In C/C++, return type of main() can be int/void but in JAVA it can only be void why ?
In the case of languages with a C-like syntax, we declare the main() method to return an int or float value (or void).  Is it possible to declare a non-void return type from main() in Java?  If not, then why not?  Does this mean that a Java program doesn't return any value to the OS?
Have a web-part display only sub-folders? I am new to SharePoint 2013. I was curious how to put a WebPart for a Document Library on a page with SharePoint 2013, not 2010.   This WebPart would then show the content of a specific library folder and not start at the root of the folder. So say I have a library with multiple folders like "Marketing", "Finance" etc,   I want to be able to create a web part that would only show the contents within the “Marketing subfolder and all of it contents. Is this possible? How can I work with customize completion? I want to add some new auto-completion but I don't know How the wizard works. It's here: User>Customize Completion I don't know what should be writen in the box. Let $q \in \mathbb C$, $\|q\|=1$ and $q^n \neq 1, \forall n \in \mathbb N$. Show that $\{q^n: n \in \mathbb N\}$ is dense in $S^1$ Let $q \in \mathbb C$, $|q|=1$ and $q^n \neq 1, \forall n \in \mathbb N$. Show that $\{q^n:  n \in \mathbb N\}$ is dense in $S^1$.  My attempt: As $(q^n)$ is limited, there is subsequence $(q^{n_j})$ convergent. So given $\epsilon &gt; 0, \exists j_0 \in \mathbb N, \quad |q^{n_j} - q^{n_k}| &lt; \epsilon, \quad \forall j,k \geq j_0$. Supose that $n_j &gt; n_k$, then  $|q^{n_j} - q^{n_k}| = |q^{n_k}||q^{n_j - n_k} - 1| = |q^{n_j - n_k} - 1| &lt; \epsilon, \quad \forall j, k \geq j_0$. So, there is a subsequence of $(q^n)$ that converges to $1$.  Using this fact, how can I ensure that for all $w \in S^1$ there is a subsequence of $(q^n)$ that converges to  $w$? How do I create a permanent Bash alias? Is the term "errored out" a grammatically correct phrase, or just a colloquial one? Can anyone explain IEnumerable and IEnumerator to me? Can anyone explain IEnumerable and IEnumerator to me? For example, when to use it over foreach? what's the difference between IEnumerable and IEnumerator? Why do we need to use it? Downloading from Play Store gives error 491 When I try to download anything from the Play Store it shows error 491 and can't finish the download. I have a Samsung Galaxy S 7582. How do I fix this? I'm heading to India next week and have a connection in Munich, Germany. I made the mistake of booking a flight with only an hour and a half layover (freaking out!) and I'm wondering if I'll have to go through customs in Munich or if I can pass right on through. Is it possible to allow usage for an app or program for a specific times on a Mac? I was trying to achieve this using a second account (which is the admin account) and Parental Controls, but it seemed this isn't possible to do so.  I know there are some programs which you can download that help you with this, (Cold Turkey, for example). But, it would be much easier if I could do this using only tools already available on macOS. DeleteDuplicates[] does not work as expected on floating point values Strictly Upper Triangular $n\times n$ Matrices form a Nilpotent Lie Algebra over $\mathbb{C}$ for $n\geq 2$ I have been attempting this problem for a while, it is an assignment problem so I don't want somebody to just post the answer, I'm just looking for hints.  Let $\mathfrak{u}(n,\mathbb{C})$ be the Lie algebra of strictly upper triangular $n\times n$ matrices over $\mathbb{C}$.  I am trying to show that $\mathfrak{u}(n,\mathbb{C})$ is a nilpotent Lie algebra for $n\geq 2$.  This is what I have looked at so far.  I have done some explicit calculations (I shall omit the bulk of them and just summarise below) for $n=2,3,4$ and have come up with some ideas.  Let $L=\mathfrak{u}(n, \mathbb{C})$.  If $n=2$,  $L^1 = [L, L] = &lt;0&gt;_{\mathbb{C}}$  So $L$ is nilpotent.  If $n=3$,  $L^1 = [L, L] = &lt;e_{13}&gt;_{\mathbb{C}}$  $L^2 = [L, L^1] = &lt;0&gt;_{\mathbb{C}} = \left\{ 0 \right\}$  So, $L$ is nilpotent.  If $n=3$  $L^1 = [L,L] = &lt;e_{13},e_{14},e_{24}&gt;_\mathbb{C}$  $L^2 = [L,L^1] = &lt;e_{14}&gt;_{\mathbb{C}}$  $L^3 = [L, L^2] = &lt;0&gt;_{\mathbb{C}} = \left\{ 0 \right\}$  So, $L$ is nilpotent.  So my hypothesis so far is that for an arbitrary $m\in\mathbb{N}$, $L^{m-1}=\{0\}$  My instinct is to do this by induction. My base case, $n=2$ has already been shown. Now I assume that $\mathfrak{u}(n,\mathbb{C})$ is nilpotent for $n=k$ ($k\in\mathbb{N}$) and consider the case for n=k+1.  However, I have no idea how to link these two cases together. I have read in Introduction to Lie Algebras and Representation Theory - J.E. Humphreys that $L^k$ should be spanned by basis vectors $e_{ij}$ where $j-i=k+1$ - however in my calculations for $L^1$, I obtain an $e_{14}$ which does not satisfy 4-1=2.  Am I missing something completely obvious? Or have I made a mistake somewhere? (I have checked my calculations numerous times, but cannot find any errors!)  Thanks,  Andy. Meaning of U suffix Orthographic Camera Zooming In XNA I am using a spritebatch to render a board. I have created a camera class which can provide me a view and projection matrix. Currently I am supplying the view matrix to my sprite batch when I call begin.  I can get the view matrix to correctly move everything around and do some zooming in and out. My problem is that I want to zoom in on a specific point (for now the center of the screen) but currently zooming just zooms in on the coordinate 0,0.   Here is how I am constructing the view matrix;          _ViewMatrix =             Matrix.CreateTranslation(                 new Vector3(                     (-_Position.X + _Width * _Zoom / 2),                     (-_Position.Y + _Height * _Zoom / 2),                     0) ) *             Matrix.CreateScale(new Vector3(_Zoom, _Zoom, 1));   How could this be altered to make it scale correctly relative to the given point. Later I will probably want to zoom to the mouse position, but if someone has a simple example I'm sure I can work out how to adapt it. In electromagnetism, why does nature prefer the right-hand rule over the left-hand rule? Is there a way to enable/disable a wireless network interface via the command line (so I can put it in a bat file)?  When I'm in the office I use a wired connection, but Windows still occasionally bugs me about my wireless connection not being connected (even though I turned off the option for notifying me when there's no connectivity).  I'm guessing the only way to stop it from bugging me is to disable the interface, but I'd rather not have to go into the network settings every time I need to do so.  I'd like to set up a bat file or a shortcut that I can use to enable/disable the wireless (preferably a single one that toggles the current state), and then just set up a keyboard shortcut for that.  I just have no idea how to do so from the command line. Say if I define a power series over some arbitrary field $F$ as   $$a = \sum^{ \infty }_{i = 0} a_{i} X^{i} $$  Then can I say:  $$ab = \sum^{ \infty }_{i = 0} \sum^{ \infty }_{j = 0} a_{i} b_{j} X^{i + j} $$ How to execute a JavaScript function when I have its name as a string Quarks in a hadron: where does the mass come from? Background  Would like to center all tables within floats, without having to add \centering to each table.  Ideas  Tried the following:  \let\originaltabular\tabular \renewcommand\tabular{\centering\originaltabular}   It compiles, but the tables remain left-justified.  Question  How would you edit the Preamble of a LyX document to make all the floating tables be centred? What is time dilation really? Please will someone explain what time dilation really is and how it occurs? There are lots of questions and answers going into how to calculate time dilation, but none that give an intuitive feel for how it happens.