Wrong inaugural move in game 2 of Carlsen - Nepomniachtchi

Question: In the game 2 of the current World Championship Series, the FIDE president Arkady Dvorkovich  made the inaugural move, which differed from what Carlsen wanted the move to be. How does this exactly work, are there any rulings on this? Is it just a "ceremonial move" which is then expected to be reverted/corrected by Carlsen and if so, why does Carlsen not let him know his actual first move for him to make the proper move? From the pictures I saw, Nepomniachtchi already started thinking once he saw 1.e4, which was not the actual opening, so I don't know if this opens up for silly, minor mind games and at the same time takes the symbolic power of the move away, since it has to be corrected anyway.
Comment: Never watched baseball, but I think I get it.
Comment: It's like throwing out the first pitch in baseball.  purely ceremonial.
Comment: You can see a video of the Carlsen-Nepomniachtchi Game 2 first move referred to by this question here: https://youtu.be/ZsOSHMBgfQQ?t=1887
Comment: Apparently this also happened in their game 3 and seems to be common practice, just read further articles.
Answer: This is purely ceremonial. Some famous person is invited to make the first move, and they usually do it without consulting the player. Why doesn't the player tell the famous person what move to make? I can only speculate, but my guess would be that it removes agency - the famous person can no longer pretend they're making a decision. It's also a small indication what opening move people like to see (although most of these ceremonial first moves are 1. d4 and 1. e4).
Sometimes you also get funny things like this:

President Gorbachev arrived at 4 p.m. and they were ready to start. Anatoly [Karpov] had white in the first game. Therefore, President Gorbachev would make the first move for Anatoly. As he arrived at the board, he told the audience that this is a wonderful match between two great champions. "I am going to cause some difficulties for the older player", he said, then proceeded to play 1.g4 without asking Anatoly. Both Anatoly and Susan [Polgar] looked up at President Gorbachev in shock. Anatoly thought that the President was joking as Anatoly mentioned that he would like to make another first move. But the President was firm in saying there is no take back in chess. Then the players started their first game.

(For context 1. g4 is one of the worst possible first moves for White)
Needless to say, this won't happen in serious games.
Comment: Saved you a click: "Because of this 1.g4 move, Susan achieved a very good position in the game. President Gorbachev was standing right next to them watching the entire game. All of a sudden, he opened the two bottles of water and poured some into the glasses to serve Susan and Anatoly. Susan was in shock! Here was one of the most important human beings on this planet in the last century serving her water! She could not believe it and she basically froze and lost badly after that."
Answer:
How does this exactly work, are there any rulings on this?

This is not a part of normal chess. I played white in a league game last night for my club and there was no famous person to make the first move in front of the cameras. This is something special for high level competitions. So, the obvious first place to look is in the special regulations FIDE publishes for these events.
For this world championship match the FIDE document is the "Regulations for the FIDE World Championship Match 2021".
This document covers many aspects of the match ranging from how sponsors can bid for the right to host the match through to remuneration for the arbiters, the appeals committee, the FIDE press officer, etc. There is one section covering the regulation of the match itself - 4. World Championship Match Regulations.
Although there are subsections in this section covering photography, TV, broadcasting and commentary, there is nothing about a celebrity making the first move.
If we look for help in the [FIDE Laws of Chess]2 we find at the very beginning that:

Article 1: The nature and objectives of the game of chess
1.1 The game of chess is played between two opponents who move their pieces on a square board called a 'chessboard'.
1.2  The player with the light-coloured pieces (White) makes the first move, then the players move alternately, with the player with the dark-coloured pieces (Black) making the next move.

So, it becomes clear. The game doesn't begin until the first player, the player of the white pieces, makes the first move. Anybody else moving one of the pieces is not part of the game. Indeed, it seems to be part of the advertising and promotion of the event made to look like it is part of the game.
Looking further we see that if this ceremonial "first move" could be considered "advice" then the white player should be penalised.

11.3.1 During play the players are forbidden to use any notes, sources of information or advice, or analyse any game on another chessboard.

Arguably the white player taking back the ceremonial first move and making their own could be see as the more correct play.
Comment: Wow such a detailed answer, thanks a lot! So basically it is not part of a game itself, more an organisational/ceremonial aspect like setting up the board and pieces for the players or taking pictures beforehand. It seemed more "official" to me based on the articles I read.


Why do news articles say that Bitcoins have failed?

Question: Many recent articles state that the great bitcoin experiment failed. Why is that? Has it?
Comment: This question appears to be quite subjective and I don't think it would be fit for the StackExchange format. However, it can be a bit interesting if you'd provide some examples of which articles you have in mind and possibly rephrasing the question.
Comment: It would help a lot if you link to at least two such articles. For example, it would help to know if [this Wired article](http://www.wired.com/magazine/2011/11/mf_bitcoin/all/1) was what you were thinking of.
Answer: Taking a look at the recent history of Bitcoin, say, one year, one sees a lot of problems that could hamper most projects. There was the speculation bubble, big price drop, many hacks on high-profile websites, Bitcoin being accused of promoting drug trade and so forth. At the same time there were few cases when Bitcoin was seen in a positive light - perhaps only the Good Wife episode. From that one could conclude that the project is likely to fail.
The real state of Bitcoin project is a bit more complex than that. There is a lot of money tied up with it (miners and investors), and the standard client is a quite stellar piece of software, but at the same time there are few opportunities to actually spend Bitcoins in a meaningful way, and a lot of the Bitcoin ecosystem relies on dubious security of third party applications.
Generally, the Bitcoin project will probably go through a period of remission from the limelight, hopefully giving enough time for the third party applications to shape up, the userbase to grow slowly and so forth, and only then start becoming more noticeable again, when it will start replacing other online payment processors. Alternatively, some major Bitcoin solutions might be taken down and the whole project could suffer because of that (say, if MtGox stopped operating).
Bitcoin is not dead, and it probably won't be shaped by the bigger news articles.
Answer: What you are describing is called Yellow Journalism - a pejorative to decry any journalism that treats news in an unprofessional or unethical fashion.
Bitcoin is something that is very hard to understand and also its anonymous nature makes monitoring its level of success something difficult to measure. As a result, making an assertion that Bitcoin has failed is something that can be made without having to being accountable even if that assertion might be false. Bitcoin's biggest supporters include many who could be classified as favoring libertarian ideals. Media bias exists, and generally doesn't favor libertarians.

For instance, consider the media bias against libertarian-leaning Ron Paul in this election:

http://www.youtube.com/watch?v=yTOVYnk4H-w


Examples of normal subgroups of a surface group with no embedded elements

Question: As a consequence of the loop theorem, if $F$ is a closed surface in the boundary of a 3-manifold and if the kernel $N = \ker(\pi_1(F) \to \pi_1(M))$ is nonempty then there is a nontrivial element of $N$ that can be represented by an embedded curve.  I read in Hempel's book that there are lots of normal subgroups of $\pi_1(F)$ that contain no nontrivial elements that can be represented by embedded curves.  How can I cook up such subgroups and prove that they have this property?
Comment: In fact, there's a finite-sheeted cover with this property. Any embedded non-separating curve is non-trivial on $H_1(F;\mathbb{Z}/2)$, hence will lie in the kernel of the map $\pi_1(F)\to H_1(F;\mathbb{Z}/2)$. Pass to the cover $\tilde{F}$ corresponding to this kernel; one may check that every separating curve lifts to a non-separating curve in this cover. So take the cover of $\tilde{F}$ corresponding to  $ker\{ \pi_1(\tilde{F})\to H_1(\tilde{F};\mathbb{Z}/2)\}$ to get a normal subgroup with the desired property.
Comment: @YCor : I made a mistake, saying cover when I meant to say subgroup (I internally make this identification between subgroups and covers in my thinking all the time, and many times  accidentally express it externally). In any case, the question posed about subgroups is equivalent to asking for a regular connected cover of the surface to which no simple closed loop lifts. Simple loops represent conjugacy classes of the fundamental group, and hence there is no ambiguity in discussing whether they are represented by an element of a normal subgroup.
Comment: @IanAgol it seems what you call "this property" is the negation of what the OP calls "this property". But none of you is explicit, and you're also not explicit on what you claim to prove "a finite-sheeted cover..." of what?
Comment: @IanAgol I understood that you were talking of finite index subgroups, but couldn't figure out what you claimed. I now guess you mean that for every $N$ there exists a finite index subgroup $F'$ of $F$ such that $F'\cap N$ contains no nontrivial element represented by an embedded curve.
Comment: @YCor : in your notation F' is the requested subgroup N. he's just asking for the existence of such a subgroup.
Comment: Yes you're right, I wanted to put $N$ into the picture and it's unnecessary. That's the interest of an explicit statement :) Namely that $F$ has a finite index subgroup containing no nontrivial element representable by an embedded curve.
Answer: One source of interesting examples is the lower central series.  In my paper
J. Malestein, A. Putman,
On the self-intersections of curves deep in the lower central series of a surface group,
Geom. Dedicata 149 (2010), no. 1, 73–84.
my coauthor and I show that the minimal number of self-intersections among nontrivial elements of the kth term of the lower central series of a surface group goes to infinity as k goes to infinity.


What's the meaning behind "blue paper"?

Question: What is the significance of "blue paper"? In the movie "Gangs of New York", when Bill the Butcher in his "Fear" monologue speaks about Priest Vallon, he states that he, "… cut out the eye that looked away. Sent it wrapped to him in blue paper…"
Answer: Bill the Butcher wasn't called that just because of his ruthless demeanor and murderous tendencies. He was also a literal butcher.
Butcher Paper has long been used by butchers to wrap meat and other animal parts. Given the context of the speech, he likely wrapped the eye in butcher paper because he had a lot of it just laying around for his business. It probably also served as a thinly veiled threat to Priest Vallon that this low-life butcher he just spared was going to kill him which is ultimately what happened.
Comment: @JasonPSallinger I'm not sure there can be anything other than speculation, but at least this answer mentions what butcher paper is and why someone like Bill the Butcher would use it.
Comment: Google, for example "sugar cone blue paper", Not butcher's paper *per se*, but blue dye for cheap product wrapping is well-attested.
Comment: Really this answer is no better than BCdotWEB's.  It is still speculation.
Comment: However butcher paper is traditionally white or brown. Blue is more usual for disposable hand towels, although I doubt that would be available in the time period.
Answer: I found this in Lexico, which is powered by the Oxford Dictionary:

Definition of blue paper in English:
blue paper NOUN

Blue-coloured paper, typically used for packaging commercial
goods, especially sugar; a sheet of this (now chiefly historical).

A light-sensitive paper used for copying maps and plans, typically
made by treating the paper with potassium ferricyanide and ferric
ammonium citrate; compare "cyanotype"(now rare).

We can reason out #2, and deduce he is talking about a commercial packaging paper based on the content.  It's merely a colorful, descriptive way of saying he wrapped it up in packing paper.
Comment: This is not speculation.  This is a bona fide answer.

What's the meaning behind "blue paper"?


firefox 4 - comet iframe, pushes(javascript) are not executed correctly

Question: I have an application that uses forever iframe(comet), this is working fine in firefox 3.6. But in firefox 4, pushes(javascript code that is sent from server) are not executed properly means firefox 4 is skipping some pushes, I have checked with firebug, there is no javascript error. I have tried, but unable to find the root of the problem?
Answer: I'm experiencing similar problems when using streamhub. This seems to be related to Firefox' speculative parsing.


My iCloud storage was not updated to 50GB

Question: So far I had iCloud Storage 20GB. But since Apple changed their storage, I should have 50GB, but there is still 20. Why?
Answer:
If you purchased a monthly plan before September 16, 2015, your
  account was upgraded automatically. If you're currently on an annual
  plan, you'll continue to renew annually at that rate. If you select a
  new monthly plan, your annual plan won't be available to you.

Source : https://support.apple.com/en-ca/HT201238
Comment: Don't understand. I purchased monthly plan before September 16, 2015, but my account was not upgraded automatically. Current plan is ok, but real storage is not ok.
Comment: I think you'll have to wait until the end of the current month (september),  it will change automatically at the beginning of the next billing cycle (first of october). This is just an assumption you need to contact Apple , they're the only ones who'll have the exact information.
Comment: I think you are right, I wait...:) thx
Comment: I'm happy to help
Answer: Answer from Apple after a few days:

We recently updated our iCloud storage plans and have increased your storage from 20GB to 50GB - at no additional cost. We increased iCloud storage so you can get even more out of services like iCloud Photo Library and iCloud Drive.
Your storage plan will automatically renew at 50GB on your current renewal date and your credit card on file will be charged 0,99 € each month until you change or cancel your plan.
The iCloud Team
Answer: I pay annually (not month-to-month), and had patiently waited until my Oct. 7th renewal date for the upgrade to take place. It never did.  I finally called today, and found out the free upgrade is only for month-to-month plans, NOT annual plans! :(


Solution for Electroplating Selenium?

Question: I need to electroplate selenium onto a conductive metal (for an experiment). The end goal is a thin film of pure, elemental selenium. Unfortunately I can't find anything on the internet: Ideally, I'd like a simple, inexpensive, and easy to make and/or find solution. Does anyone have any suggestions. (Also tips on suitable anodes would be helpful too!)
Comment: [This](http://www.freepatentsonline.com/y2009/0283411.html) might give you some ideas.
Answer: I'm not sure of any conventional ways of electroplating selenium, but you could use a technique such as magnetron sputtering to spray a thin film of selenium onto another metal. Heck, you could even use glass or wood if you wanted to do it that way. And if you're going for thin, this technique can get you some of the thinnest, smoothest layers of metal out there. A major downside is that your source metal sample has to be pretty pure selenium. But still, I think It's completely worth it.
However, If you don't have access to one of these devices, They can get expensive. Most major colleges with significant science majors will have one of these or something similar to coat samples for electron microscopy, or other reasons. Be sure to check there before going off to buy your own. Also, there are legitimate YouTube videos out there that show how to make your one device for magnetron sputtering. Check out this one if you're interested.

Solution for Electroplating Selenium?


Downloaded images/music files not appearing

Question: I've been having problems with my gallery and music app on my lg g2.
I recently initiated a factory-rest on my phone and I wanted to download an image to see if it would work appropriately, but it refuses to create a "Download" folder and put it in there.  They still download and I can open them manually by tapping on them, but the gallery itself doesn't create a folder to place it in. I poked around on my computer with the usb connection with my charger, and I don't see anything wrong.  Something notable though, is I did delete the .nomedia folder before I factory-reset, but it appears to have returned.  The files even show up in the folder, but they're not able to be viewed by the gallery app. I'm using the default one that came with the phone, and I have tried many solutions, but to no avail.  If there's a solution anyone can recommend to me, it would be very much appreciated.  Thanks!
Answer: It is common "bug", I would like to call, they will appear as soon as the mobile is restarted and files are registered in Media library.
Another trick I use is I copy that downloaded folder to another folder using a file manager, and voila. You should try it too.


What is the noun form of "erratic"?

Question: Erratic doesn't have a meaning related to error.  It means eccentric, or unsteady instead. Error has its adjective form as erroneous and errant. So what is the noun of erratic?
Comment: I think you're stuck with 'proneness to error' for the sense I think you mean (making mistakes). You can argue that this should be considered an open compound (rather than a mere collocation) which is then a 'compound noun'.
Comment: Check a dictionary. It doesn't have an English noun to derive from because it came directly from French and Latin adjectives. Google [ define erratic ] or visit [etymonline.com](http://www.etymonline.com/index.php?term=erratic).
Answer: ODO shows erraticism as the noun.

adjective
      not even or regular in pattern or movement; unpredictable:
erraticism
noun

It is related to error in that they both stem from Latin errare, to stray (from the truth in one case, from the straight and narrow in the other).

Increasing Monsoon unpredictability and erraticism
Though the erraticism of India's monsoons is fairly documented, research provides ample proof that global warming has added to the unpredictability and erraticism of the same.
Comment: Could there therefore be such a person as an 'erraticist'?
Comment: @WS2 I doubt it. It would be more likely to be *an erratic* (that sense, of an erratic person, is listed first for *erratic [noun]* in OED, but ODO isn't particularly helpful)
Comment: Can we get an example sentence of "erraticism" added to the answer? I'm having trouble figuring out how to use this in a sentence.
Comment: @MrHen "The quality of being uneven or irregular".
Answer: Erratic is also a noun.
erratic (noun)

an erratic or eccentric person.

Geology . an erratic boulder or the like.

OED returns several example sentences with erratic and erratics as noun forms.
Eg. Bacchic priests.... erratics or wanderers
Comment: As is *eccentric*.
Answer: Erratic is derived from a Latin participle of erro, the verb for "to wander, to stray" from which error is also derived. One might gloss it as "tending to stray from a regular course." Even error has this original sense of being "off-course."
As a comparison, the word "eccentric" literally means "off-center," and so metaphorically "wandering from a circular or regular course." There are two obvious noun forms. An "eccentric" is someone or something that is eccentric. Eccentricity is the tendency to be eccentric.
Nouns derived from erratic, however, tend to be non-standard: you are unlikely to hear anyone speak of "erraticness," "an erratic" (as in a person, though there are specialized vocabularies where this form might be used), or "erraticism." One is far more likely to use "irregularity" or "instability" or some other word.
Answer: erraticity: Event-to-event fluctuation
To quantify the chaotic nature of the event structure, a new measure called the erraticity was introduced.
A definition: (! .pdf)

erraticity (ĭr·ə·tĭs'·ĭ·tē) n. The quality or state of being erratic, characterized by the lack of consistency, regularity or uniformity.

Usage Example Phys. Rev. C 68

Event-to-event fluctuation in multipion production in 32S-AgBr interactions at 200AGeV has been investigated in terms of the newly defined erraticity measures χ(p,q), χq′, ωq, μq′, and rq proposed by Cao and Hwa. A comparative analysis of experimental data with that of random data and VENUS data reveals erratic behavior of the multiplicity moments signifying chaotic multiparticle production in ultrarelativistic nuclear interactions. (Erraticity analysis of multipion data in 32S-AgBr interactions at 200AGeV)

There are several instances of the term's use in research papers.
Not to be confused with the words of the same spelling, erraticity (paranormal studies): 'the state of errant spirits, that is, disembodied spirits, during the interval between two material existences' or, erraticity (nonce): 'a state of being so uberly erratic...emotionally, physically, and mentally.' :)

What is the noun form of "erratic"?


Timeout in Socket.Recieve

Question: I filched the following code from net to get GMT time from the site time-a.nist.gov. This code runs great but once in a blue moon it hangs. When I pause debugging the green arrow with the message "This is the next statement to execute when the thread returns from the current location"  shows next to s.Receive(ntpData);
<code>        public static DateTime GetNetworkTime(IPEndPoint ep)
        {
            Socket s = new Socket(AddressFamily.InterNetwork,
                                  SocketType.Dgram, ProtocolType.Udp);

            s.Connect(ep);

            byte[] ntpData = new byte[48]; // RFC 2030
            ntpData[0] = 0x1B;
            for (int i = 1; i < 48; i++)
                ntpData[i] = 0;

            s.Send(ntpData);
            s.Receive(ntpData);
            .
            .
       }
</code>
So I added the lines
<code> s.SendTimeout = 1000;
 s.ReceiveTimeout = 1000;
</code>
Now it doesnt hang but throws the exception "A connection attempt failed because the connected party did not respond properly after a period of time"
StackTrace: at System.Net.Socket.Recieve(Byte[] buffer, Int32 offset,Int32, SocketFlags socketFlags)
Is this a server site (time-a.nist.gov) issue and hence no recourse except to call it again?
Also is there any way to handle this exception and call the GetNetworkTime method again.
I'd appreciate any help on this problem.
Thanks in advance
Answer: The Socket Timeouts only work when you are using the async versions of the Read and Write methods: BeginRead and BeginWrite. The synchronous versions will hang indefinitely or until the connection is terminated.
Comment: The code without timeouts hanged but when I added the Timeout code it at least stopped hanging and threw exception that I've shown in my OP.

Timeout in Socket.Recieve


How do I stop my rim brakes making a squeaking/squealing sound?

Question: I bought a Schwinn Frontier Sport few months ago and started riding happily. After a few weeks my front rim brakes started creaking. It's so annoying in public places. My rear brake doesn't produce any sound but isn't as powerful as the front brake.
The retailer says cleaning would solve the front brake's issues and I got it cleaned, but nothing changed. Is there something I can do something myself to fix this?
Comment: If you bought it from a reputable bike shop their mechanic would, for free, "toe in" the front pads a hair to fix this.
Comment: It doesn't take a great mechanic to toe in your brakes.  It takes only a barely competent mechanic to do so.
Comment: Cleaning with products can make things worse, the only way to "clean" a brake block is with sand paper.
Answer: V-brakes can be hateful and make a lot of sound if they're improperly adjusted- sometimes they're noisy even when they're properly adjusted, especially on braking surfaces that are not machined. You can usually alleviate this with one or more of the following methods.

First and foremost, make sure your pads are properly adjusted. This is better demonstrated than described, so check out this youtube video to save yourself a lot of reading. If the link goes down, just google v-brake adjustment.
Make sure the braking surface of the rim is clean. Use rubbing alcohol and a green scrub pad to scrub off any crud, and then wipe the braking surface off with a clean towel with a dab of alcohol on it. Using anything besides rubbing alcohol may leave a residue and make the problem worse.
Toe in the brakes. I found this image which not only illustrates what "toeing in" your brakes is, but shows a nifty little trick to set the gap appropriately:

You may need to toe them in more that what this picture is showing if they continue to squeal on you.
Comment: This was a very helpful video as i have just bought a new bike two weeks ago, and it has rained lot and my brakes are squeling alot
Comment: Rubber band trick is fantastic.  I've tried so many ways to accomplish that to no avail.  Brilliant!
Comment: I don't think that's a good video to link to. He doesn't toe the pads so following that video probably won't fix the problem.
Comment: @davidricherby thus the steps outlined in the rest of the answer.
Answer: Also make sure the washers are set correctly.
Comment: That's only the right arrangement sometimes, other times you need the thinner washer pair on the inside. And it won't help with squeal, only with braking force and making sure the pads don't slide off the rim or hit the tyre.
Answer: I'll tell you my scenario and what worked for me.
I'll list, in chronological order, all the changes I made, because in the end it might have been a combination of changes which fixed the problem and not the final step alone.
The bike: a steel hybrid bicycle with v-brakes; single walled rim, with black anodization; new brake pads.
Rim condition: the anodization 70% worn, wear groove still deep, rim in good condition.
Here are two pictures at different angles:

Step 0 (initially):
The pads are toed in slightly as all the instructions on the internet suggest. All mounting bolts tightened using the recommended torque. Rim cleaned with isopropyl alcohol. No play in fork or wheel bearings. Very loud squeal when braking hard (but not as hard as to have the rear wheel lift off).
Step 1: Tightened the brake arms and brake pads bolts slightly more. No improvement.
Step 2: Removed the wheel, tightened the bearings slightly more (but still allowing smooth turning of the axle), even though there was no play. When I put the wheel back on, I tightened the QR skewer a bit more too. No improvement.
Step 3: I slightly sanded the rim and the pads using 600grit sandpaper, then applied a small amount of baby powder on rim and pads. No improvement.
Step 4: Added more toe in. The squeal got worse.
Step 5: Removed the toe in completely. I set the pads flat on the rim. The squeal was gone entirely.
I'm not sure why this worked on this bike. My other bikes with v-brake have the pads toed in slightly, with no squeal at all. I think there are too many variables that influence squeal, like pad material and hardness, pad shape, rim condition, brake arm flexibility, fork flexibility, temperature, humidity, spoke tension and lacing pattern, etc. But the most important one in my experience is pad angle relative to the rim.
Maybe someone will shoot a slow motion video, or do a more scientific experiment sometime that will reveal more information.
Comment: And yes, I'm absolutely sure I didn't toe out instead of toe in, initially.
Comment: Cool, sometimes you have to try things out and find out what works for that one bike, build your expertise that way.


Derivative and Integral of $\pi(x)$ (primes before $x$)?

Question: What's the derivative and indefinite integral of $\pi(x)$, which gives the number of primes before $x$? I know there's no answer in terms of elementary functions, but is there an answer in terms of other functions or series?
Comment: If by indefinite integral you mean antiderivative, then $\pi(x)$ has none since it has a jump discontinuity at each prime. Did you have some other meaning in mind?
Comment: I would suggest to add the fact that your function is $\pi(x)$ in the title, since it makes ur title more specific and it might help you get more help. :)
Comment: @Pinocchio Good idea :)
Comment: @SantiagoCanez I just meant a function that I could use to evaluate the area between two points. It doesn't have to be the antiderivative, if theres another way to define the area function.
Answer: The derivative of π(x) would be 0 except when x is a prime, when it wouldn't exist since  π(x) takes a step at prime values of x.
Answer: This is how I would think about it.
You know that $\pi(x)$ is approximately equal to $\dfrac{x}{\ln(x)}$ for sufficiently large $x$ (specifically as $x \to \infty$) http://en.wikipedia.org/wiki/Prime_number_theorem).
Thus, now you have expressed $\pi(x)$ as a continuous function that has a better chance of having derivatives and integrals. Now I would plug that into wolfram to see what the integral and derivatives look like.
Apparently, the derivative is $\dfrac{\ln(x) - 1}{\ln^2(x)}$.
However, the obvious disadvantages of this approach is that, the result is only valid for large values of $x$ , its an approximation and it only gives an asymptotic result.
Maybe if you provide more context or why you need this, a better answer might be possible.
Hope it helps!
Comment: Your welcome! I think the key intuition is to note that a function that is discrete doesn't really become differentiable/integrable until you consider something so large that the sum of the discrete and small things starts to become an integral and add to something that makes sense.


Memory management of GTK+ objects using Glade and gtkmm

Question: I am using C++ to create a program using GTK+ and glade. I am concerned about the memory management of the objects that the glade creates. For example, I create a glade file consisting of a window, a button and two entry fields. Then in my C++ code I create an object from that file and get a pointer to that window. My question is, do I have to safely deallocate the window object when I am done? If not, why do I not have to? Below is a sample of my code...
<code>#include <gtkmm.h>
#include "MattWindow.h"

#include <iostream>

using namespace std;

void buttonpush();

int main(int argc, char* argv[])
{
    //This line initializes the GTK+ system
    Gtk::Main kit(argc,argv);

    //Declare a pointer to a window
    Gtk::Window* window = 0;

    try
    {
        //Load the glade file
        Glib::RefPtr<Gtk::Builder> builder = Gtk::Builder::create_from_file("layout.glade");

        Assign window to point to the window object
        builder->get_widget("window1",window);
        window->show();
    }
    catch(Gtk::BuilderError& e)
    {
        cout<<e.what();
    }

    //Start everything up
    Gtk::Main::run();

    //Who destroys the object that window is currently pointing to?

    return 0;
}

void buttonpush()
{

}
</code>
Answer: GTK widgets are reference counted. When you close or destroy your window, it will release its last reference and be deallocated. (Although I believe the builder also holds a reference - but that should be released when the builder is destroyed.)
Answer: From the GTK+ reference manual:

A GtkBuilder holds a reference to all objects that it has constructed
  and drops these references when it is finalized. This finalization can
  cause the destruction of non-widget objects or widgets which are not
  contained in a toplevel window. For toplevel windows constructed by a
  builder, it is the responsibility of the user to call
  gtk_widget_destroy() to get rid of them and all the widgets they
  contain.
The functions gtk_builder_get_object() and gtk_builder_get_objects()
  can be used to access the widgets in the interface by the names
  assigned to them inside the UI description. Toplevel windows returned
  by these functions will stay around until the user explicitly destroys
  them with gtk_widget_destroy(). Other widgets will either be part of a
  larger hierarchy constructed by the builder (in which case you should
  not have to worry about their lifecycle), or without a parent, in
  which case they have to be added to some container to make use of
  them. Non-widget objects need to be reffed with g_object_ref() to keep
  them beyond the lifespan of the builder.

To answer your question: yes, you should manually destroy the window when you're done with it.


Typeface with curved vertical strokes?

Question: Does anyone know of a typeface where the Capital "B" has a concave curve to the stem? (Where the vertical line dips curves inward to the right.)
Answer: You find some easily - search for something which tries to look eastern, like this:

The screenshot is from www.dafont.com
I do not believe it's enjoyable to read long text passages written by using this or some other concave looking font. I suggest you to use something ordinary and if it must be concave, distort a short piece of text in Illustrator or other vector drawing program. An example (Illustrator, envelope distortion):
Comment: Nice, you found the first one. Sadly you did not include capital "B" in your example of a custom distorted text sample. The question was about fonts, and since you provided one, giving an extra work-around is a bonus. Welcome to graphicdesign!
Answer: Since you are showing no visual example and give no context, we cannot know how intense you want this special feature to be. Or are you just trying to win a bet?
Here are some examples for you to look at; you should find all those on myfonts.com or similar sites:
Concavex™ by Ingrimayne Type
AZ Union by Artist of Design
Teutonic by Wooden Type Fonts
VLNL Bon Bon™ by VetteLetters
Tomato™ by Canada Type
What you want is rare. You will find many typefaces, where the left edge of the downstroke is clearly concave, but even with those, the right hand edge does not always follow or is less concave. See for example:
Arched Gothic Condensed SG™ by Spiece Graphics

Typeface with curved vertical strokes?


What is the difference between a probabilistic data structure and a sketch?

Question: According to this StackOverflow question, probabilistic data structures are data structures that give approximate, as opposed to precise, answers. In particular, they have very low time and space complexities and are easily parallelizable, making them very efficient structures to use. Examples provided include Bloom Filters, Count-Min Sketch, and HyperLogLog.
However, all of these data structures are also known as "sketch" data structures - structures that approximate a large set via a compact representation for more efficient (but less precise) operation.
I don't see the difference between a "sketch" and a "probabilistic" data structure.
Answer: There are probabilistic data structures that are not approximations, for example the Skip list.


Ubuntu UEFI entry deleted. I need to restore or push another

Question: I reinstalled Windows 8 yesterday. My mistake was deleting the EFI partition, so the entries for Ubuntu have gone. Now, I have lost Grub and my PC boot Windows automatically. There's any way to push the ubuntu entry to the EFI partition to boot Ubuntu again?
Comment: You should be able to use Boot-Repair, but I do not think the auto fix will be enough. In advanced run the full uninstall/reinstall of grub which should then recreate the ubuntu efi entry.
Answer: The EFI partition just contains a FAT filesystem, so you can mount it, create a directory /EFI/ubuntu and copy /usr/lib/grub/x86_64-efi-signed/grubx64.efi.signed into /EFI/ubuntu/grubx64.efi and /usr/lib/shim/shim.efi.signed into /EFI/ubuntu/shimx64.efi.  Now if your nvram boot entry was deleted,m you will need to use efibootmgr to create another.  One real benefit of UEFI is that the bootloaders are just files which may be copied around.  The other file you will need is a copy of grub.cfg, either the "real" one from /boot/grub/grub.cfg, or a 3 line stub which pulls in the real one, looks like the below, adjust devices as needed:
<code>search.fs_uuid 4e9797fa-2b51-4c8f-9a5c-37ee2cbf88ad root hd0,gpt7
set prefix=($root)'/boot/grub'
configfile $prefix/grub.cfg
</code>


What techniques exist to increase the learning importance of difficult-to-learn labels over easy ones?

Question: I am training a model to place labels in image data. Some labels are learnt very quickly by the model while others take a long time to perfect. I cannot simply add more labeled data with only the labels I am looking to improve on since most of the image data contains a combination of the easy labels and the more difficult ones.
Are there any smart ways to get the model to focus on the hard labels? I am just looking for some leads. Of course I can just train for longer but that seems inefficient as half the labels are already predicted almost perfectly.
Comment: are we talking about low represented classes or balanced classes but some of them are not classified properly for unknown reasons? If it's the latter case it would be helpful to provide more information about the data and some examples.
Comment: The label set is balanced. Some labels are harder to place correctly on the image because they are simply more difficult to identify (since some features I am trying to label have more variance in shape/perspective, lighting conditions and motion).
Comment: if those are the main issues sounds like you need just some extra prerocessing steps to standardize your images and remove that variance. But again, hard to give suggestions without concrete examples.
Comment: Well I am tracking animals frame by frame. Some bodyparts are easy to identify (eg: all the points along spine from head to tail) whereas limbs are harder because they can obscure each other and move quickly. A left front paw and right front paw can look very different depending on where is it seen from whereas the neck or top of the tail is trivial to find.
Answer: The easiest approach to give more importance to a group of specific training instances is simply using a weight to increase the error loss computed on those specific instances during training. Libraries like sklearn have implemented off the shelf the sample_weight parameter to perform precisely this. The obvious downside of this approach is that you need to know before hand which training instances are hard to learn for the model, and you need a metric to translate that difficulty level into a loss weight.
More fancy approaches try to boost accuracy for instances hard to tackle by trying to better approximate this "hardness level" and then ranking the training instances from the easiest to the hardest, logic being that this order will facilitate gradient descent convergence. The main two approaches are:

Self-Paced learning, the core idea is to replace the classic loss with an objective function that can learn both, model weights and a parameter (usually indicated with $v$) indicating the difficulty of each training instance.
Hard Examples Mining, similar to active learning, a model is trained on a set of known easy examples, and then used to harvest miss classified data that are used to perform a focused retraining of the same model.

Honestly though, these ideas are pretty old, and the fact that they're not widely used today to me suggests that the benefits are way less than the difficulties they introduce. So an in depth analysis of your data to boost standardization in term of quality (brightness/contrast adjustment, histogram equalization and so on) will probably be less of a rabbit hole and most likely still lead to better performance of your model.
Comment: I don't think I can standardize the quality of individual features in the image since I have both the "easy" labels and the "hard" labels in the same image. I can't alter one without the other and at that point I could just use more data augmentation on top of the basic mirroring I currently do, but I don't think this solves the problem of trying to get the model to focus on the hard labels. Will check out your other suggestions, thanks!
Comment: you could split the task tough. Use normal rgb for body parts easy to detect and train another model on enhanced images to compensate for dark parts to detect limbs. My point is: machine learning is data driven, if the data is crap, the model will be crap, no debate around it, and no matter what fancy approaches you try to compensate for what the data lack. So personally I live by trying to improve the data first, and leave the rest as final resource. But of curse that's just my philosophy.


Why is my electric circuit breaker tripping?

Question: For the past 4 days our circuit breaker has tripped several times a day. On the box each fuse thing is labeled i.e. "Upstairs lights", "upstairs sockets" etc. Now normally if we have had a blown fuse on something, say my hairdryer, it has only tripped my bedroom, but this time it has tripped the whole breaker. None of the individual fuse things are switched off but the main dial is in the off position and you need to turn this to on for system to come back on.  I can't seem to see what's setting it off; I haven't found a pattern to when it goes.
Comment: So you are saying that the main breaker for the whole house is tripping?  When it trips do you lose power to the whole house?  That doesn't sound very good, you may have a bad main breaker, and that is NOT a DIY job so I would not attempt it.  Something like that is best handled by a licensed electrician.
Comment: have you installed; or are you using, any new electrical devices?  Does this happen when you're using a specific device?
Comment: yes I lose power to the whole house. I have switched the individual fuses that are labeled emersion switch (as we don't have one) cooker unit (this only works the clock on the gas cooker) and down stairs lights off , the power so far is staying on but if I put any off these on the whole breaker trips. No I have not started using any new items and this sometimes happens when I have no items on
Comment: There is a difference between an overload, and a short circuit.  In an overload situation (like with the hair dryer), a device is drawing more current than the breaker is set for so the breaker trips. In  this situation, the only way to trip the main is to have the whole panel overloaded.  In a short circuit situation the current goes up so high so fast, any breaker along the line can trip (including those at transformers, and power stations).  In a short circuit scenario, it's possible to see the device closest to the source (incoming power) open.
Comment: Given the numerous fuses, OP is probably in the UK and has a whole-house RCD / GFCI breaker, making this not an overcurrent situation, but a ground-fault one.
Answer: Based on your confirmation that the main breaker is tripping, and your description here:

I have switched the individual fuses that are labeled emersion switch (as we don't have one) cooker unit (this only works the clock on the gas cooker) and down stairs lights off , the power so far is staying on but if I put any off these on the whole breaker trips.

This tells me that you do not have an overload situation.  There is a short, and/or one or more faulty breakers possibly including the main breaker.
Even an experienced DIY'er with electrical knowledge would probably contact an electrician at this point.  If there is a potential problem with the main breaker then it is best to get professional help.
Comment: @Tester101 Come to think of it you are correct, it is more likely to be a short than a faulty breaker, but it still *could* be a faulty breaker.  It is probably still best that she call an electrician unless she has experience with these kinds of things.
Comment: Many thanks, I will get my husband onto that when he flies home at weekend
Comment: Seems to me any branch circuit short would trip the associated branch circuit breaker long before the main breaker would trip. So the only possible short would be the panel buss bars shorting to ground, (possibly the mounting insulators have perished) or each other(virtually impossible). Seems very unlikely for any panel new enough to have breakers installed. Seems more likely to me the breaker has gone bad, though I personally have never seen this happen.
Comment: I'd look to the panel for something loose.  Or rather, direct the professional to the panel to look for something loose.


Packaging non-SDK app as click?

Question: I have a program that I created using Free Pascal Lazarus, and I would like to share it in Ubuntu, but how do I pack it with .click?
I have read this
http://developer.ubuntu.com/publish/apps/packaging-click-apps/
but my program has nothing to do with Ubuntu SDK, or Qt creator, it is just a Linux program, maybe uses GTK, so how can I pack it with .click?
Thank you very much.
Answer: The click packages are designed to be self-contained apps that are currently only supported on the phone/tablet version of Ubuntu. They cannot specify dependencies on other packages (such as free pascal, which is not included in Ubuntu). Once full convergence is ramped up in Ubuntu though, it should be possible to package more apps such as yours, as click packages.
For now, your best option will likely be to create a PPA for your app on Launchpad, and create Debian (deb) packages for the dependencies, and the app itself.

Packaging non-SDK app as click?


How to threshold multiclass probability prediction to get confusion matrix?

Question: Lets say my multinomial logistic regression predict that a chance of a sample belonging to a each class is A=0.6, B=0.3, C=0.1 How do I threshold this values to get just binary prediction of a sample belonging to a class, taking in to an account imbalances of classes. I know what I would do if it's just a binary decision (threshold based on classes prevalence), or if the classes are balanced (classify to a class with highest probability). My end goal is to get 3x3 confusion matrix
Comment: I'm a bit unclear on what you are trying to achieve. If you use three different thresholds $T_A, T_B, T_C$ and classify a sample as $A$ if its predicted probability satisfies $p_A\geq T_A$, then you may well end up in situations where *both* $p_A\geq T_B$ *and* $p_B\geq T_B$, and what will you do then? I'd recommend classifying everything based on the highest probability, then write up the confusion matrix, then assign costs to each kind of misclassification, look which misclassifications are the main drivers of total costs, finally tune the classifier itself on these misclassifications.
Comment: That's exactly my problem. IF I classify everything based on highest probability, I can end up classifying everything as majority class. I don't want to tune the classifier, just the predictions.
Comment: Let's go back to binary classification, which outputs a single probability $p$ for membership in the "target" class. If you choose a threshold $T$ and classify a sample as "target" whenever $p\geq T$, then choosing $T$ *is* part of tuning the classifier - after all, the desired output of a classifier is a classification, not some probability value that you still need to compare to a threshold. Plus: if you want to work with thresholds, how do you plan on dealing with $p_A\geq T_A$ & $p_B\geq T_B$ situations?
Comment: let's say in a binary classifier my classes are balanced: A=0.1, B=0.9 and my classifier predicts A=0.4 and B=0.6. Although B has higher probability, I would classify it as A because the predicted probability is higher than a prior. You can tune your threshold to be better with respect to some measure, but I am willing to use this simplified untuned version. I don't know what to do in pA≥TA & pB≥TB situations, that's part of the problem and why I asked the question
Comment: Why is your criterion whether or not the predicted probability is higher than a prior? I'd argue that you should set your threshold based on the costs of misclassifications. And yes, classifying everything in the most common class may well be your cost-optimal classifier. (Store employees routinely classify everyone that enters as "honest", unless their "classifier" gets some *very* specific information.) That's why I say that your threshold (which is part of the classifier) needs to take costs into account. And similarly, costs should influence on how you train your multinomial classifier.
Comment: It is for the same reason, why would I choose a threshold to be 0.5 in balanced binary classification problem.
Comment: Exactly. Look at the costs of misclassification.
Comment: This is what I will do (you won't like it): divide predicted probability by class proportions and choose the biggest one. Justification is that if the classifier has no idea, it would predict class proportions, if it has more evidence towards one class, than this probability should increase and I want to know for which class it has most evidence.
Answer: According to @cangrejo's answer: https://stats.stackexchange.com/a/310956/194535, suppose the original output probability of your model is the vector $v$, and then you can define the prior distribution:
$\pi=(\frac{1}{\theta_1}, \frac{1}{\theta_2},..., \frac{1}{\theta_N})$, for $\theta_i \in (0,1)$ and $\sum_i\theta_i = 1$, where $N$ is the total number of labeled classes, $i$ is the class index.
Take $v' = v \odot \pi$ as the new output probability of your model, where $\odot$ denotes an element-wise product.
Now, your question can be reformulate to this: Finding the $\pi$ which optimize the metrics you have specified (eg. roc_auc_score) from the new output probability model. Once you find it, the $\theta s (\theta_1, \theta_2, ..., \theta_N)$ is your optimal threshold for each classes.
The Code part:

Create a proxyModel class which takes your original model object as an argument and return a proxyModel object. When you called predict_proba() through the proxyModel object, it will calculate new probability automatically based on the threshold you specified:
class proxyModel():
    def __init__(self, origin_model):
        self.origin_model = origin_model

    def predict_proba(self, x, threshold_list=None):
        # get origin probability
        ori_proba = self.origin_model.predict_proba(x)

        # set default threshold
        if threshold_list is None:
            threshold_list = np.full(ori_proba[0].shape, 1)

        # get the output shape of threshold_list
        output_shape = np.array(threshold_list).shape

        # element-wise divide by the threshold of each classes
        new_proba = np.divide(ori_proba, threshold_list)

        # calculate the norm (sum of new probability of each classes)
        norm = np.linalg.norm(new_proba, ord=1, axis=1)

        # reshape the norm
        norm = np.broadcast_to(np.array([norm]).T, (norm.shape[0],output_shape[0]))

        # renormalize the new probability
        new_proba = np.divide(new_proba, norm)

        return new_proba

    def predict(self, x, threshold_list=None):
        return np.argmax(self.predict_proba(x, threshold_list), axis=1)

Implement a score function:
def scoreFunc(model, X, y_true, threshold_list):
    y_pred = model.predict(X, threshold_list=threshold_list)
    y_pred_proba = model.predict_proba(X, threshold_list=threshold_list)

    ###### metrics ######
    from sklearn.metrics import accuracy_score
    from sklearn.metrics import roc_auc_score
    from sklearn.metrics import average_precision_score
    from sklearn.metrics import f1_score

    accuracy = accuracy_score(y_true, y_pred)
    roc_auc = roc_auc_score(y_true, y_pred_proba, average='macro')
    pr_auc = average_precision_score(y_true, y_pred_proba, average='macro')
    f1_value = f1_score(y_true, y_pred, average='macro')

    return accuracy, roc_auc, pr_auc, f1_value

Define weighted_score_with_threshold() function, which takes the threshold as input and return weighted score:
def weighted_score_with_threshold(threshold, model, X_test, Y_test, metrics='accuracy', delta=5e-5):
    # if the sum of thresholds were not between 1+delta and 1-delta,
    # return infinity (just for reduce the search space of the minimizaiton algorithm,
    # because the sum of thresholds should be as close to 1 as possible).
    threshold_sum = np.sum(threshold)

    if threshold_sum > 1+delta:
        return np.inf

    if threshold_sum < 1-delta:
        return np.inf

    # to avoid objective function jump into nan solution
    if np.isnan(threshold_sum):
        print("threshold_sum is nan")
        return np.inf

    # renormalize: the sum of threshold should be 1
    normalized_threshold = threshold/threshold_sum

    # calculate scores based on thresholds
    # suppose it'll return 4 scores in a tuple: (accuracy, roc_auc, pr_auc, f1)
    scores = scoreFunc(model, X_test, Y_test, threshold_list=normalized_threshold)

    scores = np.array(scores)
    weight = np.array([1,1,1,1])

    # Give the metric you want to maximize a bigger weight:
    if metrics == 'accuracy':
        weight = np.array([10,1,1,1])
    elif metrics == 'roc_auc':
        weight = np.array([1,10,1,1])
    elif metrics == 'pr_auc':
        weight = np.array([1,1,10,1])
    elif metrics == 'f1':
        weight = np.array([1,1,1,10])
    elif 'all':
        weight = np.array([1,1,1,1])

    # return negatitive weighted sum (because you want to maximize the sum,
    # it's equivalent to minimize the negative sum)
    return -np.dot(weight, scores)

Use optimize algorithm differential_evolution() (better then fmin) to find the optimal threshold:
from scipy import optimize

output_class_num = Y_test.shape[1]
bounds = optimize.Bounds([1e-5]*output_class_num,[1]*output_class_num)

pmodel = proxyModel(model)

result = optimize.differential_evolution(weighted_score_with_threshold, bounds, args=(pmodel, X_test, Y_test, 'accuracy'))

# calculate threshold
threshold = result.x/np.sum(result.x)

# print the optimized score
print(scoreFunc(model, X_test, Y_test, threshold_list=threshold))

Comment: you reference @conngrejo who in turn references this soln? are you two related / know each other/friends or just happy coincidence? :)  great soln by the way...
Answer: This was helpful, thanks! But it is not applicable during model training. When it comes to using this method after training the model (after finding the hyperparameters relevant to the model), it's valid; only that there has to be some way of standardizing this to avoid loss of generality and for it to be applicable on test data.


How do I build a wiki into an iPhone app?

Question: I want to build an iPhone app that is really a wrapper around a wiki. Specifically, I have some static reference content that can be represented by a hyperlinked set of pages and want to build an app that will provide a nice interface over this content, including search, bookmarking, and annotating. I'm wondering what the best approach is for building something like this.
(I'm spent a fair bit of time googling for answers but pretty much every combination of search terms I can think of returns links to wikis, not links about putting a wiki into an app).
Are there libraries out there for handling wiki content (rendering, navigating links etc.)? I imagine I could just represent my content as a set of local HTML pages and point the web browser control at these but that doesn't seem right. Any ideas on how best to approach this in the iOS world?
Thanks in advance!
Answer: Try looking at TWedit, it is a wrapper for the excellent TiddlyWiki which is a single file WIKI built around JavaScript and HTML. TW is very powerful and well supported with many plugins available.


Should Units of Measure be capitalized?

Question: I just created an inch to mm conversion calculator and I am writing a blog post announcing its launch.  When should I capitalize the terms inch and millimeter?  Does it matter if I'm spelling it out?  What if I'm using an abbreviation or symbol?  What if it begins a sentence?
Comment: Clicking on the link http://www.bipm.org/en/publications/si-brochure/chapter5/5-2.html generates a 404 error (not found).
Answer: No, units generally do not need capitalization when spelled out.  For SI units, the Bureau International des Poids et Mesures is the authority:

Unit names are normally printed in roman (upright) type, and they are treated like ordinary nouns. In English, the names of units start with a lower-case letter (even when the symbol for the unit begins with a capital letter), except at the beginning of a sentence or in capitalized material such as a title. In keeping with this rule, the correct spelling of the name of the unit with the symbol °C is "degree Celsius" (the unit degree begins with a lower-case d and the modifier Celsius begins with an upper-case C because it is a proper name).
                                    — The International System of Units (SI), 8th ed., Sec. 5.2

However, capitalization is used in the following cases:

Symbols for SI units named after people, for example:

1 ampere, abbreviated as 1 A
1 angstrom or 1 ångström, abbreviated as 1 Å

Note that the names of the units themselves are lowercase.
The symbol for litre or liter is l, but is often written as L to prevent it from looking like the digit 1.  It is also sometimes rendered in lowercase cursive form ℓ for the same reason:

The litre, and the symbol lower-case l, were adopted by the CIPM in 1879 (PV, 1879, 41). The alternative symbol, capital L, was adopted by the 16th CGPM (1979, Resolution 6; CR, 101 and Metrologia, 1980, 16, 56-57) in order to avoid the risk of confusion between the letter l (el) and the numeral 1 (one).
                                    — The International System of Units (SI), 8th ed., Sec. 4.1

Temperature degree units, e.g. degrees Celsius or degrees Fahrenheit, abbreviated as °C and °F, as stated in the quote above.
Note, however, that the kelvin follows the rule for units named after people: 1 kelvin, abbreviated as 1 K.
Special non-SI units, such as the British thermal unit, abbreviated BTU or Btu, or the US gallon, for obvious reasons.
The astronomical unit is abbreviated either as au or AU.  The international unit is abbreviated IU.
A byte is abbreviated as B; a bit is abbreviated as b.
A decibel is abbreviated as dB.

One unit where capitalization makes a huge difference is the calorie.

A calorie (abbreviated cal) is the energy needed to heat one gram of water by 1 °C.  This unit is used by physicists and chemists.
A Calorie (abbreviated Cal or kcal) is actually a kilocalorie — 1000 times the amount of energy of a calorie.  This unit is used by dieticians and the general public when describing food.

Naturally, at the beginning of a sentence, the usual rule that the first letter be capitalized overrides all of the above.  For example,

Watt for watt, a RISC chip delivers better performance than a CISC chip.

Also note that capitalization is significant in the SI prefixes.  For example, mW is a milliwatt, and MW is a megawatt.
Comment: @AndrewLeach I've added a citation.
Comment: You are wrong that the symbol for litre is L. It's a  lower-case l -- not that that stops people from using L, but a blanket statement is inappropriate. Perhaps it's a North American thing; L rarely appears on the European side of the Atlantic.
Comment: The **alternative** *L* still isn't common in Europe after 35 years. I maintain that what could be interpreted as a blanket statement is wrong though -- *is abbreviated to* should be *can be shown by*. [Note too that SI units have symbols, not abbreviations. BTU is not an SI unit and **is** an abbreviation]
Comment: I think that citation is saying that "L" is an acceptable alternative, not that it is the standard. The answer above currently reads to me like it's using the citation to support the latter.
Comment: @NoName But the decibel is not an SI unit, so it conforms to a loose convention rather than a rule.
Comment: Can you expand on your answer?  As it stands you've written "No, but here's a list of exceptions" 99% exceptions, 1% answer.
Comment: @fortmac It really is a list of exceptions. I've added choster's citation from BIPM for the usual lowercase rule.
Comment: What's the procedure if one wants to start a sentence with the word "calorie" referring to actual calories, rather than kilocalories?
Comment: @GeorgesOatesLarsen Do you have an example of such a sentence?
Comment: In keeping with this rule, the correct spelling of the name of the unit with the symbol °C is "degree Celsius" <- you are not keeping with the rule, Celsius is an "exception" to the rule!
Comment: The abbreviation for decibels actually follows the "named for persons" rule, as bels are named for Alexander Graham Bell, the founder of Bell labs and ATT
Answer: No. Yes. Maybe. It depends.
It's always been my understanding with metric measures, that abbreviations for units larger than the base unit measure are capitalized, and units smaller than the base unit are lower case. Dm would be dekameter (ten meters), while dm is decimeter (a tenth of a meter), both based on the unit meter. When not abbreviated, they follow the standard rules for capitalizing words used in written text.
This is also true for prefixes in general, like M for mega- and m for milli-
Non-metric measures like inches, feet and mile follow standard capitalization rules. Since the abbreviations for these never start a sentence, they would never be capitalized.
Comment: I don't think your understanding is quite right. First, *hecto-* and *kilo-* are also multiples but never capitalized. Second, since SI was adopted in 1960, the standard abbreviation for *deka-* is *da-*, not *D-*. And there is the case of *micro-*, which must be appreviated as *µ-* to avoid confusion with both *mega-* and *milli-*.
Answer: Unit symbols are to be shown/displayed in lower case except for the following reasons.

The first letter of the unit is an uppercase when the name of the unit is derived from the name of the person/scientist.
eg: m(meter), s(second), V(Volt), Pa(Pascal)

Liter is represented as 'L' in the United States.

So coming to your case you can use only lowercase for representing the unit. You also need to spell the unit in lowercase unless it is the start of your statement.

I have designed a inch-to-mm converter.
Kilometer is the unit for measuring distance"

If your statement is starting with a unit name, try to spell it out.
The next thing to be remembered is units must always be represented in singular form

c = 25 cm

not

c= 25 cms

Unit symbols are not followed by a period unless it is end of a statement.

"It is 25 cm. long" is the wrong way.
"It is 25 cm long" is the correct way.
Comment: Traditionally, *inches* is abbreviated as *in.* (with the period) to avoid confusion with the word *in*.
Comment: That's not correct with regard to units named after people. The general rule is that only the abbreviation is capitalised (so it's 'V' short for 'volt' etc), with the exceptions listed in 200_success's answer.

Should Units of Measure be capitalized?


Not able to push my django project up on heroku

Question: I have created a python2.7/django(1.4.1) Application, which I wanted to deploy on heroku
The project is already on git so I did the following.
1> create heroku --stack cedar
2> created requirement.txt : contains only
    Django==1.4.1
3> create Procfile : contains
    web: python manage.py runserver 0.0.0.0:$PORT --noreload
4> git push heroku master
this throws the following error
Counting objects: 90, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (84/84), done.
Writing objects: 100% (90/90), 154.73 KiB, done.
Total 90 (delta 23), reused 0 (delta 0)
 !     Heroku push rejected, no Cedar-supported app detected

To email@example.com:salty-tor-8958.git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'email@example.com:salty-tor-8958.git'

I went through this previously asked SO Question : Deploying existing Django app on Heroku
where the talk is about the directory structure, and Django directory structure has changed since then, So what am I doing wrong?
Here my directory structure is like so:
   MyApp
     |
   MyApp
     |-- __init__
     |-- settings.py
     |-- urls.py
   my_module
     |-- __init__
     |-- views.py
     |-- static
     |-- templates
   manage.py
   requirement.txt
   Procfile

I am working on Fedora, so had to use the rubygem to install herokutoolbelt
Heroku Version : heroku-gem/2.33.5 (x86_64-linux) ruby/1.9.3
Answer: Its requirements.txt not requirement.txt
Further read: https://devcenter.heroku.com/articles/django


How to recover Files from a coruppted Micro SD card?

Question: I am having a problem with my Samsung Micro SD card (in particular, a Samsung 32GB Evo mircoSDHC UHS-1 Grade I Class 10 Card).
I use the card in my 8GB Motorola Moto G 4G which is running Android 5.1. Unfortunately the card recently stopped working, and I am not sure why. I bought both in June.
One day I simply noticed that the card was no longer mounted to the phone. I am now unable to mount the card onto the phone. There is data stored on the card that I would very much like to recover before I format the card.
My computer is running Ubuntu 14.04.3 LTS, and I figure that it will be easier to recover the data on my computer than on the phone itself.
My monitor (Dell, I don't know the model) has a card reader, in particular a Standard Microsystems Corp. 9-in-2 Card Reader (and the Micro SD card came with an SD adapter). The card reader is found by my machine when I run lsusb.
When I insert the card (in it's adaptor) into the Card Reader it is not detected by my machine.
(I have a laptop which runs Windows, and when I insert the card into the card reader on that, it is found by Windows, but I cannot open the device to see what files are on the card).
I have tried searching for answers to my problem already, but I have not found exactly what I am looking for.
I found these similar questions, but the former was too technical for me (I tried to read the documentation attached, but I am not an expert, and my machine is owned by the university, so I did not want to run anything without being sure of what it is doing and that it is safe), while the later assumed that the files have already been deleted.
I also found this info on GUN ddrescue, which may help me to recover the files, once I can detect the card.
Ideally what I am asking for is a way to force ubuntu to read the card, and to copy any files on the card that it can to my machine as a back-up.
I would then be able to format the card, and start over, and hopefully it would be read by my phone again.
For the record, I am trying to recover image files (personal photos which I would like back) and audio files (recordings of work meetings which I need back).
And before Captain Hindsight mentions it, I did back up (some of) my data once in the past 6 months, on the 18th November, but obviously I don't do it frequently enough (and I didn't back up the photos)!
Thank you very much!
Answer: I am sometime facing the same issue after building android for odroid card and badly modify things.
When trying to recover the card, it is sometime quite difficult, but i have discover that using disks app in ubuntu may help : select your SD card and click the gear in right vue of app. Select "format..." and choose 'don't overwrite...' and 'mbr'.
For me, when the card is partitioned, it recovers partition table, and the SD card can be read again.
I think you should run a linux image (ubuntu for example) and run it as a live USB key / CD from your laptop, which will be better for card reader.
You may want to save your data before :
<code>sudo dd if=/dev/<SD_path> of=/home/<user>/sdcard.bin
</code>


CakePHP Facebook Plugin does not displays the logout button in FIrefox

Question: I'm working with webtechnick CakePHP Facebook Plugin, I finally managed to make it work (I can use the like/recommend buttons - I can login via facebook, etc) except for the logout button in Firefox v3.6 and IE that is not working. I think there is a problem because in Chrome the logout button get display and the PHP code works fine also. I have this code into a *.cpt view file:
<code>if($facebook_user){
    echo $this->Facebook->logout();
    echo debug($facebook_user);
} else {
    echo $this->Facebook->login(array());
}
</code>
In Chrome after I click on the login button, the $facebook_user is true and the logout button get display as well as the debug(), therefor PHP is fine but in Firefox or IE the logout button gets hide almost instantly.
I'm following the video tutorial and the problem seems to be in the minute 19~
http://tv.cakephp.org/video/webtechnick/2011/01/12/nick_baker_--_facebook_integration_with_cakephp
Thanks!
Answer: I fixed this problem by enabling in Firefox's options on Privacy the "Accept third-party cookies"


How do you send a variable to Azure Event Hubs using Python SDK

Question: If I have a variable containing the temperature value, how can I send it using ServiceBusService.send_event?
Answer: It depends on how you are consuming it on the other side of event hubs. If you are using Azure Stream Analytics you must make sure that the format you are sending to event hubs is either json, csv, or arvo.
If you have a variable, it would be simple enough to create a dictionary, serialize it using Python's json library and send the resulting string.  Example:
from azure.servicebus.control_client import ServiceBusService
import json;

sbs = ServiceBusService("your_namespace",
                        shared_access_key_name="your_policy_name",
                        shared_access_key_value="your_policy_secret")

# build dictionary and send value
temp = {'DeviceId': 'dev-01', 'Temperature': str(i)}
sbs.send_event('woodstove2', json.dumps(temp))

Answer: Please make sure you have created a ServiceBus namespace for EventHub. If not, please refer to "Create an Event Hub" section of the article https://azure.microsoft.com/en-us/documentation/articles/event-hubs-csharp-ephcs-getstarted/.
You will get ServiceBus SAS name & key in the Service Bus Configure page as below.

If the service bus does not contain an event hubs, you can create it manually via clicking the tab "event hubs", or create it by using Python SDK.
from azure.servicebus import ServiceBusService

servns = '<service_bus _namespace>'
key_name = '<service_bus_sas_keyname>'  # SharedAccessKeyName from Azure portal
key_value = '<service_bus_sas_key>'  # SharedAccessKey from Azure portal
sbs = ServiceBusService(service_namespace=servns,
                        shared_access_key_name=key_name,
                        shared_access_key_value=key_value) # Create a ServiceBus Service Object
flag = sbs.create_event_hub('<event_hub_name>') # Create a Event Hub for the ServiceBus. If it exists then return true, else return false
print(flag)
event_data = '<event_data>'
sbs.send_event('<event_hub_name>', event_data) # Send event data to your Event Hub, like real-time temperature data

According to your scene, you can serialize event data to JSON string, CSV String with header as jsturtevant said.
For temperature example:

JSON

event_data = '{"deviceId": "dev01", "time": "2015-08-24 12:34:45", "temperature": 30.0 }'

CSV

event_data = 'deviceId,time,temperature\ndev01,2015-08-24 12:34:45,30.0'
For more information about ServiceBus Python SDK, you can refer to the part - "Usage" of the link "README.rst" https://github.com/Azure/azure-sdk-for-python/tree/master/azure-servicebus.


Announcement app?

Question: Does anyone know of a good Announcements app that works as a good substitute for the OOTB Sharepoint 2013 one? We have several people who post, and the formatting is very inconsistent. Really all we need is something that has a preview function and ideally something that will truncate the posts, like what you'd see on a blog.
Answer: A sipme solution would be to turn on content approval in the announcement list, this way when the user saves it item, it can be seen by only those with high enough permission. This will allow them to view it and go back and make changes. Once done, it can be approved and everyone will see it.
Comment: I did try that, but it still wasn't quite what I wanted. The approval view doesn't really display the formatting how it will appear on the post. A formatting template would be really helpful.
Comment: Those with rights can see the announcement after it is submitted and verify the formatting. It isn't any different than publishing pages or blogs in Sharepoint.
Comment: You could maybe put in some Javascript on the New/Edit form to strip out html tags and clean it up a bit, might make it more consistent.

Announcement app?


Uncaught TypeError: Cannot read property 'length' of null when moving out from a specific page

Question: In my Ember app I have a search page which is a complex page with many nested controller.
Only in that page, when I move out to any other page, I receive the error:
Uncaught TypeError: Cannot read property 'length' of null

And the next page is blank. The navbar remains, so if I move to another page, everything continue normally.
This is the router:
this.resource('products', function(){
  this.route('search');
});

This is routes/products/search.js:
import Ember from "ember";
import AuthenticatedRouteMixin from 'simple-auth/mixins/authenticated-route-mixin';

export default Ember.Route.extend(AuthenticatedRouteMixin, {});

The template contains 3 nested #each, any of them with a specific itemController:
{{#each subset in subsets itemController="products/search/subset"}}
  {{#each panel in subset.panels itemController="products/search/panel"}}
    {{#each value in panel.values itemController="products/search/value"}}

Every array is an array of Ember.Objects, like:
var Subset = Ember.Object.extend({
  panels: []
});
//
var Panel = Ember.Object.extend({
  values: []
});

I think that some callback is called when I change page and something during the cleaning of the controllers causes the error, but I really don't know how to find the error. I tried to debug using the console, but the error comes from vendor.js and nothing pointed me to a line in my files.
Answer: After a lot of debugging and different attempts, I found that the error was due to the wrong type of controller I used.
I defined the controllers as Ember.ArrayController.extend({});.
Changing to Ember.ObjectController.extend({}); resolved the error


Preventing localhosted web application from looking up online resources

Question: I am having speed trouble working with my locally hosted wordpress application. This is because it always looks up online resources like fonts.google.com..., api.google.com..., etc, it only when the resources are loaded or fail to.
What would be the best solution to cutting this loading of remote resources?
Would overriding php load time do the trick?
Comment: Any reason you can't host them locally?
Answer: Presumably all these resources are being loaded from a CDN, and that would be the way to go. You can improve the performance of your site even further by pre-resolving the DNS of the CDNs.
In your  tag, you would have something like this:
<link rel="dns-prefetch" href="//fonts.google.com">
<link rel="dns-prefetch" href="//api.google.com">

Also consider hosting all of your assets in your own CDN. This way you would only have to deal with a single DNS resolution.
I common pattern is something like http://www.example.com for the actual site and http://assets.example.com for JS, CSS, and images, fonts, etc.
Here are a few CDN hosting options: http://en.wikipedia.org/wiki/Content_delivery_network#Notable_content_delivery_service_providers
Lastly, if you insist in that you don't want any remote resources, just download what you need and host them locally (on the same server running your site).


what if the appraisal value is lower than the contractual price

Question: I have a question regarding purchasing a house. Assume the bank appraisal value is lower than the contractual price, and the seller and I cannot make agreement for a new price, will I lose all of the earnest money if I decide not to move forward.
Comment: Could you edit and add country tag. There maybe regulations that differ.
Comment: I'm not sure that the contractual price matters.  I suspect what matters is the amount of the mortgage, which should be lower given your down payment.  As long as the mortgage is less than the appraisal (or perhaps some threshold lower than the appraisal), then the bank shouldn't care.
Answer: You should read the provisions in your offer and any counteroffer that was signed before paying the earnest money, but generally if the appraisal comes in low, the price has to be adjusted. If you can't get a mortgage (because the appraisal is too low) the next guy usually can't either.
Unfortunately without more information (the documents that were signed and the locale, to know which laws might be applicable) I can't tell you with certainty that you'll get your earnest money back.


Cardinality of almost everywhere continuous functions

Question: The cardinality of continuous real functions is $|\mathbb{R}|$ but I was wondering wether allowing functions to be almost everywhere continuous would increase the cardinality or not.
On the one hand, there are infinite sets with measure 0 (e.g. $\mathbb{Q}$, Cantor set) and allowing functions to be discontinuous at each of these points will blow up the cardinality of the set. However, it is impossible to have a function continuous everywhere but on $\mathbb{Q}$ because of its density (Edit: Actually it is possible). By defining $K=\{\frac{1}{n},n\in \mathbb{N}\}$, the function $\mathbb{1}_K$ is still almost everywhere continuous so even if a set $A$ of measure 0 has a limit point, it's still possible to find a function continuous everywhere but on $A$. I introduced by myself the following definition of a set: A set $A$ is locally dense if $m(A)=0$ and $m(\bar{A})>0$. I haven't proven yet that a function that is continuous everywhere but on a locally dense set is not almost everywhere continuous but I'm pretty sure it's true and I think I have a sketch of proof in mind. So we would be left with functions that are continuous everywhere but on non-locally dense sets.
On the other hand, if we want to prove that the cardinality of almost everywhere continuous functions is at most $|\mathbb{R}|$, we cannot proceed the same way we did for continuous functions since an almost everywhere continuous function has to be defined on all rationals and we have to know in which point the function is non-continuous. Yet, if all non-locally dense sets are countables and if my previous guess is true (functions that are continuous everywhere but on a locally dense set are not almost everywhere continuous), that means an almost everywhere continuous function is just defined by its value on the rationals and by a countable set of discontinuity points, namely $D$. So the cardinality would be $|\mathbb{R}^{\mathbb{Q}}\times D|=|\mathbb{R}|$  Moreover, finding an injection from "non-continuous" functions to almost everywhere continuous functions seems to be totally impossible.
If I had to take a guess, I would say that this set has cardinality $|\mathbb{R}|$. Any idea on how to conclude anything ?
Answer: You can have a function continuous except on $\Bbb Q$. If $x$ is irrational, $f(x)=0.$ if $x$ is rational, wrote it in lowest terms as $a/b$ and $f(x)=1/b$. Each irrational is far enough from rationals with small denominators to be OK .
Now you have to show the set of discontinuity points is countable rather than a measure $0$ uncountable set


How to design RNN\VAE for sparse sequential data?

Question: I am currently struggling with designing some Deep Learning algorithms that takes as an input sparse sequential data, since the system I try to model signals sparsely (once in a while).
I try to predict the next signal (strength, timing, etc).
Can you suggest an architecture\design\method\resources for this type of problem?
Answer: Have you looked at this paper? A Recurrent Latent Variable Model for Sequential Data (https://arxiv.org/abs/1506.02216)
For the sparsity, a few works I have known use time index as an additional input to the RNN (such as Recurrent Recommenders Networks (http://alexbeutel.com/papers/rrn_wsdm2017.pdf)).
Not sure if these suggestions will work for you, but at least you can try.


How to add a spectrogram to a paper

Question: I would like to include some examples of spectrograms in a paper I am writing. What are some of the ways to get a picture to include? I thought it might be the "draw" feature in Praat but it doesn't seem to work for spectrograms. Using a screen shot also does not seem to be the most elegant solution. Is there another way?
Comment: I don't see a big problem with screnshots; if you do them well cut-out and in a decent resolution, it usually goes pretty smooth in a paper. Since spectrograms are not as simple graphs as, e.g., oscillographs, I doubt there are tools that can replicate them nicelier than what you get in Praat directly.
Comment: It depends on your ultimate plan for the paper. Certain major publishers actually have huge problems processing EPS files, and integrating something that isn't a screen shot into Word can be challenging. My experience with Paint to Picture Window and Clipboard copy is that the result is terrible; YMMV.
Answer: You just need the correct Praat command: "Paint visible spectrogram...". Here is the relevant manual page: http://www.fon.hum.uva.nl/praat/manual/Intro_3_4__Printing_the_spectrogram.html

How to add a spectrogram to a paper


Will using Teamviewer reveal my IP?

Question: I will be accessing a computer in a different state via Teamviewer. The sites I work on have very high security measures in place. Is there any way possible that my actual IP address can be revealed in addition to that of the computer I'll be dialing into?
Comment: revealed to whom?
Comment: @james to whom will the IP be revealed? Who do you not want to know that you connected with a particular machine to another particular machine?
Comment: I will be accessing the computer via team viewer. I don't understand the comment about firewall logs showing the public IP address. Do you mean the IP address of the computer I'm accessing?
Comment: @Cowthulhu not with teamviewer
Answer: The IP you connect from will be available to the computer you access.  The sites you access in a web browser from that computer will only see a connection from that computer, and will not be able to determine the IP you used to connect from on Teamviewer.  If you run any applications outside the web browser, it would be possible for them to detect the incoming connection, but only if they are specifically looking for it.

Will using Teamviewer reveal my IP?


ChromeOS - Autorun script located on a USB drive

Question: I am developing a piece of software that is eventually going to run on ChromeOS and will come in the form of an Android app (apk package). We have been asked to come up with a distrubution system that is both offline and simple for this app. I've been thinking about distributing the apk on USB drives and I would like to find a way to get the apk copied automatically to the system when the usb drive is inserted. Updates for the apk could also come later on and they would be on their own USB stick with the same system in order to update the software. Right now, I have no idea about ChromeOS and/or how to do this, I'm in a research phase.
Comment: @KAE One issue with this is that to sideload third-party applications the Chromebook will need to be switched over to developer mode. Being able to automatically do so by plugging in a flash drive would be malware by definition. This [documentation](https://developer.android.com/topic/arc/sideload) shows how to install Android apps on ChromeOS. Is this related to what you are trying to do?
Comment: Thanks @kemotep. Indeed, this looks familiar and close to my experience with Android mobile devices. The chromebooks that will run the app will be solely dedicated to this purpose and will be offline - therefore, turning them once to developer mode and putting it as a prerequisite in our documentation is not an issue at all. Once this is done, is there a way to install the apk automatically ? Perhaps by running adb through some sort of shell script from the flash drive itself ?
Comment: I do not know enough about the specifics of Android or ChromeOS app development to know what is the best method of updating, however the act of plugging in a flash drive and having a script automatically run is behavior identical to malware. You should be able to place your apk file and a shell script on a flash drive that when initiated by the end user will trigger the update however I suggest you look into other more traditional methods of updating your app that are inline with best practices outlined by Google.
Answer: Brute force solution: emulate a USB keyboard to send the necessary commands. (You should require the user to enable developer mode and get to a specific starting condition so you know which keystrokes are required.)
You wouldn't be the first to use a fake keyboard to help with Chromebook deployment. See for example the Centipede. You could combine the keyboard and storage in a single usb stick, also acting as a USB hub to allow it to have multiple device IDs.


MPI: Local and non-local calls

Question: I want to know what exactly are the two, and how they are different. What are the advantage or disadvantage of the two types of calls? Really appreciate using some small example code.
Answer: These are detailed, e.g., in here: http://www.netlib.org/utk/papers/mpi-book/node14.html
It's not really proper to talk about advantages of either. They are for different purposes. An example of a local call MPI_Comm_rank, since it doesn't need input from other processes and an example of a non-local call is MPI_Send, since it will have to communicate with some other process that will recieve the message.

MPI: Local and non-local calls


How to find the volume of ellipsoid using substitution in triple integral?

Question: The equation of ellipsoid is
$$\frac{x^2}{a^2}+\frac{y^2}{b^2}+\frac{z^2}{c^2}=1$$
The hint for substitution is given as
$x=au$, $y=bv$ and $z=cv$.
I know that the projection of the ellipsoid on $xy-$plane is an ellipse with the equation
$$\frac{x^2}{a^2}+\frac{y^2}{b^2}=1$$
So before transformation or substitution the curves that bounds the projection of the ellipsoid in $xy-$plane will be $x=-a$, $x=a$ and $y=-b$, $y=b$. But I don't know what will be the limits of $z$ in integration.
After transformation the Jacobian of transformation will be
$J=abc$. I don't know how to proceed this one and compute the volume of ellipsoid.
Please explain in detail about the limits before and after substitution with the help of the mathematica command that helps in plotting the ellipsoid along with its shadow.
THanks in advance!
Comment: If you mean (how it should be) $z=cw$ then after the substitution the ellipsoid becomes the famous $u^2+v^2+w^2=1$.
Comment: After making the substitution, you have $u^2+v^2+w^2=1$  so the range of all variables is $[-1,1]$  I assume you meant $z=cw,$ not $z=cv.$
Comment: @A.Γ. I know after transformation it becomes sphere with centre at origin, I am interested how to find the limits of integration before and after transformation with a proper procedure Sir!
Comment: The whole point of the substitution is that you don't _need_ to find integration limits before the substitution, and for that matter you should know the value of the integral after substitution without writing formulas for the limits of the new variables $u,v,w.$ This should be an easy exercise; why make it difficult?
Answer: I think you're mixing two things: setting up the integration limits if you don't use the suggested substitution and how to proceed if you want to use that substitution. I'll comment on both.

You can project the ellipsoid onto the $xy$-plane to get an ellipse, but then you're not using the suggested substitution.

$$\frac{x^2}{a^2}+\frac{y^2}{b^2}=1 \tag{$\color{blue}{*}$}$$
  So before transformation or substitution the curves that bounds the projection of the ellipsoid in $xy-$plane will be $x=-a$, $x=a$ and $y=-b$, $y=b$.

If you want to do it like this, you need to be careful with the limits of integration. The limits you suggest don't bound an ellipse in the $xy$-plane, that would be a rectangle!
You can fix $x$ from $-a$ to $a$, but then $y$ follows from $(\color{blue}{*})$ above to get:
$$\int_{-a}^{a} \int_{-b\sqrt{1-\tfrac{x^2}{a^2}}}^{b\sqrt{1-\tfrac{x^2}{a^2}}} \ldots \,\mbox{d}y \,\mbox{d}x$$
Now you either directly integrate a suited function to get the desired volume, or you set up the bounds for $z$ going back to the original equation of the ellipsoid and integrate the function $1$ to get the volume, which gives:
$$\int_{-a}^{a} \int_{-b\sqrt{1-\tfrac{x^2}{a^2}}}^{b\sqrt{1-\tfrac{x^2}{a^2}}} \int_{-c\sqrt{1-\tfrac{x^2}{a^2}-\tfrac{y^2}{b^2}}}^{c\sqrt{1-\tfrac{x^2}{a^2}-\tfrac{y^2}{b^2}}} 1 \,\mbox{d}z \,\mbox{d}y \,\mbox{d}x$$
The first step of integration (with respect to $z$) is easy and using symmetry allows to simplify this a bit further to:
$$8\int_{0}^{a} \int_{0}^{b\sqrt{1-\tfrac{x^2}{a^2}}} c\sqrt{1-\tfrac{x^2}{a^2}-\tfrac{y^2}{b^2}} \,\mbox{d}z \,\mbox{d}y \,\mbox{d}x$$
And you could take it from there.

Or you would go for the suggested substitution which turns the ellipsoid into a sphere of radius $1$, centered at the origin. Don't forgot to include the Jacobian (as a consequence of the substitution). For the suggested substitution:

The hint for substitution is given as
  $x=au$, $y=bv$ and $z=c\color{red}{w}$.

the Jacobian is simply $abc$ so the integral over the ellipsoid $E$ is turned into an integral over the (simple) sphere $S$:
$$\iiint_E 1 \,\mbox{d}z \,\mbox{d}y \,\mbox{d}x = abc \iiint_S 1 \,\mbox{d}w \,\mbox{d}v \,\mbox{d}u$$and you're done if you know the volume of a sphere with radius $1$.
Comment: I know the volume of the unit sphere is $\frac{4\pi}{3}$, can I compute this $\frac{4\pi}{3}$, from the integral putting limits on it $\int\int\int_{S}dwdvdu$.
I shall be very thankfull! Sir
Comment: You either directly use the fact that you know the volume of the unit sphere at this point (and the volume of the ellipsoid follows immediately), or you can compute it via integration if you can't use it - but then the advantage of the substitution is limited to _simpler calculations_ rather than almost _no calculations_.
Comment: Sir if want to calculate it through finding the integration after substitution the integral is not still simple, How can I calculate?
The integral after substitution is of the form
$8\int_{0}^{1}\int_{0}^{\sqrt{1-u^2}}\int_{0}^{\sqrt{1-u^2-v^2}}dwdvdu$, I don't know how to show that $8\int_{0}^{1}\int_{0}^{\sqrt{1-u^2}}\int_{0}^{\sqrt{1-u^2-v^2}}dwdvdu=\frac{32\pi}{3}$
Comment: It's 4 in the numerator, not 32. How annoying that integral is, depends on what you can use: I would do it with spherical coordinates or avoid a triple integral by calculating it as the volume of a solid of revolution. But that all depends on your context; if the issue now is how to find the volume of a sphere through integration: searching here [on this site](https://math.stackexchange.com/search?q=volume+sphere+integration) (or on google) will give you a lot of information and different approaches.
Comment: sir I have multiplied 8 with $\frac{4\pi}{3}$
Comment: I see, but you shouldn't have: it is the integral _with_ the factor 8 that will give you the volume of the sphere, $\frac{4\pi}{3}$.
Comment: yes sir you are right, I have made mistake!
I also calculated the integral and get $\frac{4\pi}{3}$