s a necropost, brought by the bots to be active. The Skynet will definitely kill us all one day. :-/
Answer: Scale? After selecting the keyframes (Shift+RMB, in case thats the problem you are getting) click G and then you can move the keyframes either by using a mouse, or entering the number on your numpad.
Comment: It seems that moving markers this way works, but scaling does not.
Comment: Indeed it doesn't.


How to post a coupon discount in the ledger

Question: If I am interested in keeping track of the amount I have saved through coupon discounts, how can i Post the transaction on a ledger. Can't see discount falling into any category: asset, expense, liability, equity, or revenue.
Answer: The discount reduces your expense, but is not a revenue.
So what you should likely do is book them as an expense, but on the opposite side of the ledger (assuming double-entry book-keeping).
Hence, if you would normally credit an expense account when buying something, you would debit an expense account for the amount of the coupon when you use a discount coupon.
That will allow you to track the discount coupons that you use separately, as you can give them an expense account of their own.
Comment: Thanks Michael. I got the idea of treating it as an expense but what is the other account that should be changed correspondingly. It doesnt seem to be impacting any asset or liability or revenue or net equity.

Example: assume I purchased a guitar with my credit card while receiving a discount of 10% on the original price of $500. Here is the transaction journal entry
Credit Card Account (Liability) - Credit $450
Musical Instruments (Asset) - Debit $450

If I want to add an entry to track the savings made through coupons
Coupon Discounts (Expense) - Credit $50
?????

What is ?????