Why are switchgears rated in specific capacities such as 63A, 100A, 125A and so on?

Question: I am working in a consultant industry, wherein we get the switchgears from different OEMs. I wonder why the switchgears (including fuses and fuse-gears) and control gear assemblies are rated in the specific values for all the manufacturers. And these values do not deviate from the given 'slots'. One reason what I think which governs the factor for rating is the commercial feasibility, loads determined by the utility companies and consumers and safety standards, such UL, IEC. But I am skeptical if this is the only reason. By rating I mean the frame rating and not the trip rating (of course the trip ratings can be fine tuned to the desired load current). Please see attached the ratings of the Rockwell Automation's Allen Bradley breakers.
Comment: Plot them on a log scale and you'll find them reasonably close to equally spaced. This is quite an old series, also seen on (pre-1940) cameras, with lens stops at f6.3, f8, f10,f12.5,f16 etc. You can see 3 values per doubling.
Comment: Are you asking about the general benefits of standardization? Or how is your question different from "why are screws only sold in some sizes" or "why can't I buy three seventeenths of a litre of milk"?
Comment: @TooTea Is 'Standardization' followed for every electrical ratings ? I got your answer from 'why are screws only sold in some sizes'. Thank you.
Comment: @user_1818839 What is the relation of their values plotted on a log scale and their ratings being standardized ? It would be helpful if you elaborate by adding an answer. I am really interested in knowing why should we plot them on log scale.
Comment: Consider sets such as these: https://en.wikipedia.org/wiki/Preferred_number
Answer: The fuses and switches you see follow the R10 Renard series. This series of 10 numbers (1.00, 1.25, 1.60, 2.00, 2.50, 3.15, 4.00, 5.00, 6.30, 8.00), for each order of magnitude, provides an approximately-equal geometric spacing for ten component values per decade.
Why geometric spacing, and not, say, equal arithmetic spacing between successive values (e.g. 2, 4, 6, 8, 10)? It comes down to the tolerance and error allowance for each component. For R10 specifically, each value is about 1.26 times the previous value; a manufacturing process that provides a 15% tolerance can't actually make its nominally-valued components more precisely than this anyway. You might want a 117 A breaker, but any given 125 A ± 15% breaker might actually trip at 117 A (or 143 A) anyway. Better to design a system such that you know the breaker will trip before damage occurs -- either by using your 125 A breaker with components that can tolerate 150 A, or by using a 100 A breaker with your 117 A load.
Conversely, if we did use the 2, 4, 6, 8, 10 series, we'd have a mismatch: 50% tolerance in the first gap, but only 12% tolerance in the final gap. This is not particularly useful -- either the manufacturing process results in 50% tolerance and there's a lot of overlap at the higher digits, or the process can do 12% tolerance and some of the range is not covered.
A related concept is the E series of preferred numbers that you may have seen on resistors and capacitors. Capacitors with 20% tolerance usually come in the E6 range; brown four-stripe (5%) resistors frequently come in hobbyist starter kits following E12, and the blue ones match E24 or E48.
These "preferred number" patterns are everywhere. Convenient multiples across orders of magnitude are found in electronics, yes, but also (for example) in currency denominations. American 1¢, 5¢, 10¢, 25¢, 50¢, $1, $2, etc. follows this idea unevenly, but other (more sensible) currencies like the Australian dollar or the Euro follow a 1-2-5 pattern consistently. You can typically buy milk (or other groceries) in 0.25 L, 0.5 L, 1 L, 2 L, and 4 L. The A-series of paper sizes (e.g. A4) are each half the previous number's size. In photography, camera aperture F-stops and ISO film speeds both fit the bill. I'm sure you'll start seeing them everywhere.
It turns out it's really useful to say "I need the next one to be X% bigger" and these patterns just fall out of there.

(Addendum, the math):
Specifically for R10, the values are approximately \$10^{n/10}\$, where \$n\$ is an integer between 0 and 9. The values are then rounded for convenience.

Value
Nominal
Exact

1
1
1.000

2
1.25
1.259

3
1.6
1.585

4
2
1.995

5
2.5
2.512

6
3.15
3.162

7
4
3.981

8
5
5.012

9
6.3
6.310

10
8
7.943

Any \$n\$-step evenly-spaced geometric sequence can be calculated using the general formula
$$ n^{(i-1)/n} $$
where \$n\$ is the number of steps, and \$i\$ is an integer between \$1\$ and \$n\$ inclusive.
Comment: Side note: in some usage the values are *rounded*. For example, you will generally find 6A, 13A, and 32A breakers/fuses for low-precision installation use, although an order of magnitude higher, 63A, 125A, and 315A are used instead. On the other hand, small electronics fuses generally are rated at e.g. 3.15A, 6.3A etc.
Answer: I am mostly answering from a US perspective:
The ratings of fuses and non-adjustable circuit breakers are defined in the National Electrical Code:

These are very roughly a geometric series (though not the Renard series).  The general concept is explained well in other answers and the Wikipedia article on Preferred numbers.
At least historically, these ratings were approximately aligned with the nominal ampacity of standard wire gauges and the allowable overcurrent protection settings of standard distribution transformers.
But you asked about frame sizes, not trip settings:
At least at the lower ratings, it makes sense for manufacturers to offer switch and circuit breaker frame sizes and that align with standard trip or fuse values dictated by NEC so that each frame has one fixed-trip option that utilizes the full rating of the frame. (Fixed trip is very common in ratings 800A and below.)
Although manufacturers generally choose frame sizes from this list, they don't all offer the same selection of frame sizes.
Your excerpt from Rockwell gives 125A, 225A, 250A, 400A, 800A, 1200A, 2000A, 2500A, and 3000A.
Here are the frames listed in the molded-case circuit breaker catalog from Eaton:

EG-Frame (15–125 Amperes)
JG-Frame (63–250 Amperes)
LG-Frame (250–630 Amperes)
NG-Frame (320–1200 Amperes)
RG-Frame (800–2500 Amperes)

For each frame, either the minimum or maximum rating (or both) aligns with a value in the NEC.
Schneider Electric's Square D product includes these frames:

125 A B-Frame
150 A H-Frame
250 A J-Frame
250 A Q-Frame
400 A LA/LH
600 A L-Frame
800 A M-Frame
1200 A P-Frame
3000 A R-Frame

These options all align with the NEC values, but are a different set from those offered by the Rockwell or Eaton.
The choices made by each manufacturer are largely commercial or practical in nature:
Physical package sizes must be selected to enclose the required conductor and bus sizes related to each ampacity; certain trip ratings are more common in certain markets, so a frame may be offered to align with that, etc.
Eaton's product range includes some values that don't align with an NEC rating so it is most likely selected to harmonize with IEC offerings, so that the same product could be offered in different global markets.
Answer: Intersection of preferred numbers, as some have said already.  When the circuit breaker will trip is based on the amount of overcurrent, how long the overcurrent condition has existed, the design of the breaker itself, and the ambient temperature.  It's not exact, which is why circuit breaker datasheets have trip curves instead of a single +/- %.  This has big implications for selective tripping schemes, where you want a malfunctioning device to trip its own branch without affecting other branches.  Say you have a motor on a 50 A breaker and a control circuit on a 1 A breaker; you wouldn't want to have both powered from a 51 A breaker since it's very possible that the 51 A breaker could (because of manufacturing tolerances) trip before the 50 A breaker.  The preferred numbers space the values out at certain percentages so you don't have confusing situations like this.
The other "preferred numbers" situation arises from the installation.  The adage is that the circuit breaker is there to protect the wiring.  Wire is generally available in certain sizes with certain ampacities, not an infinite range.  Rockwell states that their 125+ A breakers are rated for 75 C wire.  Looking at ampacity tables, we see 100 A for 2 gauge wire, 150 A for 1/0, 175 A for 2/0, and so on.  If you're protecting the wire, it doesn't make sense to have breaker ratings that are too low to use the full capacity of one gauge of wire while being unsafe for the next smaller size.


Number of elements in an array char

Question: What kind of function can I use to know how many elements are in an array char?
sizeof() gives the number of 'spaces' available so it doesn't work for me.
Comment: Can you give an example please? eg. `char foo [100] = "bar";` - is that what you mean? You want the answer: 3?
Comment: yes that's right
Answer:
You want strlen.
char foo [100] = "bar";
Serial.println (strlen (foo));   // --> prints 3

Comment: If the answer worked for you please click the "accept" button (it looks like a tick). That way other people will know that the solution worked.
Comment: I had to wait a couple of minutes to do that
Comment: Note that this will *only* work if the data in your `char[]` contains an ascii string, and is properly null-terminated. Furthermore, if you have a long string in the `char[]`, and you overwrite it with a shorter string without adding the null-termination, you will get the size of the older string.
Comment: Quite right. My answer was for the question as presented. The things you mention should be taken into account for null-terminated C strings.
Answer: I know you have your answer from @NickGammon, but I'd just like to add a bit more in-depth information about how all this works.
sizeof() is not a function in the normal sense of the word.  It is an operator which gives you the number of bytes of memory allocated to whatever you pass to it.  If you pass it an array then it returns the number of bytes that array has available to it.  If you pass it a pointer to an array then it returns the size of that pointer, not the size of the array.  If you pass it an integer variable it returns the number of bytes used by that integer variable (2 on an 8-bit system like AVR, 4 on a 32-bit system like the Due).
So some examples:
char array[50] = "hello";
// sizeof(array) = 50.
char *array_p = array;
// sizeof(array_p) = 2 or 4 depending on architecture.
char single = 'a';
// sizeof(single) = 1.
char string[] = "hello";
// sizeof(string) = 6 (5 letters plus \0) - it allocates the memory at compile time to fit the string

Now strlen().  How exactly does that differ from sizeof()?  Simply put, strlen() counts the number of characters in a character array up until it reaches the character \0 which is the "NULL" terminating character of a C string.  Let's take the examples before but use strlen instead:
char array[50] = "hello";
// strlen(array) = 5.
char *array_p = array;
// strlen(array_p) = 5.
char single = 'a';
// strlen(single) = ERROR!  strlen() doesn't operate on single characters.
char string[] = "hello";
// strlen(string) = 5.

You notice it always returns the number of characters in the string up to, but not including, the trailing \0 character.
In its simplest form the strlen() function might look like this:
int strlen(const char *data) {
    int c = 0;
    const char *p = data;
    while (*p) {
        c++;
        p++;
    }
    return c;
}

Basically it starts at the first character in the string (*p = data), examines if it's a \0 or not (while (*p)), increments the count of characters (c++) and moves on to the next character in the string (p++).
If you want to iterate through your string in your program you could call strlen() first to get the number of characters in the string then use that value in a loop.  That is a bit wasteful, since strlen() first iterates through the string, so you end up iterating through it twice.  It is far more efficient to learn how best to step through each character in the string until you find the terminating character, such as how the strlen() function uses the pointer to move through memory.  You can also see just how vital it is that you ensure the \0 character exists at the end of the string, otherwise how will functions like strlen() know when to stop?  They can't know how long the string is (sizeof() will return the size of the pointer it is passed, not the size of the array), so they have to have some kind of manual marker, and the convention in C is to use \0.
Note that Arduino's print() functions actually do it very inefficiently.  If you do something like:
char message[] = "Hello";
Serial.println(message);

It will actually do quite a lot of work it doesn't really need to.  Taken step by step it:

calls println(message)
which calls write(message)
which gets the string length with strlen(message)
and calls write(message, length)
which then loops from 0 to length-1 sending each character of message to write() in turn.
finally prints the \r\n for the new-line.

So it actually ends nested around 4 functions deep, and iterates the entire string twice. A classic example of how to waste processing time.  By iterating through the string once looking for the \0 character in the write(message) function (step 2) it would operate at least twice as fast.  Good old Arduino...
Comment: Re "In its simplest form the strlen() function might look like this", in a shorter (perhaps simpler?) form it  could look like:  `int strlen(const char *data) {
    const char *p = data;
    while (*p++);
    return p-data-1;
}`
Comment: @jwpat7 I said "simplest", not "shortest and most compact".  That form, while smaller and more efficient, is much much harder for the OP (who is obviously *not* a programmer) to understand.
Comment: Agreed :)  Also easier to make mistakes in.  And if the `\0` is the last accessible byte in a segment, the `*p++` will fault. But `int strlen(const char *data) { const char *p = data; while (*p) ++p; return p-data; }` avoids that problem.
Comment: Actually, `*p++` won't fault even if the `\0` is the last accessible byte in a segment; the `*p` part will access the last byte; the ++ part will set `p` to an invalid address; but as that  invalid address doesn't get referenced, on a typical machine no fault occurs.
Comment: *It is a compile-time macro ...* It's not a **macro**, it's an **operator** (like "+" and "-" are operators). They are lower-level than macros which are things done at pre-processor time. See [sizeof operator](http://en.cppreference.com/w/cpp/language/sizeof). Also [Operators in C++](https://www.tutorialspoint.com/cplusplus/cpp_operators.htm)
Comment: Indeed it is. Three years ago I thought differently.

Number of elements in an array char


Is there a theoretical upper bound on the mass any new particles can have?

Question: One possible outcome of the collision experiments at LHC is the discovery of new elementary particles with large mass. Is there a theoretical way to derive an upper bound on the mass of elementary particles? For example, we have the electron, the muon and the tau particle. Can we be sure that there are no heavier elementary fermions with charge $e$? (Maybe there are some symmetry arguments?)
Comment: If Higgs counts as "new particle", then there is.
Also, there are lots of new particles at the scale of grand unification. And there may be an infinite tower of massive Kaluza-Klein particles if extra dimensions exist.
Comment: Well, this would be a bound on the mass of a particular particle. I'd be interested in whether there's a bound for the mass of *any* particle.
Answer: This needs an input from a theoretician. From my experimentalist's view point of the matter, the answer is "probably not" .
We do have the standard model, and it is symmetry based and masses are limited within this symmetry. Nevertheless, there are tantalizing indications of physics beyond the standard model, from deviations of measurements and theoretical calculations in several quantities.
Higher symmetries are envisioned, as supersymmetry, and indeed there, there would be an upper limit in the masses of all the particles, except that theoreticians will embed it into strings which are another ball park, where even a black hole can be considered an excitation on the string. So no upper bound calculable.
This question then will be answered by the Theory Of Everything, strings, according to string theorists. Or we will keep opening russian dolls to higher and higher symmetries and particles, as fans of the unpopular composite theories contend, until an alternate  TOE tells us whether we have reached a top mass.
Comment: Coming from a phenomenologist (in training :-p), I'm inclined to agree - at least, I can't think of anything we know to be true that would provide an upper mass limit. But I'm hesitant to definitively say "no" in case there's something I just don't know about or am forgetting.
Answer: A candidate for such an upper mass would be the Planck mass, at least from well accepted main stream physics. It is the mass where the Compton wavelength and Schwarzschild radius become equal.
http://en.wikipedia.org/wiki/Planck_mass
Regards, Hans
Comment: In string theory there are massive excitations of arbitrarily large masses. So it's not correct to claim that main stream physics constraints particles masses to be below the Planck mass.
Comment: @felix: but the heavier excitations are classified as black holes, not elementary particles. There is a continuous transition between elementary particle and black hole in string theory.


Word that describes an argument but particularly one of a savage, uncivil nature?

Question: I'm looking for a word that means an uncivil argument. Particularly one that would evoke images of aggression and vulgar word usage with no self control. I realize that I could just describe it like the above but I was wondering if there was a specific word that meant the above.
Comment: https://www.thesaurus.com/browse/free-for-all
Answer: Knock-down Drag-Down jumps to mind.  This is a metaphorical description that implies a physical fight which keeps going even when one of the combatants has been knocked down and they drag the other guy to the floor to continue the fight.  Describing an argument this way is very evocative.
Also tumultuous meaning loud, violent, and turbulent (which is also a good word).
Answer: "a stink" seems like a good fit, as in "raise or make a stink".
"I just can't believe you're making a stink over such an insignificant matter."
"The old lady raised a stink when the taxi-driver tried to overcharge her."

"raise a stink" - to be very vocal in one's displeasure about something; to make a scene.

My mom raised a stink when the store refused to accept her return without a receipt.
One of the customers is raising a stink about the service charge we included on his bill.
Answer: A tirade noun  OED

A volley of words; a long and vehement speech on some subject; a declamation; a protracted harangue, esp. of denunciation, abuse, or
  invective.

Tirade, akin to the Italian word tirata: volley, a very angry hurling of harsh words and strings of profanity. Tirades don't necessarily have to include cursing as any long, drawn out speech or epic declaration can be a tirade.
Answer: Might throw in "vitriol" to color that narrative.
Definition of vitriol
1: something felt to resemble vitriol especially in caustic quality
especially : virulence of feeling or of speech
Comment: Don't use code formatting in ELU.


Ground loop between Pc and projector via VGA cable

Question: Our hall has a projector hooked up to a PC via a VGA cable but we're seeing horizontal bars on the projector image when we turn on the lights in the hall.
I'm think it's a ground loop problem. I'm trying to eliminate ground loop between PC and projector via a VGA cable. I've tried hooking them to the same power socket which didn't eliminate the horizontal bars on the projector image.
I disconnected the safety ground inside the projector plug and the horizontal bars on the image went away, but I believe this is not a long term safe option. but does seem to indicate that the ground loop is the cause of the horizontal flicker/bars.
Is it possible to disconnect the ground signals inside the VGA cable to eliminate the ground loop without making it unsafe/losing the picture entirely? (pins 5-8, pin 10?) What would be the consequences of doing so?
I don't want to degrade my image quality, or risk damage. I'm also not super keen to "experiment"if I might damage something, and also re-soldering the vga cables is fiddly work.
Comment: Don't disconnect the ground wires in the VGA cable! The signals are not differential, they're single ended, in coaxial cables. They need the ground, otherwise what is their voltage referenced against? Disconnecting the ground isn't an option. With no ground reference, the signals will certainly have more 50 Hz buzz on them. You also run the risk of having the half-supply-voltage appear on the pins, maybe 60 V, which will destroy the projector, computer or both.
Comment: @tomnexus That was what I thought might be the case, but also I'm not comfortable with disconnecting the earth on the 3 prong plug which is the only thing I've tried that works so far. the common power cord extension didn't work, I think because the ground loop is caused by EM interference from the lighting system (old CFLs). The VGA cable and power cable run up the wall and across the ceiling to the ceiling mounted projector. Websearching found a VGA isolator cable but I can't find a local one to try out (I'm in South Africa)
Comment: I realise this is kinda old, but to anyone else going here (like I did today), if you also have an audio cable plugging into the computer that may create bit of a ground loop also, I fixed my flicker/bars issue with just adding a Ground Loop Isolator to the audio cable.
Answer: That approach is common in audio and industrial sensor signals for the reasons you've identified. The screen is usually left connected at the transmit end and disconnected at the receive end so that may be worth a try. Get a short male-female cable to hack and install it at the projector end.
We're short a few details on your setup. What kind of lights? Fluorescent, incandescent, dimmers, etc.
Ground loops cause problems because of either a) a difference in ground voltages between the signal source and destination or b) because of induced currents in the loop due to EM interference.
Something that may be worth a try is to power the PC and projector from the same socket. This should eliminate any ground potential differences. A temporary extension lead should be good enough to give an indication.
If you can run the mains cable close to the video cable it will reduce the cross-sectional area of the loop and that may help too. (I know this is usually not considered good practice and you may get some switched mode power supply interference.)
Comment: This is a terrible idea! VGA signals are not differential, they're single ended! Disconnecting the ground isn't an option. With no ground reference, the signals will certainly have more 50 Hz buzz on them, but you also run the risk of having the half-supply-voltage appear on the pins, which will destroy the projector, computer or both. What you're thinking of is disconnecting the *screen* from a differential cable, which is a valid way of stopping a ground loop. VGA cables are coaxial, the outer is not a screen, it's the other half of the signal (and there's an overall screen).
Comment: You're right about the power extension cord idea, that should solve the ground loop problem.
Comment: I tried the power extension cable idea before I disconnected the safety earth. That didn't work. The lights causing the problem are CFLs
Comment: @tomnexus: Good point about VGA not being differential but where would half-supply voltage come from? Which supply - mains or DC?
Comment: Mains. If one end were to be badly earthed, which can happen on a desktop and is often the case on a laptop, then the chassis might float at about half the AC voltage. Very little current available, so it is grounded as soon as you plug in a printer or a screen and there's no problem, just a bit of audio buzz maybe. But if there's no signal ground, it's bad. There's a question about this voltage each week on ee.se.
Answer: What you really want is a video 'longitudinal stop coil' sometimes known as a 'video Humbucker', basically a big common mode choke on the video lines.
It acts as a current balun, and push comes to shove you could build one out of a VGA cable and suitably large power transformer core by winding as many turns as possible of the vga cable onto the core.
One other thing that may help is to run a heavy gauge earth conductor in parallel to the video cable (Tape it to the side of the cable so the loop formed has minimum area), The objective is to bond the projector and the source so that the flowing current (Not a problem in itself) develops little voltage between the two because the parallel earth conductor is of such low impedance.
In really nightmare cases, both can be used, but the need seldom occurs.


capture key press event using xlib

Question: while trying to capture the F1, there is a problem, i can't capture it, because the system hook was execute showing the "help" content before my program,
could anyone help me?
Is there any ways to execute my hook before the system hook.
In Linux, when an Xserver executed an hook, it won't execute the next hook on the same-key press event.
Any helps would be preciate.
Answer: There is no "system hook" in X, just programs that started before yours and already grabbed the key (in this case, probably the window manager).   If this is just for your use, change the configuration of the other program.   If this is a program you're making for others, you'll need to make your keys configurable anyway, since you never know what keys the users
have already assigned to other applications to use, and they're more likely to discard your app if you try to force your keybindings on them.

capture key press event using xlib


In Python, when is platlib != purelib?

Question: Python has the ability to install platlib and purelib in different locations. What's the difference, why does this feature exist, and when is it used in practice?
Comment: you can install platlib or purelib in anything location as you like, python will check out the
PYTHONPATH environment var, and ~/.pythonstartup profile file etc when python start process. python moduel system depends on PYTHONPATH, site.py etc.
Answer: On 64-bit Red Hat-based platforms platlib and purelib are different. Here's the values for CentOS 7:
    'purelib': '$base/lib/python$py_version_short/site-packages',
    'platlib': '$platbase/lib64/python$py_version_short/site-packages',

This allows the binary extensions to follow the system convention of putting 64-bit binaries in a lib64 directory while the architecture independent files are places in a lib directory.
Answer: To quote from Installing Python Modules:

for example, if you want to maintain all Python module-related files under python in your home directory, and you want a separate directory for each platform that you use your home directory from[.]

(I.e., you're in a heterogeneous network environment where computers may run different operating systems but each mounts your homedir from a network storage server.)
Comment: I know platlib /can/ != purelib, but is it really done in practice?

In Python, when is platlib != purelib?


I want bring my desktop pc to the US, will the customs pass it?

Question: I'm traveling to the US from Malaysia and I will be bringing my computer desktop and monitor. Will I face any issues with US customs?
Answer: Generally speaking, you will not have any problems.
However please note that software piracy is a serious offense in the US and if you are suspected of carrying pirated software, your hard drive may be confiscated.
Please make sure you place your desktop and monitor in your checked-in luggage; because if you bring it with you in your carry-on - according to new rules, you'll be asked to turn it on at the security checkpoint. If you cannot turn it on, it will be confiscated.
Comment: The "turn it on" rules apply to things like laptops, tablets, phones, etc.  I doubt they would confiscate a desktop, since it is easily inspected for explosives by removing the side panels.  I carried a desktop on board earlier this year without incident, as there is no way I was checking it and risking someone stealing it and the data on the hard drive.
Comment: If you are carrying a traditional desktop "tower" then yes, but if you are carrying a compact desktop computer - like a mac mini or one of those small alienware boxes, then you have the same restrictions as the laptop.


What is this SMD component

Question:
Just out of curiosity I am trying to find out. What type of component is the green flat one in the picture?
Answer: It is a Polyfuse- a kind of self-resetting current limiting device.  There are a few different names for them. Here is a datasheet.

As far as names go, here is Wikipedia's take on it:

These devices are sold by different companies under various trademarks, including PolySwitch (TE Connectivity), Semifuse (ATC Semitec), "Fuzetec" (Fuzetec Technology), Polyfuse (Littelfuse) and Multifuse (Bourns, Inc.).[4] PolySwitch is the earliest product of this type, having been invented at Raychem Corporation (now TE Connectivity) and introduced in the early 1980s. Due to common availability, electronics engineers and technicians often refer to this device as a "polyswitch", in the generic sense, regardless of actual brand.
Comment: Awesome. Thanks a bunch. I suppose it is the same one that you can find on many arduino boards?
Comment: They are available with many (thousands) of different ratings and other specifications, so maybe not exactly the same.
Comment: I see, it is a PTC. I know what that is. ;) And it makes sense, of cause.
Comment: I've never liked PTC since they don't really have a Temperature Coefficient like the NTC Steinhart-Hart equation but most of the other names (like Polyfuse) are trade names, so I suppose it will have to do.

What is this SMD component


Why the change in gravitational potential energy of the two particle system remains same even when the both the masses are moving?

Question: When we calculate Gravitational Potential energy of the two masses, we fix one mass and calculate the force acting on the other mass. Work done by the the force which is acting on the fixed mass is zero. But Suppose both Mass acted upon by a conservative force (gravitational force on each other) so both the conservative force is doing work as both masses are moving so dont the potential energy= -Work done by conservative force of 1st mass + (- work done by the conservative force of 2nd mass). But in book this case has also the same formula for change in potential energy= -GMm/R which is the formula when one mass is fixed and other mass moving?
Answer: It appears that this question can be answered by a strict application of  Newton's gravitational law, undisturbed by any  intuition.
F=Gm1m2/r2 where r is the distance between the two objects translates into F=mgh, and "height" becomes distance. Both work and potential energy are to be calculated as you describe.
In the case you describe - both moving -  that is not different. It's a choice you make considering the planet, the apple, or the earth as "conservative", as point of reference. The formula disrepects the movements of both objects.
The formula applies in both ways, and the work or force only depends on height which is distance.
Distance may change if the conservative mass is seen as being moved. Even this is not different from the non-conservative mass being moved. Both changes distance, and the formula is to be applied anew.
When calculating the acceleration of the apple, the acceleration of the earth must be counted out; I think that's what the word conservative is about. It's either the apple or the earth that is taken for the conservative part, and  - "it works".


Will a magnetic flashlight attached to a metal junction box cause problems?

Question: I have a metal light switch box that is mounted on the outside of a wall and I would like to set a magnetic flashlight on it. Is electricity adversely affected by having a magnet near it?
Comment: Do you rune PowerLine ethernet anywhere?
Answer: Short answer: No.
Long answer: Nnnooooooo.
Serious answer: A permanent magnet, even one a thousand times stronger than the one holding your flashlight in place, placed near your home wiring but not moving has no effect on the circuit at all. A permanent magnet as small as the one on your flashlight, when moved around near your home wiring (eg. when you take the flashlight and put it back), will theoretically generate tiny surges of current in the wires. In order to measure those surges you would have to be a very careful physicist.
A magnet moved around near a metal junction box will generate tiny surges of current in the box walls. In order to measure those surges you would have to be a very careful physicist with pernicious insomnia. Theoretically a tiny amount of magnetic influence makes its way into the interior of the junction box, via screw holes etc. In order to measure those surges you would have to be a very careful physicist who is going through a bad divorce and expects to never sleep again.
All this is of no practical consequence. Any magnet you would have around the house cannot interfere with your domestic electric supply.
Comment: This won't affect GFCI and the likes? I can imagine them going partially blind, similarly to what happens if a DC current is present.
Comment: @Mast: Interesting. - The metal junction box should defend the GFCI from any nearby moving magnet. - But that would be an interesting experiment -- trying to trip a GFCI, that is not in a metal box, by waving a strongish magnet at it.
Comment: If that's your serious answer, I'd hate to see a flippant one!
Comment: I like the Llloooooong answer too!
Answer: Won't make a difference
For one thing, the steel box is going to weaken the magnetism.
But even if the magnet were in direct contact, it still wouldn't have an effect.  Because you don't have anything like a transformer or motor winding there.
(To answer the inevitable question, magnets can reduce the effectiveness of a transformer core.  Imagine you're jogging around your oval 1/4 mile high school track, round and round. Then the glee club sets up a stage, intruding on one end and forcing you to shortcut, that's like static magnetism intruding upon and saturating a transformer core.   Now it's not 1/4 mile anymore.  Thieves stick magnets on old style electric meters hoping it would under-report how much power they used.)
Answer: Going to tack-on an answer.
Even though your specific question has been answered 100% correctly, I want to point out that you should never stick anything magnetic to a computer or other delicate electronics.
When putting the light on the junction/switch box the amount of EMI generated is so tiny it really can't hurt anything.
When putting that magnet on a computer or similar, it could really mess things up.
First it could effect magnetic storage (tapes, and hard drives for example), and in some cases it could alter the "signal" voltage in, for example, Ethernet cables enough to cause issues.  Mostly though, the magnet, could, if strong enough, alter the voltages enough on the circuit lines of delicate electronics enough to cause issue.
The most common effect is likely to be distortion of other magnetic fields though, and not that of actual voltage.
That said, it's perfectly fine to stick where your describing, I just wanted to pop in and make sure it's clear that it's not ok to sick on, say, the back of a plasma TV, or your favorite collection of floppy disks.
Comment: As evidence of this, my son, when younger, discovered that holding a magnet up to the TV made the picture look "cool". He got bored but left the magnet there for a while. After discovery of the magnet and a stern lecture about it, it took about a week for the TV to not look so "cool" any more. (When said child was younger, the world only knew of CRTs, not LCD TVs...)
Comment: That's because the magnet adds a bit of magnetism to the colour (or color) mask in the CRT display and the added magnetism bends the electron beams. Some monitros used to have a degauss button that could be used to blip the stray magnetism off the mask... most useful when a company I worked for gave everyone a publicity -printed magnetic pyramid covered in paper clips and many users put them on top of their screens.
Comment: You can remove the part about it impacting PCs.  There is no component in a PC that will be impacted in any amount by a magnet the average person has access to.
Answer: In general no, it will be fine.
I would however avoid putting strong magnets near electricity meters. The accuracy on some models can be affected by the magnetic field, and others have sensors that will indicate a "tampering event" to the electricity company if they detect a strong field.


Raspberry Pi Camera Module, Time Lapse Photography

Question: I have created a Raspberry Pi time lapse photography by following the steps in this website:
http://computers.tutsplus.com/tutorials/creating-time-lapse-photography-with-a-raspberry-pi--cms-20794
What I'm trying to do now is how can I send the pics taken to a website or to a place where I can retrieve the photos on my computer
Any ideas?
Comment: If you google grieve.py you'll find a script which backs up /syncs your entire pi to a google drive account with instructions to add to the corn table. If you YouTube pimothion, you'll also find a really great video.
Answer: You could use samba on your raspberry to make the folder where your photos are saved  a samba share (windows filesharing) and connect this share to your computer as an own drive letter. So you can access the filesystem of your raspberry from your computer very easily.
-->  http://raspberrywebserver.com/serveradmin/share-your-raspberry-pis-files-and-folders-across-a-network.html
Or you can mount your raspberrys filesystem to your desktop box by using the ssh filesystem.
--> http://www.howtoforge.com/mounting-remote-directories-with-sshfs-on-debian-squeeze
Answer: I am using a Python script and Dropbox to put pictures which taken by my RPi server to my dropbox account. So when RPi takes picture Dropbox sync it to my computer automatically. Also i am using a Pushbullet service call to inform me about taking a picture. (You need to login pushingbox.com and create a scenario for this.)
You need 2 scripts;
1) dropbox_uploader https://github.com/andreafabrizi/Dropbox-Uploader
First, download then run dropbox_uploader to configure it. It will ask for your dropbox credentials and path for pictures.
2) shot-pushinbox-dropbox.py
<code>#!/usr/bin/env python
import StringIO
import subprocess
import os
import time
from datetime import datetime
from PIL import Image
import urllib2

# File settings
saveWidth = 1280
saveHeight = 960

# Save a full size image to disk
def saveImage(width, height):
    time = datetime.now()
    filename = "capture-%04d%02d%02d-%02d%02d%02d.jpg" % (time.year, time.month, time.day, time.hour, time.minute, time.second)
    # Take a shot
    subprocess.call("raspistill -w 1296 -h 972 -t 100 -e jpg -q 15 -o %s" % filename, shell=True)
    # Inform PushingBox that we have take a shot
    # Put your "devid" or comment it to disable pushingbox call.
    response = urllib2.urlopen('http://api.pushingbox.com/pushingbox?devid=vXXXXXXXXXXXXX&image_name=%s' % filename)
    # Upload motion image to dropbox
    subprocess.call("bash /usr/local/bin/dropbox.sh upload %s /" % filename, shell=True)

saveImage(saveWidth, saveHeight)
</code>
Edit as your need.
Answer: Another method you could use, is to install a ftp server on your PC and have the PI upload to the server periodically. If you are running an ssh server on the pi then there is always sshfs (ssh file system), sftp which is ftp over ssh (not the same as ftps) and scp (secure copy). The possibilities are endless. Any of these methods can be scripted for autonomy. It's funny I've been researching the same thing today for a PI bird box camera.


Wheel of life and bodhicitta

Question: Why is the desire/attachment in the middle of the
Wheel of Life considered negative and the desire of bodhicitta considered positive?
What is the difference between them?
Answer: You can think of this in terms of addiction.
For the most common example, let's take addiction to alcohol. The more you desire alcohol and the more you let your desire drive your action, the more you sustain your addiction, which makes you helpless and creates all kinds of trouble for you and others.
Bodhicitta is like desire to stop drinking. You desire to be free from the addiction. Which means you desire to be your own master. You develop the will power to abstain from drinking. You learn to resist the temptation. Moreover, you learn to generate the same type of relaxation and joy that you used to get from alcohol - through other, more healthy means.
The same idea is at play in Buddhism - except in Buddhism the context is much broader, we are not talking about any specific addiction - we are willing to be free from them all, any dependency on anything whatsoever. This is why it's called Liberation, being not bound, not dependent, not addicted, not controlled, free.
The state of mind when you are determined, intent on, convinced, motivated - to be free - which means being actively determined to make every action in context of the four right efforts - is called relative bodhicitta, while the state of having attained Liberation, or rather, mastered it, which basically means having completely mastered the four right efforts - is called absolute bodhicitta.
Now, somewhat counterintuitively, attaining liberation is not always done through passive means like letting go and acceptance. It also requires mastery of will power - particularly mastery over ones thoughts, emotions, mood, motivation, and energy. Not just mastery in the sense of being able to stop them and suppress them or accept - but in the sense of being your own power generator, your own mood maker, your own sustenance. It's the four right efforts, not the two right efforts - this is a very important point!
So these are two very different desires - one is the desire of weakness and addiction, to get your satisfaction from the outside - the other is the desire to be strong and not dependent.
Comment: Sadhu! Maybe an information or quote of what are the 4 balams would be good. The whole is correct, while the last sentence gives space to wrong, or: "the other is the desire of strength, to generate your own satisfaction." Nyom Andrei? It cortadicts the freedom or? And is just the way desire.
Comment: ok, I fixed it. Is this better, Samana Johann?
Comment: Looks much better from my persons view, yes. What about the famous Dhammapada verse about 1000 battles not equal conquering one self, Andrei?
Comment: yes, that's good too :)
Answer: The wheel of life is about the causes that create suffering, which is unrelated to bodhicitta.
Bodhicitta (the wish to attain enlightenment motivated by compassion for all sentient beings) requires a pure altruistic intention. Where as the wheel of life includes both unwholesome & wholesome desires that result in attachment & suffering.
This is the difference between them.
Comment: doesn't the wheel of life include wholesome desire too? and if there's a difference, then why say they're "unrelated". just being confused by your answer !
Answer: Within the Pali suttas I recommend the Bhikkhuni Sutta and the Brahmana Sutta.
Even though something (such as desire, for example, or conceit) is to be abandoned in the end it may be, if used rightly (if it has a right goal, or intention), a means ("by relying on it") for arriving there.
Comment: Evidence that what, is the evidence of what symbol? I assume that by "the symbol" you mean "the graphical depiction of the the Wheel of Life" ... so you're asking, "do you have any evidence that (what?) is the origin of the wheel of life"? I don't understand what your comment is asking.
Comment: oops my mistake, I misread the grammar of the question *Why is the desire/attachment, considered negative, in the middle of the Wheel of Life? and the desire of bodhicitta not and considered positive?*
Comment: i would like to upvote, but do you have any evidence that's the origin of the symbol?
Answer: Cary Jin,
let Atma give an explaining, and may it be of good use for Cary Jin and all those able to take and rejoice with it.
- Namo tassa bhagavato arahato sammā-sambuddhassa -
In the case "Bodhicitta" is understood as aspiration to reach "Bodhi", Awakening, the end of suffering, e.g. the wandering on in samsara, such is a Noble aspiration in the context of the path and a very needed desire to reach Nibbana, called usually positively "chanda" and not "raga" or "lobha".
Without this kind of "Bodhicitta" it's not possible to complete the path and go beyound suffering.
Such a "Bodhicitta" arises undestructable for the rest of the path with reaching the Stream, hence a person of such "Bodhicitta" can be understood as Noble One.
In the case understanding "Bodhicitta" as a motivation behind the aspiration, to reach the end of suffering, e.g. a higher wordily reason or wordily purpose, to reach "Bodhi", such is a defiled aspiration and the "Bodhicitta" of a wordling, merely seeking for becoming, not having heared and being familar of the good Dhamma. While it can be a helpful aspiration to set out in search for a path, here mostly still with a wordily aim, it is in most cases the greatest obstacel, even if standing right in front of the door to stream-enter.
Liking to become a Buddha is based on wrong view.
A very useful essay to get ride of the defilement of self-view, sakkāyadiṭṭhi, of this kind is Freedom From Buddha Nature, starting with:

"What is the mind [citta]? The mind isn't 'is' anything."
— Ajaan Chah
"The mind is neither good nor evil, but it's what knows good and knows evil. It's what does good and does evil. And it's what lets go of good and lets go of evil."
— Ajaan Lee

and it is useful to give it a read, for all those who like to do the task fist, given by the Bhagavato, Arahato, Sammāsambuddho of our times, who knew the path of "being simple a pathfinder" better then anyone, find the path to an end of suffering finally, and left the path, out of inmeasureable goodness - for the worlds beings with less dust in the eyes - behind. So to take it, the sacrify, rightly, is a matter of gratitude, which goes hand in hand with a beings possibility to gain a Noble kind of "Bodhicitta" and the reason why liberation always starts with "Namo". To understand "Namo" rightly , here also a "tantric" approach by Ajahn Mun

A Heart Released - Muttodaya
Practice is what keeps the true Dhamma pure.
The Lord Buddha taught that his Dhamma, when placed in the heart of an ordinary run-of-the-mill person, is bound to be thoroughly corrupted (saddhamma-patirupa); but if placed in the heart of a Noble One, it is bound to be genuinely pure and authentic, something that at the same time can be neither effaced nor obscured.
So as long as we are devoting ourselves merely to the theoretical study of the Dhamma, it can't serve us well. Only when we have trained our hearts to eliminate their 'chameleons' (see § 10) — their corruptions (upakkilesa) — will it benefit us in full measure. And only then will the true Dhamma be kept pure, free from distortions and deviations from its original principles...

And a "nice", maybe insiring "lovestory" around the change for a corrupt "Bodhicitta" to a "Noble Bodhicitta": "THE SPIRITUAL PARTNER"
Anumodana!
(Note: This is a gift of Dhamma, came into being by goodness received and gratitude and so given by goodness and gratitude, and not meant for commercial purpose and trade in the world, or any wordily gain.)

Wheel of life and bodhicitta


Physician's scale with sliding weights

Question: To me, a doctor's scale has eye-level weights that can be adjusted for maximum accuracy. Do such scales exist in France? What are they called?
Comment: I went ahead and edited your question to remove the part about where one can buy such a scale since that bit is off-topic. Otherwise your question is good to go :)
Comment: @GeorgesDupéron Done. Mais bon, j'ai toujours du mal à faire des réponses évidentes et qui ne demande aucun effort de recherche, je ne vois pas trop en quoi ça peut bénéficier à la réputation du site.
Comment: Really!!! Thanks for being so open-minded.
Answer: If that's you call a doctor's scale I haven't seen any of those in France for ages. I've had a look around and they can still be bought, they're called Pèse-personne à colonne mécanique. Pèse-personne being the word for "scales", à colonne for the vertical rod and mécanique as "mechanical".
Comment: The OP is asking for a *pèse-personne*, but for completeness I think it is important to note that the general translation for *scales* is *balance*. When scales are used for measuring the weight of a human, one mostly uses *pèse-personne* instead.
Comment: @Law29 OP was asking for a specific object (not about scales in general, a word he most certainly knew)  with the intend to buy one ("and where can one buy them") so I gave him the commercial name so that he could find one easily...
Answer: They are called pèse-personne à colonne as indicated by Laure.
The colonne signifies that there's a vertical rod or column, at the end of which the weight measurement can be read. Some "pèse-personne à colonne" are mechanical, some are electronic (based on how the weight is displayed).
The mechanism with the counterweights that slide on a horizontal bar is called "contrepoids coulissants" (sliding counterweights). There are other ways of mechanically indicating a weight, e.g. with a round display.
The full description of what you're looking for is a "pèse-personne mécanique à colonne à contrepoids coulissants".

Physician's scale with sliding weights


Is EF-SET English Certificate accepted?

Question: Is EF-SET English Certificate accepted for higher education or jobs across the world? Did anyone try using that? I have not yet seen any place where they accept this.
Comment: In my experience, no.
Answer: The EF-SET English certificate is a test you take online without any supervision. From the EF-SET FAQ:

If the test is available to the public online, how is it secured from cheating?
Because it is intended as a learning tool, using the EF SET to its fullest advantage is the learner's own responsibility. [...]. As an adaptive English test that covers multiple CEFR levels from beginner to advanced, the EF SET is designed to be useful to an individual as a measure of growth in proficiency over time and as a proxy to other expensive, high-stakes English tests like TOEFL, TOEIC or IELTS. To take advantage of this design, we advise that the test taker follow the timing guidelines and not try to cheat the test.

The homepage of EF-SET has three "buttons":

Check your students
Evaluate your employees
Check your English

So the EF-SET test is intended either as a self-assessment tool, or as a tool that can be used by universities or companies to evaluate their students/employees, in which case the company or university will take care of the supervision.
If you come with an EF-SET certificate that you got by yourself, the institution has no way of knowing that it was really you who took the test. Therefore, it does not make much sense to accept this as proof of English knowledge. I have never seen this accepted at a university.
Answer: I Was told to get the EFSET test from a company abroad and send the certificate to evaluate my English level. So I would say that it has some power. In fact, its a good test and very reliable if you are serious IMO.
Answer: I use EF SET to enroll in Japanese University (Monbu Scholarship) and has been accepted by the University for further step. Now I still waiting the announcement for the scholarship in June.
Comment: FYI, I've been accepted by MEXT and got the scholarship last year (2021)...now I studying at Japan university and next year will be graduate in March. Good luck to everyone!

Is EF-SET English Certificate accepted?


Transaction ACID properties with Hibernate Search + Infinispan Directory

Question: I have the following setup:

JPA (2.0) through Hibernate (4.1)
Infinispan as 2nd level cache (5.1)
Hibernate Search connected to Hibernate (4.1)
Infinispan as Directory for Hibernate Search (Lucene)
Connected a JDBC CacheStore for the Infinispan Directory
PostgreSQL (9.1) database to store both entities and Lucene directory.
Bitronix (2.1.2) as Transaction Manager
I'm not using Java EE, but Spring (3.1)

Infinispan as Second Level Cache is fine, no recovery is needed and you can read changes in your own transaction because of the nature of the Cache.
After hours reading source codes, when I update an Entity, Hibernate Search does not update the Lucene Directory but at the end of the transaction (if it commits), so it I wanted to do a search of the text I've just updated, inside the same transaction, wouldn't I be able?
But moreover, Hibernate Search does the updates to the Directory in a different thread, after transaction completion. So if one of the Directory Updates fails, then Lucene will be inconsistent to my entities? And if something happened before the updates were dispatched to the Directory and a recovery was needed, would those updates be lost?
Assuming this "first" transaction committed successfully, the updates were sent to the Infinispan Directory. A new transaction would be started here. By whom? Lucene has the options to send the updates using JMS. Let's say that option is activated, so the JMS message initializes the new transaction.
Infinispan will modify its memory directory with the updates it receives, but the persistent CacheStore will again be updated at this transaction completion, after commit. Therefore there is a chance that if something happens while updating the jdbc CacheStore, it will be left with no updates, but Infinispan Memory Directory will have them applied.
My question is, considering that all the modules I'm using support transactions, and that they even  support joining to global transactions (XA), is there a way to achieve true transactionality? Maybe I'm just not seeing it.
Answer: I'm working on a very similar setup. With these versions true transactionality is not possible. There are a few reasons, some of which you have noted:

Hibernate Search does index updates in commit phase
Hibernate Search processes on background threads - even when 'synchronous'
Infinispan cache store updates are done in commit phase

Here the transaction phase is important as the eventual inserts into the database need to be done in the main body of the transaction and committed at the end.
My solution was to ignore transactionality for index updates, it wasn't strictly necessary in my case.


Muddy sound from guitar

Question: I hear many guitar player saying that the sound of this electric guitar is very 'muddy' . I am a beginner. What does muddy means?
Answer: It can mean a number of things, but the result can generally be summarised as your playing sounds not clear enough.
Lack of treble brilliance is one factor, but not necessarily the most important. What I call a muddy sound is usually caused by too many low-ish pitched notes sounding together in an uncontrolled fashion. This is best adressed by

Having a clear concept of what you actually want to play. Don't play notes that don't really fit in a chord, especially not open bass strings. Jazzy variations can also be culprits.
Make sure that only the notes you deliberately play actually sound. Guitar strings aren't isolated systems like the tone generators of a synthesizer; if you simply leave them open they may ring even though you've never actually played them. Always watch out carefully for such "rogue sympathetic vibrations" and make sure you properly stop strings that sound in unintended ways.Similarly, make sure you stop notes after their intended duration is over (typically after each chord change).
Make sure the notes you do want to play actually come out well-audibly. Good technique and dynamics go a long way here. Listen to your playing and take care that important melodic notes really come out, whereas accompaniment is often better subdued. Palm mute is useful so you can give notes a distinct loud attack without causing an indistinct muddle of cross-ringing notes. Also, make sure you play well in time and with good intonation.
Sound also factors into this, though I'd argue equipment is less critical than playing technique. But a muffled high-impedance humbucker makes it much harder to bring out the right notes than a twangy Tele singlecoil. And in particular, distortion can quickly make an utter mess out of an only slightly muddy clean signal. So, keep the gain down when playing more chordal stuff, and treble up especially when doing delicate arpeggios etc..OTOH, sympathetic resonances can actually sound quite good on acoustic guitar, giving a nice "wide-open space" sensation. And be sure to actually know the sound. Always listen carefully to how the end result sounds, and if you want a high-gain sound on stage you should at least occasionally also practice with distortion.
Comment: Whilst agreeing mostly, I've heard good players using someone else's guitar, and that can and does sound muddy. Must be to do with the guitar in those cases. Done it myself!   One person's dull/muffled is another's muddy.
Answer: Usually referring to lack of brilliance, the strings probably old, and no brightness left in their sound. Like all the treble has been rolled off.
Comment: The sound of too old strings is better described as _dull/muffled_. This may contribute to a muddy sound, but it's not what I'd most associate with it.
Comment: @leftaroundabout It's not exactly a precise term... Depends who's talking.  Ignoring playing technique, I would absolutely call a guitar "muddy" sounding if something like a D over F# (as in 200232)  or had no clarity to it, and that can be caused by old strings (and I mean ooooold).

Muddy sound from guitar


Language Choice for Algorithm Competitions

Question: Hi everyone
I have just started taking part in online coding competitions.I would like to know which language would be better as regards efficiency and ease of debugging. I tend to avoid c++ and generally go with java.
1. Would some other language be suitable? How about c sharp or python or some other (No issues with learning a new one.)
2. Is proficiency in C++ necessary to do efficient programming?
3. And out of java & c# which is better for algorithm competitions?
Comment: Use whitespace or brainf*ck or just choose the one you know better.
Comment: x86 Assembly is still supported in the ACM regionals and World Finals
Comment: Second vote for Clojure if you are comfortable with Functional Programming.
Comment: Clojure, anyone?
Answer: I think this should be posted on programmers SE but this are my two cents:

I would suggest you to be proficient with C. Simplicity, examples and the thing that is the base of Java and C# will serve you as preparation for futures. Also, lots of example and demos are C based. See statistics at this site as an example.
I don't think c++ knowledge is necessary. But believe C one is.
Between Java and C# I'll go with C# for flexibility.
Comment: Do you feel hamstrung by the lack of built in data structures -- what if you need a linked list, self balancing tree, or hash table or something? Do you find it annoying that you'd have to be diverted spending time debugging these secondary building blocks that C#, Java, or C++ might give you?
Comment: @Doug - IMO, it's easier to work with links directly that to use a linked-list library, for basic operations at least. For more complex data structures, library containers usually win - but with the reservation that typically it's impossible to augment them, or to add extra operations that need internal access to the structure. Boost intrusive containers may be a good answer to that, but I haven't played with them enough to be sure.
Comment: @Steve314 -- Do Boost intrusive containers work in C? Boost is strictly a C++ library AFAIK.
Comment: @Doug - right - I should have said "for C++".
Answer: Use python
Firstly, python is shorter which in a competition scenario is a significant advantage.
Consider:
std::map<string, int> foo;
std::stringstream str(input);
while(!str.eof())
{
      std::string x;
      str >> x;
      foo[x] += 1
}

vs:
foo = Counter( text.split() )

Its not just that python eliminates useless typing, but it provides more powerful constructs which enable you more rapidly create your code.
Secondly, debugging works well.
Objects print out in a helpful way. Your can "print" any object. Containers will show their contents. This can be helpful when doing print style debugging. If you use a graphical debugger (I use winpdb), the introspective and dynamic capabilites of python give it the ability to easily view and manipulate all aspects of an object.
However:
The biggest problem is that contest has to support python. Things like the ACM typically require C, C++, Java, or similiar. However, many of the online contests do support python.
The second issue is speed. However, this is typically not that much of a concern because your algorithm is not supposed to suceed based on the speed of execution but rather on cleverness of algorithm. I.e. C++ may let you execute your O(n^5) algorithm better, but the whole is really to find the O(n) algorithm. If you find the right algorithm, the language doesn't matter.
Answer: I participate in the ACM competitions in the US and some online ones as well. For the competition's I choose Java for ease of debugging and coding. For online Judge's I tend to use c++/C because the judge computers are slow and I would rather just code the algorithm than spend time using different input/output methods in Java to get it to run (as some time limits are ridiculous and Java is a little slower at handling I/O sometimes). This is just my opinion but you're free to use whatever you want. The most popular language's are C++ and Java for competitions if you look at the final results language categories so you probably can't go wrong with either of those (obviously many others are supported just not used often).
Answer: I'd go with either java or C# both are very easy to debug with. In Java you have to find a good IDE which supports in debugging like
breakpoints
call stack
watched variables
watched locals.
But in C# you don't have to worry about anything all this already is built in the Visual C# IDE
Comment: ACM Regional is done on linux machines sometimes so you have MonoC# (MonoDevelop), Emacs, and Eclipse at your disposal
Comment: Oh snap yeah Visual C# won't work on linux, MonoDevelop is pretty good for cross-portability
Comment: It's about the same, I haven't seen any submissions in it because at the regionals it was c++ and java (my team uses both) and at WF it was mostly C++
Comment: Don't forget `gdb` for powerful C/C++ debugging. There are also some good GUI debuggers to interface with `gdb`.
Comment: @Jesus your region allows C#? In SoCal it's C, C++ or Java -- same as finals.
Comment: @Daniel, yep SE region
Comment: @Daniel, I should say it's in the list of supported languages which changed last year I believe because of that new annoying website based judge that they use (I freaking hate that thing)
Answer: Functional languages like F# and Haskell are worth a look if you're doing algorithms. Features like discriminated unions and pattern matching make mathematical/computational tasks a lot easier to conceptualize, prototype and polish.
F# is probably more approachable since it's multi-paradigmatic (it's also just as fast and often faster than C#), but Haskell is a fun challenge.
Comment: +1, but I'd suggest Objective CAML rather than Haskell. I'm not going to say Haskell is a bad language (though I have been an idiot about it in the past), but things like being in-place and order of execution are important in algorithms. Monads are *very* interesting, but the imperative-to-functional-and-back-again means you're pretty dependent on the optimizer to preserve your performance claims, and there are oddities with things like expressing a `while` loop (the condition must be within the monad) that strongly encourage a recursive style and make some things a tad awkward.
Comment: @Steve I left out OCaml because F# is a dialect of OCaml (it also supports monads) -- so they kind of fill the same needs, minus non-Windows interoperability if you really hate Mono. There seem to be some algorithms that are more natural to express in Haskell due to the powerful type system and lazy evaluation, such as some kinds of parsers. At the same time, there are some that are easier to express in F#/Caml due to its fundamentally imperative nature -- most famously Quick Sort. I think although Haskell is more challenging and slightly less practical, it's a good language to learn.
Comment: Absolutely Haskell is a good language to learn, I just have some odd criticisms. Very few compared to most languages, and I still can't really claim to know how significant they are in practice, but they really give my principles a hard time. Quicksort is a good example - pure functional code for Quicksort is commonly given as an example of how good Haskell is, but that code is *not* in-place and doesn't give in-place performance. Working with immutable arrays rather than the usual linked lists (!), you'd get O(n log n) expected **array copies**, for O(n^2 log n) *expected* performance.
Comment: Obviously that point basically means that you should use lists rather than immutable arrays, or use a monadic quicksort in a mutable array. But the lists version has a storage overhead for the links, and maybe a locality issue too. And the monadic version gets you beaten up for not writing properly functional code.
Comment: @Steve Totally. That's why I say F#/ML are better for things like Quick Sort. I honestly think that the immutable Quick Sort frequently used to demonstrate pure functional programming should really have a different name.
Answer: If the competition is timed, and any language is permitted, I would choose Perl.  Java is far too verbose, and the C standard library is much too limited.  Perl is so much better for programming competitions that it was banned for the UCLA Undergraduate Computer Science Association competition in 1998.
Answer: I've already upvoted...

Language Choice for Algorithm Competitions - for C
Language Choice for Algorithm Competitions - for Python
Language Choice for Algorithm Competitions - for F# (Objective CAML is it's parent language).

This is kinda stuff that should be in comments, but there's too much of it...
C gets rid of a lot of the unnecessary large-system stuff that's supported by C++, C# etc. You don't need OOP, templates etc to write small algorithm-centric systems.
That said, C++ has it's plus points - if you know it and you know how/when to avoid data hiding and other layers-of-abstraction-getting-in-the-way issues, use it.
Once upon a time, I'd have suggested Modula 2 (or a non-standard Pascal, possibly even Ada) as an alternative to C. There are some advantages to stricter typing, some disadvantages to the less rich set of operators, yada yada. These days, the world has mostly left these languages behind, though, so they're probably not real options any more.
Python will probably give you a much faster development speed, depending on what you're doing. It has OOP, of course, but it's easier to avoid it when you don't need it than C# or Java. The issues are (1) that the run-time performance may not be there if you're doing all the low-level stuff yourself (rather than use libraries that were written in C), and (2) there are times when you may want to manage memory yourself in low-level code - keeping things on the stack rather than cluttering the heap, not relying on garbage collection etc.
Python generators/iterators are also a very useful tool that you don't see in many other languages.
Writing critical components in C modules for use in Python is an option, but I'd be very nervous about getting into multi-language development with the time-constraints of a contest - there's at least twice the scope for things to go disasterously wrong.
Objective CAML is an impure functional language. It can do all the things a normal imperative language can do, and it has some very useful tricks from the functional world too. I'm not that experienced with it, but I certainly believe claims that it eliminates a lot of clutter, letting you focus on what you're doing - pattern-matching supports that claim for a start. And it's a native-compiled language that runs fast - though the "may want to manage memory for yourself" probably applies to Objective CAML (and F#) too.
Haskell - absolutely learn it, but not with the goal of using it for contests with a strong algorithms focus - but if you reach the point where you think it'll be a good choice, and you've understood my criticisms and rejected them (or found them valid but unimportant) - don't fight it either.
Answer: I think most easy to debug and language is C# (VS has many things to do is better.)

Is proficiency in C++ necessary to do efficient programming?

Not so! You should also know mechanism of machine.

And out of java & c# which is better for algorithm competitions?

C# but java is not so bad too. If you worked more with java in NetBeans, choose java.
Because after NetBeans its hard to get use VS.
Answer: Some competitions have a specific set of allowed languages, you don't have the luxury to use what ever your want.
For competitions I prefer a scripting and dynamic language, You need to code fast and see the result faster. More important you need to change code quickly.
Python, Ruby or JavaScript are strong candidates.
I participated in Google Jam in the past and Java wasn't the best choice.
If you are really comfortable with Functional programming (and I mean really comfortable), then I recommend this route.
Lisp, Haskell or Erlang are my personal choices.
Answer: I participated in IOI a couple of times, and coded in C. At the time, I did not know of OO, or even how to allocate memory on the heap (I allocated all memory I needed on the stack). All focus was on the algorithm.
However, nowadays, I'd stick to Java, because of the large library of algorithms and data structures available. But, of course, take into consideration that at IOI, you are not allowed to bring any prepared code, so a huge library of algorithms and structures is a great advantage.
Online competitions is probably another matter...
Answer: The problem you have is that different developers prefer different languages and this isn't always about a sound technical argument, rather which style of development they feel most comfortable in.
Personally I would hold a competition which has a category for each language.  The competition for each language should be set by someone who is a fan of that language (so the task will be something which appeals to other fans of that language)
Answer: I would use Common Lisp, because it is very pragmatic and expressive.
Comment: Care to elaborate on that.


When there is more than one amino group in a molecule, which group is more likely to react when forming an imine?

Question:
Why does the third group react in this example and not the first?
Comment: Perhaps, you can also elaborate on your thoughts as well?
Comment: Well the 1 group is an amide and the 2-3 group is a hydrazide.
Answer: Imine formation essentially involves an nucleophilic amine and an electrophilic carbonyl group. To decide which is the nucleophilic $\ce {N}$ atom which performs the nucleophilic attack on the electron-deficient $\ce {C}$, we would have to first consider each $\ce {N}$ atoms nucleophilicity, which we can interpret here to be the ability of the $\ce {N}$ atom to donate its lone pair of electrons.
For 1 and 2, the lone pair is delocalised into the carbonyl group and they can be seen as behaving as amides. This delocalisation significantly reduces their nucleophilicity. As discussed by Ron here, the delocalisation is so strong that restricted rotation about the $\ce {C-N}$ bond is observed. For 3, there is no such delocalisation present, thus the lone pair of the $\ce {N}$ is readily donated to electrophiles, making it the likely nucleophilic atom for the imine formation.
Another possible effect that raises the nucleophilicity of that $\ce {N}$ atom is the alpha effect, also discussed here. The following diagram (p. 513) from Clayden, Warren, & Greeves (2012) illustrates the molecular orbital theory basis of the effect. Although it is used to illustrate the effect for peroxide, the same concept can be extended to our case of nitrogen atoms. The adjacent $\ce {N}$ atom with the lone pair can increase the nucleophilicity of the $\ce {N}$ atom. However, the alpha effect may be less prominent for our case since the lone pair of the adjacent $\ce {N}$ is also being strongly delocalised into the carbonyl group. Nonetheless, it is an interesting consideration, further justifying why 3 should be most nucleophilic among the three.

Reference
Clayden, J., Greeves, N., & Warren, S. (2012). Organic Chemistry (2nd ed.). New York : Oxford University Press Inc.
Answer: This is semicarbazide semicarbazone reaction which is a nucleophilic addition reaction with the elimination of water. This addition reaction, like any other, involves a nucleophile (lone pair on N here, which one - we will see) on the nucleophilic center (carbonyl group). Thus the reaction will go more forward if the reacting nucleophile is more electron rich and thus more nucleophilic.
Now, 1st and 2nd groups are participating in conjugation (I presume you know about resonance, etc.) with -C=O group and hence their lone pair electrons (cause for nucleophilicity for them)are delocalised and thus less available making them weak nucleophiles. Thus, the 3rd group is the most nucleophilic and proceeds with the reaction.
Hope this helps!


UITableView reorder with tap within table

Question: A question for those who have used a UITableView in the past
I am currently using a UITableView in edit mode and I have the following data source / delegate methods implemented

(void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
//which tells me where the cell has been moved to
(NSIndexPath *)tableView:(UITableView *)tableView targetIndexPathForMoveFromRowAtIndexPath:(NSIndexPath *)sourceIndexPath toProposedIndexPath:(NSIndexPath *)proposedDestinationIndexPath
//which tells me where it may be moved

What I want to achieve:
when I pick a cell and reorder it, the cell should move up and down in the table view only while the finger is within the table view. Which means if I start from within the table view and move outside it, the cell should snap back in position and not let me reorder the cell.
The problem is that there is no way to find out (that I know of) where my finger is while the reorder is being performed. If I can find out where the finger is then it might be possible to achieve this.
Any ideas?
Answer: Take a look at the (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath function.  HTH.


How to get a single issue of a print journal

Question: My friend recently published in a big journal, and his article was also chosen to feature in the print version. However, he doesn't have a print subscription so he was not able to get a copy of the issue that featured his research. Is there any way I can surprise him by getting a copy of that specific print issue without paying for the yearly subscription?
Comment: Ask the journal.
Comment: Or ask someone who subscribes to give you a copy.
Comment: I agree with @JRN ... Many print journals do sell individual issues on their web site.  But it is likely not cheap!
Answer: It is likely that your friend already has reprints of the article; probably several, though they won't be the complete issue that the article appeared in. That is (or was, at least) standard practice. Having the issue itself probably has limited value for them.
Or, ask them for one of the reprints and have it hardbound with a nice cover as a gift back to them. If that isn't possible, a print of a PDF from the web can be bound.
I'd suggest you also consider something different, such as a bottle of some culturally appropriate beverage or something like a fancy pen or pencil inscribed with the date of issue of the article. That is both useful and a nice remembrance.
Comment: Maybe reprints are still common in some fields, but in mine they haven't been part of standard practice for a while now, though at least some publishers still offer them at a cost. C.f. [Have most journals recently stopped providing off-prints to authors?](https://academia.stackexchange.com/q/17512/17254), a question that was posted 10 years ago.
Comment: @Anyon, I am so (so) old. One can also have a pdf copy from the web bound as a remembrance. I retired before that linked article was posted and didn't join here until after. Live and (sometimes) learn.
Answer: Ask the publisher, this falls squarely in their domain. Try to reach the publisher's staff that handle the journal - most journals will have an email address on their webpage and/or ways to contact them, e.g. here's a form for the World Scientific journal Journal of Uncertain Systems.
Only caveat is that this is not likely to be cheap.
(PS: It's possible a library which subscribes to the journal will be willing to give you their print copy after a while. You could try asking them too.)


errors when using jQuery Booklet plugin with multiple jQuery libraries

Question: I'm trying to put the jQuery Booklet plugin on a site that uses the 1.3.2 library - I can't remove this reference or upgrade. I have successfully used noConflict in the past with other plugins that require a newer version of jQuery on this site.
When I test locally and include the 1.3.2 reference, Firebug console tells me:
but the book still loads correctly and functions. Not sure what that error means.  When I put the code onto my development site, the images in the book appear one stacked on top of the other, navigation buttons are missing, and I see an error in the Firebug console that says
TypeError: p2.offset(...) is undefined
[Break On This Error]
p2.offset().left + pWidth - hoverFullWidth,
In IE it tells me:
SCRIPT5007: Unable to get property 'left' of undefined or null reference
jquery.booklet.latest.js, line 1205 character 2
This is the code in question, part of jquery.booklet.latest.js
        p3.draggable({
        axis: "x",
        containment: [
            target.offset().left,
            0,
            p2.offset().left + pWidth - hoverFullWidth,
            pHeight
        ],

Something isn't loading correctly. The scripts look like this in my page in my development environment:

        <link href="/opencms/opencms/CVWEB/css/jquery.booklet.latest.css" type="text/css" rel="stylesheet" media="screen, projection, tv" />

Is there something extra I need to do with noConflict since there are so many other scripts? Do I need to modify the jquery.booklet.latest.js file to include noConflict somehow? I tried declaring the variable and replacing $ like above but that didn't do anything.
I looked here and here to try to solve the easing error, but I am already including all the correct scripts.
I tried the solution here of using jQuery instead of $ with no luck.
I'm still pretty green when it comes to jQuery so any help is appreciated.  Thank you.
I am about to move on to a different option but wanted to post here so I can learn what the problem is.
Answer: It must be your incomplete src location.
It should be something like this, as if running from localhost:


Asymptotic relation between $n^{lg (c)}$ and $c^{lg (n)}$?

Question: Assume that $c > 0$ is a constant and that $n$ is a positive variable. Then why is $n^{lg (c)} = O(c^{lg (n)})$? Furthermore, can you explain why $n^{lg (c)}$ is not $o(c^{lg (n)})$, that is $n^{lg (c)} \neq o(c^{lg (n)})$?
Answer: Taking the lg of both gives $\operatorname{lg}(c)\operatorname{lg}(n)$ so they are actually equal. Hence the provided asymptotics follow from $f\in\mathcal O(f)$ but $f\notin o(f)$.
Comment: I know that I have already accepted. But I wanted to say thank you. It really means a lot :)


How to detect incomplete multibyte character in WinAPI?

Question: I'm using MultiByteToWideChar to convert an UTF-8 encoded stream to wide characters. When there is an incomplete character and the end of conversion buffer, this function replaces it with '?' sign.
What checks/settings should I implement to detect incomplete characters for them to be prepended to the next buffer?
Answer: If you take a look at the Wikipedia entry on UTF8, there's a handy table that shows the possible types of multibyte configurations. The key thing with UTF8 is that initial bytes all follow one set of bit patterns, while follow bytes all follow another bit pattern. Notably all the follow bytes have the bit pattern 10xxxxxx.
It seems you can find a suitable break point by scanning backwards from the end of the string until you find a byte that does not match 10xxxxxx; if that byte is 0xxxxxxx, then end the string after that byte (since it's a single-byte sequence), otherwise end the string at/before it (since its the start of a multi-byte sequence), and add the byte(s) after it to the start of the next string.
Answer: how they do it in Python
Unfortunately that seems to be wrong as they only detect leading byte in a single position, while it can be a part of three or four byte long character and therefore harder to locate :(
Moreover that method works only for a few selected encodings, says documentation on IsDBCSLeadByteEx. And this article explains why, but doesn't make life any easier.


Need help logging on to 192.168.1.1

Question: trying to reset my security password- and same problem as listed- tried using admin for admin and password for password at  http://192.168.1.1  but seem to have locked myself out.
What should I do to unlock?
Comment: What is the make and model of your router?
Answer: When you reset a device to its standard, the default username and password will be used.
This can be admin / admin, admin / , admin / password or any combination.
The best thing to do is look for the model and make of the device, and google for that + default password. Also, if you have the booklet, it will also mention what the default username and password is. Mostly used is admin / admin
Answer: If you have reset your device to factory defaults then the username and password should be on the back of the device, if you know the make/model of the device you can also go to this website and lookup the default username and password for your default.
Some of them most common ones are

admin , blank
admin , admin
admin , password
admin , root
root , root

Need help logging on to 192.168.1.1


Can I compare items of both my main hand and off hand to a 2-handed weapon?

Question: I know you can perform a quick look at your off hand by pressing alt, but is there a  easier/quick method to compare both your main hand and off hand weapon to a two handed weapon?  (When I try compare them, it only shows it against my main handed weapon -besides doing some math)
Answer: Then you dual wield two weapons, and you compare a 2 handed weapon, it automatically compares it to both your main hand and off hand at the same time on the damage gains section.
I equipped a one handed crossbow. compared it to my 2 handed bow for an upgrade of 4197 points of damage. Keeping the same Hand crossbow in my primary I equipped another hand crossbow to my offhand, which increased my damage. Then I compared it to my 2 handed bow again for an increase in if 2940 damage.
It shows the status upgrades versus the main hand but its factoring in both weapons. It also factors in a shields stats if you use one.
EDIT:  As of patch 1.0.3, 2 handed weapons are now compared against the weapons in both of your hands.
Comment: It definitely does not consider the effect of removing your off-hand item, at least if that off-hand item is a shield or a wizard source. Equipping a two-hander means getting rid of a shield, but the protection is not factored in. Similarly, two-handers often report that they'd increase your damage, but then don't because of the loss of bonus damage from a source or bonus primary stat from a shield.
Comment: As of patch 1.0.3, 2 handed weapons are now compared against the weapons in both of your hands.
Comment: I'm pretty sure this has been fixed now such that a 2-handed weapon will correctly compare against the items in both of your hands.


When I attempt to calibrate extruder steps the increased values don't correspond to physical increases

Question: I am attempting to follow these instructions to calibrate the extruder, however when I increase the value for DEFAULT_AXIS_STEPS_PER_UNIT the change in physical output does not correspond with the changes.
I started by testing how much filament goes through the extruder when sending G1 E100 F100 to my printer, instead of the 100 mm I get about 38 mm (#define DEFAULT_AXIS_STEPS_PER_UNIT   { 80, 80, 400, 93 } in Marlin). I increased the value to DEFAULT_AXIS_STEPS_PER_UNIT   { 80, 80, 400, 149.73 } which should take it to 100 mm, when I tested the physical output the increase was only negligible so I repeated the calculation with DEFAULT_AXIS_STEPS_PER_UNIT   { 80, 80, 400, 387.8007 } as the new value. The new physical output is about 64 mm, I think this suggests a mechanical problem rather than a firmware configuration problem, but I am not sure where to go from here.
My printer is the Ender 3, running Marlin 1.1.9 with a BlTouch and an aluminium bowden extruder mod

(installed after the extrusion problem began).
Any help you can give will be greatly appreciated.
Answer: Mechanical?
You basically answer your own question that there could be a mechanical issue.
If 93 steps gives you 38 mm, to get to 100 mm, you need to divide 100 by 38 = 2.63 times. This implies that you need 2.63 x 93 = 244.7 steps/mm (not 149.73).
You even tried close to 400 steps per mm to see you are not extruding 100 mm of filament. This implies that you are either missing a lot of steps (increasing the stepper current or increasing the temperature of the hotend would help out) or the extruder gear slips on the filament (increasing the pressure on the extruder gear and filament could solve this).
Or not mechanical?
Furthermore, it could be another issue than mechanical. If your extrusion rate is too fast, the stepper might not be able to cope the high speed and miss steps. I have had this before with a too high of a retraction speed.
Comment: I sorted the problem, I took the extruder apart and put it back together again (although I don't think this did anything), and I changed the rate that the material is extruded down from 100 to 60 mm/min which I think is the speed the printer normally prints at and I was able to follow your steps and get 100mm of material for a 100mm extrusion command.


How to use singular form of noun for plural things?

Question: "The villagers reared goat and buffalo" is the same as "The villagers reared goats and buffaloes" even though the noun forms used for the animals in the two sentences are different. Why can we use "goat" instead of "goats" and "buffalo" instead of "buffaloes" even when the villagers reared more than one goat and one buffalo? Shouldn't plural form be the only correct form for the animal nouns here?
Answer: There is a tendency to treat some herding animals as having the same plural form as the singular form.  For some words this is always done: a sheep, many sheep; many deer.  In other cases it is optional but may carry particular nuance: many fish/many fishes. This is the case with "buffalo" which can be used as a plural noun "There are many buffalo in the field"
For goats it is unusual to do this. The choice of the singular is probably influenced by the presence of "buffalo". It also gives the nuance of thinking of the product as "meat" (non-count) rather than "animal".

The villagers reared pork and beef.

The villagers reared pigs and cows.
Comment: There is also a tendency to use the singular form for plural animals being hunted, e.g. three lion, four antelope, and there is an American expression 'loaded for bear', meaning 'prepared to attack a big opponent'.


can I install magento 1.9 module to magento 2

Question: I have one Magento 1.9 module, can I install to magento 2? There are any solution there? Because Folder Structure are difference in magento 1.9 and magento 2, If Migration tool can Migrate Single magento 1.9x Module to Magento 2.
Comment: How, tell me suggestion to do this?
Comment: Sorry there was a silly mistake in my comment, you can not install magento 1x  module on magento 2
Answer: You can not install magento 1.9(1.x) module to magento 2.
Because magento 2 have different architecture than magento 1.

Hope this helps
Answer: The magento1.x folder structure and the magento2 folder structure are different. So you can not install magento1.x module to magento2.
If you take a look on magento official document about migration you can see that there is only data migration available.
Check this migration document link http://devdocs.magento.com/guides/v2.0/migration/bk-migration-guide.html
Answer: You can't install magento 1.x module in magento 2.x beacuse of diffence in directory structure but you can convert your magento 1.x custom code to magento 2.x code using code migration tool. For more information follow the link - https://github.com/magento/code-migration. This  tool will automate the process of code conversion.


are words more independent from syntax in non-analytical languages? Does this affect language processing?

Question: When we think about the morphology and syntax, the debate arises. Even if they are protagonist parts of linguistic debates, and even if they are usually address separately, the importance of each concept and the confusion between them will vary depending on the main language of study. When it comes to Analytic languages, such as English, Morphology does not play a major role, so the lexicon is highly dependent on syntactic features. However, non-Analytic languages, such as Russian, rely mostly on the morphology of the word. Therefore, in these languages the distinction between morphology and syntax is very clear. However, there is not a strong consensus of where they differ and where they come together. Therefore, this arise the question, are words more independent from syntax in non-analytical languages? Does this affect language processing?
Comment: Generally, there is a lot of overlap between syntax and morphology; there are periphrastic constructions and shortened phrases. So analytic languages rely more on syntactic resources and synthetic ones rely more on morphological ones, but both can convert as needed. That's what the [Grammaticalization Cycle](http://www.umich.edu/~jlawler/Grammaticalization.pdf) is all about.
Comment: what do u mean by "independent from syntax"?
Comment: Actually you can say morphology is just syntax on a lower level.
Comment: As Annix recommends, you really need to explain the concept of "independent from syntax," how the degree of this quality can vary.   Please provide examples.
Answer: Though there is no clear measure for linguistic independence, I'd be tempted to say no to your question: "are words more independent from syntax in non-analytical languages?".
Analytical languages rely heavily on word order to convey a particular meaning whereas say agglutinating languages are a lot more generous so word or constituent orders. But there are still subtle differences in focus:
For reference:
<code>Mariska - nominal subject
kitette / tette ki - past tense verb with a locative adverbial particle
a - definite article
macskat - nominal object

+-------------------------------+-------------------------------------------
|  Hungarian                    |   English
|  Mariska kitette a macskat.   |   Mary put out the cat.
|  Mariska a macskat tette ki.  |   It was the cat Mary put out.
|  A macskat Mariska tette ki.  |   It was Mary who put out the cat.
|  Mariska a macskat kitette.   |   Mary PUT OUT the cat
|                               |   (as opposed to some other action she could have done to the cat)
+-------------------------------+--------------------------------------------
</code>
So clearly the syntax plays a major role in differentiating in terms meaning even though the same morphological constituents are at play.


Transferring ownership of a question

Question: Often enough, by the time I get a reasonable answer to a question, I've already worked around it or upgraded software far past the problem (e.g. I don't even own this camera anymore.)  That puts me in the position of not being able to test out answers to give a checkmark.  Is there a way to contact question upvoters and transfer ownership to someone still interested in the problem?  If there isn't is there a way for me to recommend it as a feature?
Comment: Upvoting does not mean that they have that camera and interested in the solution
Comment: I agree personally contacting upvoters would be a messy spammy thing, I was hoping there might be some stackexchange mechanism.
Answer: If you no longer have a vested interest in the question and it hasn't been reasonably answered (or you can no longer provide requested details). Just flag it to be closed at too localized. If someone comes along with a similar issue they'll be able to start their own question about it and follow up with it.
Comment: Really?  That question has what looks like good answers to a good question.  Does closing the question remove it from public view?
Comment: Like I said, "If you no longer have a vested interest in the question and it hasn't been reasonably answered (or you can no longer provide requested details)" It appears that question has been sufficiently answered. There's really no need to transfer ownership to someone else. If the answer doesn't work for someone new they can open a new question, citing your original question as their starting point, and the conversation can move forward from there.

Transferring ownership of a question


Teichmuller uniqueness theorem with marked points

Question: Let $S$ be a genus $g$, $g > 1$ Riemann surface, and let $h \colon S \to S$ be a homeomorphism of $S$. We denote by $[h] \in \text{Map}(S)$ the corresponding element of the mapping class group of $S$. We can without loss of generality assume that $h$ is quasiconformal. By Teichmuller's uniqueness theorem, among all quasiconformal mappings which are isotopic to $h$, we may choose $h$ to be a unique quasiconformal mapping which has the smallest dilatation.
Now let us add some marked points.
Let $S$ be a surface with $k$ marked points $x_1,\ldots,x_k$, and let $\text{Map}(S,k)$ be the group of isotopy classes of mappings of $S$ that fix the set $x_1,\ldots,x_k$ (the pure mapping class group).
Let $[h] \in \text{Map}(S,k)$. My questions are:
Will it be possible to find a mapping $h$ such that it has the smallest dilatation among all quasiconformal mappings which correspond to the element $[h] \in \text{Map}(S,k)$? In other words, do we have extremal quasiconformal mappings among mappings fixing $k$ points?
Given some extremal mapping, is it unique? defined up to a biholomorphism preserving marked points?
In particular, I am interested in the case where $S$ is the Riemann sphere and $k > 3$.
Answer: Yes. See, for example, W. Abikoff, Real analytic theory of Teichmuller space, Springer, 1980, Chap. II, section 1.5 Theorem 2.


How to change account and basket icons in RWD theme?

Question: I would like to change these icons to my own custom ones:

Anyone know how I can do this?
Answer: This is using image sprite.
You can find the image on rwd skin folder > images > icon_sprite.png.
So you need to edit the image on photoshop.
Answer: You can find the PSD file that was used to create the sprites in the RWD theme by looking for the Working With Sprites heading on this page: http://www.magentocommerce.com/knowledge-base/entry/ee114-ce19-rwd-dev-guide#customize-theme-images