how to install libmysqld-dev on ubuntu 12.04?

When I enter the command:  sudo apt-get install libmysqld-dev  I get this message:  Reading package lists...  Done Building dependency tree Reading state information...  Done Some packages could not be installed.  This may mean that you have requested an impossible situation or if you are using the  unstable distribution that some required packages have not yet been created or been moved out of Incoming.  The following information may help to resolve the situation:  The following packages have unmet dependencies: libmysqld-dev : Depends: libmysqlclient-dev (>= 5.5.32-0ubuntu0.12.04.1)  E: Unable to correct problems, you have held broken packages.   How do I solve this problem?


My specific question is that I have 3.9GB of ram, but I don't have an AMD processor. I have the Intel i5. Do I install i386, or the AMD x64 version of 14.04? Let me know if there are other specifics I should tell you guys.


how do I connect an Apple Thunderbolt display to a PC?

I have .  it works fine with my Macbook Pro. I also want to connect it to my Windows laptop via HDMI. I bought this , which converts the HDMI signal to DisplayPort. Everything plugs in just fine, but the display just does not turn on. I tried a variety of resolution settings.  Note: this display does not have a power button. It just turns on when I plug it into a Mac. There is no activity when I plug it into the DisplayPort converter.


how to permanently change ownership of a file?

When I change ownership of /sys/class/backlight/intel_backlight/brightness with chown its ownership changes again to root after system startup.


I have a feeling that my PC is infected with a RAT (remote administration tool). It all started when I logged on an mmorpg (online game). It's not popular and at this time I had a port open by me going on this game the admins can see my IP. how far could this go if they port scanned me?  Anyway I need to make sure 100% that my PC is clean of rats and backdoors.  Even if there wasn't a way to do so, and my last hope is installing a new OS, what should I do then to prevent reinfection?


Is it possible to get from Canada to Greenland by road or ferry?

Are there any roads (or ferry service) that would allow a person to travel from Canada to Greenland without taking a plane?


A function that is continuous at the origin but not differentiable there

Show that $f(x,y)=\dfrac{xy^2}{x^2+y^2}$ (with $(x,y)\not=(0,0)$ and $f(0,0)=0$) is continuous but not differentiable at $(0,0)$.  I tried to show continuity with an $\epsilon -\delta$ argument but I don't know how to factorize the expression so that I can have something useful.   For differentiability I think I should show that the partials are not continuous at $(0,0)$. But finding the partials is also painful.


How much marmelade can I bring into the US?

I want to bring homemade berry marmelade in little glass jars with me to the US from Europe as gifts for friends. I have found the following site on importing foods into the US  and would assume that marmelade falls under the condiments category, which should be admissible. However, I am wondering however if there is any limit to how much one is allowed to bring. Will there be any issues if, say, I bring 3 kilograms (6 lbs 10 oz)?   Also on related note, would they be suspiscious when they see many glass jars in my bag? Do I risk getting my bag searched or getting asked what the jars are? Is there anything I can do to avoid any such trouble?


When is differentiating an equation valid?

I wonder that Is it true to differentiate an equation side by side. Under which conditions can I differentiate both sides. For example, for the simple equality $x=3$, Is ıt valid to differentiate both sides with respect to x. I know that I am missing some basic point but I cant find it. Thanks for your helps.


I have a battery supply consisting of 3 AA batteries of each 1.5V.  I need an operating voltage of 3.3V.  Which choice of buck converter or regulator would be better?  My application requires 100mA of current. So are AA batteries a better choice or the conventional 9V battery? Last time i didn't have any info regarding the current requirements now i do.  My choices currently are AA batteries or a 9V battery .  If there any better choices of batteries plz let me know.  Also yes last time i received an excellent answer from swineone, but i am still confused with the best choice for the regulators. ( Whether LDO or switching regulator)


Legend inconsistent in QGIS map print layout

After I did styling my vector data set to be classified by graduated circle and categorized by type, it appears beautifully consistent in the map canvas as shown below:   But when I create a print map layout and after adding the map, I add the legend and it come out ugly inconsistent like this:    So, I would like to ask for help to make the legend in the map print layout consistent as the legend shown in layer panel. I use the latest version QGIS 3.10.2 64bit.


Vertical Column Dividers are discontinuous in a table

I am a beginner in latex. I want to draw a table in latex. But, unfortunately, the last vertical lines are discontinuous. Is there a way to fix it?  Latex Code:  \begin{tabular}{||c||c||}     \hline \hline \\[-0.2cm]     \textbf{Duration of course} & Month/Year - Month/Year\\[0.1cm] \hline \\[-0.2cm]     \textbf{No. of credits} & $\#$ of credits\\[0.1cm] \hline \\[-0.2cm]     \textbf{Course Slot} & slot letter allocated to the course, if slotting system is followed\\[0.1cm] \hline \\[-0.2cm]     \textbf{Course Timings} & Day: Time slot\\[0.1cm] \hline \\[-0.2cm]     \textbf{Evaluation Pattern} & Evaluation Pattern and Weightage\\[0.1cm] \hline \\[-0.2cm]     \textbf{TAs} & Name of TA, Designation, Roll no:\\[0.1cm] \hline \\[-0.2cm]     \textbf{Course Overview} & Overview of the course\\[0.1cm] \hline \hline \end{tabular}   Output:


What causes the permittivity and permeability of vacuum?

When light travels through a material, it gets "slowed down" (at least its net speed decreases).  The atoms in the material "disturb" the light in some way which causes it to make stops on its path.  This is expressed in the material's permittivity and permeability:  Its ability to transmit electromagnetic waves.  But then what causes the limited permittivity and permeability of vacuum?  There are no atoms there to disturb the light, so what is keeping it from travelling at infinite speed?  Is there a special property of space itself which determines the speed of light?  Or is it the virtual particles in vacuum which interact with the light?


Latex cannot find reference in my LaTeX file - no .bbl created

I have the following article file:  \documentclass[11pt]{article} \usepackage{cite}  \begin{document}  \title{My Article} \author{Nobody Jr.} \date{Today} \maketitle  Blablabla said Nobody ~\cite{Nobody06}.  \bibliography{mybib} \bibliographystyle{plain} \end{document}   In the same folder there is a mybib.bib file that contains the following code:  @misc{Nobody06, author = "Nobody Jr", title = "My Article", year = "2006" }   When I compile using Texmaker, I get the following warning:   Citation 'Nobody06' on page 1 undefined   and a [?] is at the citation place.  I have been compiling the main file with latex, bibtex, latex, latex as suggested in  . And no .bbl file is created.  The .blg file looks like the following:  This is BibTeX, Version 0.99d (TeX Live 2015/Debian) Capacity: max_strings=35307, hash_size=35307, hash_prime=30011 The top-level auxiliary file: Appendix1.aux The style file: plain.bst Database file #1: mybib.bib You've used 1 entry,             2118 wiz_defined-function locations,             508 strings with 4242 characters, and the built_in function-call counts, 576 in all, are: = -- 56 > -- 26 < -- 2 + -- 9 - -- 8 * -- 44 := -- 90 add.period$ -- 4 call.type$ -- 1 change.case$ -- 6 chr.to.int$ -- 0 cite$ -- 1 duplicate$ -- 24 empty$ -- 44 format.name$ -- 8 if$ -- 127 int.to.chr$ -- 0 int.to.str$ -- 1 missing$ -- 1 newline$ -- 8 num.names$ -- 4 pop$ -- 7 preamble$ -- 1 purify$ -- 5 quote$ -- 0 skip$ -- 20 stack$ -- 0 substring$ -- 37 swap$ -- 13 text.length$ -- 2 text.prefix$ -- 0 top$ -- 0 type$ -- 4 warning$ -- 0 while$ -- 6 width$ -- 2 write$ -- 15   Any idea what I'm missing?


How to calculate time complexity of existing code in production

I have gone through a couple of examples in understanding the time complexity of a program using the operation count and step count technique but these examples are small and straight. However in real-world programming, if someone gives you the production or live code to find the worst case time complexity of it. How does one start analyzing it? Is there any technique or thumb rules for analyzing the program? say I have a function as shown below that has if and for conditions. For some values of n, it goes deep but for some values, it does not. So maximum number of operations is the worst case and the minimum number of operations is the best case. How can we know when do maximum operations occur if we have this kind of conditional statement? (Other functions can go much deeper conditional and not the loops) int l = 0; while (l <= n){   int m = l + (n-l)/2;          if (arr[m] == x) return;      if (arr[m] < x) l = m + 1;     else n = m - 1;   }   How does one calculate the worst and best case by looking at the above code? Do the perform step count for the above program and by substituting n = 1 till 20 and get some values and then trying to derive the function? I would like to know how do people analyze time complexity for existing code when they have this kind of branching statements. Step by Step analysis or Set of statements to follow to solve the above problem would be greatly helpful.


I don't understand why this card trick works

So a friend of mine showed me a very interesting card trick that I don't quite understand.  You have 52 normal cards from any regular deck you can buy anywhere. The Ace is worth 1 while 2 through 10 are worth their number value. Jack is worth 11, Queen is worth 12 and King is worth 13.  You shuffle the cards any way you want. Then you take the first card from the top of the deck and put it down on the table face up. Now, if it's a king you put it back in the deck and try again. If it's anything else you read the value on the card. Lets say you picked a 3. Now you have to put down cards from the deck in your hand on top of the 3 until you have counted 13. So 13 - 3 = 10. So you place 10 cards from the deck face up on the 3 on the table. It does not matter what the cards you place on top have in terms of values.  Now you move on to make a new set of cards on the table after the same principle. Again you cannot start on a king. If you reach a point where you can no longer put down 13 cards you keep the cards in your hand.  So I carried this out and ended up with 5 sets of cards on the table.They started with 3, 6, ace, ace and 10 leaving me with 3 cards left on my hand.  Now you take three of the decks, turn them around so they lie face down and then you pick up the rest of the cards to your hand. Now you choose 2 decks of cards and make the first card turn around so that they are face up. I have a 3 and a 10 and I have 24 cards on my hand. With 3 and 10 facing up you put that together which is 13. You have to add an extra 10 to whatever number you get so it will become 23. Now I put down 23 cards from my hand which leaves me with one card. This means that the last card currently facing down of three sets of cards on the table will be an ace.  And it was.  Why does this work?  My friend told me this could be explained or at least proven to work 100 % of the time with a mathmatical formula.


What is the correct way to translate variable_get string values entered in admin input fields?

I'm developing a simple module with and admin page, where admin can fill some textfields with custom strings that will generates a piece of html to be used later.  So for example I have fields like this in admin page:  function MYMODULE_admin_page_arguments() {   $form = array();    $form['MYMODULE_link'] = array(     '#type' => 'textfield',     '#title' => t('Conditions link path'),     '#default_value' => variable_get('MYMODULE_link', 'conditions'),   );   $form['MYMODULE_link_text'] = array(     '#type' => 'textfield',     '#title' => t('Conditions link text'),     '#default_value' => variable_get('MYMODULE_link_text', 'conditions'),   );   $form['MYMODULE_link_target'] = array(     '#type' => 'textfield',     '#title' => t('Conditions link target'),     '#default_value' => variable_get('MYMODULE_link_target', '_blank'),   );   $form['MYMODULE_prefix'] = array(     '#type' => 'textfield',     '#title' => t('Conditions link prefix text'),     '#default_value' => variable_get('MYMODULE_prefix', 'I agree to the '),   );   $form['MYMODULE_suffix'] = array(     '#type' => 'textfield',     '#title' => t('Conditions link suffix text'),     '#default_value' => variable_get('MYMODULE_suffix', '.'),   );    return system_settings_form($form); }   Then the above values are managed after by my module to compose an output like:  // Create label $prefix = variable_get('MYMODULE_prefix', 'I agree to the '); $suffix = variable_get('MYMODULE_suffix', '.'); $path = variable_get('MYMODULE_link', 'conditions'); $text = variable_get('MYMODULE_link_text', 'conditions'); $target = variable_get('MYMODULE_link_target', '_blank');  $label = $prefix . l($text, $path, array('attributes' => array('target' => $target))) . $suffix;   Now I need that all these values are available for string translation, so the first think I thought was to pass all of them through t(), for example:  $label = t($prefix) . l(t($text), $path, array('attributes' => array('target' => $target))) . t($suffix);   but I read here  that I should never pass variables directly to t(), so for e.g t($prefix) is a bad stuff.  So, what is the correct Drupal way to accomplish this?


How do I install an app from Windows Store using Powershell

I know if I have .appx package file, I can install it via powershell with the Add-AppxPackage cmdlet. However, I simply want to download & install Microsoft Store packages by name.  I don't want to have to go to the Microsoft Store page, start fiddler, start the download, capture the .appx file URL and then manually download it so that I can use Add-AppxPackage. (See how Windows OS Hub did that )  That could be fun - but it will be flaky.  I need a robust scriptable method for managing Windows Store apps.  (There are a few software packages that are only accessible via Microsoft Store. Everything else I can get via Chocolatey or direct msi download.)  One example that I can't yet script is installation of the HEIF Image Extensions (needed to view the image format from iPhones: *.HEIC format.  Once I install this from the Windows Store, it shows up with Get-AppxPackage  PS C:\Tools> Get-AppxPackage | Where-Object {$_.Name -eq "Microsoft.HEVCVideoExtension" }   Name              : Microsoft.HEVCVideoExtension Publisher         : CN=Microsoft Corporation, O=Microsoft Corporation, L=Redmond, S=Washington, C=US Architecture      : X64 ResourceId        : Version           : 1.0.31053.0 PackageFullName   : Microsoft.HEVCVideoExtension_1.0.31053.0_x64__8wekyb3d8bbwe InstallLocation   : C:\Program Files\WindowsApps\Microsoft.HEVCVideoExtension_1.0.31053.0_x64__8wekyb3d8bbwe IsFramework       : False PackageFamilyName : Microsoft.HEVCVideoExtension_8wekyb3d8bbwe PublisherId       : 8wekyb3d8bbwe IsResourcePackage : False IsBundle          : False IsDevelopmentMode : False NonRemovable      : False Dependencies      : {Microsoft.VCLibs.140.00_14.0.27810.0_x64__8wekyb3d8bbwe} IsPartiallyStaged : False SignatureKind     : Store Status            : Ok   What I want is the cmdlet: Download-AppxPackage so that I can do:  Download-AppxPackage -Name "Microsoft.HEVCVideoExtension"   Does anyone know how I can do this?


can't install third party .deb packages with the new ubuntu software app (ubuntu 16.04 )

The new Ubuntu Software Center - GNOME Software - fails to install any .deb package,  e.g., Steam, Google Chrome, etc.   When I double click the package the 'Ubuntu software' opens but when I press install it flashes a progress bar for a second then an icon appears in the dash saying "waiting to install"!  And nothing seems to happen at all!  P.S 1. I am running Ubuntu 16.04 LTS,  fresh installed (not upgraded) with Unity desktop.   GDebi successfully installs any .deb package


"Angela was reading to Frank and I" vs. "...to Frank and me." Which is correct?

I stated the following:     Angela was reading to Frank and I.     Someone corrected me, stating      "Frank and me"    Which is right?


I have done a boxplot to represent my claim frequency. However make 2 and 4 have only 1 whisker. How do I interpret that?


Specifications  [midas@localhost ~]$ uname -a Linux localhost.localdomain 4.0.4-301.fc22.x86_64 #1 SMP Thu May 21 13:10:33 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux  and  [midas@localhost ~]$ cat /etc/issue Fedora release 22 (Twenty Two)  Problem preface  I was trying to install a new package through dnf on my Fedora 22. (Linux 4.0.4) When the package stopped downloading at 52% and the terminal window didn't show any more advancement.  I aborted the download and attempted to restart it using the same dnf install [package name] command.  I then received the following notification: Waiting for process with pid 2967 to finish.  Turns out dnf was still running in the background:  [midas@localhost ~]$ ps -A | grep 2967  2967 ?        00:00:01 dnf  Problem  I figured I could just kill the process, however:  [midas@localhost ~]$ kill 2967 bash: kill: (2967) - No such process [midas@localhost ~]$ sudo kill 2967 kill: sending signal to 2967 failed: No such process  How come ps can list the process but kill can't find it?  I know a reboot will solve this (or a bit of patience even). But I'm just curious as to why there is such a difference between these 2 commands.


Performing Raster Noise Reduction and Edge Smoothing?

I have a raster image like this  I want to delete the isolated noise point and smooth the edge (say the white single points, and I want the edges of the entity look smooth). How can I do this in ArcGIS or in R?  The cell size is 30*30.


Run a command on GUI (TTY7) on boot/login

I am using an Xenial Xerus minimal Ubuntu install.  I want a command ("antimicro") to be run on boot/login (doesn't matter) to map my Bluetooth controller buttons to keyboard keys. The farthest I could get is:  DISPLAY=":0" antimicro --hidden   Which does not work as a cron job, gdm postlogin commands or ~/.profile (gdm and Kodi not running), it seems to require a logged in terminal. It worked well when I execute it manually on tty1, it will display log and "occupies" the terminal until the application is closed.  I don't mind turning on auto login or disabling password etc. It's a HTPC running Kodi, and that's why I want it to be run automatically on each boot.  I am quite new on Linux and this may just be a stupid question, sorry if that's the case. I have tried my best to find information online.  EDIT: it's probably not a duplicate, none of the solutions worked.


I edited this phrase:  the farther the negative from the lens, the more light needed to expose it properly and the longer the exposure  to read:  the farther the negative from the lens, the greater the amount of light needed to expose it properly and the longer the exposure  I am sure the former is not grammatical but I am having a hard time explaining why the edit is necessary. Can someone help?


AO Bake has random black pixels on some faces

This is what my baked AO texture looks like (not in all places -- for most faces it looks fine):    What is the cause of this?  What can I do to resolve it?  I do not have any overlapping UVs and my mesh is manifold.  Here is the mesh if you would like to take a look:   Thank you all for your help!


I'm looking for a reference for a matrix-norm inequality that I used in , which has a few equivalent forms.  I will use notation that applies to complex vector spaces with a sesquilinear inner product, but of course the same applies over real matrices.  The statement is as follows:     Take $A,B \in \Bbb F^{n \times n}$.  Then    $$\vert\operatorname{tr}(A^*B)\vert \leq \sigma_1(A)\sum_{i=1}^n \sigma_i(B) = \|A\| \operatorname{tr}|B|$$   where $\sigma_i$ denotes the $i$th singular value, $|B| = (B^*B)^{1/2}$, and $\|\cdot\|$ denotes the spectral norm (induced Euclidean norm).   I did manage to find some references, but they're overkill, and the texts themselves are not readily accessible to the faint of heart (Bhatia's text is dense and Pedersen's is not about matrices in particular).    A suitable reference would be greatly appreciated.


EDIT: @EugeneSh.  I ment how can I build a hub Double edit: Sorry everyone, I mentioned how can I build a USB hub...  I'm looking to build a very small USB Y splitter for my Nexus 7 2nd Gen so it has 2 USB ports. The reason why I'm not buying one from eBay (ect.) is because i don't want a cord and I want to build something like the "sugoi hub" mentioned below. I WAS going to buy a  but those things are nowhere to be found!  Anyways, do any of you guys have an easy wiring diagram for a (micro) USB 2.0 Y splitter?


Wanted to upgrade my Old Ubuntu Desktop(installed in 2011) to Current stable version

Update Manager is asking me to update to 11.10 which is old.  I wanted to upgrade my Old Ubuntu Desktop(installed in 2011) to Current stable version. Old configuration is really very stable and there are no more updates available for this version. This is the only reason, I am looking forward for updating same to current version.   Please suggest my options. Thank you.


I was reading something which I found really special. It goes like this : Imagine we have a line with unity division (0,1,2,etc.) Now, we have a point on this line. The point can be on a point of division or it can be contained between two points of division. If it isn't on a point of division, then we can continue cutting the line into 10 equal pieces. (The first piece being 0, the second 1, the third 2,...) So, if my point was between 1 and 2, I'll have 1.0,1.1,etc. We continue this cutting until our point arrives at a point of division.If this arrives, we have two choices : We can pick the interval on the left or the interval on the right. And we can continue this way at infinity.  We also have the following formulae to express our numbers : g+a/10+a2/100+a3/1000+... g being an integer and a being the number of the piece which contains our point.  Now, my question concerns this :    How can it be possible that we can have 1/4=0.2499... and 1/4=0.25000... Also, for this idea to be valid, must it necessarily be an infinite decimal expansion or I could have the following 1/4=0.249 and 1/4=0.250 ?  Thank you !


Does orbital refer to a locus where the probability of finding an electron is maximum?

If I want to draw a certain circle or parabola, I will need an equation from which I can plot points on a polar or cartesian co-ordinate.   If orbitals refer to locus of equipotential points where the probability of finding an electron is maximum, there must be an equation for locus from which I will be able to plot points on cartesian or polar co-ordinate.  When I draw a circle after plotting all the points, I can say that its shape is 'round.' Likewise, If I have necessary equation for plotting points for the orbitals, then I can say that s orbital is 'spherical' and p orbital is 'dumbell shape.'  So, where's the equation of drawing the locus of s orbital or p orbital?


Narrow results by typing case sensitivity issue

I have a search box that limits options available in a dropdown menu on keyup. I'm having an issue with case sensitivity - how can I modify this function to ensure my option contains upper or lower case versions of the character typed?  Fiddle:  Notice how the results differ between 'i' and 'I'    $(document).on('keyup', '#condition-search', function(e) {   var str = $('#condition option:contains(' + $(this).val() + ')');   if (str) {     $('#condition option').hide();     str.show();   } else {     $('#condition option').show();   } }); <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <input type="text" class="form-control" id="condition-search"> <select class="form-control" id="condition" size="15" style="overflow-y: scroll" ;>         <option class="cat-1">Item1</option>         <option class="cat-2">item2</option>         <option class="cat-3">Item3</option>         <option class="cat-4">item4</option>         <option class="cat-5">Item5</option>     </select>


Does the canonical commutation relation fix the form of the momentum operator?

For one dimensional quantum mechanics $$[\hat{x},\hat{p}]=i\hbar. $$  Does this fix univocally the form of the $\hat{p}$ operator? My bet is no because $\hat{p}$ actually depends if we are on coordinate or momentum representation, but I don't know if that statement constitutes a proof. Moreover if we choose $\hat{x}\psi=x\psi$ is the answer of the following question yes?  For the second one   $$(\hat{x}\hat{p}-\hat{p}\hat{x})\psi=x\hat{p}\psi-\hat{p}x\psi=i\hbar\psi, $$  but I don't see how can I say that $\hat{p}$ must be proportional to $\frac{\partial}{\partial x}$. I don't know if trying to see that $\hat{p}$ must satisfy the Leibniz rule and thus it should be proportional to the $x$ derivative could help. Or using the fact that $\hat{x}$ and $\hat{p}$ must be hermitian  Any hint will be appreciated.


I want start writing latex document under windows. So I downloaded texmaker, but I get some errors when I try to create the pdf (command not found "...pdflatex...").  I have to install other things? Or texmaker contains all the necessary?


Why is ordered pair representation as a set correct?

Textbook shows ordered pair as the following set. Why so ?  $\left (  a , b\right) = \left \{ \left \{ a \right \},\left \{ a,b \right \} \right \}$  If the RHS is a set it is unordered there RHS can be re-written as $\left \{ \left \{ a,b \right \},\left \{ a \right \} \right \}$ or even $\left \{ \left \{ b,a \right \},\left \{ a \right \} \right \}$  Is $(b,a)$ representation as a set really different from $(a,b)$


What kind of content is in the Canonical Partners repository? Is it as secure & safe as the Main repo?

In Software Sources under the Other Software tab, there is an option of enabling "Canonical Partners" repository: software packaged by Canonical for their partners.  Do I understand correctly that this repo includes third-party created applications that by arrangement are packaged and maintained by Canonical?  Does this mean Canonical can look at the source code of these third-party applications and hence ensure the security and stability of these apps in Ubuntu, making them as secure & stable as the software in the Main repo?


Applying for a Schengen Visa without itinerary

I am currently residing in Ireland with work authorization permit. In the next few months I am planning for a trip to few schengen countries. I have not yet decided my itinerary. Is there any Schengen country embassy which can process a tourist Schengen visa for 90 days?


The notion I have received while trying to study Measure theory that it is helpful when we move from discrete domain to continuous domain because in discrete domain we can count individual entities but in continuous domain we can't count. So are we replacing counting to measuring in such scenarios? A set has a measure defined on it such as an open set of $\mathcal{R}$ because its domain is infinite?


Mean and variance of the median estimator

We are given an i.i.d sample of size n, $X_{1},...,X_{2}$.  We also know that for all i, $EX_{i}=\mu,Var{X_{i}}=\sigma^{2}$.   Let us define $\hat{X}_{median}$ as the median of these samples:  $\hat{X}_{median}(X_{1},...,X_{n})=median(X_{1},...,X_{n})$ .   Is there any known way to explicitly express the mean and variance of the median estimator ($E(\hat{X}_{median}), Var(\hat{X}_{median})$) In terms of $\mu,\sigma$?  Thank you!


disambiguation surprise in textcite with biblatex, biber, and authoryear

Here is behavior that surprised me and took me a while to track down, so I thought I would share it.  In  \documentclass{article} \usepackage[backend=biber,style=authoryear]{biblatex} \bibliography{test} \begin{document} \textcite{fama-french:1992}, \textcite{fama-french:1997}, \textcite{fama-french:2002}, \printbibliography \end{document}   with the test.bib file of   @article{ fama-french:1997,   year =         1997 ,   author =       { Eugene F. Fama And Kenneth R. French },   title =        { Industry costs of equity },   journal =      { Journal of Financial Economics },   volume =       43,   pages =        { 153 - 193 } }  @article{ fama-french:2002,   year =         2002,   author =       { Eugene F. Fama and Kenneth R. French },   title =        { The Equity Premium },   volume =       57,   journal =      { The Journal of Finance },   pages = { 637-659 } }  @article{ fama-french:1992,   year =         1992,   author =       { Eugene F. Fama and Kenneth French },   title =        { The Cross-Section of Expected Stock Returns },   volume =       47,   journal =      { The Journal of Finance },   pages =        { 427-465 } }   then the latex file will cite as Fama and K. French (1992) (and Fama and K.R. French (1997)) instead of Fama and French (1992).  Apparently, if initials are not completely identical, then the year alone is not sufficient disambiguation.  it's probably a feature rather than a bug, but not immediately obvious behavior.


first alias works second doesn't throws invalid identifier

Recently I came across a very strange issue (Oracle 12c), the LISTAGG works for the first alias column but not for the second one (both are almost identical) throwing ORA-00904: "PARAMDESC": invalid identifier. Here is the SQL:   SELECT s_sample.s_sampleid,    b.u_tarolotnumber,    p.productdesc,    s_sample.productid,    LISTAGG(wi.s_departmentid, '; ') WITHIN    GROUP(ORDER BY wi.s_departmentid) Department,     wi.workitemid,     s_sample.sampletypeid,     NVL((SELECT sa.aliasid            FROM sdialias sa          WHERE sa.sdcid = 'Workitem'            AND sa.keyid1 = wi.workitemid), wi.workitemdesc)workitemdesc,     NVL((SELECT sa.aliasid           FROM sdialias sa          WHERE sa.sdcid = 'ParamList'             AND sa.keyid1 = p.paramlistid), p.paramlistdesc) paramdesc   FROM s_sample  JOIN s_batch b ON s_sample.batchid = b.s_batchid             AND s_sample.classification = 'ReagentQuality'  JOIN s_product p ON s_sample.productid = p.s_productid  JOIN sdiworkitem sdi ON sdi.keyid1 = s_sample.s_sampleid                   AND sdi.sdcid = 'Sample'  JOIN workitem wi ON wi.workitemid = sdi.workitemid               AND wi.workitemversionid = sdi.workitemversionid  JOIN sdiworkitemitem sdiwi ON wi.workitemid = sdiwi.workitemid                         AND sdiwi.keyid1 = s_sample.s_sampleid                         AND sdiwi.sdcid = 'Sample'  JOIN paramlist p ON p.paramlistid = sdiwi.itemkeyid1               AND p.paramlistversionid = sdiwi.itemkeyid2               AND p.variantid = sdiwi.itemkeyid3  WHERE s_sample.s_sampleid IN ('S100')  AND 1 = 1  GROUP BY s_sample.s_sampleid,       b. u_tarolotnumber,       p.productdesc,       s_sample.productid,       s_sample.sampletypeid,       wi.workitemid,       workitemdesc,                 paramdesc;   Did lot of googling, but no luck! Any help would be highly appreciated.  Thanks in advance Suv


Power supply unit for Intel server motherboard S1200v3RPS with Xeon E3 processor. 5-pin aux power cable missing

I am trying to put a server together to install Ubuntu. I bought an Intel S1200v3RPS motherboard and plugged an Intel Xeon E3 processor into it. I purchased a 1U chassis from Supermicro with a power supply.  The power supply does not have a 5-pin cable to the motherboard's Auxiliary Power Supply socket. A bit of research did not give any definite answer on the need for the 5-pin connection. The motherboard does not power on and the CPU fan is off. I tested the power supply on a desktop Intel motherboard and it works fine.   I would like to buy a new power supply but could not find one which expressly stated that it comes with the 5-pin aux power supply cable. Any recommendations on a power supply unit for this motherboard would be helpful. Any comments on the problem would be greatly appreciated.


How to install multiple linux os on a single cd/dvd?

I don't have any empty DVDs, but I have one with enough free space. It currently has Zorin os 8 installed on it, which is 1.6 gb iso file. I would like to install Ubuntu 14.04 on it as well, so I can install it on Zorin os 8. Is that possible?


Editing text file with Vim does not update tail -f

I'm using tail -f a.txt to watch updates on a file called a.txt.  If I update the file using something like ls -a >> a.txt in a second virtual console, the changes will display in real-time in the first one.  If I update the file using Vim in a second virtual console, the changes will not display in the first one.  I don't necessarily expect it to trigger an update in that window - but why exactly doesn't this update the terminal running the tail -f command?


New Programmer: For Loops and While Loops(python)

I'm a new programmer and I'm having a lot of trouble understanding for loops and while loops. In what situations would I know to use a for loop and in what situations would I know to use a  while loop?   Also, could you explain to me what these 2 codes mean? I have a a  lot of confusion.   1 function:   def every_nth_character(s, n):       """ (str, int) -> str        Precondition: n > 0        Return a string that contains every nth character from s, starting at index 0.        >>> every_nth_character('Computer Science', 3)       'CpeSee'       """        result = ''        i = 0        while i < len(s):              result = result + s[i]             i = i + n        return result   ****What does s[i] mean?****  2nd function:    def find_letter_n_times(s, letter, n):       """ (str, str, int) -> str        Precondition: letter occurs at least n times in s        Return the smallest substring of s starting from index 0 that contains       n occurrences of letter.        >>> find_letter_n_times('Computer Science', 'e', 2)       'Computer Scie'       """       i = 0        count = 0       while count < n:             if s[i] == letter:                    count = count + 1             i = i + 1        return s[:i]   what does s[i] and s[:i] mean??


Why gcd(a,b) is the same as solving for gcd(b,a-b) in the Euclidean algorithm

I am a number theory hobbyist, and have recently started to read the book . I am at a point where the author is trying to reason why Euclid's algorithm for finding the gcd of 2 numbers work. I am unable to get my head around the fact that gcd(a,b) is the same as solving for gcd(b,a-b). Is there some way I can intuitively understand why this is so? I have gone through several explanations where they use modular arithmetic and Euclid's division algorithm to explain it and I am afraid I dont get it.


Let $a, b, c, d, e, f$ be nonnegative real numbers...

Let $a, b, c, d, e, f$ be nonnegative real numbers such that $a^2 + b^2 + c^2 + d^2 + e^2 + f^2 = 6$ and $ab + cd + ef = 3$. What is the maximum value of $a+b+c+d+e+f$?   I need help proving that $a+b+c+d+e+f \leq 6$


Check if a bitmask consists of multiple flags

Note, this is not a dupe of this question:    I need to validate whether or not a bitmask consists of multiple flags.  I've come up with this method, but I don't like it a whole lot because of the enumeration and casting.   [Flags] enum MyFlags { a = 1, b = 2, c = 4, d = 8 }  var flags = Enum.GetValues(typeof(MyFlags)).Cast<MyFlags>();  Console.WriteLine(flags.Any(f => f == (MyFlags.a | MyFlags.c))); //false Console.WriteLine(flags.Any(f => f == MyFlags.b)); //true


Is salt really necessary for cooking pasta?

I never put salt into the water when I boil it to make pasta even though cooking directions always suggest I do that and the pasta comes out fine. How necessary it is?


Here i want to print the value of Brick[][] matrix. But it is showing me the output as java.lang.Nullpointerexception


Proof of the irrationality of $\sqrt{3}$ - logic question

Prove $\sqrt{3}$ is irrational. (Proof by contradiction).  Let $\sqrt{3}$ be a rational number in simplest form $\frac pq$.   So squaring both sides of $\sqrt{3}=\frac pq$ we get $3=(\frac {p}{q})^2$ which translates to $3=\frac{p^2}{q^2}$.   Multiply both sides of the equation by $q^2$ yields $3q^2=p^2$. Now $p^2$ is taken to be divisible by 3 and thus an odd number, $p$ is also odd because any odd number squared is also odd.   So let $p=3s$ where s is an integer. Then $3q^2=(3s)^2 = 3q^2=9s^2$. Dividing both sides of the equation by 3 leaves us with $q^2=3s^2$.   Here is is taken that $q^2$ is divisible by 3 and is odd and so is $q$.   Therefore both $q \text{ and}\; p$ have a common factor of being odd and divisible by 3, proving that the $\sqrt{3}$ is irrational.  Are there any gaps that I could improve on?


How to quickly get a world that has a desired set of features?

The Terraria 1.2 update introduced  that make generated worlds varied not only in layout, but in availability of various features as well. What is the fastest way to get a world that has the features I need? Is there a program that can help goad Terraria to generate a world that fits my criteria, or perhaps a tool that will let me quickly tell if a generated world has the features I have in mind?


Video and music editing software that can be used on Ubuntu 14.04? I installed Kdenlive, and seems to work okay, except that it tends to slow down the system a little. It also takes a bit of time to get your head around it. But I was wondering if there were other alternatives that I should try out as well.


If $A$ is a commutative ring with unit, $a \in A $ and $S = \lbrace a^n \mid n \geq 0 \rbrace $ then there is an isomorphism $$S^{-1}A \cong A[x]/(1-ax).$$   In fact we can consider the homomorphism $$\phi : A[x] \to S^{-1}A$$ $$p(x) \mapsto p\left(\frac{1}{a} \right)$$  Then obviously $(1-ax) \subseteq \ker(\phi) $, but why $\ker(\phi) \subseteq (1-ax) $ ?


Use the sine rule to prove trig identity

Using the sine rule: $$ \frac{a}{\sin(A)} = \frac{b}{\sin(B)} = \frac{c}{\sin(C)}$$  prove, for triangle ABC:  $$\sin\left(\frac{B-C}{2}\right) = \frac{b-c}{a} \cos\left(\frac A2\right)$$  Using the sine rule it's easy to translate the RHS into:  $$\sin\left(\frac{B-C}{2}\right) = \frac{\sin(B)-\sin(C)}{\sin(A)} \cos\left(\frac A2\right)$$  Yes, I can expand out the LHS, and use the difference of 2 sines in the RHS, but neither makes an obvious equality, especially with terms in a and A in the RHS.  A nudge in the right direction would really be appreciated. Thanks.


Why does subsurf modifier cause weird deformation at the end of a cylinder?

My problem is simple. I think that the strange deformations on the top are there because there are so many vertices in one face. How do I fix this while maintaining nice topology?  Although I triangulated the top polygon, the problem still persists.


The Intergral of $\sin^4x$ without using reduction formula

So I've been trying to compute $$\int\sin^4(x)\mathrm{d}x$$ and everywhere they use the reduction formula which we haven't learned yet so I've been wondering if theres another way to do it? Thanks in advance.


Why are my drop-out values NOT affecting the accuracy in my recurrent neural model? (IMDB dataset, TFLearn)

So in the code below, which is pretty standard LSTM training for the IMDB dataset, I have run extensive experiments where I changed the drop-out value from 0.5 all the way up to 1, and the accuracy on the test set is ALWAYS ~78%, never deviating by that very much. I even tried extremely low drop-out values, such as 0.2 and 0.1, and got the exact same result. Does anyone know why the accuracy of the trained model seems impervious to the drop-out rate? Going along with the same code, I then happened to tweak a few parameters: changed the learning rate from 0.001 to 0.005, and the batch size from 32 to 25, and NOW the drop-out values do have a large impact on the accuracy of the trained model. Again, why is that?     from __future__ import division,  print_function, absolute_import  import tflearn from tflearn.data_utils import to_categorical, pad_sequences from tflearn.datasets import imdb  # IMDB Dataset loading train, valid, test = imdb.load_data(     path='imdb.pkl', n_words=10000, valid_portion=0.1) trainX, trainY = train testX, testY = test validX, validY = valid  # Data preprocessing # Sequence padding trainX = pad_sequences(trainX, maxlen=100, value=0.) validX = pad_sequences(validX, maxlen=100, value=0.) testX = pad_sequences(testX, maxlen=100, value=0.)  # Converting labels to binary vectors trainY = to_categorical(trainY, nb_classes=2) validY = to_categorical(validY, nb_classes=2) testY = to_categorical(testY, nb_classes=2)  # Network building net = tflearn.input_data([None, 100]) net = tflearn.embedding(net, input_dim=10000, output_dim=128) net = tflearn.lstm(net, 128, dropout=0.1) net = tflearn.fully_connected(net, 2, activation='softmax') net = tflearn.regression(     net, optimizer='adam', learning_rate=0.001,     loss='categorical_crossentropy')  # Training model = tflearn.DNN(net, tensorboard_verbose=0) model.fit(trainX, trainY, n_epoch = 3,           validation_set=(validX, validY), show_metric=True,            batch_size=32)  score = model.evaluate(testX, testY) print('Test accuracy: %0.4f%%' % (score[0] * 100))


java.lang.NullPointerException at java.io.Reader.(Reader.java:78) at java.io.InputStreamReader.(InputStreamReader.java:72)

What can it be the reason to get NullPointerException sometimes with below code piece.    Exception in thread "main" java.lang.NullPointerException      [java]  at java.io.Reader.<init>(Reader.java:78)      [java]  at java.io.InputStreamReader.<init>(InputStreamReader.java:72)      [java]  at helloworld.HelloWorld.fixture(Unknown Source)      [java]  at helloworld.HelloWorld.replaceScheduler(Unknown Source)      [java]  at helloworld.HelloWorld.test(Unknown Source)      [java]  at helloworld.HelloWorld.main(Unknown Source)     My code i trying to read that file extension .fscript ; the problem is getResourceAsStream(name) is returning null  Here is all code:    public class HelloWorld {     FScriptInterpreter fscript;     Node rootNode;           private Reader fixture(String name) {         InputStream stream = HelloWorld.class.getClassLoader().getResourceAsStream(name);         return new InputStreamReader(stream);     }        private Component getChildByName(Component parent, String name)             throws NoSuchInterfaceException {         ContentController cc = Fractal.getContentController(parent);         for (Component child : cc.getFcSubComponents()) {             if (name.equals(Fractal.getNameController(child).getFcName())) {                 return child;             }         }         return null;     }    public void replaceScheduler(Component root) throws Exception {         Component client = getChildByName(root, "client");         fscript.loadDefinitions(fixture("replace-scheduler.fscript"));         fscript.apply("replace-scheduler", new Object[] { rootNode });         Component newScheduler = getChildByName(client, "client1");         assertNotNull("New scheduler not found.", newScheduler);     }     public void test() throws Exception {       Factory factory = FactoryFactory.getFactory(FactoryFactory.FRACTAL_BACKEND);          Component root = (Component) factory.newComponent("helloworld.ClientServerImpl",new HashMap());          Fractal.getLifeCycleController(root).startFc();          ((java.lang.Runnable)root.getFcInterface("r")).run();          replaceScheduler(root);      }           public static void main(String[] args) throws Exception {            HelloWorld h=new HelloWorld();      h.test();     } }


Timer function to provide time in nano seconds using C++

I wish to calculate the time it took for an API to return a value. The time taken for such an action is in the space of nanoseconds. As the API is a C++ class/function, I am using the timer.h to calculate the same:   #include <ctime>   #include <iostream>    using namespace std;    int main(int argc, char** argv) {        clock_t start;       double diff;       start = clock();       diff = ( std::clock() - start ) / (double)CLOCKS_PER_SEC;       cout<<"printf: "<< diff <<'\n';        return 0;   }  The above code gives the time in seconds. How do I get the same in nano seconds and with more precision?


Eevee in render and in viewport, and material preview also not showing after updating my drivers

material preview, Eevee in viewport and also in render giving this blank object even in cycles. It's all start after I updated my Amd driver's. I have factory reset my pc but the problem still remains help!! Plz.     Pc spec: AMD Radeon Rx 560x series 4gb, ryzen 5 3550h with Vega 8 graphics


what does this do, what is this and why do we use this

i have this but unable to understand what does it do, int[] newArray = new int[3 << 1]; what it does to newArray Please help me to understand it.


Add caption to image included with includegraphics within center environment

I have copy+pasted a portion of my latex source here. I'd like to add a caption at the bottom of each of the images load_8.png, load_9.png, load_1.png and load_1.1.png, but can't find an easy way to do this. I've also attached the output of processing this latex code.  . Can someone please show me the way?  \documentclass{article} \usepackage{graphicx} % Required for including images \usepackage[font=small,labelfont=bf]{caption} % Required for specifying captions to tables and figures \begin{document} \begin{center} \includegraphics[width=0.49\linewidth]{fig/load_8.png} \includegraphics[width=0.49\linewidth]{fig/load_9.png} \captionof{figure}{Probability distribution with loading level of a): 0.8 ; b) 0.9} \end{center} \begin{center} \includegraphics[width=0.49\linewidth]{fig/load_1.png} \includegraphics[width=0.49\linewidth]{fig/load_1_1.png} \captionof{figure}{Probability distribution with loading level of a) 1.0 b) 1.1 } \end{center} \end{document}


How to avoid being prompted for a password by sudo?

I know I can become root (super user) via the su command but I have to authorize it after entering the commands. Is there a way I can become root and authorize (with password) in one line


How can I lower the delay after incorrectly entered login and sudo passwords?

I am horribly impatient and can't stand the (for me subjectively long) delay of around 2 seconds after entering an incorrect password in the login screen or also as sudo password, before I can retry typing it correctly.  Is there a way to modify the delay and reduce it to around half a second or turn it completely off, both for sudo and the login screen?   The optimal solution would include a longer delay after maybe 3 or 5 incorrect passwords, to still prevent brute-forcing.  PS: I am currently using vanilla Ubuntu 16.04 with Unity Desktop and lightdm.


Possible Duplicate:          This is the Bertrand's Box Paradox I read about on Wikipedia:     Assume there is three boxes:       a box containing two gold coins,       a box with two silver coins       and a box with one of each.       After choosing a box at random and withdrawing one coin at random,       if that happens to be a gold coin,       the probability is actually 66% instead of 50%.      And the problem is equivalent to asking the question       "What is the probability that I will pick a box with two coins of the same color?".   No matter how hard I try, I just couldn't comprehend this..   How is the possibility of picking a gold coin the same as the probability of picking a box with two coins of the same color?  Does this imply there is a 66% chance of picking a gold coin and a 66% chance of picking a sliver coin?   If so, can we just say there is 50% chance of picking either one of them since both stand a 66% chance....?! and suddenly everything makes no sense..  [UPDATES] It is actually the probability of the remaining coin to be gold is 66% but not the probability of obtaining the gold coin is 66%.. I've misread it....   And everything makes sense now :D !


What part of speech is "baking" in "baking is fun"?

In the sentence "baking is fun," what part of speech is "baking"?


Show that $e^{x+y}=e^xe^y$ using $e^x=\lim_{n\to\infty }\left(1+\frac{x}{n}\right)^n$.

I was looking for a proof of $e^{x+y}=e^xe^y$ using the fact that $$e^x=\lim_{n\to\infty }\left(1+\frac{x}{n}\right)^n.$$  So I have that $$\left(1+\frac{x+y}{n}\right)^n=\sum_{k=0}^n\binom{n}{k}\frac{(x+y)^k}{n^k}=\sum_{k=0}^n\frac{1}{n^k}\sum_{i=0}^k\binom{k}{i}x^iy^{k-i}=\sum_{k=0}^n\binom{n}{k}\sum_{i=0}^k\binom{k}{i}\left(\frac{x}{n}\right)^i\left(\frac{y}{n}\right)^{k-i}$$  But I can't get $$\left(1+\frac{x+y}{n}\right)^n=\sum_{k=0}^n\binom{n}{k}\left(\frac{x}{n}\right)^k\sum_{i=0}^n\binom{n}{i}\left(\frac{y}{n}\right)^i.$$  Any idea ?


So, for example, when I type man ls I see LS(1). But if I type man apachectl I see APACHECTL(8) and if I type man cd I end up with cd(n).  I'm wondering what the significance of the numbers in the parentheses are, if they have any.


SIgnificance Testing of an Opinion before and after an intervention

How can I test the responses of students of a single question (Opinion) before (n=84) and after an intervention (n=81) with responses based on a 5 point Likert scale (SDA-1, DA-2, N-3, A-4. SA-5)?  For most of the students, before and after are same. But some students dropped out later, or didn't respond after the intervention, so its a different sample size.


How to take Time value from date time in formula or workflow

I have date time field on my object. In another field i need to display only the time value of the field.  Date value field: 7/21/2017 12:12 AM  Desired field output: 12:12 AM.  I tried the below formula:       RIGHT(TEXT(Datevaluefield__c),8)   It is returning 7:12:00Z, in GMT format. Can some suggest a way to get time value alone from datetime field.  Thanks in advance.


How to update my Windows Subsystem for Linux?

I have two computers, one laptop and one PC. My laptop was the first to get the Anniversary update. I successfully installed WSL and get it working. Only a few bugs like inotify or my main one socket hang up randomly popping up when trying to do test units in node.js on local server... Later I updated my tower to anniversary and set up WSL. This one still had the inotify issue, but no more socket hang up. So I guess a new update fixed it. I tried removing WSL on my laptop using lxrun /uninstall /full and the reinstall, but still same issue. Windows is up to date. How can I update my WSL system on laptop?


Add attribute from underlying polygon based on maximum shared area

The image below is of vineyard blocks on different soil types (four larger polygons - all different layers).    I would like to create a new attribute in the vineyard layer called soil type and fill it with the value from the four different soil type layer's attribute called description.  In the case where the soil types overlap the vineyard blocks, the attribute soil type should be where more than 50% of the block lies within the soil type. I have looked, but cannot find a answer.  I have tried geomwithin('Alluvial', 'Description') - a function I get in the field calculator after I installed the plugin refFunctions. However, this only works, of course, if the vineyard polygon is completely within the soil type. I have played around with Union, but I cannot see how that will help me.  Can someone please help me? I would prefer a expression, as I have no knowledge of scripting.


I have a command that has been floating around in my standard preamble for a while:  \newcommand{\xeq}[1]{\stackrel{\;#1}{\cleaders\hbox{=\!}\hfill}\:}   It is meant to mimic the AMS-LaTeX extendible arrow symbols \xleftarrow and \xrightarrow.   It's not perfect for two reasons:   It does not take the optional lower argument like the AMS \xrightarrow[down]{up} The overlap of the constituent equals signs is slightly visible.   Does anyone have a better command or know of a package with such a command?


With mesh (stairs) following the curve path. Few stairs are in align rest as it goes up the stairs bending. Rotation scale applied. Tilt is also 0. Whats going wrong. Any suggestion or help Thanks.


JLabel seticon error, Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException

I'm using the desing view to add components to the JFrame, I create a package "res" and copied the images files and add the image to the JLabel with options, properties/icon/Image with Project/ selecting res package and the file .png, but i don't know why I'm getting this exception:   line 75 exception: jLabel5.setIcon(new javax.swing.ImageIcon(getClass().getResource("/res/icons8customer32px1.png"))); // NOI18N  If I remove the icon it doesn't crash, if any have an idea why this happen? thanks   private void initComponents() {   jLabel5.setIcon(new javax.swing.ImageIcon(getClass().getResource("/res/icons8customer32px1.png")));         }// </editor-fold>   I'm using this steps for handling images:


The eighth installment of the Filipino comic series Kikomachine Komix features a peculiar series for the golden ratio in its cover:    That is,  $$\phi=\frac{13}{8}+\sum_{n=0}^\infty \frac{(-1)^{n+1}(2n+1)!}{(n+2)!n!4^{2n+3}}$$  How might this be proven?


Why does light have only 3 primary colours and why don't then non primary VIBGYOR colours disperse?

While light has so many wavelengths why only 3 colours exist as primary colours?  Why do some colours disperse while VIBGYOR colours don't (except the primary ones which satisfy the logic as they are basic colours)


What is the exact relation between a full rank matrix and its determinant?

I would like to know in particular whether a full rank matrix necessarilly has a determinant equal to/different from zero. Also, would the answer change based on the matrix being squared or not?


Subject verb agreement question regarding "seem/seems"

Sentence: "Two weeks seems to be the virus's maximum incubation period."  What is the subject of the sentence? I can't figure out if it's the virus or the incubation period. Also, generally, when you have a plural noun, you're supposed to use "seem" (eg. Those cats seem upset) as opposed to "seems" when you have a singular noun (eg. That cat seems upset), but here, "seems" works alongside "two weeks". Why?  Thank you.


Has anyone considered the potential of having a Twitter ID field in the profile (or fields for other similar microblogging/social networking services) so that those who want to can advertise their other profiles, allowing people to network with people in their field?  The particular value of this, I feel, is more in Stack Exchange sites where the sites are often much more specialised and you are participating in a small community where it's useful to keep tabs on who's doing what.


Multiplying floats occasionally produces a large trail of decimals

It's not really a major issue, but on occasion when I look for the output of a float number (usually to the thousandths place) and an int, I get a number that has the correct answer, but then a bunch of trailing zeroes and another integer. Here's some code I encountered this in, and my various tests to try isolating the problem: Code: def returnit():     return float(17.556)  var1 = 17.556 var2 = (17.556 * 3) print(returnit() * 3) print(var1 * 3) print(var2) print(str(17.556 * 3)) print(17.556 * 3)  The output for all of them is 52.668000000000006. Honestly I'm just curious as to why this happens, and the sum of my research has yielded "uhh... floating points don't do amazingly with math sometimes?"


Squares in Polynomial Quotient Ring $ (\mathbb{Z}/2)[x] /(x^{17} - 1) $

Let $R = (\mathbb{Z}/2)[x] $ and $I$ the ideal generated by the polynomial $x^{17} - 1$. Is there a non-zero element of $R/I$ s.t. the square of that element is zero in $R/I$? I know a quotient ring $R/P$ is an integral domain iff $P$ is a prime ideal, and since $R$ is a PID, the prime elements are the irreducible, but $x^{17} - 1 $ is reducible in $R$, hence $R/I$ is not an integral domain. So there are nonzero $a,b \in R/I$ s.t. $ab = 0 $, but $b$ might not be $a$, and that's where I got stuck. I've also tried finding $f \in R$ s.t. $ f^2 = g \cdot (x^{17} - 1)$, but don't know how to attack this methodically.


I have a fresh install of Windows 7, and my RAM in normal startup goes up to 2.5GB. I looked at Task Manager, and there's at least 1.5GB missing from there and in Resource Monitor as well. There's no indication of what's using that RAM. Can someone tell me how I can find out what's consuming my memory? I believe it's a virus, but none of the free antivirus programs tracked it down.   I added the pictures below. If this is normal usage of Windows 7 as some answers imply, then I don't get this at all.   P.S. My Windows 8 Installation was running below 2.5GB, actually it was 1. something, until recently that I transferred some files from another computer which had the same problem that mine has now. I deleted Windows 8 and installed Windows 7, since I would do that anyway, and now I'm getting high memory usage in Windows 7 as well.   (Click images to enlarge)


I want to tame a wild horse or a donkey in Minecraft but I don't really know where to start.


Effects of Polyjuice Potion on the Pregnant

Some friends and I were swapping hypothetical scenarios regarding the Potter universe. Polyjuice potion, of course, brought up a number of interesting questions, but perhaps the most unsettling was what the effect might be if, say, a 9-months-pregnant witch consumed Polyjuice Potion made with the hair of an adult male. What would happen - would she successfully transform, with the infant being absorbed into her body and incorporated as part of the transformation? Or would the child remain unchanged within the new male body, as it is a separate entity? Or - the most horrifying possibility - would the infant ALSO transform into a second copy of the adult male, as it is directly connected to the mother's bloodstream, thereby certainly killing its own mother and likely itself in the process?  Cheers.


Is this logic behind the derivative of $x^x$ a coincidence?

As many of you probably know, when you take the derivative of $x^x$, you cannot treat it as either a exponential function ($a^x$) or like a function of the form $x^a$.   If you treat it like $x^a$ then you get an aswer of $xx^{x-1}$, which is just $x^x$.  Treat it like $a^x$, and you get $x^xln(x)$.  The correct derivative is $x^x(ln(x)+1)$, which you get by doing implicit differentiation after taking the natural log of both side.  This is the same as $x^xln(x)+x^x$, which happens to be the combination of the "wrong" derivatives you get when treating $x^x$ as the 2 different types of functions I specified earlier.  Is there any real logic behind this or is it coincidence. Also, could this also be applied to other function hybrids like $x^x$?


I have imported this file before an it has worked but not this time. I have pressed Numpad . and that just zooms me into here the picture below. I am not in local view.Last time it worked it had imported absolutely huge bugs scaling it down doesn't seem to work. thanks for your help!


Why does $\textbf{F}=- \boldsymbol{\nabla} V$?

From the  I asked just now, I now know that the plus or minus doesn't matter for $ \boldsymbol{\nabla} V$ in math (since the opposite vector field $\vec{-F}$) must be conservative as well. $$ \textbf{F}=- \boldsymbol{\nabla} V$$ Since I think it's more appropriate to open a new question, then my question is: why does $F = -\boldsymbol{\nabla} V$ in the first place?


Objective  To confirm if the understanding is correct regarding the reason why Lagrangian Dual is used in SVM.  Background  While Machine Learning, gradient descent is used at regression, logistic regression, back propagation, etc. However for SVM, suddenly Lagrangian Dual pops up. Trying to understand why.    It looks to me gradient descent is possible to solve "primary" issue of SVM as in the left side of the image below (please correct if it is wrong). However never saw any articles or books which mention using gradient descent. Instead, always Lagrangian Dual and KKT conditions pop up out of blue and do not explain well why.    Question  I suppose using the dual reduces the dimensions , e.g (x1, x2) to λ in the image, and results in a formula that produces definite solutions.    Is it the only reason to use Lagrangian Dual, or are there any other reasons?     Is there any reason why Gradient Descent cannot be used?


Is there an easy way to swap a rigged character for an updated one?

I have a character that's in a scene and I didn't like how he was weight painted and some anatomy needed to be tweaked, now it looks better than before. But I edited the model from its own file where it's just the character and not from the scene he is in. I was thinking there must be a way to update the old model to take over with the new version, considering it's not unusual that when there's a collaboration effort there's a need to update an asset.   Is there something for that kind of situation in Blender?   Manually, it ends up being a real challenge, copy, paste, parent, unparent, unbind, bind. I'm still trying to get it done, so far Blender crashing, not getting something done in the right order having to start over. Parts moving when unbinded as it was moved when binded. Now the fingers aren't bending as the modifiers are in the wrong order. Still at it. It's a real headache.


What is a continuous function on the rationals that hasn't a continuous extension on the reals?

In a  of H.R. Pitt's Integration, Measure and Probability, Sir John Kingman wrote,     The author is often careless about details, asserting for instance (on page 105) that a function continuous on the rationals has a continuous extension to the reals.   Using the properties of Cauchy sequences and completeness of $\mathbb R$, I can prove that if $f:\mathbb Q\to\mathbb R$ is uniformly continuous, then there exists a continuous function $g:\mathbb R\to\mathbb R$ such that $f=g$ on $\mathbb Q$.  It follows that any inextensible $f$ cannot be uniformly continuous on $\mathbb Q$. However, I am unable to come up with a concrete example.


What are some intuitive examples of categories which aren't made from structured sets and functions between them?

In my loose reading about category theory, categories are usually introduced in terms of sets, often with some structure (such as algebraic or topological), and functions between them that preserve that structure. I find this easy to intuit, and makes ideas like commutative diagrams easy to understand.  However, I know that categories can be much broader than this, even before we get into higher notions like functors and such, and that categories describing structured sets and the functions between them are only an important but small portion of them. Despite this, I find it hard not to unconsciously interpret diagrams and category theoretic statements in these terms unless I completely strip all meaning from the symbols and treat the whole thing as a purely syntactic game, and the times where I've seen people discussing categories where the morphisms aren't structure preserving functions have been very abstract and gone right over my head.  So what I would like are some simple, intuitive examples of things which can be described by category theory, but where -  A) The objects are not sets,  B) the morphisms aren't (possibly structure preserving) functions, or  C) both.  I've wanted to learn more about category theory for a while, but I've found I kept being held back by my lack of a strong, accurate mental model for the sorts of things categories can represent, in the way that I have a strong model for the ways sets work and the things they can represent.


Do Ukrainian citizens require a transit visa at Vienna travelling form Ukraine to Serbia?

I am travelling from Ukraine to Serbia, transfer via Vienna airport? Do I need transit visa in this case?


Program only crashes as release build -- how to debug?

I've got a "Schroedinger's Cat" type of problem here -- my program (actually the test suite for my program, but a program nonetheless) is crashing, but only when built in release mode, and only when launched from the command line.  Through caveman debugging (ie, nasty printf() messages all over the place), I have determined the test method where the code is crashing, though unfortunately the actual crash seems to happen in some destructor, since the last trace messages I see are in other destructors which execute cleanly.  When I attempt to run this program inside of Visual Studio, it doesn't crash.  Same goes when launching from WinDbg.exe.  The crash only occurs when launching from the command line.  This is happening under Windows Vista, btw, and unfortunately I don't have access to an XP machine right now to test on.  It would be really nice if I could get Windows to print out a stack trace, or something other than simply terminating the program as if it had exited cleanly.  Does anyone have any advice as to how I could get some more meaningful information here and hopefully fix this bug?  Edit: The problem was indeed caused by an out-of-bounds array, .  Thanks everybody for your help in finding this problem!


Setblock Command not working with specific parameters in Minecraft

I am trying to make a game for myself and my friends to play, and I have a prototype working in my test world that works perfectly, however, the game relies on the fact that we will be playing on a random seed, and because of that I am converting all of the command blocks into one long command that can be run to set up the game on a new world very quickly. In doing this I have found one command that does not seem to work, I have tested it all I can but cannot find what syntax I have wrong.  The command ("/kill @e[type=item,nbt={Item:{id:"minecraft:compass"}}]") works perfectly when I type it into another command block or chat.  Here is the command:  /setblock ~6 ~-1 ~1 repeating_command_block[conditional=false,facing=up]{Command:"/kill @e[type=item,nbt={Item:{id:"minecraft:compass"}}]",auto:1b} replace   According to the game, there should be another "}" right after the "{id", I have no idea why this is happening.


Evaluating the integral with trigonometric integrand

While solving another problem I have come across this integral which I am unable to evaluate. Can someone please evaluate the following integral? Thank you.      $$\int_0^{2\pi}\frac{1}{(2+\cos\theta)^2}\,d\theta.$$


Math in paper title is wrong size (too small)

The title of my paper contains a math mode expression. Usually this renders correctly, but with the style file I am using for the proceedings in which it will appear, the math mode part appears in normal-size font while the rest of the title is title-size, making the math part look very small. This also happens in section headings.  The style file is here: www.sheridanprinting.com/typedept/sig-alternate-2013.cls  Minimal working example:  \documentclass{sig-alternate-2013} \begin{document} \title{Proving that $1 > 0$} \maketitle \section{Proving that $1 > 0$} \end{document}   Any advice as to how to to fix this would be great, thank you.


i am sure there is a simple answer, but i have seem to have forgen it. How do you calculate the relative apparent size of the subject   i have seen a formula with the field of view and tangent, but i am looking at a simple way to estimate on the fly what lens to use to make the subject 3X larger or smaller than where it is at, with a 50mm for instance.  i seem to remember halfing and doubling focal lenght, but that doesn't seem to work, 400mm is a lot more magnified than X3 (50 to 100 to 200 to 400mm)  Since "super zooms" like 24-240mm are 10X optical zooms, is it based on the starting 24mm lenght, which gives 10 increments, the relative X2 magnification would be 24-48-72-96-120-144-168-192-216-240mm  but that logic seems to break with other applications...  i though of angle of view, but 10° increments of fov, gives only 7 steps from 24 to 240mm (84-74-64-54-44-34-24-14° but 14° diagonal angle of view is 130mm and the next logical step 4° is 500mm  any simple way to estimates?


How can I get the timestamp when a Contact enters a journey?

I am building reporting using SQL Activities. SQL is bucketing success events into tranches that represent the time window for a communication to claim success- i.e. email 1 is from 0 to 24 hours, email 2 is from 24-72 hours, etc.  I have a journey where about 60% of the contacts achieve success before the 1st communication. Which DataView can I find the EventDate for a contact entering a Journey? I want the complete list. If I use the first communication _Sent EventDate, this will exclude contacts that did not reach this point in the Journey.  Is it possible to get the timestamp for when a contact enters a Journey using SQL? If not, how?


How to twist a mesh for cloth-like effect?

I would like to create geometry and model it (not sculpt it), as to have a cloth-like effect, wrapped around a blade's handle (reference image shows this).   How would I go about doing this? When I attempt to do so, twisting a plane, or a cube, provides certain "artefacts" due to the fact that the rotation is alongside the Z axis for 180 degrees (out of logical reasons, having to align everything perfectly).  To summarise: How do I twist a mesh as to create the overlapping cloth effect?  Issue seen here:


Equations that may relate to monotone convergence theorem?

I want to show the following equations, assuming that $X$ is a non-negative random variable. $\lim_{n \to \infty} n E(\frac{1}{X}I_{\{X>n\}}) = 0$ $\lim_{n \to \infty} \frac{1}{n}E(\frac{1}{X}I_{\{X > \frac{1}{n}\}}) = 0$ I think they may be related to the monotone convergence theorem, but I have no clue how to approach them. Any hints?


Drop "not constructive", combine "noisy", reword "rude" and "other" comment flags

The problem Comments are terrible; no one agrees on what they're for, or how long they should be kept. Comment flags are equally terrible, because if no one's on the same page as far as what should be posted in the first place then no one can agree on what should be removed either. On top of that, we have this confusing set of flags where two mean "noise", one means "vile", one means "moderator, help!" and one means nothing at all - the end result is that it's all but impossible to even analyze comment flagging. The solution (or, part of it) Two years ago, in a fit of rage, I . Nothing got done. As always, everyone has a different idea of how things are supposed to work, and I'd bitten off more than I could chew. So, here we are, two years later, and comment flags still suck. So let's start by just cutting the fat: if we can trim down the list of flags to a set of clearly distinct problems, we might have something we can build on. Here's what I'm proposing, based on the past two years of discussion:   Re-word the "rude or offensive" flag to read,  rude or abusive: this comment violates .   Remove the "not constructive", "obsolete" and "too chatty" flags.  Add a new comment flag:  no longer needed: this comment is obsolete, chatty or otherwise unnecessary   Re-word the "other..." flag:  in need of moderator attention: these comments require action by a moderator. Be specific and detailed!    That's it; that's all I'm proposing to start out - simplify things so that we have something to build on. See also:


Cron: Execute python script, capture stdout & stderr and send via msmtp

I try this for almost 4 hours now, in different ways. I googled a lot, but nothing I try work as expected.  I have a simple .msmtprpc file, that allows me to send mails like this:  echo -e "Subject: foobar\r\n\r\nContent" | msmtp my_mail@gmail.com   However, I can't seem to concatenate the full output of a Python script as content of the message.  This command:  ( echo -e "Subject: aaa\r\n\r\n" ; python foo.py 2>&1; ) | msmtp foobar@gmail.com   works in my terminal, but not as a cron command. Perhaps we can improve it ?  Thanks for your time.


Is it possible to get amazon ec2 instances to hibernate?

I've tried hibernating instances on amazon ec2. You get the shutdown signal in Linux, but the aws instance doesn't get stopped, and after a hard reboot it then refuses to boot. The only way out is to terminate the instance, as far as I can tell.  Is there a technical reason why this shouldn't work?


Show convergence of a serie with unknown exponent

For $\sum a_n$ convergent and also $\forall n \in \mathbb{N}$: $a_n\geq0$, show that:   $$ \sum \frac{\sqrt{a_n}}{n^\alpha}$$ converges for $\alpha> \frac{1}{2}$.   My idea was to use the Direct comparison test, I'm pretty sure that's the way to prove it, and to find a bigger series that also converges, but I haven't been able to find one appropriate series.   It would be very helpful if you could give me a hint on how this bigger series.  Thank you very much


How do I prove that $(A + B)^2 = A^2 + 2AB + B^2$

Assume that $A$ and $B$ are both $n\times n$ matrices, how would I prove that $(A + B)^2 = A^2 + 2AB + B^2$ for any $n\times n$ matrices?


What is the preferred way to mention Stack Overflow from Twitter?

I wanted to tweet something on the lines of "Stack Overflow is awesome". When I do this kind of stuff, I usually use a username (for example: ) or a hashtag ()  I found , but it seems it is from someone unrelated with Stack Overflow.  Is there a Twitter account I can reference, or should I use a hash-tag? Should I just point to the site?  Thanks!  (Notice: I've seen lots of questions regarding Twitter and Stack Overflow, but those are mostly about integration/login with Twitter for the users accounts; I'm just asking for a single account for Stack Overflow; probably for announcements and PR, which is different)


'date' Command Failure in Ubuntu 18.04 LTS

I am getting errors on the date command if I use the timezone designation stored in the system: $ date -d "2019-12-10 23:26:30 EDT +4 hours" date: invalid date ‘2019-12-10 23:26:30 EDT +4 hours’  $ date -d "2019-12-10 23:26:30 EST +4 hours" Wed Dec 11 03:26:30 EST 2019  Here's what I get when I ask to display the time zone information: $ date +"%Z %z" EDT -0400  Is this an error on my part or has something changed in the system? I am running Ubuntu 18.04.4 LTS x86_64 with kernel 5.7.1-050701-generic.


Can I use Choice Ethanol Gel Chafing Dish Fuel to cook marshmallows, or do I have to use a certain kind.


I'm studying SHA-3 and I dont understand quite a bit how the padding 10*1 works. Can someone explain me step by step how is it work? Also I know that on SHA3-512 r is 576. On the sponge construction what you need to XOR the first padded message P0 with the r vector. What is the r vector in any situation? (Please be nice with me Im just studying crypto for the first time also Im not an english native speaker)


How can a program physically leave the Grid in Tron: Legacy?

I'm sure someone has thought to ask this before, but I couldn't find it. In , the end of the film sees our hero Sam      returning to the real world WITH his ISO girlfriend Quorra. In addition, we find that the antagonist's plan is to leave the Grid and bring "order" to the real world.   How is this possible? As I understand it, an ISO is merely a program-based lifeform that evolved spontaneously rather than being written by a User. And CLU is esentially just a super-powerful AI built to run the TRON world. However, no matter how advanced the AI behind a program is, it's still just a program that exists as code in the computer. There's no body to digitize, and no other known way to contain the code in the real world.  How is it possible for any program to leave the Grid and enter the real world?


There is a particular integral which comes up frequently in physics which a friend and I spent hours trying to figure out with no success. I don't know if this integral has a name so googling has been fruitless. Arfken states the solution in the back flap but I have no idea how to find it  $$\int_{-\infty}^{\infty}{\frac{e^{i\mathbf{k}^{.}\mathbf{r}}}{k^{2}+m^{2}}\frac{dk^{3}}{(2\pi)^{3}}}=\frac{e^{-mr}}{4\pi r}$$  Limits go from -inf to inf for all k. Note that k and r are vectors. Presumably r on the right hand side is $\lvert\mathbf{r}\rvert$ (I could be wrong).  If someone could show how this is derived or provide a link to its derivation it would be greatly appreciated.


I don't know if this is the right place to ask this question, there may also be duplicates,  I just want to ask: Which will be the best DE for: Pentium 4 3.6 GHz (2007), 1GB DDR2 RAM, Intel 915G chipset. Basically I am limited in terms of graphics capabilities by that chipset. So, could you recommend a light weight DE to go with Ubuntu?


Ubuntu upgrades blocked due to insufficient disk space for linux-image

I am running Ubuntu Server 14.04 LTS on a desktop at my home that I was intending to turn into a server, but I never really did much on it. I then decided to turn it into a send-only SMPT server, but when I tried sudo apt-get install postfix to install postfix, I got this error:  You might want to run 'apt-get -f install' to correct these: The following packages have unmet dependencies:  linux-image-extra-3.19.0-42-generic : Depends: linux-image-3.19.0-42-generic but it is not going to be installed  linux-image-extra-3.19.0-56-generic : Depends: linux-image-3.19.0-56-generic but it is not going to be installed  linux-image-generic-lts-vivid : Depends: linux-image-3.19.0-56-generic but it is not going to be installed                              Recommends: thermald but it is not going to be installed E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).   I tried running sudo apt-get -f install, but that didn't work:  Preparing to unpack .../linux-image-3.19.0-56-generic_3.19.0-56.62~14.04.1_amd64.deb ... Done. Unpacking linux-image-3.19.0-56-generic (3.19.0-56.62~14.04.1) ... dpkg: error processing archive /var/cache/apt/archives/linux-image-3.19.0-56-generic_3.19.0-56.62~14.04.1_amd64.deb (--unpack):  cannot copy extracted data for './boot/vmlinuz-3.19.0-56-generic' to '/boot/vmlinuz-3.19.0-56-generic.dpkg-new': failed to write (No space left on device) No apport report written because the error message indicates a disk full error                                                                           dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.19.0-56-generic /boot/vmlinuz-3.19.0-56-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.19.0-56-generic /boot/vmlinuz-3.19.0-56-generic Preparing to unpack .../linux-image-3.19.0-42-generic_3.19.0-42.48~14.04.1_amd64.deb ... Done. Unpacking linux-image-3.19.0-42-generic (3.19.0-42.48~14.04.1) ... dpkg: error processing archive /var/cache/apt/archives/linux-image-3.19.0-42-generic_3.19.0-42.48~14.04.1_amd64.deb (--unpack):  cannot copy extracted data for './boot/vmlinuz-3.19.0-42-generic' to '/boot/vmlinuz-3.19.0-42-generic.dpkg-new': failed to write (No space left on device) No apport report written because the error message indicates a disk full error                                                                           dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.19.0-42-generic /boot/vmlinuz-3.19.0-42-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.19.0-42-generic /boot/vmlinuz-3.19.0-42-generic Errors were encountered while processing:  /var/cache/apt/archives/linux-image-3.19.0-56-generic_3.19.0-56.62~14.04.1_amd64.deb  /var/cache/apt/archives/linux-image-3.19.0-42-generic_3.19.0-42.48~14.04.1_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)   I tried installing other packages and the error persists across all uses of apt-get install.  I also followed the instructions at  to run sudo apt-get clean, but that still didn't solve my problem.  So what is wrong? What must I do to get apt-get working again?  I do not know much about this issue, so I may not have provided all the necessary information. Please comment if I need to add more.


Difference between "Present Simple" and "Present Continuous" or "Gerund"

I have a very confusing exercise in my workbook. There are 4 options. This is the question: I wouldn't like _____ in bed until noon, although I enjoy _____ 1) to lie, to sleep  2) lying, sleeping  3) lying, to sleep  4) to lie, sleeping I have no idea. Hopefully you can help me.  Greetings


Why dynamic_cast returns null on item from vector?

I have such hierarchy of classes for saving entities found in DXF file: class MyDxfItem {    public: DL_Attributes usedAttributes;    virtual ~MyDxfItem() {} }; class MyDxfLayer : public MyDxfItem {     public:     MyDxfLayer(const std::string& name, int flags, bool off = false): LayerInfo(name,flags,off) {      }     public: DL_LayerData LayerInfo;           };  class MyDxfCircle : public MyDxfItem {      public:          MyDxfCircle(DL_CircleData inCircleInfo): circleInfo(inCircleInfo) {          }              public:      DL_CircleData circleInfo; };  class MyDxfArc : public MyDxfItem {     public:     MyDxfArc(DL_ArcData inArcData) : arcInfo(inArcData) {      }     public: DL_ArcData arcInfo; }; class MyDxfLine: public MyDxfItem {     public:         MyDxfLine(DL_LineData inLineData) : lineInfo(inLineData) {      }     public: DL_LineData lineInfo; }; class MyDxfPoint : public MyDxfItem {     public: DL_PointData pointInfo; };  class JovanDxfStruct { public: std::vector<MyDxfItem> MyListLayers; public: std::vector<MyDxfItem> MyListItems; } ;  extern JovanDxfStruct* globalPtrToDxfStruct;  MyDxfLayer is a subclass of MyDxfItem, MyDxfLayer expands and extends MyDxfItem. Base class has virtual destructor. I keep instances of MyDxfLayer in vector: std::vector<MyDxfItem> MyListLayers, it is legal by inheritance. Here is my code how I add item to this vector: if (globalPtrToDxfStruct != nullptr) {         MyDxfLayer layerDataMy(data.name,data.flags, data.off);         layerDataMy.LayerInfo = data;         layerDataMy.usedAttributes = attributes;         globalPtrToDxfStruct->MyListLayers.push_back(layerDataMy);     }  I create here instance of MyDxfLayer and add it to std::vector. But when I try to downcast it back to its original class I get nullptr:  Right after the element was added to array it gets trimmed to baseclass and information stored in instance or derived class seems like lost. Why is this happening? Why the code: dynamic_cast<MyDxfLayer*>(&(globalPtrToDxfStruct->MyListLayers[0]))  returns null? you may see that globalPtrToDxfStruct->MyListLayers[0] is not null. I am adding the instance of derived class to vector of instances of base classes. I have referenced to example from  , there is an example without vector, but I think it should be similar


The comment section gets partially overlapped on downvoted and accepted answers

The below image shows what I am talking about ()


When did television become known as the 'tube'?

I searched Google's "YouTube", it seems like "tube" is a nickname for "television". So, when did television get this nickname, and why?  EDIT  I have once considered tube as TV cube, does it make sense?


What are the best practices for avoiding xss attacks in a PHP site

I have PHP configured so that magic quotes are on and register globals are off.  I do my best to always call htmlentities() for anything I am outputing that is derived from user input.  I also occasionally seach my database for common things used in xss attached such as...  <script   What else should I be doing and how can I make sure that the things I am trying to do are always done.


I have a problem with $PATH export. The only place I found where I modify $PATH is /etc/environment:  ANDROID_HOME="/opt/ADT/adt-bundle-linux-x86_64-20130522/sdk" PROJECT_HOME="/home/tomaszchabinka/Dokumenty/tempFile/android_stb" PATH="/opt/gradle-1.10/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"   But when I type in terminal echo $PATH it returns:  /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/lib/jvm/jdk1.7.0/bin   I don't have /usr/lib/jvm/jdk1.7.0/bin directory so I don't understand why my $PATH export doesn't works and where does /usr/lib/jvm/jdk1.7.0/bin come from.  Also $ANDROID_HOME and $PROJECT_HOME exports correctly; only $PATH export doesn't work.  Can anyone help me?


Prove that the function $\xi\in R \mapsto {e^{i\cdot \xi\cdot λ}-1\over i\cdot \xi}-λ$ is $C^{\infty}$

Prove that the following function is $C^\infty$ in the point $\xi=0$:   $$f:\Bbb R\to\Bbb C:\xi\mapsto {e^{i\cdot\xi\cdot λ}-1\over i\cdot\xi}-λ$$   Any ideas how to prove this?  I am trying to think some ideas but I cannot find any way to prove it.


Transactional Replication to DB on Same Server instance

We have a SQL Server 2012 instance that contains a database with data for many product lines.   We are looking for a way to take subsets of this data into another database on the same instance.  This doesn't have to be continuous as we are looking for ways to make it easy to export backups of the subsets that we can send out to vendors (we have a company that loads this data into their own sql server to produce a product we sell, naturally its huge and we want to trim it down to just the product lines they work with on a regular enough basis) or use to load SQLite DB's for use with offline applications.  ProductDB - the superset of all product line data.  ProductLine1DB - A subset identical in structure to ProductDB, but with data only relevant to product line 1.  ProductLine2DB - A subset identical in structure to ProductDB, but with data only relevant to product line 2.  This can be done nightly, weekly, as often as we need to but not a continuous replication.  We don't want to add in distributor servers or even extra subscriber servers. We would like the replication to happen on the same server with the subscriber databases being on the same server.  Is this a good candidate for transactional replication?  Why or why not?  We obviously have other options to load this data, but it seems like this might be a good case to use something like transactional replication. I've heard its powerful but prone to issues when not setup optimally.  Note: I am not a DBA, simply a developer, but we are currently looking for a new DBA and some of us are taking over duties like this temporarily.


how can I "become" user#1000 and recover the "right" to make backup copies?

I've installed Ubuntu 16.04 and effectively lost control of my computer which worked just fine under Ubuntu 14.04. I just need a simple command line instruction(s) so I can save my files on my 2tb backup drive, reformat my hard drive and start all over again. Even though I don't want to use it I've even lost access to the partitions with Windows 7 on them.


how to compare age with birthdate in where clause? Somthing like this code:  myRepository.Where(x =>     fromAge <= x.BirthDate.Age && x.BirthDate.Age <= toAge)     .Select(x).toList();   Data Types:  fromAge, toAge : int  x.BirthDate: DateTime


I'm new to Blender. I've been working on a scene with a lighthouse, and I'm all done with the geometry. I tried an eevee render of the scene, but uh-oh! When the glass preset is applied to the window section, its not letting the cone-light pass through.  I took a look at the same scene with cycles, and ended up with this,  (I only used 8 samples because my laptop is rather weak) Even though its just 8 samples, you get the idea. It's very noisy Anyway, I looked around for a way to get a less noisy cycles render, and found this node setup, called Tricky-glass by the user:  I sorta understood how it worked, so I tried it. It still didn't get rid of the noise. I, anyway, tried to do a 128 sample render with the denoiser, hoping it would fix the noise. Before the de-noising, the render was looking really pristine, except for a little noise here and there. Right after the denoising, my eyes were treated to this:  That's right, the entire geometry turned into some kind of mush. To everyone that's about to say I'm too new to be working on this stuff- you are right! That's why I am here. Please direct me to any helpful resources, and/or help me fix the problem mentioned  above. My ultimate goal is to get a clean cycles render of the scene, with good-looking volumetric lighting. My blend file (Could be messy and disorganized, pardon me for that):


I am in the position of needing footnotes for my document. I found that the syntax is:  Something pretty complicated\footnote{This complicated thing needs details.}   This will make my source hard to read so I have to ask you guys: is there any method to work like this?  Something pretty compLicated\footnote{ref:1}  \footnote{1}{This complicated thing needs details.}


I was wondering if anyone has a good suggestion for a textbook on numerical analysis. I am an undergraduate with little prior knowledge about topics in numerical analysis since I have never taken a formal course in the subject; and I probably will not have time to given my schedule. I would like to spend some time over winter break/summer break learning the material myself. Thus, the ideal text would be written for an undergraduate audience that is easily accessible for someone who may not have a professor to ask questions for clarification. Furthermore, it would be preferred if the text did not require some sort of software (e.g. MatLab, Mathematica, etc.) as I may not have access to such software.


Munkres - Topology p.143  Let $p:X\rightarrow Y$ be a quotient map.  Set $x\sim y$ iff $p(x)=p(y)$.  Let $X/\sim$ be the quotient space of $X$ with respect to $\sim$.  Let $\pi:X\rightarrow X/\sim$ be the projection map.  Then, there exists a bijective quotient map $\phi:X/\sim\rightarrow Y$ such that $\phi\circ \pi = p$.  Why is this $\phi$ a homeomorphism?


I don't know anything from fotos techniques.I hope to help me.I take mirror and I see that I am a handsome man. I attract many woman's.I can't with easy way managed to have a good foto.In the most of the fotos I am ungly. I can't understand why this happens. I don't use software's on my devices not after when i have the image.Should I?What's your opinion to achieve a nice foto of my face with those devices?It's my first visit on this forum I was health and many other in case this question is off close it but i would like to give me a nice answer because you are experts.Thanks in advance


What is the purpose/benefit of putting "./" at the begining of a path?

Is there ever a benefit to preceding a path with ./ (dot slash)?   In most cases, cd ./home is equivalent to cd home (and also cd ./././././home).   Is there ever a case where these two paths would NOT evaluate to the same path? Is there some benefit or drawback to either having or NOT having ./ at the beginning of a folder or file path?  What if from inside a program or script, I wanted open a config file, i'm hard coding a file to open, should it be:  resource/config.txt  OR  ./resource/config.txt  Does POSIX (or common Unix implementations) give any semantic difference between opening these two paths?


Static Class - Node Class inside the HashMap source code?

I was looking at source code of JDK8's HashMap Implementation. I noticed Hashmap is uses a array of Nodes.   transient Node<K,V>[] table;   There is a Node Class defined inside the HashMap Class.  Node Class is declared as a static class. Below is the code for Node Class   static class Node<K,V> implements Map.Entry<K,V> {         final int hash;         final K key;         V value;         Node<K,V> next;          Node(int hash, K key, V value, Node<K,V> next) {             this.hash = hash;             this.key = key;             this.value = value;             this.next = next;         }          /*         Some other methods         .         .         .         .         .         */       }   I would like to know if the class has static keyword, how are we able to create object of this static class ?  What is the significance of creating a static class if we are creating objects for this class.( Static is something that is not associated with instances )  Why has this class been created as Static Nested Class as compared to inner class(non-static nested class) if we wanted to create objects of this class.


I am a newbie in stats, and while reading:   I don't seem to understand why is an imbalanced dataset wrong? And why should we rebalance…  I imagine this example: let’s say on a classification problem, for a very rare disease, where we have 1M rows for ‘no’ and only one row for ‘yes’.  My way of thinking is that, the dataset is unbalanced for a reason, (it’s a rare disease!) then wouldn’t balancing it remove that knowledge we have about it being rare?? I feel like by balancing we are discarding a very important piece of information…  (also I thought this was a vital piece of the bayesian world, 'the prior', aren't we removing the prior when we balance?)


$\ker \phi = (x_1-a_1, ..., x_n-a_n)$ for a ring homomorphism $\phi: R[x_1, ..., x_n] \to R$

Let $R$ be a commutative ring, $a_1, ..., a_n$ its elements and  $\phi: R[x_1, ..., x_n] \to R$  defined by  $ \phi(f(x_1, ..., x_n)) = f(a_1, ... ,a_n)$  a ring homomorphism.  Prove: $\ker \phi = (x_1-a_1, ..., x_n-a_n)$  It is obvious that $(x_1 - a_1, ..., x_n -a_n) \subseteq \ker \phi$. I'm not sure how to prove the converse.  At this point I don't know any division algorithms for multivariable polynomials, only for the ones in $R[x]$(and the book from where I taken the exercise doesn't assume the reader to know something beyond basics of rings and ideals, and the division algorithm for $R[x]$). Though I know this could be solved for $i = 1$ by dividing by $x-a$:   Let $f(x) \in \ker \phi$, divide by $x-a: f(x) = q(x)(x-a) + r, f(a) = r = 0$, so $f(x) = q(x)(x-a) \in (x-a)$.


Bash: search for keywords PDF files and return pages

Hopefully somebody can help me out with this,  I'm looking for a small script which does a keyword search in a PDF file (actually a folder of PDF files), and it needs to return all pages including the name of the file, where the keyword is found.  I have found the following script (over here ):  #!/bin/bash  [ "$*" ] || { echo "You forgot a search string!" ; exit 1 ; }  found=1  for file in ./src/*.pdf ; do    [ "$file" = '*.pdf' ] && echo "No PDF files found!" && exit 1    pages=$(pdfinfo "$file" | awk '/Pages:/ { print $NF }')    for ((i=1 ; i<=$pages ; i++)) ; do       match=$(pdftotext -q -f $i -l $i "$file" - | grep -m 1 "$*")       [ "$match" ] && echo "Page $i in $file" && found=0    done done  [ "$found" -ne 0 ] && echo "No search string matches found"   It does return most of the hits, but still, the search functionality inside Adobe Acrobat Reader and Mac Preview does return way more matches. Anyone who recognises what might be the problem?  My guess is it fails on a character before and/or after the search keyword, but that's just a guess .   If it includes the number of matches per page, it's truly perfect!


Constrain to any 2 axes during transform?

I want to be able to lock my translation/scale operations to two axes at a time, say xy, xz or yz. It currently takes two operations (one for each axis).  Example, say for a cylinder, I would like to reduce the radius. I currently have to scale on the x axis first, then on the y axis, or I have to manually input the scale values in the object properties panel.  This option is easily accessible in 3dsmax via the axis constraints command bar. Or I can click the intersecting area between the 3d manipulator of the axes in question and move in that plane.


Exporting sharepoint list items to excel by csom c#

I am getting items from a list using caml query. After that I need to export to excel by csom (c#). I dont want to use pnp .


Difference between ARM A and M series processors?

When I'm asking this, I think on microcontrollers, whats the difference between A and M series of ARM processors. Many microcontrollers such as Beagle Bone now have A type of Cortex?


I'm very new to Blender and I made a guy made out of blocks for a Game I'm working on in Unity. I made the armature and made it Parent with automated weights, now my Problem: When I for example move my right arm, it deforms the right side of my torso like it's glued to the arm, I dont know what to do please help.


Best way to test if a generic type is a string? (C#)

I have a generic class that should allow any type, primitive or otherwise. The only problem with this is using default(T). When you call default on a value type or a string, it initializes it to a reasonable value (such as empty string). When you call default(T) on an object, it returns null. For various reasons we need to ensure that if it is not a primitive type, then we will have a default instance of the type, not null. Here is attempt 1:  T createDefault() {     if(typeof(T).IsValueType)     {         return default(T);     }     else     {         return Activator.CreateInstance<T>();     } }   Problem - string is not a value type, but it does not have a parameterless constructor. So, the current solution is:  T createDefault() {     if(typeof(T).IsValueType || typeof(T).FullName == "System.String")     {         return default(T);     }     else     {         return Activator.CreateInstance<T>();     } }   But this feels like a kludge. Is there a nicer way to handle the string case?


Installing ubuntu on a separate hard drive

so my laptop has two hard drives, the first one already has windows 10 installed, i want to install ubuntu on the second one, my question is, will that cause any problems after installing ubuntu ? can i boot into windows 10 normally without any issues ?


How to find out if an item is present in a std::vector?

All I want to do is to check whether an element exists in the vector or not, so I can deal with each case.  if ( item_present )    do_this(); else    do_that();