Difference - "e.preventDefault();" and "return false;"
event.preventDefault() vs. return false
How can swapoff be that slow? Somehow I happened to swap out 14 GB of memory. After having killed the culprit, I have tons of free memory again, so I thought I could  again. So with 5 GB out of 32 GB used and 14 GB of swap space used, I ran swapoff -a.... and 4 hours later about half of the work was finished.  This means less that 1 MB/s, while I can easily copy 200 MB/s. My swap is encrypted but so are all normal partitions and with  it leads to no noticeable CPU load (and filling the swap space took only a few minutes). I see that there's no special reason to optimize swapoff, however I wonder how it could get that slow?    Just adding some more data: My main memory is 32 GB and I have 32 GB swap space on each of 4 harddisks (surely an overkill, but who cares?). The whole swap space can be  (decrypted and) read in less than 5 minutes:  time -p sudo sh -c 'for i in /dev/mapper/cryptswap?; do md5sum $i &amp; done; wait' 014a2b7ef300e11094134785e1d882af  /dev/mapper/cryptswap1 a6d8ef09203c1d8d459109ff93b6627c  /dev/mapper/cryptswap4 05aff81f8d276ddf07cf26619726a405  /dev/mapper/cryptswap3 e7f606449327b9a016e88d46049c0c9a  /dev/mapper/cryptswap2 real 264.27   Reading a part of a partition can't be slower than reading it all. Yet reading about 1/10th of it takes about 100 times longer.  I observed that during swapoff both the CPU was mostly idle (maybe 10% of one core) and so were the disks ("measured" by the LEDs). I also saw that the swap spaces were turned off one after the other. How can I recover photo files from a memory card with a corrupt filesystem? I know this is not specifically a photography issue but since many of us with prosumer/professional-level DLSRs use Compact Flash cards, it is bound to happen to others as well.  I have a Sandisk 16GB Ultra card that occasionally had the camera reporting inability to access the card. I had to reinsert the card to continue using it. I was able to read the card and transfer the photo files to my computer drive. Today, the same thing happened again, just that nearing the capacity of the card, it failed one last time and the camera was subsequently unable to read it anymore. Despite reinsertion.  My other CF cards never once exhibited this problem, so it's pretty much isolated to this card.  The card is similarly unrecognisable on my computer CF card reader. I think the filesystem is toast, but I suspect the photo files are still intact. I would like to find ways where I can inspect the raw binary data in the card and hopefully recover the photos? Errors in matrix equation? I'm getting errors in a matrix equation. When I compile it looks fine, but I'd like to fix them so I don't have to press return for every error at compile time. The code for the equation is:  \begin{equation*}  \begin{bmatrix} U(1,t)  &amp; \cdots &amp; U(n,t) \\  \vdots &amp; \ddots &amp; \vdots \\ O_{n1} &amp; \cdots &amp; O_{nn}  \end{bmatrix} \times \begin{bmatrix} W(1,1)  &amp; \cdots &amp; W(1,n) \\  \vdots &amp; \ddots &amp; \vdots \\  W(n,1) &amp; \cdots &amp; W(n,n)  \end{bmatrix} = \begin{bmatrix}  D(1,t)  &amp; \cdots &amp; D(n,t) \\ \vdots &amp; \ddots &amp; \vdots \\ I_{n1} &amp; \cdots &amp; I_{nn} \end{bmatrix}  \end{equation*}   The errors I'm getting are related to missing $'s inserted. App keeps crashing & rendering error since update to 1.0.68 I can reproduce that every time now, I go to a site, open an article, then to the next site, open another article. The Feed page pops up for a second, the article page lays over this with some some transparent areas (see picture). The same app-version is ok on a Smartphone with Android 4.4.2. I also sent in some bug reports.    Edit  1.0.71 isn't the solution yet. I go to Meta SE, then to an article. When I want back to Meta SE again, it crashes. Much earlier than before. I already sent in a bug report for this.  Another Edit  I can describe it better now. From the questions-page of a site I go to a post. When I use the back button, everything is ok, I can go to the next site. When I try to go to the next site directly from the post, it crashes. This only happens on the Nexus 10 with Android 5.1.1, App version 1.0.71. Hope this helps.  Edit3  This is fixed in 1.0.73 now. Thanks again. How do I protect Python code from being read by users? Let $r$ be the smallest positive integer such that $a^r \equiv 1 \bmod{n}$. Prove $r \mid \phi(n)$. Let $a \in \mathbb {Z}$, $n &gt; 1$ a natural number with $\gcd(a, n) = 1$, and let $r$ be the smallest positive integer such that $a^r \equiv 1 \bmod{n}$. Prove that $r \mid \phi(n)$.  Euler's generalization of Fermat's Little Theorem: If $n \in \mathbb {N}$ and $m \in \mathbb{Z}$ such that $\gcd(m, n) = 1$, then $m^{\phi(n)} \equiv 1\bmod(n)$.  By Euler's generalization I would have $a^{\phi(n)} \equiv 1\bmod{n}$.  Then I could say $a^r \equiv a^{\phi(n)} \equiv 1 \bmod{n}$. At this point I can see that $r$ clearly must be some multiple of $\phi(n)$.  If I want to show that $r \mid \phi(n)$, then I can show that $\phi(n) = rk$, for some $k \in \mathbb {Z}$.  However, I am a bit stuck about how to make this last step showing that  $\phi(n) = rk$, where $k \in \mathbb {Z}$. Order of elements is lcm-closed in abelian groups How can I prove that if $G$ is an Abelian group with elements $a$ and $b$ with orders $m$ and $n$, respectively, then $G$ contains an element whose order is the least common multiple of $m$ and $n$?  It's an exercise from Hungerford's book, but it's not homework. I could not solve it when I take the course on groups and I think it should be easy. There is a hint that says to first prove when $m$ and $n$ are coprimes. I did this part. But I have no idea how to solve the general case.  Thanks. Unexpected output for this following code How do you disable anonymous login? Not sure if this option ever existed, but the new QGIS version hides a lot of things somewhere else and this seems so simple that I'm kind of convinced it was possible to do this before. I have quite a large data set with ship tracks. I now want to analyse individual ship tracks (made from point layer with  Plugin). However, it is so crowded that it is hard to look at individual tracks. I don't want to save each single track as a new layer, so I wonder if it is possible to select one track in the Attribute table and display only that one on the map/hide the others? Binary Search in Array How would I implement a binary search using just an array? How to add the word "Figure" to the list of figures? How to delete files from a folder using a list of file names in windows? i have a folder with 2K+ files in it, i need to delete around 200, i have a txt file with all the file names i need removed ordered in a list, how do i remove the specific files from the folder using the list? (OS is windows 7) How to disable notifications for a single mailbox in Mail? JavaFX: Undecorated Window Run command on another(new) terminal window I have a current view set up that displays a feed of stories and is sorted in descending order. I now need to have the first 4 stories display as a different style then the remaining ones. I have pagination set to 10. I only want the first 4 to show differently on page 1, and then the current style will show on the remaining pages. Is there a way to do this? Unintentional mouse movements, am I paranoid? This is tricky. I would like to install Ubuntu on a machine that is intended to work as server, and for some reason I do not have an option to connect a screen to it.  I expect this may be similar to remote installation. However, there is currently no OS on that machine, so I will have to set up everything from scratch.  On the other hand, I do have a physical access to that machine. Therefore I can get it to boot from a CD/USB. But that's not enough.  Is there a way to do such installation remotely? Is there a version of Ubuntu image that comes with a SSH server preinstalled, and starts it once booted, so that I can boot the machine with such image, connect to it via SSH and process the installation from a different computer?  If not, what other options do I have? I have basic programming skills (I program simple vba python and lisp scripts and had gone through a java course a long time ago), but it seems to me (judging by ESRI publications) that there is no escaping the need to learn .NET for future relevance in the GIS job market (even as an analyst). I've gone through a basic c# course and can program (regrettably) quite poor programs, but I have no idea how to link the c# knowledge to actually programming for ArcGIS in order to progress.  I know the differences aren't big, but does ArcGIS use .NET or C#?  I know the best way to further my experience in .NET is to program more and more but are there any good .NET programming books or courses I can learn techniques from?  In your opinion, what is the best way to learn to program in .NET for ArcGIS? Are there any useful books or websites?   I seek your comments regarding ArcGIS 10 (and will be saving them for later) but also for ArcGIS 9.3.1.