Why does mysql give different result for this summations?
sum of double precision gives weird results
Full Wi-fi/ethernet signal but no internet I'm really hoping someone here can help me, as I'm getting pretty frustrated with my macbook now. I have a late 2011 model 15" macbook pro running OSX 10.9.5 that refuses to connect to Internet on my home network. I have the same problem whether it's WiFi or through ethernet cable, I have full signal but not getting online. Every other device connects fine; android phones and tablets,xbox one, iPhone and other macbooks, all online and browsing the net. I have had no problems connecting to other networks with my macbook pro before and I just tried at a friend's house to check, with no problems. A little something, that may be a clue to someone: when I open network diagnostic tool, my macbook pro connects for something that seems like a microsecond and it tells me I'm connected to Internet and everything seems fine. My IP is 192.168.0.5 subnet mask 255.255.255.0 and IPv6 is set to automatic. None of the options are checked under the proxies tab. Now I've tried the following, in different order and a number of times, to no avail:   Renewing/turning off&amp;on/inputting manually DHCP.  Restarting/resetting the router and the macbook.  Turning WiFi on/off. Remove &amp; add services (WiFi &amp; ethernet). Checked and copied all network settings from another macbook pro that's connected and online on my network. Ran network diagnostic and assistant tools Duplicated/removed/added location Removed the /Library/Preferences/SystemConfiguration folder. Removed network password from keychain.      I've tried other things too, but can't remember what else right now.  Response from ifconfig en1:  en1: flags=8863&lt;UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500              ether 28:cf:da:e6:95:0a              inet6 fe80::2acf:daff:fee6:950a%en1 prefixlen 64 scopeid 0x5               inet 192.168.0.5 netmask 0xffffff00 broadcast 192.168.0.255              nd6 options=1&lt;PERFORMNUD&gt;              media: autoselect               status: active    I'm praying that someone out there has the magic words or the 2-click solution for me, but I would be grateful for a long thorough guidelines to solve it too! &lt;3        Regards Trond How is Bohr's model related to electron cloud models via the correspondence principle? When I place a multipage pdf file into InDesign CC, the pages go outside of my document settings, making this function useless.  What do I have to do to make the placed  pdf pages go within my document settings, which in this case is 11 in. Length X 8.5 in. width, .5 in. margins on all sides, with two columns per page. I would greatly appreciate an answer to this, Thank you. Why does volatile exist? What does the volatile keyword do? In C++ what problem does it solve?  In my case, I have never knowingly needed it. Can Selenium interact with an existing browser session? I would like to set my monitor's scale under 100%, but Win10 only lets me set it to 100% or higher. Why won't Windows let me do that? Is there any workaround to do that? I am aware of the fact that scaling below 100% will result in merged pixels. Infinite series $\sum _{n=2}^{\infty } \frac{1}{n \log (n)}$ Recently, I encountered a problem about infinite series. So my question is how to know whether the infinite series $\sum _{n=2}^{\infty } \frac{1}{n \log (n)}$ is convergent? Conditional \endinput I want to prevent processing rest part of a package in case if it is loaded not from lualatex. For some reason I cannot load ifluatex package, so I borrowed definition of \ifluatex from that package and invented the following chunk of code:  \expandafter\ifx\csname luatexversion\endcsname\relax % = not \inluatex   %\typeout{^^J********************** not LuaTeX^^J}   \PackageError{babel}{     ^^J\space\space * Option russianu is intended for LuaTeX only.              ^^J\space\space * Option russian  is used instead.                     }   \relax   \input{russianb.ldf}     \let\@next@action\endinput \else   %\typein{^^J********************** LuaTeX^^J}   \let\@next@action\relax \fi \@next@action   It seemed to work but Is there a better solution. In particular, it is desirable to avoid introduction of \@next@action because it is used the only time.  Just to explain: my goal is to hack babel with option russian to make it working painlessly with LuaLaTeX without any additional hacks (as described, eg, in  and ) I see many posts on both this forum and elsewhere the discuss the use of a wide angle on a crop sensor.  For example, they discuss how at 14mm lens is 14mm on a 35mm film or full frame, but with a 1.6x crop sensor it is an effective 28mm.  My question is, is a 14mm on a crop sensor the same image as a 28mm on a full frame.  Or does "effective" include some other conotation.  I read that a 14mm can create distortion on a full frame and some vignette, so people seem to say using it on a crop takes out some of those edge problems. My confusion is how the lens is actually taking in the extra image.  Reading kenrockwells blog I learned that wide angle keeps lines straight, while fish eye actually skews the lines.    So with this as my understanding, I am still a bit confused how a lens that is curved in order to get a greater angle of view, will be the same as a cropped version of a less curved lens.  Or does "effective" only refer to the objects to the sides but not to the distortion of the image.  Or, if it is different, is it so small that for photography it does not matter?  A technically description would be welcome as long as a basic understanding of the situation.  Thanks!  Edit: To be more clear after the comments,  I am specifically talking about the end resulting 2d projection from 3d space.  I have read both those previous answers.  the first one is closer to what I am talking about.  However, it is still confusing for me.  I have experience with 3d modeling and projection matricies, which might be confusing me with this.  But for example, i dont understand the images having a 50 mm lens being drawn Starting from the sensor, so it shows a different fov for crop and full frame . If the lens is the same, it takes the same amount of information from the world, which makes a ray from a certain degree off the last lens projected into a smaller space, there is no projection from the sensor, so drawing the line from the sensor doesnt make sense to me.  The distance of the sensor to the rear of the lens must have some impact on the light projected but is not represented in the images.  Further, again from that first answer it says cropping is the same as zoom, but from what i understand from how perspective works, it is different, since a wide angle will project lines differently than a small fov to the same size, so cropping the center of a wide angle and zooming into something is very different.  This is easily recreated in an opengl application with varying fov projection matrix, i imagine in painting class people learn this as well.  A fisheye would be a good example, since if cropping was the same as zooming, a fish eye lens would keep the center exactly like a normal lens and then a gradient weighted towards the outside would rapidly create a warped perspective, but from what I see, it is even.  To me those images just look like its comparing cropped with full frame in regards to orthogonal projections. How can I improve the performance of Minecraft? Gauge symmetries and elementary particles The  (disclaimer: I don't know this wikipedia entry) is usually mentioned as the reason why gravitons may not be composite particles. I do understand the proof of the theorem, but not the previous conclusion.   The theorem states that in an interacting and Poincare invariant quantum field theory, there are not massless, spin-2 particles unless there exists a gauge symmetry — which makes the energy-momentum tensor non-covariant (actually covariant up to a gauge transformation) under Lorentz transformations in the Fock space. So the immediate conclusion of the theorem is that the existence of a massless, spin-2 particle (like a graviton) requires linearized diffeomorphisms.  My question is: why do linearized diffeomorphisms imply that gravitons are elementary particles? Or, more in general, why  the particle corresponding to a gauge field must be elementary (I know that a gauge symmetry must be exact, but why this implies that the corresponding particle must be elementary?). Here's my proof in my own words, does it stack up?   Showing $A$ is complete implies $A$ is closed. Let $(x_n)$ be a convergent sequence in $A$. $A$ is complete $\implies (x_n) \to p \in A$. Hence $A$ is closed. Showing $A$ is closed $\implies$ $A$ is complete. Let $(x_n)$ be a convergent sequence in $A$. $A$ is closed $\implies (x_n) \to p \in A$. As every convergent sequence is a Cauchy sequence, $(x_n)$ is a Cauchy sequence in $A$ that converges to $p \in A$ and hence $A$ is complete.   That sound ok?  As an aside, it seems to me that the definition of completeness and closed are basically identical, why are there two definitions for the same thing? Am I missing something here? "No such file or directory" when trying to remove a file, but the file exists? I am trying to remove a png image that was uploaded to my server via a PHP script. Whenever I try to delete it both through ftp and terminal, I get the error   No such file or directory   However, when I ls in the dir, the file is listed and it is also listed in my ftp client. I have tried creating a file with the same name and I end up getting two files with the same name.   I can open the file that supposedly does not exist, but I still can't remove it. I have also tried rebooting my server. Any ideas what may be the issue? I am running a 64 bit version of Ubuntu, but I don't think its a 32/64 bit issue. I should also note I have removed many other png files uploaded by the same PHP script.  Output for ls -l  total 224  -rw-r--r-- 1 www-data www-data 222838 May 13 04:14 qyxdshyikfr_fishing_timeout.png  -rw-r--r-- 1 root root 272 May 14 06:54 upload.php   Output when trying to rm  rm: cannot remove ‘qyxdshyikfr_fishing_timeout.png’: No such file or directory   upload.php: How to delete a file in Windows with a too long filename? My wife has several files and folders that somehow ended up having filenames that have caused them to be undeleteable (can't be deleted) by normal means or via the command line. I believe the filenames are too long due to the depth of the folder structures. Does anyone know of a good utility for cleaning up files like this? I am writing pseudo code in the algorithmic environment. It is quite long and doesn't fit on one single page. Instead of it continuing on the next page, it is cut off. I tried inserting it into a figure environment, but the problem persists. Is there a solution to have the code continue on the next page? Resize multiple layers around their respective anchor points I have 50 or so layers (imported images as smart objects) that I would like to scale down, while they stay in place. Is there a way of doing this? I know After Effects has, is there a similar Scale property in photoshop? I am trying to use the Alt+Right Click to select edge loops in Linux Mint but this shortcut doesn't work it is already used for Linux to reduce a window. I have checked the keyboard shortcut but it doesn't appear. /ə/ in a stressed syllable? According to , the schwa /ə/ doesn't occur in stressed syllables. But , Oxford Advanced Learner's Dictionary and Longman Pronunciation Dictionary say otherwise: the word "because" has been variously transcribed as /bɪˈkəz/ or /bəˈkəz/. So in which source should I believe? Or is there any error in transcription going on here? Or is "because" the only exception? And are there others? Customizing tray/taskbar date display in Ubuntu with GNOME 3 Search for emails from contacts with multiple email addresses