While working on , the joys of TDD helped me stumble upon a really strange (at least as i occurs to me) behaviour exposed in the javascript engines.  No matter if entered into the console or performed inside a script, this is what happens:  -1 + 0.85     --&gt; -0.85               ✓   -1 + 1        --&gt; 0                   ✓    -1 + 1 + -.15 --&gt; 0.15                ✓ -1 + 1.15     --&gt; 0.1499999999999999  ?!?   This is tested and reproduced exactly under following Browsers / OS's:   FF 24.0 (Debian 3.10)  Chrome 30.0.1599.114 (Debian 3.10)  Chrome 30.0.1599.101m (Win7SP1) Internet Explorer 10.0.9200.16721 (Win7SP1)   As this is consistent throughout different vendors, i assume there must be a specific reason for this, so:   What is the reason for this? What is the best practice to circumvent this behaviour, as it poses a problem for exact calculations with JS     Update: Best lay-comprehensible explanation incl. answers and workarounds for multiple programming languages so far found at   (thanx @RocketHazmat)
Consider the following code:   0.1 + 0.2 == 0.3  -&gt;  false   0.1 + 0.2         -&gt;  0.30000000000000004   Why do these inaccuracies happen?
piping in real time This is more a conceptual thing than a current problem.  Would it be possible to do this:  tail -f &lt;file&gt; | grep "string" | sed 's/stuff//g' &gt;&gt; output.txt  The problem I'm thinking is that tail -f never terminates so it won't progress in the command. I'm trying to read and output a file in real-time. If this doesn't work how would I do it? A get() like method for checking for Python attributes If I had a dictionary dict and I wanted to check for dict['key'] I could either do so in a try block (bleh!) or use the get() method, with False as a default value.  I'd like to do the same thing for object.attribute. That is, I already have object to return False if it hasn't been set, but then that gives me errors like     AttributeError: 'bool' object has no attribute 'attribute' How can I accept the Microsoft EULA agreement for ttf-mscorefonts-installer? After a recent update, ttf-mscorefonts-installer prompted me to accept its license agreement.     ┌─────────────────┤ Configuring ttf-mscorefonts-installer ├─────────────────┐  │                                                                           │   │ TrueType core fonts for the Web EULA                                          │                                                                               │ END-USER LICENSE AGREEMENT FOR MICROSOFT SOFTWARE                             │                                                                               │ IMPORTANT-READ CAREFULLY: This Microsoft End-User License Agreement           │ ("EULA") is a legal agreement between you (either an individual or a          │ single entity) and Microsoft Corporation for the Microsoft software           │ accompanying this EULA, which includes computer software and may include      │ associated media, printed materials, and "on-line" or electronic              │ documentation ("SOFTWARE PRODUCT" or "SOFTWARE"). By exercising your          │ rights to make and use copies of the SOFTWARE PRODUCT, you agree to be        │ bound by the terms of this EULA. If you do not agree to the terms of          │ this EULA, you may not use the SOFTWARE PRODUCT.                              │                                                                               │                                  &lt;Ok&gt;                                         │                                                                           │   └───────────────────────────────────────────────────────────────────────────┘    Screenshot:   For some reason my terminal will not allow me to accept, or for some reason I am pressing the wrong hotkey...  I've tried every letter on the keyboard and Enter among others...  I'm sure there is a very simple and obvious solution to this.  I've also just tried to remove the package completely however the terminal states that due to the package not being correctly installed, I should reinstall the package before removing it.  Very frustrating!  Essentially, because I cannot successfully install this package, I can't really ever upgrade my system because I always have to end up terminating the terminal with the license agreement (thus the upgrade fails). String output: format or concat in C#? Let's say that you want to output or concat strings. Which of the following styles do you prefer?   var p = new { FirstName = "Bill", LastName = "Gates" }; Console.WriteLine("{0} {1}", p.FirstName, p.LastName); Console.WriteLine(p.FirstName + " " + p.LastName);   Do you rather use format or do you simply concat strings? What is your favorite? Is one of these hurting your eyes?  Do you have any rational arguments to use one and not the other?  I'd go for the second one. How to show that $P(A\cup B) = P(A) + P(B) - P(A\cap B)$ Say we have a venn diagram with A on the left, intersection C in the middle and B on the right.   I want to show that $P(A\cup B) = P(A) + P(B)  - P(A\cap B)$  I know what it can be written as A+B+C, but a lot of the proofs  go from:  $P(A\cup B) = P(A) + P(B)  + P(C)$ to  $P(A) + P(B) = P(A\cup B)  + P(C) $  and then rearrange to  get the proof and get $P(A\cup B) =P(A) + P(B)-  P(C) $ . I just don't get how the left side of the inequality get go from $P(A\cup B)$  to $P(A) + P(B)$. Doesn't that only happen if we assume that they are disjoint. In this case, do we assume that they are disjoint? I know how to write the proof but just having a hard time actually understanding it. Generate a log of all the installs on a system (whether apt-get/yum/pip/npm/...) How did the writers not notice that the mailbox of Leela's parents says "Turanga," and not "Leela"?  Turanga Leela is Leela's proper name, with Leela being her surname, so shouldn't it follow that her folks would be the same? Rubbing eggplants in salt Calling a parent window function from an iframe It is me who am to blame.    It is I who am to blame.      Which one is correct here? I am bewildered about these two sentences. I need to find node voltage at A. This seems like a trivial question, but when I set up the resistive voltage divider equations they are not equal to each other. Am I doing something wrong?  My equations are \$V_A = V_1(R3/(R3+R1)) = V_2(R3/(R3+R2))\$      I tried solving this problem with an LTSpice simulation and with the superposition method, but my answers did not match (although very close to each other). Is this because the simulator uses an approximation? Can someone compare results? LaTeX templates for writing a thesis Aside from CTAN, what are good resources/repositories for Latex templates? In particular, I'm looking for some pretty Thesis templates (I'm familiar with classicthesis) How to link dataframes in ArcGIS or QGIS? The below image shows a layout in ArcGIS 10.1 with four dataframes.  Each dataframe is of the same geographic area, although they are different images. For example, the top left image is a 1989 DOQ, the top right image is a reversed 1989 DOQ, the bottom left image is a 2012 DOQ, and the bottom right image is a reversed 2012 DOQ.   Is it possible to link the dataframes so that panning the image in one dataframe pans the images in all of the other dataframes (i.e. similar to how you can "Link Views" in Erdas Imagine)? Is this possible in QGIS? Linux: clnt_create: RPC: Program not registered NFS mounts recently automatically got un-mounted. When I checked, the NFS service status it was shown to be running.  [root@hsluasrepo]# service nfs status rpc.svcgssd is stopped rpc.mountd (pid 4083) is running... nfsd (pid 4148 4147 4146 4145 4144 4143 4142 4141) is running... rpc.rquotad (pid 4079) is running...  [root@hsluasrepo]# service rpcbind status rpcbind (pid  4203) is running...  [root@hsluasrepo common]# rpcinfo -p 10.80.3.154    program vers proto   port  service     100000    4   tcp    111  portmapper     100000    3   tcp    111  portmapper     100000    2   tcp    111  portmapper     100000    4   udp    111  portmapper     100000    3   udp    111  portmapper     100000    2   udp    111  portmapper   But showmount output was showing an error.  [root@hsluasrepo ]# showmount -e 10.80.3.154 clnt_create: RPC: Program not registered   After restarting the NFS service, showmount output displayed the NFS server's export list.  Can anyone tell me the root cause of this issue and How to avoid this problem in future?  /var/log/messages:  Jul 7 03:22:01 hsluasrepo rsyslogd: [origin software="rsyslogd" swVersion="5.8.10" x-pid="1188" x-info="rsyslog.com"] rsyslogd was HUPed Jul 7 03:22:02 hsluasrepo rhsmd: In order for Subscription Manager to provide your system with updates, your system must be registered with RHN. Please enter your Red Hat login to ensure your system is up-to-date. Jul 8 03:22:01 hsluasrepo rhsmd: In order for Subscription Manager to provide your system with updates, your system must be registered with RHN. Please enter your Red Hat login to ensure your system is up-to-date. Jul 8 16:36:55 hsluasrepo kernel: nfsd: last server has exited, flushing export cache Jul 8 16:36:55 hsluasrepo rpc.mountd[4083]: Caught signal 15, un-registering and exiting. Jul 8 16:36:55 hsluasrepo rpc.mountd[24463]: Version 1.2.3 starting Jul 8 16:36:55 hsluasrepo kernel: NFSD: Using /var/lib/nfs/v4recovery as the NFSv4 state recovery directory Jul 8 16:36:55 hsluasrepo kernel: NFSD: starting 90-second grace period Jul 8 16:37:32 hsluasrepo rpc.mountd[24463]: authenticated mount request from 10.60.5.208:1004 for /common/PROD (/common/PROD) Jul 8 16:38:09 hsluasrepo rpc.mountd[24463]: authenticated mount request from 10.60.5.181:869 for /common/PROD (/common/PROD)  Jul 8 16:38:43 hsluasrepo rpc.mountd[24463]: authenticated mount request from 10.60.5.180:825 for /common/PROD (/common/PROD) Jul 8 16:39:12 hsluasrepo rpc.mountd[24463]: authenticated mount request from 10.60.5.176:688 for /common/PROD (/common/PROD) Asked again to review a paper, when the authors don't wish to modify it I have received a manuscript to review for a journal. The interesting thing is, I had already reviewed this article (exact same title, abstract and author list, almost exact same content) for another journal a few weeks ago where I recommended that it be published, but only after major revisions of both form and content. When I first reviewed it, I wrote a two-page review, listing some questions and several “actionable” comments, ranging from some concerns about exactness of the text (some conclusions didn't seem fully backed by the results) all the way down to trivial stuff (grammar, a few typos, graphic issues with the figures, etc.).  Now, the manuscript has come to me for review again, but it is almost unchanged from the first version. None of the serious stuff has been addressed, and even most of the trivial stuff was not fixed (there's at least one remaining typo, and the figures still aren't fully legible). However, I think this behavior from the authors is clearly a bad signal, which should be somehow conveyed to the editor: they're not willing to amend their work, and would rather do some journal-shopping.  What would you suggest me to do? Should I just re-send my earlier review? Add a note to the editor about my knowledge of the “history” of the paper? Or maybe even include it in my review, so the authors are aware that people know of their behavior, and maybe feel bad enough to change their ways?    PS: I wrote it in the present tense, but it's actually a story from my past. I'm not sure I did the right thing at the time, and I think it's better to actually formulate it as an open question… To show that $2$ | $x^{2n} - x^n$, $n \in \mathbb{Z^+}$ is the following adequate? Show that $2$ | $x^{2n} - x^n$, $n \in \mathbb{Z^+}$   Let $x^n = a$ then $\frac{a}{2}$ $\implies a = 2q + r$ such that $r = 0 \vee r = 1$.   So $x^{2n} = (x^n)^2 = a^2 = (2q + r)^2$, which means that $2|[x^{2n} - x^n ]= 2| [(2q + r)^2 - (2q + r)]$. If $r = 1$ we get $(4q^2 + 4q + 1) - 2q - 1 = 4q^2 + 2q = 2(2q^2 +1)$. Thus $2$|$x^{2n} - x^n$, $n \in \mathbb{Z^+}$. Is this reasoning correct? Is it adequate? I got a flat/puncture on my bike tube, how can I fix it myself without going to the nearest bike shop? What kind of equipment would I need? I am on a multiplayer Minecraft realm in 1.16 and I was wondering if there was any way to set a chest's Items to a player's entire Inventory including the offhand and armor slots. Using data modify &lt;chest coordinates&gt; Items set from entity &lt;player&gt; Inventory, I was only able to copy over the hotbar and the top two rows of a player's inventory. I honestly don't care if it takes 50 command blocks, any response is gladly appreciated. Limit $\lim_{n\to\infty}\left(1-\frac{1}{3}\right)^2\left(1-\frac{1}{6}\right)^2\cdots\left(1-\frac{1}{\frac{n(n+1)}{2}}\right)^2$ How can I find the following limit :$$\lim_{n\to\infty}\left(1-\frac{1}{3}\right)^2\left(1-\frac{1}{6}\right)^2\left(1-\frac{1}{10}\right)^2\cdots\left(1-\frac{1}{\frac{n(n+1)}{2}}\right)^2$$There are four options $(a)\frac1{3}(b)\frac1{9}(c)\frac1{81}(d)0$ Thanks! Creating a new DOM element from an HTML string using built-in DOM methods or Prototype I have an HTML string representing an element: '&lt;li&gt;text&lt;/li&gt;'. I'd like to append it to an element in the DOM (a ul in my case). How can I do this with Prototype or with DOM methods?  (I know i could do this easily in jQuery, but unfortunately we're not using jQuery.)