Using center twice on a page
Centering sections
In C, what is the difference between using ++i and i++, and which should be used in the incrementation block of a for loop? Show $1/(1+ x^2)$ is uniformly continuous on $\Bbb R$. Which way does the scale tip? Best choice between using \\ or leaving space after each paragraph to end the paragraph Here is the thing, I have always used a blank space between paragraphs in order to tell latex that there is a new paragraph. But there is someone I work with very often that keeps using \\ to break a line after a paragraph...  This is really annoying so I wanted to know if there is a real advantage of using \\ over just leaving a space.  Note that I am not referring to the paragraph environment, but to the simple term paragraph. After upgrading from 10.04 to 12.04 I am trying to install different packages.  For instance ia32-libs and skype (4.0).  When trying to install these, I am getting the 'Unable to correct problems, you have held broken packages' error message.   Output of commands:  sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.   After running this:  sudo dpkg --configure -a foo@foo:~$ sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. Vertically centered horizontal rule filling the rest of a line? I'd like to have a horizontal line extending from the end of the text on a line to the right margin. So far I've found \hrulefill and \leaders\hrule\hfill, but these draw a line that's flush with the baseline of my text — how can I get it to be vertically centered? What is the difference between a static and a non-static initialization code block My question is about one particular usage of static keyword. It is possible to use static keyword to cover a code block within a class which does not belong to any function. For example following code compiles:  public class Test {     private static final int a;         static {         a = 5;         doSomething(a);     }     private static int doSomething(int x) {         return (x+5);     } }   If you remove the static keyword it complains because the variable a is final. However it is possible to remove both final and static keywords and make it compile.   It is confusing for me in both ways. How am I supposed to have a code section that does not belong to any method? How is it possible to invoke it? In general, what is the purpose of this usage? Or better, where can I find documentation about this? Dirac equation as Hamiltonian system Let us consider Dirac equation $$(i\gamma^\mu\partial_\mu -m)\psi ~=~0$$ as a classical field equation. Is it possible to introduce Poisson bracket on the space of spinors $\psi$ in such a way that Dirac equation becomes Hamiltonian equation   $$\dot{\psi}~=~\{ \psi,H\}_{PB}~?$$  Of course, such Poisson bracket would be graded (super Poisson bracket), but if it exists this would explain on classical level why $\frac{1}{2}$-spinors correspond to fermions. How can I prevent SQL injection in PHP? Is there a Google Drive client available? When there are X New Questions, the views don't update untill you refresh the page How do I kill processes in Ubuntu? How do I kill all processes running by my own non-root account?  I have some spinning smbd  processes that I caused from my windows machine and so I telnetted into the linux server and I want to kill those spinning processes.   I don't have authority to restart services or reboot the machine. List View Visibility Novel from 50s or 60s - Good vs. Evil I'm not sure I recall enough of this story for a good identification, and the below is definitely out of story order, but...  The POV character goes to his home town and finds it different. He later finds that he's trapped in the town; there are two young people who turn out later on to be ... avatars ... of Ormazd and Ahriman, and the town is a battleground; what he is seeing of the town is Ahriman's effect on the town, and he turns out to have some limited ability to see the original town, which is more-or-less Ormazd's version of reality. In the end, Ahriman's avatar is destroyed, and the town restored.  I read this in the '80s or earlier; it was part of my father's collection, and the book was showing its age; I think it more likely to be the '60s rather than the '50s, and was probably by a prominent name in SF, but not one of the Masters. Finding the roots of complex numbers $(2i)^{1/2}$  $(1-\sqrt{3}i)^{1/2}$  $(-1)^{1/3}$  $(-16)^{1/4}$  How can I find the roots of the complex numbers above? How can I get file extensions with JavaScript? $a+1,a-1$ invertible for nilpotent element Given a ring $R$ (with unity), prove that if $a \in R$ is nilpotent, then $a+1,a-1$ are both invertible.   Suppose $a^n=0$. Then $1=1-a^n=(1-a)(1+a+\ldots+a^{n-1})$, so $1-a$ is invertible.  If $n$ is odd we can use $1+a^n=(1+a)(1-a+\ldots+a^{n-1})$.  But what if $n$ is even? How to export SVG without lines, polylines and polygons? Have a look at   One of the bolds works, and the other one just turns up as ** in the actual post.  This is the string that isn't working: **x**ml n**ib**  Which renders as: xml nib What is IEEE 802.3 Ethernet's communication type: Synchronous or Asynchronous? In the IEEE 802.3 frame structure there is a 7 byte preamble section for synchronization. If it is really for synchronization does that mean Ethernet is synchronous and not asynchronous?    Ethernet structure for reference: