I am using date() function in the format date('Y-m-d H:i:s'). It shows 2013-11-22 06:26:25 when the actual time is 2013-11-22 11:56:25. My code,  echo    $today = date('Y-m-d H:i:s');
Some issues with timezones in PHP have been in the back of my mind for a while now, and I was wondering if there are better ways to handle it than what I'm currently doing.  All of the issues revolve around reformating database stored dates:  When dealing with a site that has to support multiple timezones (for users), to normalize the timezone offest of stored timestamps I always store it with the server timezone using the CURRENT_TIMESTAMP attribute or the NOW() function.   This way I don't have to consider what timezone was set for PHP when the timestamp was entered (since PHP time functions are timezone aware). For each user, according to his preference I set the timezone somewhere in my bootstrap file using:  date_default_timezone_set($timezone);   When I'm looking to format dates with the php date() function, some form of conversion has to take place since MySQL currently stores timestamp in the format Y-m-d H:i:s. With no regard to timezone, you could simply run:  $date = date($format,strtotime($dbTimestamp));   The problem with this is that date() and strtotime() are both timezone aware functions, meaning that if the PHP timezone is set differently from the server timezone, the timezone offset will apply twice (instead of once as we would like).  To deal with this, I usually retrieve MySQL timestamps using the UNIX_TIMESTAMP() function which is not timezone aware, allowing my to apply date() directly on it - thereby applying the timezone offset only once.  I don't really like this 'hack' as I can no longer retrieve those columns as I normally would, or use * to fetch all columns (sometimes it simplifies queries greatly). Also, sometimes it's simply not an option to use UNIX_TIMESTAMP() (especially when using with open-source packages without much abstraction for query composition).  Another issue is when storing the timestamp, when usage of CURRENT_TIMESTAMP or NOW() is not an option - storing a PHP generated timestamp will store it with the timezone offset which I would like to avoid.  I'm probably missing something really basic here, but so far I haven't been able to come up with a generic solution to handle those issues so I'm forced to treat them case-by-case. Your thoughts are very welcome
When I log in with LightDM on my laptop running Debian Unstable, it recently started to hang for around 2 minutes until journalctl shows the message kernel: random: crng init done. When I press random keys on my keyboard while it hangs, it logs in faster (around 10 seconds). Before I didn't have this issue, is there any way I can fix it?  Edit: using linux-image-4.15.0-3-amd64 instead of linux-image-4.16.0-1-amd64 works, but I don't want to use an older kernel. Changing color of already printed text For making a small quiz in class I am working on a presentation in beamer.  I want to change the color of statements to red (wrong statement) or green (right statement) but only after my class answered the question.  I was searching the internet, but only found the color package, where you apparently can only change the text color before it appears.  Can someone point me into the right direction? FaceTime and iMessage - an error occurred during activation I couldn't log in to FaceTime so I did a factory reset of my MacBook. It worked for a brief period of time and then suddenly it just logged out.  I believe it might have been after iCloud synced with keychain or after I changed my local host name and computer name.  I have seen other users facing this issue but no solutions. Is there a troubleshooting guide or should I just contact Apple support since I can't use their service without activation to my Mac? Why are our planets in the solar system all on the same disc/plane/layer? How to "find and replace" in a PDF on OS X? Can Jupiter be ignited? Our solar system itself contains two candidate "Earths"  One is Jupiter's moon Europa and another is Saturn's moon Titan. Both of them have the problem of having at low temperature as Sun's heat cannot reach them.    Jupiter is made up mostly of Hydrogen so is our Sun. Can we ignite Jupiter so that it will produce enough heat to warm these two earth like planets/satellites? What can be consequences of any of such attempt? linear dependence proof using subsets When using the Stack Exchange App for Android, I encountered a problem when uploading multiple images to the same post.  After uploading a single image, the image Markdown is inserted normally, e.g.:  ![enter image description here][1]     [1]: http://i.stack.imgur.com/Cbh1m.jpg   As I upload more images, the list of URLs at the bottom of the post should be appended to. After uploading the above in a new post, I tap to place the cursor at the end of the first line, enter a newline and the toolbar reappears. I then upload a second image with this result:  ![enter image description here][1] ![enter image description here][2]     [1]: http://i.stack.imgur.com/Cbh1m.jpg   [2]: http://i.stack.imgur.com/V5nXV.jpg   Now I edit the image descriptions, to make sure I can keep track of all my images, place the cursor at the end of the second line and enter a newline. The edit box contains:  ![a black circle of utter blackness][1] ![the best planet earth clip art ever][2]      [1]: http://i.stack.imgur.com/Cbh1m.jpg   [2]: http://i.stack.imgur.com/V5nXV.jpg   I then upload a third image. What's interesting is that as the screen reloads, for an instant I see the best planet earth clip art ever replaced by more image markup, so the second line is this:  ![![enter image description here][2]][2]   But only for a moment. Then the screen updates, and the edit window is left in this state:  ![the best planet earth clip art ever][2] ![the best planet earth clip art ever][2] ![enter image description here][3]     [1]: http://i.stack.imgur.com/Cbh1m.jpg   [2]: http://i.stack.imgur.com/V5nXV.jpg   [3]: http://i.stack.imgur.com/6Ra5w.jpg   I correct the first line and insert a line break after the third line in preparation to upload the first image again (I really love blackness). Before uploading, the edit window looks like this:  ![a black circle of utter blackness][1] ![the best planet earth clip art ever][2] ![a fast computer][3]      [1]: http://i.stack.imgur.com/Cbh1m.jpg   [2]: http://i.stack.imgur.com/V5nXV.jpg   [3]: http://i.stack.imgur.com/6Ra5w.jpg   After uploading:  ![a fast computer][3] ![the best planet earth clip art ever][2] ![a fast computer][3] ![enter image description here][4]      [1]: http://i.stack.imgur.com/Cbh1m.jpg   [2]: http://i.stack.imgur.com/V5nXV.jpg   [3]: http://i.stack.imgur.com/6Ra5w.jpg   [4]: http://i.stack.imgur.com/ILUCC.jpg   Now, instead of adding a newline, I position my cursor at the end of the third line. The toolbar isn't visible so I insert a space and then delete it. I upload another copy of the third image from this position adjacent to other image markdown, and now the result is:  ![a fast computer][3] ![the best planet earth clip art ever][2] ![a fast computer][3]![enter image description here][4] ![enter image description here][4]      [1]: http://i.stack.imgur.com/6Ra5w.jpg   [2]: http://i.stack.imgur.com/V5nXV.jpg   [3]: http://i.stack.imgur.com/6Ra5w.jpg   [4]: http://i.stack.imgur.com/jG0fk.jpg   [5]: http://i.stack.imgur.com/ILUCC.jpg   Notice:   The new image, the fifth I have uploaded, goes in as image [4]. Not a problem, so far, but: The previous image description is still linked to image [4], now a different URL; and The first URL in the list has been overwritten by the URL of the third image, which happens to be immediately adjacent on the line where I inserted the most recently-uploaded image.   Reproduced at the time of this question revision, with the following specs:   Device: Moto G 2013 OS version: 4.4.4 App version: 1.0.57 How can I rename many files at once? How to verify $H\otimes K \cong \bigoplus\limits_{i\in I}H$ Let $H,~K$ be the Hilbert space. if $\{v_{j}\}_{j\in J}\subset H$ and $\{w_{i}\}_{i\in I}\subset K$ are the orthonormal bases, then how to construct the isomorphic mapping: $H\otimes K \rightarrow \bigoplus\limits_{i\in I}H$. Here, the $H \otimes K$ is the tensor product of two Hilbert space. Replace preg_replace() e modifier with preg_replace_callback I'm writing an application that allows users to upload images onto the server. I expect about 20 images per day all jpeg and probably not edited/resized. (This is another question, how to resize the images on the server side before storing. Maybe someone can please drop a .NET resource for that in the comment or so).  I wonder now what the best place for storing uploaded images is.   Store the images as a file in the file system and create a record in a table with the exact path to that image. Or, store the image itself in a table using an "image" or "binary data" data type of the database server.   I see advantages and disadvantages in both.  I like a) because I can easily relocate the files and just have to change the table entry. On the other hand I don't like storing business data on the web server and I don't really want to connect the web server to any other datasource that holds business data (for security reasons)  I like b) because all the information is in one place and easily accessible by a query. On the other hand the database will get very big very soon. Outsourcing that data could be more difficult. Impulsioned jumping There's one thing that has been puzzling me, and that is how to implement a 'faux-impulsed' jump in a platformer. If you don't know what I'm talking about, then think of the jumps of Mario, Kirby, and Quote from Cave Story. What do they have in common? Well, the height of your jump is determined by how long you keep the jump button pressed.  Knowing that these character's 'impulses' are built not before their jump, as in actual physics, but rather while in mid-air - that is, you can very well lift your finger midway of the max height and it will stop, even if with desacceleration between it and the full stop; which is why you can simply tap for a hop and hold it for a long jump -, I am mesmerized by how they keep their trajetories as arcs.  My current implementation works as following:    While the jump button is pressed, gravity is turned off and the avatar's Y coordenate is decremented by the constant value of the gravity. For example, if things fall at Z units per tick, it will rise Z units per tick.  Once the button is released or the limit is reached, the avatar desaccelerates in an amount that would make it cover X units until its speed reaches 0; once it does, it accelerates up until its speed matches gravity - sticking to the example, I could say it accelerates from 0 to Z units/tick while still covering X units.  This implementation, however, makes jumps too diagonal, and unless the avatar's speed is faster than the gravity, which would make it way too fast in my current project (it moves at about 4 pixels per tick and gravity is 10 pixels per tick, at a framerate of 40FPS), it also makes it more vertical than horizontal. Those familiar with platformers would notice that the character's arc'd jump almost always allows them to jump further even if they aren't as fast as the game's gravity, and when it doesn't, if not played right, would prove itself to be very counter-intuitive. I know this because I could attest that my implementation is very annoying.    Has anyone ever attempted at similar mechanics, and maybe even succeeded? I'd like to know what's behind this kind of platformer jumping. If you haven't ever had any experience with this beforehand and want to give it a go, then please, don't try to correct or enhance my explained implementation, unless I was on the right way - try to make up your solution from scratch. I don't care if you use gravity, physics or whatnot, as long as it shows how these pseudo-impulses work, it does the job.  Also, I'd like its presentation to avoid a language-specific coding; like, sharing us a C++ example, or Delphi... As much as I'm using the XNA framework for my project and wouldn't mind C# stuff, I don't have much patience to read other's code, and I'm certain game developers of other languages would be interested in what we achieve here, so don't mind sticking to pseudo-code.  Thank you beforehand. Java is the key here. I need to be able to delete files but users expect to be able to "undelete" from the recycle bin.  As far as I can tell this isn't possible.  Anyone know otherwise? Why cofinality is a cardinal. I want to learn to use biper and biblatex in Lyx. This is how I would do it in LaTeX traditionally with biblatex and biber  \documentclass[12pt,a4paper,oneside,pdftex]{report} \usepackage[backend=biber]{biblatex} \addbibresource{minCuts.bib} ... \printbibliography \end{document}   The error is apparently originating from the \bibliographystyle command and biblatex package getting mixed, by . But I have no \bibliographystyle command in Preamble so they should not be mixed unless Lyx is somehow importing the \bibliographystyle.   How to resolve the biblioraphystyle error in Lyx with Biber and Biblatex?    Settings by the instructions  and Error        Document > Settings > Bibliography > Biber                  In Document > Settings > LaTeX Preamble                   Insert > List / TOC > BibTeX Bibliography...                        Package biblatex Error : '\bibliographystyle' invalid. What is the distribution of primes modulo $n$? Output of getent group CentOS 7 DVD ISO vs Everything ISO different How can I get sql string, generated by Linq2SQL ORM?