I have a string "2013-10-09 00:00:00" and I use the code below to change it to a timestamp  date_default_timezone_set($timeZone); $timeStamp = strtotime("2013-10-09 00:00:00"); //echos 1381269600   When I do   date_default_timezone_set($timeZone); date("Y-m-d H:m",$timeStamp);   I get 2013-10-09 00:10:00. This is completely strange. Why do I get this 10 minutes difference?
I have a datetime column in MySQL.   How can I convert it to the display as mm/dd/yy H:M (AM/PM) using PHP?
When is it appropriate to end a sentence in a preposition? How to find image coordinates of the rendered vertex? I have a simple mesh of a cube.  I would like to know what are the coordinates of each vertex in the rendered image (i.e. for each 3d vertex I'd like to know it's pixel coordinates).  Is there a way to do this?  Clarification:  I'm experimenting with a pose estimation algorithm (i.e. finding out the 3d pose of the object) from a (set of) 2d image(s).  Instead of taking an image of a real object with a real camera I synthetically render the image of a cube using blender.  In this way I know the pose of the object and the intrinsics of the camera, so I can easily validate the results of the pose estimation algorithm. Pose estimation algorithms usually require to provide them with world points on the object and the corresponding image points.  So what I'm looking for is a way to produce a dump of correspondences of the 3d point &lt;--> image point as a byproduct of the rendering procedure. Thanks, Alex Diagonal lines in table cell I need this table:    (each row and column should have the same height and length, last cell should be divided by diagonal line). I tried the following code:  \documentclass[11pt]{article} \usepackage[T1]{fontenc} \usepackage{array} \usepackage{makecell} \newcolumntype{x}[1]{&gt;{\centering\let\newline\\\arraybackslash\hspace{0pt}}p{#1}} \begin{document} \setlength{\extrarowheight}{0.1cm} \begin{tabular}{|x{0.5cm}|x{0.5cm}|x{0.5cm}|x{0.5cm}|x{0.5cm}|}\hline &amp;&amp;&amp;&amp;20\\ \hline &amp;&amp;&amp;&amp;30\\ \hline &amp;&amp;&amp;&amp;45\\ \hline 15&amp;12&amp;18&amp;50&amp;\diaghead(-3,2){\hskip \hsize}{$a_i$}{$b_j$}\\ \hline \end{tabular} \end{document}   but text in the last cell is displayed incorrectly and cells are not the same.     How can I change that? Getting my File Manager to link to my Google Drive I have a very small amount of storage on my computer and would like to conserve it, so I would like to know if there is a way to mount my Google Drive in Thunar or Nautilus on Ubuntu 12.04.5 LTS.   Yes, I know, it's weird that I'm saying that I have a small amount of storage when I have 2 file managers installed, but I literally have 5GB out of 16GB left. macOS Catalina File Structure: Cannot remove &gt; sudo rmdir /sw rmdir: /sw: Read-only file system  &gt; mount | grep read /dev/disk1s5 on / (apfs, local, read-only, journaled)  &gt; sudo mount -o rw / &gt; mount /dev/disk1s5 on / (apfs, local, journaled) &gt; sudo rmdir /sw rmdir: /sw: Operation not permitted     root /&gt;$ mkdir a root /&gt;$ rmdir a root /&gt;$ rmdir sw &lt;b&gt;rmdir: sw: Operation not permitted&lt;/b&gt; root /&gt;$ rmdir opt &lt;b&gt;rmdir: opt: Operation not permitted&lt;/b&gt; root /&gt;$ rmdir mnt &lt;b&gt;rmdir: mnt: Operation not permitted&lt;/b&gt; root /&gt;$ rmdir home &lt;b&gt;rmdir: home: Operation not permitted&lt;/b&gt;   What exactly is preventing me from removing these directories even with SIP disabled? Proof of $\frac{(n-1)S^2}{\sigma^2} \sim \chi^2_{n-1}$ It's a standard result that given $X_1,\cdots ,X_n $ random sample from $N(\mu,\sigma^2)$, the random variable $$\frac{(n-1)S^2}{\sigma^2}$$ has a chi-square distribution with $(n-1)$ degrees of freedom, where $$S^2=\frac{1}{n-1}\sum^{n}_{i=1}(X_i-\bar{X})^2.$$ I would like help in proving the above result. Thanks. Purpose of memory alignment Admittedly I don't get it. Say you have a memory with a memory word of length of 1 byte. Why can't you access a 4 byte long variable in a single memory access on an unaligned address(i.e. not divisible by 4), as it's the case with aligned addresses? Two different solutions to integral How do you photograph rain? What are recommended settings for my Nikon Coolpix P1 to best portray rain?  Here's what I got. No retouching was applied.   The picture I took when the rain was heavy with the automatic settings:  The picture I took with the "Sports" program; by then, however, the rain was not as hard. Ugh, ugly gray strip at the bottom, that was the flat surface I put my camera on to get a stable picture.   My main problem is that the actual rain and hailstorm is very hard to see in the picture. The overall effect is, instead, of fog.    Follow-up from the thread, courtesy of more rain, now with less hailstorm and more thunder.  The feedback amounted to flash and faster shutter. I took a few photos and I'm having some trouble to reconstruct what I did to get each result. Two representative results:   Fast shutter, with some guest starring:I'm talking about that horrible building obviously. Faster shutter and flash:Kinda difficult to say those pictures were taken sixty seconds of each other. :)   I'm not sure, however, that either of this is really an improvement of the original results. When the loop is the figure shown below will be rotated in clockwise direction the the slip ring connected to the red segment of the loop will give us the positive voltage and the slip ring connected to the black segment of the loop will give us negative voltage according to the Flemings right hand rule.  What if the loop is rotated in counter clockwise direction ? Will the slip rings provide us the same polarities which they were giving when the loop was moving clockwise ?  Plus  The voltage from the loop is given by the equation.  V(t) = Vmaximum * sin (theta)  Where theta is the positive angle the red segment makes in the clockwise direction or in counter clockwise direction from this position ? Finite $G$ with involutory automorphism $\alpha$ with no nontrivial fixed points. Proving properties of $\alpha$. The question at hand is:     Let G be a finite group and $\alpha$ an involutory automorphism of G, which doesn't fixate any element aside from the trivial one.    1) Prove that $ g \mapsto g^{-1}g^{\alpha} $ is an injection    2) Prove that $\alpha$ maps every element to its inverse    3) Prove that G is abelian    I think I've found 1).  I assume $ g_1^{-1}g_1^{\alpha} = g_2^{-1}g_2^{\alpha} $ and from this I get $ (g_2g_1^{-1})^\alpha = g_2g_1^{-1} $, so $g_2 = g_1$ (is this correct?)   For 2) I'm sort of stumped though, not sure how to start proving that, so any help please? How to flatten a non-planar face to a targeted plane? Let's take a non-planar quad here for a simple example, how to only move one vertex on it, to finally make it planar while keeping the other three vertices still? Number of Homomorphisms from $\Bbb{Z}_m$ to $\Bbb{Z}_n$ iOS app stalls phone when on weak wifi sign I've recently noticed a bug on the Stack Exchange IOS app. When I open the Stack Exchange app on weak wifi, it hangs on the blue load screen as it launches and either crashes the app or the entire phone lags and didn't respond for about a minute.  I'm running iOS 8.4.1, I have the most up to date version of the app, and by 'weak' wifi I mean two out of four bars of strength. How do I show that there exists variational/action principle for a given classical system? We see variational principles coming into play in different places such as Classical Mechanics (Hamilton's principle which gives rise to the Euler-Lagrange equations), Optics (in the form of Fermat's principle) and even General Relativity (we get Einstein's equation from the Einstein-Hilbert action). However, how do we explain this very principle, i.e., more mathematically, I want to ask the following:      If I am given a set of generalized positions and velocities, say, $\{q_{i}, \dot{q}_{i}\}$, which describes a classical system with known dynamics (equations of motion), then, how do I rigorously show that there always exists an action functional $A$, where    $$A ~=~ \int L(q_{i}, \dot{q}_{i})dt,$$    such that $\delta A = 0$ gives the correct equations of motion and trajectory of the system?    I presume historically, the motivation came from Optics: i.e., light rays travel along a path where $S = \int_{A}^{B} n ds$ is minimized (or at least stationary). (Here, $ds$ is the differential element along the path). I don't mind some symplectic geometry talk if that is needed at all. How can I recover contact information from a stolen phone? All of a sudden, Safari on my Mac has started misbehaving. I can't select the text in the address bar, and so I can't go to any new websites. When it redraws, it goes all weird:    I've tried deleting the cache, clearing all cookies, disabling all plugins and rebooting. These things didn't help. I've had to switch to Chrome for the time being. Can anyone suggest some other possible remedies? Can you cast a spell learned from the Magic Initiate feat using spell slots? Say I play a wizard who learns cure wounds by taking the Magic Initiate feat. Could I cast that spell using the Wizard's spell slots? Suppose $A$ is a general $n \times n$ matrix and $B$ is obtained by interchanging two rows of $A$. Prove that $\det(B) = -\det(A)$ Suppose that $A$ is a general $n \times n$ matrix and $B$ is obtained by interchanging the first two rows of $A$. Prove that $\det(B) = -\det(A)$.  By general $n \times n$ matrix, I mean $$\left[\begin{matrix} a_{11} &amp; a_{12} &amp; \cdots &amp; a_{1n} \\ a_{21} &amp; a_{22} &amp; \cdots &amp; a_{2n} \\ \vdots &amp; \vdots &amp; \ddots &amp; \vdots \\ a_{n1} &amp; a_{n2} &amp; \cdots &amp; a_{nn} \end{matrix} \right]$$ I'm thinking of using the cofactor expansion of the 2nd row of the first matrix, yielding $$ \det(A) = c_{21} a_{21} + c_{22} a_{22} + \cdots+ c_{2n} a_{2n}  $$ which will be positive or negative depending on $n$ and the values of $a_{21}, \ldots,a_{2n}$, and using the same on the first row in matrix $B$ to get $c_{11} a_{21}$ etc. and then use the fact that the power of the $c$ subscripts will alter $\det(B)$ to be the opposite sign, but I'm not sure how to express all of this mathematically in a proof directly. Help please? Remotely changing hard drive boot order, windows 7 I have one workstation chassis with two hard drives.  Depending on which one I boot from, I get one of two different operating systems: both are windows 7, but they have different static IPs, serve totally different purposes, etc.    The workstation has a modern asus motherboard, core i7 intel CPU, 32 GB ram.   Is there a way to remotely change which hard drive is booted from on a reboot?  Both systems have remote users, and i'd like a solution that is more elegant than being physically present and selecting boot order manually.