states that:     Reads and writes are atomic for reference variables and for most primitive variables (all types except long and double).   Now I wonder why the volatile keyword is necessary in the following example to prevent an endless loop - the change of the int variable should be atomic and therefore instantly visible to everyone, shouldn't it?  public class HelloWorld {      // This doesn't work as expected      private static int x = 0;      //Following would work: private volatile static int x = 0;       public static void main(String []args) throws Exception      {          Thread t1 = new Thread(() -&gt; {             try             {                 Thread.sleep(1000);                 x = 1; //Should be atomic, right?              } catch (InterruptedException e) {}         });           System.out.println("Begin");          t1.start();           //The evaluation of the condition should also be atomic, right?          while(x == 0)          {          }           t1.join();          System.out.println("End");      } }
At work today, I came across the volatile keyword in Java. Not being very familiar with it, I found . Given the detail in which that article explains the keyword in question, do you ever use it or could you ever see a case in which you could use this keyword in the correct manner?
Evaluation of $\displaystyle \int_{0}^{1}\frac{x\ln (x)}{\sqrt{1-x^2}}dx$   $\bf{My\; Try::}$ Let $\displaystyle I = \int_{0}^{1}\frac{x\ln x}{\sqrt{1-x^2}}dx\;,$ Put $x=\cos \phi\;,$ Then $dx = -\sin \phi d\phi$  and Changing Limit, We get  $$\displaystyle I = -\int_{\frac{\pi}{2}}^{0}\cos \phi \cdot \ln(\cos \phi )d\phi = \int_{0}^{\frac{\pi}{2}} \ln(\cos \phi)\cdot \cos \phi d\phi$$  Now Using Integration by parts, We get  $$\displaystyle I = \left[\ln(\cos \phi)\cdot \sin \phi\right]_{0}^{\frac{\pi}{2}}+\int_{0}^{\frac{\pi}{2}}\frac{\sin^2 \phi}{\cos \phi}d\phi$$  So $$\displaystyle I = \left[\ln(\cos \phi)\cdot \sin \phi\right]_{0}^{\frac{\pi}{2}}+\int_{0}^{\frac{\pi}{2}}\frac{(1-\cos^2 \phi)}{\cos \phi}d\phi$$  So $$\displaystyle I = \left[\ln(\cos \phi)\cdot \sin \phi\right]_{0}^{\frac{\pi}{2}}+\int_{0}^{\frac{\pi}{2}}\sec \phi d\phi-\int_{0}^{\frac{\pi}{2}}\cos \phi d\phi$$  So $$\displaystyle I = \left[\ln(\cos \phi)\cdot \sin \phi\right]_{0}^{\frac{\pi}{2}}+\left[\ln\left|\sec \phi+\tan \phi\right|\right]_{0}^{\frac{\pi}{2}}-\left[\sin \phi\right]_{0}^{\frac{\pi}{2}}$$  So $$\displaystyle I = \left[\ln(\cos \phi)\cdot \sin \phi\right]_{0}^{\frac{\pi}{2}}+\left[\ln\left|\sec \phi+\tan \phi\right|\right]_{0}^{\frac{\pi}{2}}-1$$  Now How can I solve after that, Help Required, Thanks What units does the rotation argument expect when creating objects? I want to create a lamp in blender using python. I want to give the lamp some rotation. As per the  I can set the initial rotation using a tuple of numbers in the function call like this rotation=(0.0, 0.0, 0.0) this is the specifc documentation for the rotation parameter:  rotation: (float array of 3 items in [-inf, inf], (optional)) – Rotation, Rotation for the newly added object  What units is this parameter specified with? It does not seem to be in degrees or radian.  When I try with my example code here where I use rotation=(0, 1, 0) to get 1 degree on the y axis. I end up getting 57.296 degrees after running the code.  import bpy  bpy.ops.object.lamp_add(type='AREA', view_align=False, location=(0, 0, 0), rotation=(0, 1, 0), layers=(True, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False)) Assume that $Y_0,\ldots , Y_n$ are independent random variables with the following identical distribution: $Y_i=1$ with propability $p$ and $Y_i=0$ with propability $1-p$. Also set $S_0=0$ and $S_n=Y_0+\ldots + Y_n$.  It's quite trivial that $(Y_n)_{n\geq 0}$ is a Markov chain, and I managed to show that $(X_n)=(S_n)_{n\geq 0}$ is also a Markov chain, by showing that  $\mathbb{P}(X_{n+1}=i_{n+1}\,|\,X_0=i_0,\ldots,X_n=i_n)=\mathbb{P}(X_{n+1}-X_n=i_{n+1}-X_n\,|\,X_0=i_0,\ldots,X_n=i_n)=\mathbb{P}(Y_{n+1}=i_{n+1}-X_n\,|\,X_0=i_0,\ldots,X_n=i_n)=\mathbb{P}(Y_{n+1}=i_{n+1}-i_n)=\mathbb{P}(Y_{n+1}+i_n=i_{n+1})=\mathbb{P}(X_{n+1}=i_{n+1}\,|\,X_n=i_n)$  However I am now running into the problem that I have to find whether or not $(X_n)=(S_0+\ldots + S_n)_{n\geq 0}$ is a Markov chain. I suspect that it isn't, but i'm having trouble finding a counterexample. I also need to find if $(X_n)=(S_n, S_0+\ldots+S_n)$ is a Markov chain, but I think this actually might be one, since $X_n$ gives "more information" (so to speak) to $X_(n+1)$. Again, having trouble actually proving that.  I appreciate any help, tips etc you can give me. Array versus List: When to use which? MyClass[] array; List&lt;MyClass&gt; list;   What are the scenarios when one is preferable over the other? And why? It's been more than a month since I have started using . It has these users with user names in the format of "user-random number". I have observed them in some of the stack activities, most of the time asking questions.   Does the moderators create them for their own purpose. If yes what purpose do they serve?   I mean a user is free to have any user name. But it's just a hunch that such users are actually moderators. I may be wrong; just need some clarification. Windows 10 doesn't shut down properly I have visited tons of websites and watched dozens of Youtube videos, yet I can't find a solution to my problem.  I recently upgraded my laptop to Windows 10, and now it won't shutdown properly.  I have turned off fast startup and sleep mode from power options.  Here is what happens:   Start menu > Power > Shut down It exits windows and apparently turns off (black screen) The power lights are still on and my computer apparently doesn't shutdown. I want to change my field from molecular biophysics to theoretical ecology. While they are basically required some same basic background (physics, math, programming), the rest is quite irrelevant. In my current draft of this part, about a half is about this the problem and the result of the work, another half is for my contribution and what I've learnt. Having said that, should I focus less on describing the work and leave space for the thing that will be useful for the next research?  Below is copy from .     What have you already done? What problems have you solved, or at least worked on? What independent projects have you been part of? What were your key contributions? What did you learn? What did you teach the world? How do your results compare to what was already known? What original ideas are you most proud of? Be specific, technical, credible, and confident (but not arrogant). Refer the reader to your web page for more details. Have a web page with more details: preprints, project reports, source code, videos, etc. Why an abstract class implementing an interface can miss the declaration/implementation of one of the interface's methods? Text Distortion Effect (like it is written on a page) I want to display a text like it is written on some surface like notebook page or wall via Photoshop CS6. I added two example.   This image seems like image distortion:    And this image looks like text distortion:    I tried this with distort and skew transformation but I'm unable to get this much clear &amp; real effect. How to prove that compact subspaces of the Sorgenfrey line are countable? How to prove that every compact subspace of the  is countable? How to prevent updating of a specific package? Because of  I'd like to prevent apt-get upgrade and Update Manager from updating the "libgtk2.0-0" package.   How can this be achieved? Lookup City and State by Zip Google Geocode Api Try Ubuntu - Where does it store my files? I am wondering, when you select the option of just "Try Ubuntu" instead of installing, where does Ubuntu store the files that you download / copy / save?  I right click in the Home folder, and it specified I had 4GB free space. Where did it get this 4GB space from, and if I transition to another OS system, how can I access or delete all the previous data from the session of "Try Ubuntu"?  Thank you! There are two directories shown by 'ls'.  Normally directories anywhere are blue on black background.  But the first one is blue on green and impossible to read.  Why is this?  How to make it blue on black, or at least something light on something dark?  This is on Ubuntu 12.04, using bash in Gnome Terminal.  In Konsole, the blue is slightly darker, and possible to read, though could be way better. How To: Execute command line in C#, get STD OUT results Class is not key value coding-compliant In Random forest algorithm, Breiman (author) constructs similarity matrix as follows:   Send all learning examples down each tree in the forest If two examples land in the same leaf increment corresponding element in similarity matrix by 1 Normalize the matrix with number of trees   He says:     The proximities between cases n and k form a matrix {prox(n,k)}. From their definition, it is easy to show that this matrix is symmetric, positive definite and bounded above by 1, with the diagonal elements equal to 1. It follows that the values 1-prox(n,k) are squared distances in a Euclidean space of dimension not greater than the number of cases.    In his implementation, he uses sqrt(1-prox), where prox is a similarity matrix, to convert it to distance matrix. I guess it has something to do with the "sqaured distances in a Euclidean space"-quoted above.  Can somebody shine a little light on why it follows that 1-prox are squared distances in a Euclidean space and why he uses squared root to get distance matrix? Could not make temporary scratch layer permanent I want to make a temporary scratch layer permanent but it shows  Could not make temporary scratch layer permanent. Error: Creation of field addr:street_1 failed (OGR error: Can't create field addr_str_4 in Shape DBF file, reason unknown.) How can I fix this error?  This is my attribute table. While I've done quite a bit of travel now and back myself to handle situations when it comes to border guards, sorting accommodation and / or transportation, one thing I still struggle to come to terms with is haggling in the markets, be it for food, clothing or other.    Image © Peter Morgan, 2014   What is the best way to go about this? I'm generally either worried I'll offend them, or that they're trying to rip me off anyway, so it's a weird combination of awkwardness inside my head ;) Can you raise $\pi$ to a real power to make it rational?