I have seen that many questions are now marked [on hold]. I have already enough reputation to cast close votes on questions but I don't see how can I put questions on hold. How can I do it? Is it done within casting close votes, or is it a separate mechanism? If it is a separate mechanism, how much reputation do I need for it?


I have a problem. I want to write an IP into a file with sed  newsource=1.2.3.4/24 sed -i 's/.*#source*/&\n'"$newsource"'/' file   $newsource is an IP, which CAN contain a net-mask /24 or not. Right now the sed writes the full IP but not the /24. How can I change that?


I have written a program that is supposed to go through each character in a string and prints it out. However, something isn't working... #!/bin/bash  function name {   read -p "Enter your name: " username   for i in {0.."$(( ${#username} -1 ))"}; do     echo "${username:0:i}"   done }  name  However whenever I run it I get the error: line 7: username: {0..2}: syntax error: operand expected (error token is "{0..2}")  (By the way the input was Bob but it doesn't work with other cases either) Is there a way to fix the code? Is there a more efficient way to do this? (I intend to use the "${username:0:i}" part later, so just printing the characters to the terminal is not what I'm looking for!) Cheers!


recognizing custom packages in latexmkrc

I have a file, jtc.sty, that houses all the repetitive stuff that normally goes into a latex document (usepackage statments, turning paragraph indent off, and some formatting stuff) that I include in pretty much all of my tex files. However, I find it annoying to manually copy over that file every time I want to use it. Is there some way to configure latexmkrc so that it knows where to find jtc.sty whenever I use it?


If the value of the US dollar is greater than what I originally exchanged it for, is it considered capital gain? If so, how do I determine the amount I gained?  EDIT:  For example, I traded $100 USD for Mexican pesos. I spent some of that money (logically I now have less than $100 USD). But for some reason, the value of the peso skyrocketed so when I go to trade my remaining pesos for USD, I get back $1000.


This was a series; I seem to remember reading it no later than the early/mid ’90s.  An important plot point was a set of non humans—blue, I think—that operated in a group mind to understand the ecology of a world. They could decide whether it was safe to colonize the world, and could assist a colony to set up on such a world to know exactly what was safe to eat, to do, where were good places to locate the colony, and so on. There was a fair amount of mysticism attached to it, and somehow a human woman became part of one of these group minds.  The bluemanoids weren’t inherently a group mind; normally, they were as much individuals as humans - but some of them had the talent to join into these ecology-aware group minds. When they were joined, only one of them could interact with other people, as the “voice” of the group mind.


Can you please explain the statement in the David Morin's Classical Mechanics?

For example, in a hanging massless rope, or in a massless rope hanging   over a frictionless pulley, the tension must be the same at all  points, because otherwise there would be a net force on at least one tiny piece, and then $F = ma$ would yield an infinite acceleration for    this tiny piece.   What happen if the tension is different at some point?How it yields an infinite acceleration?


I have always wondered how illustrations like above are drawn. What is the usual and efficient way? Do designers do sketches first and then trace over them or there is a technique?  It looks specially crafted to look hand drawn, but still is clear in its function. This style is most used in videos describing some new website etc.  I would like to produce this either using Photoshop or Illustrator and I can use a graphic tablet.


Are toasts not generated in standalone app or in VF page?

I am dynamically creating a toast as shown below. This toast is created when response is received from server. I have created a component for toast and am dynamically creating it using $A.createComponent. The toast is getting fired when I am testing it in SF1 simulator or when I  have added my component in app builder. However, it is not getting thrown on screen, thought it is generated as seen in console.log, in case when I test it using standalone app (adding parent component to .app file and then preview) OR when i render my component using ltng:out in a VF page. What may be the reason for this?     controller from where dynamically toast is created:   . . . if (component.isValid() && state === "SUCCESS") {             console.log("Values updated successfully!");             //$A.get('e.force:refreshView').fire(); //this is also not working             this.createToastComponent(component, 'success', 'Success!', 'Record Saved successfully!');      createToastComponent : function(component, type, title, message){      $A.createComponent(         "c:ToastComponent",         {             "type" : type,             "title" : title,             "message": message         },         function(newToast, status, errorMessage){             if(errorMessage === null){                 //do nothing             }             else{                 console.log('Toast errorMessage: '+ errorMessage);             }         }     ); },      toastComponent UPDATED:   <aura:component > <aura:attribute name="type" type="String" /> <aura:attribute name="title" type="String" /> <aura:attribute name="message" type="String" />

             Success             <button class="slds-button slds-notify__close slds-button--icon-inverse" title="Close">                 <c:SVGIcon svgPath="/resource/SLDS214/assets/icons/action-sprite/svg/symbols.svg#close"                            class="slds-button__icon slds-button__icon--large" assistiveText="Close"/>                 Close             </button>

{!v.message}

        toast component controller:   ({ handleInit : function(component, event, helper) {      var toastEvent = $A.get("e.force:showToast");     console.log('toastEvent: '+ toastEvent+ 'title: '+ component.get("v.title")+ 'message: '+ component.get("v.message"));     toastEvent.setParams({         "title": component.get("v.title"),         "message":  component.get("v.message"),         "type": component.get("v.type")     });     toastEvent.fire(); }   })     Output in console.log:   toastEvent: SecureAuraEvent: [object Object]{ key: {"namespace":"c"} }title: SUCCESS!message: Record created Successfully


See the above excerpt from John Lee's Introduction to Smooth Manifolds. In differential topology and linear algebra, there's an operator called the interior product or contraction operator, denoted $\iota_X(\omega)$ or alternatively with some other "half box" like operator $X_|\omega$. Does anyone know how to markup that operator in LaTeX?   Google has turned up nothing except for this thread:   That thread did receive an accepted answer, which was \invneg from the MnSymbol package, but the suggestion given there does not seem correct to me. Or at least, it does not match what I'm familiar with. That answer results in an inverted negation symbol, whereas the contraction operator should have a stroke down at the floor of the line, and a long stroke going up almost the full height of the line. It can be found in many texts, but why can I not find the correct LaTeX markup?


Summation of series $\sum_{n=1}^\infty \frac{n^a}{b^n}$?

How can we evaluate this series  $$\sum_{n=1}^\infty \frac{n^a}{b^n}?$$  Here $a$ and $b$ are positive integers. If $b=1$ then series will be diverging, in other cases, it will be converging, but how to find this sum?  Isn't there a simple solution which doesn't involve Stirling numbers?


In the past a lot of people have argued to get rid of review badges all together. For example  and . To an extent these questions are a bit old, and are based on different mechanics of the review system. But still, there are people that feel we shouldn't have badges for reviews. Reviewing is important There are a lot of posts, especially on bigger sites that hardly get any attention, and the only viable option of the subpar ones getting closed is the Close Vote review queue. On SO it will never be empty, so essentially we need more reviewers, especially ones as dedicated as . Now ofcourse there is a problem with people doing poor reviews, which was discussed a lot over the past few months, and features to remediate (at least part) of the issue . Badges Currently there are 3 review badges to be earned per queue:  Custodian (bronze) - Complete at least one review task. This badge is awarded once per review type Reviewer (silver) - Complete at least 250 review tasks... Steward (gold) - Complete at least 1000 review tasks...  So after doing 1000 reviews in a queue the incentive to do more reviews ends. While we could really use more good reviewers. Hence I propose we add badges that award more reviews, with incremental bigger gaps between them in terms of requirements. For example 2500, 5000, 10000 etc. As the current steward badge is already a gold badge these new badges would, of course, also be gold. Unless we are willing to implement something like platinum (which I don't see as very useful). Alternatively we could make the steward badge be awarded for every 1000 reviews completed per review type.


ffmpeg performance with multiple core cpu and windows

I call ffmpeg command to generate mp4 using input of mp3 and folder of images   my problem is running 3 instance of ffmpeg cause 8 GB 6 core to be full with 100% cpu this is the command I use , any idea or anything wron with the command i use   ffmpeg.exe -r 25 -start_number 1 -i D:\%d.Jpeg -i D:\yyyyy.m4a -c:v libx264 -r 30 -pix_fmt yuv420p D:\xxxx.mp4"


Calculating total score for a scale including polytomous and dichotomous items

I have a variable that is measured using a 13-item, 4-point Likert scale with the exception of one item (yes $=1$, no $=2)$.  How can I calculate the total score for this variable?


Why an euclidean map defined onto a domain $R$, so a map $\delta\colon R\smallsetminus\{0\}\to\mathbb{N}$, satisfies $\delta(a)\leq\delta(ab)$ for every $a,b\in R\smallsetminus\{0\}$?  In some books, this property does not belongs to the definition of euclidean domain, and now I have to prove it.


Why Should AbstractSet.removeAll Throw NullPointerException When Passed null?

The OpenJDK implementation of AbstractSet throws a NullPointerException when you pass a null value to removeAll.        public boolean removeAll(Collection<?> c) {     Objects.requireNonNull(c);   e.g.      Set<String> parent = new HashSet<String>();     Set<String> children = null;     parent.removeAll(children);   Results in  Exception in thread "main" java.lang.NullPointerException     at java.util.AbstractSet.removeAll(AbstractSet.java:152)   What is the architectural logic behind this?  Why wouldn't it do a null check and return modified = false instead of throwing a NullPointerException?  What is the benefit in this case between differentiating between null and an empty set?  EDIT:   I know the interface specifies it. You can ask the same question about the interface. The point of the question is that removing nothing from something leaves you with the original. There doesn't seem to be a logical reason for throwing a NullPointerException.  For those that say any null should be fixed, that isn't a logical reason for throwing a NullPointerException in this case.  It isn't a duplicate question of   because I am asking about the architectural design of a specific method and not asking what a NPE is.


jquery sortable cancels events defined on table cells

I have a table that looks like this:

     	     Key	     Value

     	     key1	     value1

     	     key2	     value2

     	     key3	     value3

  I have several event functions attached to the tds in table: $("#tb td[id^='upd_td_']").focus(function(e) {...}); $("#tb td[id^='upd_td_']").blur(function(e) {...}); $("#tb td[id^='upd_td_']").keydown(function(e) {...});  Now my definition of sortable looks like this: $("#tb").sortable({     items: 'tr:not(:first)',     cursor: 'grabbing',     axis: 'y',     dropOnEmpty: false,     start: function(e,ui){         doStuff();     },     stop: function (e, ui){         doOtherStuff();     } });  Now all I want is to make only the first td of every row but the first one grabbable to move the trs up/down. The problem is that none of the event functions get executed (focus, blur, keydown) it obviously "sortable" that cancels them out. Nothing happens when I click on the cell no 2 and 3 in row 2, 3 and 4. If I remove the sortable part , it works normally. What am I doing wrong here and how can it be fixed? Cheers


How to view files, created by Linux and programs in /tmp directory? The file names are hidden, command ls -al /tmp only show the presence of files not their names.  Edit: I find that place in saved session logs:  # ls -al /tmp drwxrwxrwt    2 0        0              40 Jan  1 00:00 . drwxr-xr-x   19 1005     1005          219 Aug  2  2017 .. # grep -r config /tmp # grep -r bin /tmp # umount /mnt # ls -l ---- drwxrwxrwt    2 0        0              40 Jan  1 00:00 tmp ---   Third line show that /tmp directory have 19 files(?), but I don't see it. Or I have missed something?


Upgrade Windows Server 2008R2 to support SNI

I have a "Windows Server 2008 R2" with the "IIS7.5" and stumble now, when it comes to the topic of SSL: IIS7 does not support SNI.   How can SNI be retrofitted or alternatively how can I install "IIS8" (which does support SNI) on WIN2008R2?  Here what I want in bullet points:   IIS7.5 SNI retrofit?   or how can I   IIS8 Install on WIN2008R2?


I am a little confused at the moment I am trying to setImageResource to some Images in an ImageView Array. I replicated the error in a simpler project so here is the code. I am sure this must be a silly mistake but I have tried a lot and could not figure out the proper execution.  I can't understand why images is a null object reference since I already initialised it in every way I could think of. I am getting this error in the line mentioned in the code.  java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setImageResource(int)' on a null object reference.  package com.example.test;  import android.media.Image; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.widget.ImageView;  public class MainActivity extends AppCompatActivity { private ImageView image1; private ImageView image2; private ImageView image3; private ImageView image; private ImageView[] images = {image1, image2, image3, image}; @Override protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);      image1 =(ImageView) findViewById(R.id.image1);     image2 = (ImageView) findViewById(R.id.image2);     image3 = (ImageView) findViewById(R.id.image3);     image = (ImageView) findViewById(R.id.image);      setImages();  }  public void setImages() {     //This is where I am getting the error     images[0].setImageResource(R.drawable.a);     images[1].setImageResource(R.drawable.b);     images[2].setImageResource(R.drawable.c);     images[3].setImageResource(R.drawable.d); }  }


How can I do a presence check in Java? i am getting an error.

i am trying to do a presence check in java on 10 JTextFields. I want it so that if all 10 of my textfield have something in them, it will do my code.   String input1 = tfQ1.getText(); String input2 = tfQ2.getText();   etc.   I have put   IF(input1==("")&&input2==("")&&input3==("")&&input4==("")&&input5==("")&&input6==("")&&input7==("")&&input8==("")&&input9==("")&&input10==("")) { //DO SCORES ETC }   However, this doesnt do anything... (my button does not work weather there are things in the text fields or not) Please and someone help with presence check validation? Thanks =)


Find a formula for: $$ \binom n0 + 2\binom n1 + 4\binom n2 + 8\binom n3 + \cdots + 2^{n-1}\binom n{n-1} + 2^n\binom nn $$ using a counting argument.  I just used the binomial t. to show it's $3^n$ but I can't find a combinatorial way. Any help?


Symbols that are usually put at the end of a paragraph

I'm looking for Latex command of the symbols that are usually put at the end of a paragraph. For example, it maybe a flower in this below image.        Could you please inform me where to find such symbols?


What are differences between "advice" and "advise"?

When we can use advice instead of advise? Can somebody help me?


I've made a very simple MOSFET LED driver that uses the PWM of an  to switch a MOSFET which controls the power for about 16 meters of LED strip.  I am using .  I am controlling RGB LEDs, so I use three MOSFETs one for each colour and when all 16 meters of LED strip is running I'm drawing about 9.5 amperes.  9.5 A/ 3 channels = 3.17 A maximum load each.   The MOSFET has a fully on resistance of 0.8 Ω, so my heat should be my I2R loss of  3.17 amperes^2 * 0.08 ohms = 0.8 watts   Datasheet says I get 62.5 °C of heat per watt, maximum operating temperature is 175 °C and expected ambient temperature is less than 50 °C  175 °C - (0.8 W * 62.5 °C/W) + 50 °C = 75 °C for margin of error   I am running these MOSFETs without a heat sink, and I have left it running all night on a program that just cycles red green blue white non stop and it didn't overheat. I am expecting this circuit to be able to run 16+ hrs per day.  I am using a 12 V powersupply for the LEDs and a 5 V control signal from the Arduino, so it shouldn't be possible for me to exceed the drain gate voltage of 60 V or the gate source voltage of 20 V.  After I was playing with it by my desk in my airconditioned office today I found that I couldn't turn the red channel off as I could earlier in the day. And measuring gate to drain with no power connected I found 400 Ω on the red channel and unmeasurably high resistance on the green and blue channels.  This is the schematic I'm working with. It's the same thing just repeated three times and the 5 V is a PWM signal from the Arduino and the single LED without a resistor is just a stand in for the LED strip which has resistors and a solid setup that I didn't feel I needed to model.    I think it failed after I plugged the Arduino in and out of its pin headers about 50 times though I'm not sure what significance that has as the Arduino still works.    So given that it worked for a few days including one day of high load, my questions:   Could hotswapping the Arduino in and out of this circuit somehow damage the MOSFETs, but not the Arduino? Could ESD somehow be the culprit here? My desk is a resin coated wood or laminated wood. It should be noted that the source of all three MOSFETs is the common GND. I don't have a fancy soldering iron, and I have no idea if it goes above 300 °C. However, I used lead solder and I spent as little time as possible on each pin and I would solder pin one of the first MOSFET and then pin one of the second MOSFET, etc, not doing all pins from one chip consecutively and if too much solder heat was the issue why wouldn't that have created the issue immediately? Why has it popped up now? Is there something I have missed or an oversight in my calculations?


\documentclass{article} \usepackage{amsmath} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \begin{document}     \begin{align}         \hat{\alpha} &= \begin{cases}                       \tan^{-1}\frac{\hat{\alpha_1}}{\hat{\alpha_2}},  \,    &\text{if }  \hat{\alpha_1}>0 \, \hat{\alpha_2}>0 \\                      \tan^{-1}\frac{\hat{\alpha_1}}{\hat{\alpha_2}}+\pi,  \,  &\text{if }  \hat{\alpha_1}<0 \\                      \tan^{-1}\frac{\hat{\alpha_1}}{\hat{\alpha_2}}+2\pi,   \, &\text{if  }\hat{\alpha_2}<0 \,  \hat{\alpha_1} >0 \\                      \text{undefined}, & \hat{\alpha_2}=0 \, \hat{\alpha_1}=0                 \end{cases}      \end{align}  \end{document}   I need to numbering of this cases but when i put align code , the file not compiling because \par .... what is wrong please help me i attempt every probability to solve this


Convert from LyX/Latex to wordpress post

I have some documents in LyX/Latex and I want them as a wordpress post. I have tried converting latex to HTML (with latex2html) and afterwards, pasting that code in the wordpress editor but everything looks ugly. Do you know a better approach?


The goal is to apply a CSS style to iterated <div>s to display that the field has been modified. I think I am close but my indexVar is returning the error "Cannot read property 'dataset' of null" in my controller. This leads me to believe I'm not handling the indexVar properly.  Component  <aura:iteration items="{!v.layoutAPIFieldsList}" var="e" indexVar="idx">     <lightning:layoutItem>         <div aura:id="editDivId" data-record = "{!idx}">             <lightning:inputField aura:id = "inputField" name = "{!e.APIName}" onchange = "{!c.changeInputField}" />          </div>     </lightning:layoutItem>   </aura:iteration>   JS Controller  changeInputField : function(component, event, helper){        var selectedItem = event.currentTarget;      var index        = selectedItem.dataset.record;     var selectedIdx  = component.get("v.layoutAPIFieldsList")[index];     $A.util.addClass(selectedIdx, 'unsavedChanges'); },   CSS  .THIS .unsavedChanges {     background-color: #f9ffb8; }


I can't understand what does "OFF of" means?

Well, I am a freelancer and not a native English speaker.  I am taking a look at job requirement what my client sent to me.  Here is what I am asking.  "We want this product built OFF of XXX platform".  Client brought XXX from a marketing site.  As seen above, OFF is being with upper-case letter that seems like my client is going to emphasize something that is most important.  I can't understand what is client's need really and exactly.


Is it possible, if a subscriber wants to enter wp-admin, that the page would be rdirectet to any page I want ?  If yes, please how :) ?


Combinatorics - find $n!$ using inclusion-exclusion

difficult question I need help with.  We are asked to show that $n! = \sum_{k=0}^n (-1)^k\binom{n}{k}(n-k)^n$  There is also a hint "try to think of the number of permutations of n elements using inclusion-exclusion"


Correctly delete posts with meta and attachments

I am having an overview of custom post types. These have custom tax and also an attachment.  In my overview I need to provide links to delete the entries. With that I also need to delete the attachment and the meta data.  I was using this:      if ( !current_user_can( 'delete_bkroadkill', $post->ID ) )         return;      $link = "ID, 'delete-post_' . $post->ID) . "'>".$link."";     echo $before . $link . $after;   I found  but there is no solution provided.  Which will not delete anything else than the post. What is the proper way to do this?


Why is the compiler showing undefined control sequence?

Why is the compiler showing undefined control sequence for the below code: Note that I have already given the preamble of \usepackage{amsmath}     A Hoheisel Algebra is a core structure with $R=\mathbb{C}\ \ S=\mathbb{R}$, $A$ a commutative algebra, $B$ finite with $\beta_{iiH0}\in\mathbb{R}_{\ge0}\forall i\in I$.   Any hints? Thanks beforehand.


$ sudo apt-get update                  Hit:1 https://dl.winehq.org/wine-builds/ubuntu xenial InRelease                 Hit:2 http://archive.ubuntu.com/ubuntu xenial InRelease                         Hit:3 http://archive.canonical.com/ubuntu xenial InRelease                      Hit:4 http://ppa.launchpad.net/plushuang-tw/uget-stable/ubuntu xenial InRelease Hit:5 http://ppa.launchpad.net/webupd8team/java/ubuntu xenial InRelease        Reading package lists... Done                        E : Failed to fetch https://dl.winehq.org/wine-builds/ubuntu/dists/xenial/InRelease       Unable to find expected entry 'main/source/Sources' in Release file    (Wrong sources.list entry or malformed file) E: Some index files failed to download. They have been ignored, or old ones used instead.


Graphics problem on debian 8.0 with Kaby Lake CPU

I'm having some problems with the graphical configuration of a fresh Debian 8 install: things like HTML Canvas, Videos, Games etc. are insanely slow.  I spent some time trying to fix things in the xorg.conf file but it hasn't changed anything atm .  Here is the Device section of my xorg.conf file:  Section "Device"     Identifier  "Intel Graphics"     Driver      "modesetting"     Option      "AccelMethod" "glamor"     BusID       "PCI:0:2:0" EndSection   I get this in glxinfo:  OpenGL vendor string: VMware, Inc. OpenGL renderer string: Gallium 0.4 on llvmpipe (LLVM 3.5, 256 bits) OpenGL version string: 3.0 Mesa 10.3.2 OpenGL shading language version string: 1.30   And the informations I find relevant in the Xorg.log file:  [     1.689] (II) Module ABI versions: [     1.689]    X.Org ANSI C Emulation: 0.4 [     1.689]    X.Org Video Driver: 18.0 [     1.689]    X.Org XInput driver : 21.0 [     1.689]    X.Org Server Extension : 8.0 [     1.689] (II) xfree86: Adding drm device (/dev/dri/card0) [     2.427] (--) PCI:*(0:0:2:0) 8086:5912:1458:d000 rev 4, Mem @ 0xee000000/16777216, 0xd0000000/268435456, I/O @ 0x0000f000/64, BIOS @ 0x????????/131072 [     2.428] (II) "glx" will be loaded. This was enabled by default and also specified in the config file. [     2.428] (II) LoadModule: "glx" [     2.430] (II) Loading /usr/lib/xorg/modules/extensions/libglx.so [     2.436] (II) Module glx: vendor="X.Org Foundation" [     2.436]    compiled for 1.16.4, module version = 1.0.0 [     2.436]    ABI class: X.Org Server Extension, version 8.0 [     2.436] (==) AIGLX enabled [     2.436] (II) LoadModule: "dri2" [     2.436] (II) Module "dri2" already built-in [     2.436] (II) LoadModule: "glamoregl" [     2.436] (II) Loading /usr/lib/xorg/modules/libglamoregl.so [     2.445] (II) Module glamoregl: vendor="X.Org Foundation" [     2.445]    compiled for 1.16.4, module version = 1.0.0 [     2.445]    ABI class: X.Org ANSI C Emulation, version 0.4 [     2.445] (II) LoadModule: "modesetting" [     2.445] (II) Loading /usr/lib/xorg/modules/drivers/modesetting_drv.so [     2.446] (II) Module modesetting: vendor="X.Org Foundation" [     2.446]    compiled for 1.16.4, module version = 0.9.0 [     2.446]    Module class: X.Org Video Driver [     2.446]    ABI class: X.Org Video Driver, version 18.0 [     2.446] (II) modesetting: Driver for Modesetting Kernel Drivers: kms ... [     3.916] (==) modesetting(0): Backing store enabled [     3.916] (==) modesetting(0): Silken mouse enabled [     3.916] (II) modesetting(0): RandR 1.2 enabled, ignore the following RandR disabled message. [     3.977] (==) modesetting(0): DPMS enabled [     3.977] (WW) modesetting(0): Option "AccelMethod" is not used [     4.077] (--) RandR disabled [     4.087] (II) SELinux: Disabled on system [     4.088] (II) AIGLX: Screen 0 is not DRI2 capable [     4.088] (EE) AIGLX: reverting to software rendering [     4.150] (II) AIGLX: Loaded and initialized swrast [     4.150] (II) GLX: Initialized DRISWRAST GL provider for screen 0   Here is my kernel version : 4.11.0-trunk-amd64 #1 SMP Debian 4.11-1~exp2 (2017-05-05) x86_64 GNU/Linux  Thanks for your help, feel free to answer more details if you want.  Edit : Updating to Debian 9 fixed the problem


Proving by induction that $1^3 + 2^3 + 3^3 + \ldots + n^3 = \left[\frac{n(n+1)}{2}\right]^2$

Need guidance on this proof by mathematical induction. I am new to this type of math and don't know how exactly to get started.   $$ 1^3  +  2^3  +  3^3  +  \ldots  +  n^3  =  \left[\frac{n(n+1)}{2}\right]^2 $$


Photons in expanding space: how is energy conserved?

If a photon (wave package) redshifts (stretches) travelling in our expanding universe, is its energy reduced?  If so, where does that energy go?


Save Leaflet drawn features with attributes to PostGIS

Goal:  In order to have a fully interactive map, I would like to be able to save some drawn features (in a second step with some attributes that may be grabbed through an input mask form or pop-up) on a Leaflet map to a PostgreSQL (PostGIS) database table.  Technical details:  I am using Lighttpd as webserver + geoserver (based on jetty) to serve my base vector layer on which I'd want to write the new features.  What I have read and tried:  Based on this code :   it is possible to "export" the features as a GeoJson string to a local file.  Related resources that I've tried but doesn't work:   And with this, I'm able to print out to the console a GeoJSON string that is ready to be written in a database field but I do not know how to technically communicate it to the database:    Related to the Geoserver documentation (the "demo" menu on the left column), it is not possible to write a GeoJson string to the connected PostgreSQL database: WFS-T only allows to write features using the GML format...  I remember (long time ago, so it is blurry in my mind) some functions with OpenLayer that could do some parsing on a GeoJson string to make it "GML ready" but I can not find any equivalent within Leaflet.     Am I stuck or is there an elegant way to store drawn vector features from a Leaflet map into a PostgreSQL database (based, or not, on Geoserver)? If not possible, which other (light) techniques would be nice to use?   The raw code example:    Edit:  The answer given in the thread on which this question was marked as duplicate (  ) is to use the Leaflet-WFST plugin: .   When I tried the first command: npm i leaflet-wfst --save   I get an error "command not found". So it doesn't work in my really simple case where I use Geoserver. What I would like to find is a small function that converts a geojson object (which I already have!) to a GML one (which is the only format available with Geoserver WFST protocol).


How to decrypt a substitution cipher using a Base64 alphabet

Let us consider a cipher that works like the following:   Plaintext is encoded to Base64. The characters in the encoded plaintext are substituted with a randomly shuffled character set (a-z, 0-9, A-Z, /, +).   The shuffled alphabet are the key. How do I decipher it to get the base64 encoded string without knowing the shuffled character set?


I'm thinking about upgrading the CPU in my MacBook Pro from its current  dual core processor to a  quad core processor.  Is there any reason why this wouldn't be a good idea? The socket, operating temperature, instruction set, wattage, and memory specifications match perfectly.  It's a summer 2012 production model, 13" unibody, FCPGA988 socket, 4GB DDR3 1600 MHz RAM (upgrading to 8GB shortly), with 10.8.3.


Proving $\text{card}(A\times A)=\text{card}(A)$ by transfinite induction?

The fact that for infinite sets $A,B$,  $\text{card}(A\times B)=\max\{\text{card}(A),\text{card}(B)\}$ depends on the axiom of choice or Zorn's lemma, so presumably, it can be proven by transfinite induction. Here is my attempt to prove this by induction.  Note that this is obviously true for $|A|=|B|=\aleph_0$. Now suppose for some cardinal $\kappa$, $\text{card}(A\times B)=\max\{\text{card}(A),\text{card}(B)\}$ is true for all $|A|,|B|<\kappa$. Let $\alpha<\kappa$ be an ordinal. Then by induction assumption, we have $|\alpha\times\alpha|=|\alpha|$. So  $$ |\alpha\times \kappa|=|\alpha\times \alpha\times \kappa|=\left|\bigcup_{\beta<\alpha} (\{\beta\}\times \alpha\times \kappa)\right|\\ \left|\alpha\times \kappa\times \bigcup_{\beta<\alpha} (\{\beta\})\right|=|\alpha\times\kappa||\alpha|. $$ But this is very far from the desired $\kappa.\kappa=\kappa$. How can I finish the proof?


How to clear the field {pages} for book entries only?

I need to clear the field {pages} for book entries only, so I can't simply use \AtEveryBibitem{\clearfield{pages}} since that would remove pages-information from articles as well. I have tried \AtDataInput[book]{\clearfield{pages}} but that doesn't seem to work. Any ideas?  I know that I could simply delete the field in my .bib file, but the database from which I pull entries often contains {pages} for books, so I would prefer a general solution to the problem.   Thank you


Transit visa from Amsterdam with Caribbean visa

I'm visiting St. Maarten from Sri Lanka. I have a Caribbean visa from the Netherland Embassy. Transit period in Amsterdam Airport is 4 hours. Do I need a transit visa to go through Amsterdam?


Which natbib file should I save in an archive

I work with a very large bibtex file when I write articles. The bib file is in version control and is collaboratively edited by a large group of scholars with similar interests. This creates a 'moving target', which means that if I go back to compile an article that was written years ago, some of its references may have been changed, so the result does not equal the original, as it would have compiled then. At the same time, creating multiple copies of this very large bib file would be very inefficient.  One solution is to simply save a pdf of the compiled document in version control (I do this currently, and will continue to do this). Additionally, I also wondered if it is not possible to just add the bbl file to version control. That way you don't need to access any bib file to compile the document as it was. Is this a valid approach? Any drawbacks? Other suggestions?


Does a unique ID and title in URL slug improve SEO?

Stack Exchange posts have URLs like this:  http://webmasters.stackexchange.com/questions/9848/squeezing-all-the-seo-out-of-a-url-as-possible   Which is the format: /questions/{id}/{slugified-post-title}  The 9848 is obviously the unique identifier of the post, which is all that is necessary to look up the question in a data source. What is the title there for then? Is it strictly for SEO reasons and maybe to make the URL more readable? Or are there other reasons as well?


Is a Wine prefix similar to a entire installation of Windows?

I cannot grasp the idea of what is a prefix: some guy in r/leagueoflinux says that is better to make a separate prefix to install League of Legends, because LoL requires "some workarounds" from time to time, I suppose that those workarounds are DirectX or something like configurations, so I do what he says. I install LoL in that different prefix, that means that if I install LoL in the default prefix, it is going to let me do it without saying that is already another copy of the game installed like it was another OS? And what if I try to install more than one thing in the different prefix? It is totally separated from the default prefix? Aside, I have seen commands to create prefixes, but not to delete them, that means that maybe the space required to make a prefix is insignificant?


Check if remoteMessage.getData().get("Pic") != null

I'm using Firebase cloud messaging and one of the parameters is optional. I have following method below  public void onMessageReceived(RemoteMessage remoteMessage) {     if (remoteMessage.getData().size() > 0) {         Log.d(TAG, "Message data payload: " + remoteMessage.getData());         String picUrl = null;          String toTel = remoteMessage.getData().get("To").toString();         if (remoteMessage.getData().get("Pic") != null)             picUrl = remoteMessage.getData().get("Pic").toString(); }   However I'm getting an exception at the if statement line  java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.String.toString()' on a null object reference   How can I successfully check to is there is a value for "Pic"?


Why didn't Harry call Kreacher to help when in the trio was captured in Malfoy Mannor

On at least two occasions Harry just yells "Kreacher!" and the house-elf has to appear.  This happened once at Privet Drive, at the start of Half-Blood Prince, and once again at Hogwarts.  Why didn't Harry call Kreacher again when they were in trouble? After the Ministry break-in they decided to avoid contacting Kreacher, just because they were not sure how he would react. Still, at Malfoy Manor, they were already in deep trouble, so no more harm would have been caused if Harry had tried to summon Kreacher to help.


If the universe has a fixed amount of mass, does it mean it has a fixed amount of energy or not? Because of the whole $E=mc^2$ thing?

$E=mc^2$ states that Energy equals matter times the speed of light. So, can't we just turn all the energy into mass and it would come out to a fixed amount of matter?


So I ran a mission and rescued Bottle & Cappy. They now show up randomly, and I've seen some people's happiness rise, one in particular went from 10% to 75%.  Now one of my quest runners (basically my Avatar in the game, so I keep a close eye on him). He recently died, and on revival, his happiness has dropped to 10%. Now, since he's one of my primary quest runner, he doesn't get assigned to a room.   So will Bottle & Cappy cheer him up while he's wandering around the vault?


How can i use the '&' symbole in a GET parameter

I need to create GET parameters containing '&'s without creating new parameters for each '&'s.  For instance the following URL :  http://example.com/?action=redirect&url=http://web.com/home.aspx?action=add&ref=aaa   will give me :   action = 'redirect' url = 'url=http://web.com/home.aspx?action=add' ref = 'aaa'   But I want :  action = 'redirect' url = 'url=http://web.com/home.aspx?action=add&ref=aaa'   It's in the context of a c#.net application and i'd rather not use POST parameters.  Is it even possible ?  Thanks


Combinatorics problem on $20$ people, $12$ months, and distinguishable groups

Given $20$ people, what is the probability that, among the $12$ months   in the year, there are $4$ months containing exactly $2$ birthdays and   $4$ months containing exactly $3$ birthdays?   I am less concerned about knowing the answer than making sure I have thought about the problem correctly.   The general problem seems to be finding the distinct integer-valued vectors that satisfy $$x_1 + x_2 + ... x_{12} = 20\ \ \ \ \ \ \ \ \ x_i \ge 0, i = 1, ..., 12$$  It can be proven that there are $\binom{20+12-1}{12-1}$ such vectors. I am presuming this to be the sample space.  (Please correct me if I'm wrong)  $4\cdot 2 + 4\cdot 3 + 4 \cdot 0= 20$, so there are $3$ distinct groups of $4$ months. Therefore we have $\binom{12}{4\ 4\ 4}$ possible ways to get the desired distribution of months.   The probability I get is $$\frac{\binom{12}{4\ 4\ 4}}{\binom{20+12-1}{12-1}} $$. The answer in the back of the textbook is $1.0604 \times 10^{-3}$ so my answer is off. I just want to know where I went wrong.


Center figure that is wider than \textwidth

I have a figure that is wider than the \textwidth of my document. (I don't want to change the \textwidth.) As a result, the leftmost part of the figure is flush with the left margin, while the rightmost part spills into the right margin too much. I'd like to center the figure, so that it will exceed the \textwidth equally on both sides.


Does anyone read declination reasons on Community's flags?

I have been declining some of flags created by Community, in particular "Closed without comment" when the close reason was a custom one (which is comment enough).  Does anyone inspect such declinations or should we report undesired behaviour here on meta.SE?  Note  which requests to not ask for decline reason on Community flags.  asks to not flag for missing comments when there already is one.


I was searching for a precise way to multiply two floating point numbers in Java, and I read that I should use BigDecimal, however it doesn't work as expected. What am I doing wrong?  My code:     BigDecimal a = new BigDecimal(3.53); BigDecimal b = new BigDecimal(3.59); BigDecimal c = a.multiply(b);  System.out.println(c);   Result:  12.672699999999998796873512674210388041622697702955394242845497954075284496866515837609767913818359375   Expected result:  12.6727


I have a very simple doubt regarding this Interfaces in sales force, Actually what it says is "This class will have a method but the body will be empty. And body for this method will be provided in another class" My doubt is if we are writing a class and method again what is the use of empty method in interface class ?   See this is one interface class  public interface PurchaseOrder {      Double discount(); }   this is my class and empty method  Here i'm providing body to that empty method  public class CustomerPurchaseOrder implements PurchaseOrder {     public Double discount() {         return .05;  // Flat 5% discount     } }   this is my another class where i'm defining class name and same method name and i'm providing body.....how is it different from normal class and method ?


Why is deadpools cancer not healed like it was supppose to be?

The question I am looking for is, why didn't his healing factor kill the cancer cells. Isn't it strong enough to kill them. Why did his cancer cells stay?


Sum of all the positive integers problem

The staff of  has shown that the sum of all the integers from $0$ to $\infty$ is $-\frac1{12}$. Recently I was looking for the sum of all the (positive) integers from $0$ to $n$ and I found that: $$\sum_{i=0}^n i=\frac{n(n+1)}{2}$$  So I decided to take the limit: $$\lim_{n\to \infty}\frac{n(n+1)}{2}$$ but that tends towards $\infty$ when I expected that to be $-\frac1{12}$! Where did I got wrong? (the result is also confirmed by Wolfram Alpha)


Tensors in neural network literature: what's the simplest definition out there?

In the neural network literature, often we encounter the word "tensor".  Is it different from a vector? And from a matrix? Have you got any specific example that clarifies its definition?  I'm a bit confused about its definition. Wikipedia doesn't help and sometimes I have the impression that its definition depends on the specific machine learning environment used (TensorFlow, Caffee, Theano).


How can I remove a specific user from the Ubuntu login screen?

I am using Ubuntu 14.04LTS. When I login, there is an extra user called 'Oracle' present. How can I hide this?


Prove that the function f(x) = ax +b is uniformly continuous in R

Clearly, this problem requires applying epsilon, delta definition of uniform continuity. im having trouble finding values that will work here and hence, writing the proof in general.


How does the correlation coefficient differ from regression slope?

I would have expected the correlation coefficient to be the same as a regression slope (beta), however having just compared the two, they are different. How do they differ - what different information do they give?


I know the , but that definition is at face value useless.  I want to know how to adjust my beliefs given the evidence presented.  Does p-value relate to any of the terms in Bayesian inference?   $P(H|E) = \frac{P(E|H)P(H)}{P(E)}$  I had previously thought that p-value could corresponded to the P(E|H) term, but not sure if that's true.  EDIT:  H is hypothesis, E is evidence


Is there a hook that runs after a user logs in?

I am writing a plugin that fetches some extended user info from a remote service and I need it to execute its function each time a user logs in.  Is there a hook that gets fired after login that I can add an action to?


I am using texlive 2013, and just ran the following command to update the packages.  sudo ./tlmgr update  -all   After it finished, I tried to compile tex documents that uses tikz package as the following MWE shows:   \documentclass{article}  \usepackage{tikz}  \begin{document}       aaaa  \end{document}   Then pdflatex complains; it said:   (/usr/local/texlive/2013/texmf-dist/tex/latex/pgf/utilities/pgfrcs.sty  (/usr/local/texlive/2013/texmf-dist/tex/generic/pgf/utilities/pgfutil-common.tex  ! I can't find file `pgfutil-common-lists.tex'.  l.556 \input pgfutil-common-lists.tex   The problem is that, pgfutil-common-lists.tex is indeed in the directory:   /usr/local/texlive/2013/texmf-dist/tex/generic/pgf/utilities/   Why is that? pdflatex should be able to find it, right? I even download the  again, and replace the pgf directory in   /usr/local/texlive/2013/texmf-dist/tex/generic/   Nothing changed at all........... Any idea? Thank you for your critics.  %=====================================================================  Then followed the comments, I type the following command in the terminal:    sudo mktexlsr gives me command not found;  mktexlsr gives me:  mktexlsr: /usr/local/texlive/2013/../texmf-local: directory not writable.     Skipping...  mktexlsr: /usr/local/texlive/2013/texmf-config: directory not writable. Skipping...  mktexlsr: /usr/local/texlive/2013/texmf-dist: directory not writable. Skipping...  mktexlsr: /usr/local/texlive/2013/texmf-var: directory not writable. Skipping... mktexlsr: Done; Forkpsewhich pgfutil-common-lists.tex, nothing pops up.


ctr-click skim pdf world to corresponding line on vim latex editor

I am using vim latex on my mac to compile .tex files whose output pdf is shown on skim to visualize them. I would like to know if there is a way to couple the two programs in such a way that when perform a ctr click or double click on a world on the skim pdf it goes to the corresponding line on mac vim, like when you double click or ctrl click on the pdf on texmaker and send your cursor on the corresponding line on the editor page.


Show that if $b_k\uparrow \infty$ and $\Sigma_{k = 1}^\infty a_kb_k$ converges, then $b_m \Sigma_{k = m}^\infty a_k → 0$ as $m → \infty$.

Suppose that $\Sigma_{k=1}^\infty a_k$ converges. Prove that if $b_k\uparrow \infty$ and $\Sigma_{k = 1}^\infty a_kb_k$ converges, then   $b_m \Sigma_{k = m}^\infty a_k → 0$ as $m → \infty$.  Attemtp: Suppose $\Sigma_{k=1}^\infty a_k$ converges, and $\Sigma_{k = 1}^\infty a_kb_k$ also.Then we know by Abel's Formula that the sequences converge only iff its partial sums converge. If we let $\Sigma a_k = \Sigma \frac{a_kb_k}{b_k}$, then because $b_k$ is increasing we have $\frac{1}{b_k}$ is decreasing to zero. So we almost have a telescoping series.   Then let $c_k = \Sigma_{ j = k}^{\infty} a_jb_j$. Then $\Sigma_{k = n}^m a_k = \Sigma \frac{a_kb_k}{b_k}= \Sigma_{k = n}^m \frac{c_k - c_{k+1}}{b_k}$  I don't know how to continue. I am having trouble applying Abel's Formula and the subscripts are confusing. Can someone please help me? I am suppose to use Abel's Formula.  Thank you very much.  Abel's Formula: Let $a_k,b_k$ be real sequences, and for each pair of integers $n \geq m \geq 1$ set $A_{n,m} = \Sigma_{k =m}^n a_k$ $\Sigma_{k = n}^m a_kb_k = A_{n,m}b_n - \Sigma_{k = m}^{n-1} A_{k,m}(b_{k+1} -b_k)$


Tensors are mathematical objects that are needed in physics to define certain quantities. I have a couple of questions regarding them that need to be clarified:   Are matrices and second rank tensors the same thing? If the answer to 1 is yes, then can we think of a 3rd rank tensor as an ordered set of numbers in 3D lattice (just in the same way as we can think of a matrix as an ordered set of numbers in 2D lattice)?


The question count in the network profile's account tab is sometimes incorrect.  E.g.:     vs. :


I've recently taken up a position in an all Mac workshop - We have Intel based Apple machines. Can I dual boot Ubuntu on my machine, if so how?


Is there a string that's hash is equal to itself?

I was wondering if there's any string that has a hash equal to itself, so that – when using any (none specific) hash function – the hash would be equal to that string?  so that:  hash(x) = x   Note that this is not an assignment or anything. I’m just curious and couldn't find any specific answer or reference. And I’m not sure how to go and prove/disprove that to myself!


How does gravitational attraction relate to weight?

I understand that gravitational attraction is the attraction of a particle by another particle or matter, which in this case is the earth. But I don't understand why this (gravitational attraction) is related  to weight. I mean gravitational attraction is just attraction and not a force. Please explain.


Format whole disk as NTFS (without partitioning)

TL;DR: # mkntfs --label media1 --fast /dev/sdb  /dev/sdb is entire device, not just one partition. Refusing to make a filesystem here!  Why does the script "refuse to make a filesystem on the entire device"? In detail: What are the possible downsides if the whole disk is formatted as NTFS? I.e. not one single big partition taking up all the space, but the disk itself. I imagine that as a system disk (i.e. for running Windows) it would not work, because there would be no space for a boot loader. (Or would be? Does formatting the whole disk also overwrite the MBR area?) But what if the disk is used only as a data storage? (This is the part that is more relevant to me at the moment.) Would all the OS-es that support NTFS (Windows/Linux/...) still be able to correctly read and write files? Would all other devices handle it correctly? (E.g. HDD connected to a TV via USB.) Or is there any chance that this could cause irreversible damage to the disk? (This is what is preventing me from simply trying it out.) Remarks:  I know that I could force formatting the whole drive with the mkntfs -F flag, so the question is not how to do it, but whether I should or not?  Why would I want to do that in the first place, you may ask? The answer is, why waste space on the partition metadata, if I'm going to use the whole disk as data storage anyway? (But I'm interested in the system-disk POW too, just for broadening my perspective.)


Is adding comments to apparently good quality answers inappropriate?

I came across :  Sort the other range only, and then use .  I thought, that answer may be the solution, but instead of simply posting a link, the AP should elaborate a bit, adding even the smallest code example in case the linked resource ceases to exist. When I did that, I saw the Big Bad Blame Screen of Death:  STOP! Look and Listen. This was an audit, designed to see if you were paying attention. You didn't pass. Your review was inappropriate. This was a high quality post and you should have considered leaving it as-is or even upvoting.  OK, is adding a comment something so bad that I should be ashamed of trying to do that with so highly upvoted answer? Maybe it's time to fix review audits a bit? --edit-- I've  anyway!


Miscellaneous quest text present even after quest completion

I’ve completed the quest ‘Find the word of power at Archwind’ , but the text is still there in the miscellaneous. What to do?


Do I have to re-register a new Facebook account to change my facebook.com/USERNAME?  Or are there any ways to change it?


Super key not working on external keyboard

I am using an external keyboard on my laptop and the Super key doesn't work. The laptop's keyboard works just fine, every key is regularly detected.  I tried using xinput to debug this issue. Here you can see the output of xinput list, the device I am having issues with is the Cooler Master Technology Inc. MasterKeys Pro L White.  ⎡ Virtual core pointer                      id=2    [master pointer  (3)] ⎜   ↳ Virtual core XTEST pointer                id=4    [slave  pointer  (2)] ⎜   ↳ SynPS/2 Synaptics TouchPad                id=15   [slave  pointer  (2)] ⎜   ↳ Bluetooth  Mouse                          id=16   [slave  pointer  (2)] ⎣ Virtual core keyboard                     id=3    [master keyboard (2)]     ↳ Virtual core XTEST keyboard               id=5    [slave  keyboard (3)]     ↳ Power Button                              id=6    [slave  keyboard (3)]     ↳ Video Bus                                 id=7    [slave  keyboard (3)]     ↳ Video Bus                                 id=8    [slave  keyboard (3)]     ↳ Power Button                              id=9    [slave  keyboard (3)]     ↳ Sleep Button                              id=10   [slave  keyboard (3)]     ↳ Chicony USB 2.0 Camera: Chicony           id=13   [slave  keyboard (3)]     ↳ AT Translated Set 2 keyboard              id=14   [slave  keyboard (3)]     ↳ Cooler Master Technology Inc. MasterKeys Pro L White  id=11   [slave  keyboard (3)]     ↳ Cooler Master Technology Inc. MasterKeys Pro L White  id=12   [slave  keyboard (3)]   I tried running xinput test-xi2 12 to see if the events from the keyboard where issued. All keys are working except for the super keys. I tested the keyboard with my desktop PC and all keys are working fine.   I am running Ubuntu 16.04.5 with kernel version 4.13.0-45-generic, Unity as Desktop Environment and Compiz as Windows Manager.


Why did the Crown allow giving Highgarden to Bronn?

According to  about the ending of Game of Thrones, Bronn gets Highgarden:     Kingdom of the Reach - Unknown Ruler: Bronn; Highgarden is part of the six kingdoms; Bronn was given highgarden as payment of the Lannister debts.   This was of course part of the deal the Lannister boys made with Bronn so he wouldn't kill them. The remaining Lannister does not seem to have the power to give away other kingdoms.   It seems very likely that King Bran has agreed with Bronn getting Highgarden? Is this somehow explained in the series?  In particular, Bronn seems a bad choice because he does whatever monetary incentives are in play. If anyone, Bran would know that Bronn just does what whomever pays the most tells him to do    This is not a duplicate of , which asks about Tyrion's power. I am asking about why the King agreed to this, or if that's not clear from the series.


Find smallest natural numbers $x,y$ such that  $$ 49x = 125y.$$  Will this require some special modular arithmetic property or am I missing something?


How can we communicate short messages long-distance?

In our 5e game, we stole a boat. And a horse carriage. And a lot of other stuff for moving things between cities.   Our DM meant for this to be a way to skip road encounters. We decided to fund a shipping company and hire managers (Knights retainers, etc.) to turn a profit. The DM ruled that these would cover lifestyle expenses, provide us with easy smuggling, etc.   However, we want to keep tabs on the treasure we're moving back and forth.   What can we use for communicating with our managers from anywhere in the world? What about from say, across the city?  We don't need to communicate often or for long - a single round will work. All we need is for the manager to say "we need you back"


We know path connectedness implies connectedness . Is the other direction true or false? I ve been trying to prove it but cannot do it. I cannot find a counter-example either. math is hard.


In-universe, a lightsaber is basically a controlled, fixed-length plasma stream that can be used as a sword. As such, the blade wouldn't have any mass (or infinitesimal mass if you want to get technical about E=mc2).  Anyone familiar with fencing or swordplay knows that the weight of the handle and blade, and thus the overall balance of the weapon, is critically important while fighting. A sword that is too blade-heavy is unwieldy; it is difficult to start, stop, and change the path of the blade as it's swung, which is vital to outmaneuvering your opponent in a duel. Conversely, a sword with too light a blade (equivalently, too heavy a hilt) is too easy to swing around. it's hard to "feel" where the blade is, and thus to make the minute changes needed to block a blow or land one. It can also be just as exhausting, in a different way, to wield such a sword; because most of the mass is behind your hand, it takes muscle power to point the blade forward instead of upward, while a balanced weapon would point directly forward from the user's hands. You also get no mechanical advantage while swinging it.  Obviously, out-of-universe the props were full "swords" that were then rotoscoped to paint the beam blade over the white wooden (later plastic) dowel that protruded from the saber. This gives the actual prop used by the actors a more realistic weight and balance, which can be seen in the duels (Darth Maul has to heave a bit to get that double-saber staff moving, and you can see the effort behind a full baseball swing of the sword by Luke or Vader in the original trilogy).  Was there any attempt in-universe to explain the weight and balance that an active lightsaber seemed to possess?


I've been trying to answer the following question, but I don't know what topological property I should be looking at.  For each natural number $n$ we consider a space $X_n$ that is obtained by removing $n$ distinct points from $R^2$. We consider the 1-point compactification $X_n^+$ and we denote by $∞_n ∈ X_n^+$ the point at infinity (so that $X^+_n = X_n ∪ ∞_n$). Show that if $X_n$ and $X_m$ are homeomorphic, then $n = m$.  My approach so far has been to assume that $n≠m$ and then trying to find a difference in topological properties between $X_n$ and $X_m$. The most obvious one to me was showing that they are homeomorphic to a sphere with $n+1$ and $m+1$ missing points respectively and that these spheres are not homeomorphic to each other. Is this a correct approach and if it is, how would i go about proving that these punctured spheres are not homeomorphic?


Difference between a gerund acting as subject and an infinitive acting as a subject?

I am wondering whether there is any difference between a gerund acting as subject and an infinitive acting as a subject.


How does the phrase "Is something the matter?" make sense?

Is something the matter?  I've read or heard this usage of matter many times. For instance, in The pleasure of finding things out, R.P. Feynman writes:  I could tell that something was the matter.  This usage doesn't seem right to me. It's hard for me to pinpoint what exactly bothers me, but I think it has to do with the use of the definite article "the" when the existence of a problem hasn't even been confirmed/acknowledged yet. I know this usage of matter is accepted by many, but how does it make logical/grammatical sense?  Instead of:  Is something the matter?  I would much prefer  Is there a problem?  Instead of  I could tell that something was the matter.  I would prefer  I could tell that there was a problem/issue.  Note that my issue is with the choice of article, not with that of the noun.


The choice of measurement basis on one half of an entangled state affects the other half. Can this be used to communicate faster than light?

It is often stated, particularly in popular physics articles and videos, that if one measures a particle A that is entangled with some other particle B, then this measurement will immediately affect the state of the entangled partner.  For example, if Alice and Bob share an entangled pair of electrons and Alice measures her spin in the $x$ direction, then Bob's spin will also end up spinning in that direction, and similarly if she measures in the $z$ direction. Moreover, the effect will be instantaneous, regardless of the spatial distance between the two particles, which seems at odds with special relativity.  Can I use a scheme like this to communicate faster than light?


So I got my laptop with a broken monitor and defect keyboard that sometimes just doesn't want to use an external monitor. I have Debian 8 running on it (don't ask how I managed to install it) and I'm able to connect to it via SSH. Is it somehow possible to nuke everything and install Ubuntu server on it? I have physical access and could power cycle it but I won't be able to see anything on the monitor.


Salesforce query on profile not working on user language change

I have a query on profile like  profilename = [Select name from profile where id=:userinfo.getUserprofileid ].name  Now I have a check in  VF page  like  profilename  == 'System Administrator' . this works fine if the logged in user language is english. If the user language is different then profile name will be  'System admin' in that language . So how to prevent this beahviour?   Also  is there any particular field in profile which I can use  to identify the profile is system admin? so that I can have check on that field instead of checking for name which is causing the problem, for example I think modifyall filed is only checked for system admin.


How to handle apt-get update failing to fetch old packages *without* upgrading

I'm using Ubuntu 13.04. When I try sudo apt-get update --fix-missing, I get a bunch of 404/Not Found and 403/Forbidden errors and it's preventing apt-get from working most of the time.  I can paste the full output if it's helpful, but here are just a few lines that might indicate the issue:  Err http://us.archive.ubuntu.com quantal-backports/main i386 Packages   404  Not Found [IP: 91.189.91.23 80] Err http://us.archive.ubuntu.com quantal-backports/restricted i386 Packages   404  Not Found [IP: 91.189.91.23 80] Err http://us.archive.ubuntu.com quantal-backports/universe i386 Packages   404  Not Found [IP: 91.189.91.23 80] Err http://us.archive.ubuntu.com quantal-backports/multiverse i386 Packages   404  Not Found [IP: 91.189.91.23 80] W: Failed to fetch http://apt.basho.com/dists/quantal/main/binary-amd64/Packages  403  Forbidden  W: Failed to fetch http://apt.basho.com/dists/quantal/main/binary-i386/Packages  403  Forbidden  W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/quantal/main/source/Sources  404  Not Found [IP: 91.189.91.23 80]   I know that .   I don't really care about using Quantal stuff -- and in fact I'm not quite sure why these Quantal packages are here given that I'm using 13.04.  I don't want to upgrade to 14.  As a single isolated example, I'd like to install the default Java development kit:  user@device:~/ $ sudo apt-get install default-jdk   but this results in the above package errors, and more package errors if I try apt-get update --fix-missing, as noted.  How should I go about using apt-get to install the JDK without upgrading to a different version of Ubuntu?


javascript multi-line strings gives Javascript ILLEGAL Token error; How to solve this?

I have below code in php  <? php      $articleContent = "  Blah ..                         The game is on                          Foo "; ?>   Also I have below JavaScript Code Also  <script>    var articleContent = "{$articleContent}";  // from php        /* I WANT TO USE THIS  articleContent variable , but it cannot take it , it displays a ILLEGAL token error due to multi line string !*/ </script>


..."Can" is more likely when you are addressing a particular person. "Can" expresses ability, so we tend to make some sort of appraisal of whether the person being addressed actually has that ability. When addressing a general audience, some of them may be so unimaginative that they cannot imagine whatever it is. "Could" is far less assertive,...  I've seen many native speakers use this sort of "when + present participle" construction where the subject of the main clause does not match with that of the dependent clause. Isn't this a case of dangling modifier? Or unlike "after + present participle" and "before + present participle", the construction "when + present participle" is an exception?


Finding all and every continuous function $ \mathbb{R}\to\mathbb{R} $ such that $ f(x+y)=f(x)\cdot f(y) $

How to find all and every continuous function $ f $ from $ \mathbb{R} $ in $ \mathbb{R} $ that verifies $$ f(x+y)=f(x)\cdot f(y)\quad\forall x,y\in\mathbb{R} $$  All I could find is $ f(x)=f\left(\frac{1}{-x}\right) $... but I don't like that answer at all... any hints please??


apologies in advance for the basic question.  I need to identify the log of mounted/unmounted devices in Unix (including the timestamps when these actions where performed).  I noticed that using the mount command is not very helpful for this purpose, since there is no indication of the timestamps when the mount/unmount operations where performed. Can anyone indicate me a possible alternative?  Thank you in advance! :-)


I'm trying to use python to automate some admin scripts. For example:  wget --output-document=- https://www.monetdb.org/downloads/MonetDB-GPG-KEY | sudo apt-key add -   I tried:  subprocess.call   But it has an error with the '|' arg


$(P(X), C_R)$ may be a choice structure even if $R$ is not a rational relation.

Would you please give me an example to show that $(P(X), C_R)$ may be a choice structure even if $R$ is not rational (i.e., complete and transitive).  Clarification:   For any nonempty set $X$, let $P(X)$ denote the set of all nonempty subsets of X.  For any nonempty subset $B$ of $P(X)$, a function $c: B \rightarrow P(X)$ is called a choice function iff $c(A) \subset A$ for all $A \in B$. The pair $(B, c)$ is called a choice structure. For any binary relation $R$ on $X$, define the function $C_R : P(X) \rightarrow P(X) \cup \{\emptyset\}$ as follows: $$C_R (A) = \{x \in A : ( \forall y \in A ) ( xRy ) \}.$$


How can insert in the text special characters as "%" without begin a comment or insert a "becarre" (keyboard shortcut)?


How to make the label to move into middle of graph

1 How to make the whole diagram alight to my words in my page? I am using \documentclass[12pt,oneside]{book}   How to make the graph label in the center? I had change from south east to east, but not working.  legend style={cells={align=right, font=\small}},  legend pos=north,     Diagram   MWE:  \documentclass[12pt,oneside]{book}   % \documentclass[tikz,border={10pt 20pt 5pt 5pt}]{standalone}  \usepackage{pgfplots} % \pgfplotsset{compat=1.5}   % <--- \begin{document}  \begin{tikzpicture}     \pgfplotstableread{ interval  carT  carD     1    68    32     2    94   6     3    84   16     4   100    0     5   100     0     6   83      17     7   100     0     8   100     0     9   100     0     10  89      11      11  100     0     12  100     0     13  100     0     14  95      5     15  95      5     16  84      16     17  68      32     18  84      16     19  95      5        20  89      11         }\mydata    \begin{axis}[     width=0.9\linewidth,     height=.8\linewidth,     ybar=0.5mm,         % <--- distance between bars (shift bar)     bar width=2mm,    % <--- width of bars     % legend style={legend columns=-1,     %   outer sep=1mm,    % <---     %   font=\scriptsize, % <---     %   anchor=south,     %   at={(1.2,1)},     %               },    legend style={cells={align=right, font=\small}},     legend pos=north,                       nodes near coords,     nodes near coords style={font=\scriptsize, inner sep=2pt}, % <---     nodes near coords align={vertical},     ylabel={Classification Accuracy (\%)},     xlabel={Test Case},     ymin=0, ymax=100,     % <---                   xtick=data,     scale only axis,     % <---         ]     \addplot table[x=interval,y=carT]{\mydata};     \addplot table[x=interval,y=carD]{\mydata};     \legend{Correct, Incorrect}     \end{axis}      \end{tikzpicture}  \subsection{The Results} Testing123 Testing123 Testing123  \end{document}


Novel where a group of scientists in a spaceship encounter various aliens

I read this novel long back, possibly 2 decades ago. The story is narrated from one scientist's (male) POV. The team is on an exploration mission, and come across threats like:   an alien which looks like a cat an alien which is a solar system sized cloud which envelops their ship a group of aliens on a planet who can talk telepathically, but would cause the deaths of everyone on board, so the spaceship has to run away.   There are a couple more encounters.  It is not Star Trek.


Google bot trying to access /mobile/ and /m/ links

Webmaster tools show in "URL Errors" links to m/ and mobile/. My site have no active links to these URLs and they are not mentioned in sitemap.  Why google trying to access them?


Any thoughts on how one might clear the Android Marketplace search history? For instance, if I recently searched for an android app in the marketplace, the marketplace search maintains a history list of which apps/keywords that I have recently looked for.    Thanks in advance!


Why is my smoke simulation not showing up with the default renderer?

As per the picture, the fire/smoke is not showing up with the blender internal renderer. Is this a common issue?  Are there any obligatory steps to make it show like it does in the preview?  Thank you.


What does "physical" mean to philosophers?

A childish question (literally) -    My 8 year old asked me this morning: "Dad, what does 'physical' mean?" - and I found myself at loss for an ordinary language answer.   Every answer I could come up with ended up sounding like a definition of empiricism: "physical things are those things that can be observed", "physical means something that can be measured", "whatever can be verified and tested", etc....   Claiming that things that are physical are those things which are material or things that are described by physics seems circular.   Google:     phys·i·cal   ˈfizik(ə)l/   adjective   1.   relating to the body as opposed to the mind.   "a whole range of physical and mental challenges"   synonyms:   bodily, corporeal, corporal, somatic; More   2.   relating to things perceived through the senses as opposed to the mind; tangible or concrete.   "pleasant physical environments"   synonyms:   material, concrete, tangible, palpable, solid, substantial, real, actual, visible   "the physical universe"   And various dictionaries (here Merriam-Webster):      Definition of physical   1   a :  of or relating to natural science   b (1) :  of or relating to physics (2) :  characterized or produced by the forces and operations of physics   2   a :  having material existence :  perceptible especially through the senses and subject to the laws of nature   everything physical is measurable by weight, motion, and resistance — Thomas De Quincey   b :  of or relating to material things     lead to similar definitions.   How can one define "physical" in ordinary language terms? Is there a way of defining "physical" that doesn't presuppose empiricism? What is the rationalist definition of 'physical'?   Is there a definition that doesn't commit to either dualism or empiricism or to any epistemology?


Are these polynomials irreducible in $\mathbb{Q}[x]$?

$$x^3+x^2+x+1$$  $$x^5+x^3+x^2+1$$  $$x^5+x^3+x+1$$  I've tried applying Eisenstein criterion but I can't figure it out. Thanks in advance.


Can we define an inner product such that its induced norm is $\ell^{1}$-norm or others?

Let $F$ be a field. Then the Euclidean inner product on $F^n$ is defined as $\langle \mathbf{x},\mathbf{y}\rangle=x_1\overline{y_1}+\cdots+x_n\overline{y_n}$ for all $\mathbf{x}=(x_1,~x_2,~\cdots,~x_n),~\mathbf{y}=(y_1,~y_2,~\cdots,~y_n)\in F^n$. Then its induced norm, $\lVert x\rVert:=\sqrt{\langle\mathbf{x}, \mathbf{x}\rangle}$, is a $\ell^2$-norm on $F^n$. From this, I come up with a doubt that can it be possible that we define an inner product on $F^n$ such that its induced norm is $\ell^1$-norm, or $\ell^{\infty}$-norm, or even $\ell^{p}$-norm?


Android - change Date format to - dd.mm.yyyy HH:mm

I have a Date object like this:  Fri Jan 29 13:22:57 GMT+01:00 2016   And I need it to look like this:  29.01.2016 13:22  How can I do that ?


I would like to create a series of containers in the same size but with different contents, making such that the contained text reduces its font size if it would not fit the container otherwise.  Is there any way to automatically reduce font size to avoid overflowing of the container?  This question is a duplicate of .


If $\lim_{x\to c} f'(x)$ exists, does $f'(c)$ exist?

Here's a problem on differentiability at a point and continuity of the derivative function at the same point. I'm stating the problem and presenting my solution to it. I'm not entirely confident on my solution (especially about interchanging the limits). So I'd greatly appreciate if someone checks the solution and tell me if there's any gap in my arguments. Thank you.     The Problem : Let $f:(a,b) \to \mathbb{R}$ is continuous on $(a,b)$ and is differentiable except possibly at $c \in (a,b)$. Assume that $\lim_{x \to c} f'(x)$ exists. Show that $f'(c)$ exists and $f'$ is continuous at $c$.   My Approach : Given that $\lim_{x \to c}f'(x)$ exists, we can write \begin{align} \lim_{x \to c}f'(x)&=\lim_{x \to c} \lim_{h \to 0} \frac{f(x+h)-f(x)}{h}\\ &=\lim_{h \to 0} \lim_{x \to c} \frac{f(x+h)-f(x)}{h} ~~\text{[Since the double-limit exists]}\\ &=\lim_{h \to 0} \Big[\frac{1}{h} \cdot \lim_{x \to c}\big\{f(x+h)-f(x)\big\}\Big]\\ &=\lim_{h \to 0} \frac{f(c+h)-f(c)}{h} ~~\text{[Since $f$ is continuous]}\\ \end{align} Since $\lim_{x \to c}f'(x)$ exists, so does $\lim_{x \to c} \frac{f(c+h)-f(c)}{h},$ i.e. $f'(c)$. Clearly, $\lim_{x \to c}f'(x)=f'(c)$. Hence $f'$ is continuous at $c$. $~\blacksquare$  P.S. The problem is from an exercise consisting of Mean Value Theorem (MVT)-related problems. So it is highly likely that MVT should play a role here, which makes me suspect this is a comparatively simple, probably too-simple-to-be-correct solution.


What comment should I leave on link-only answers?

When downvoting a post,  explaining how the author can improve their post.  What type of comment should I leave on ? Is there a comment template we can use for these scenarios? I've considered forwarding users to "", but explaining my downvotes with a link-only comment feels a bit hypocritical.


How do you get the Apple Watch out of Power Reserve mode?

I got it into power reserve but can't figure how to resume normal mode. I have tried tapping and pressing the screen and holding both side buttons.


how to check if nvidia or intel graphics is being used

I have a laptop with nvidia graphic. How can I find if the program is running with nvidia graphics card or with the intel graphics.I searched for this query but could not find the suitable answer?


How to lock my computer after a certain amount of time from login?

I have an 8-year-old son, who likes to spend too much time playing computer games and browsing the internet. I have allowed him an hour of computer time in the morning and an hour in the evening. However, I can't be there all the time to watch if he keeps to our agreement.  What could I do to make the computer automatically close after X minutes. I don't want a solution, where you have to put a time, like 10:30AM for when the computer closes. I want to be able to start a kind of timer from when he logs on and then make it shut down or lock the computer after X minutes.  I have a Windows 7.


MySQL: Error reading communication packets

I get this warning in mysql,   [Warning] Aborted connection 21 to db: 'MyDB' user: 'MyUser' host: 'localhost' (Got an error reading communication packets)   I have been through few topics in google and according to some suggestion I increased the max_allowed_packet from 128 to 512 to 1024 still the same behaviour.   I am using Drupal 7, and yes there are lots of blob data types, but 1024 Mb of max_allowed_packet should be enough in my opinion.  Any other workaround how to overcome this warning ?  EDIT:  Added some settings as @Rolando's suggestions/answer, I still get the same warning.  My mysql config looks like this:  [client] port        = 3306 socket      = /tmp/mysql.sock default-character-set = utf8  [mysqld] port        = 3306 socket      = /tmp/mysql.sock skip-external-locking key_buffer_size = 16K  max_allowed_packet = 1024M  table_open_cache = 128  sort_buffer_size = 64K read_buffer_size = 256K read_rnd_buffer_size = 256K net_buffer_length = 2K thread_stack = 192K # Query cache disabled thread_cache_size = 8 myisam-recover = BACKUP max_connections = 100 thread_concurrency = 10 tmp_table_size = 128M max_heap_table_size = 128M log_error                = /var/log/mysql/mysql-error.log log_slow_queries        = /var/log/mysql/mysql-slow.log long_query_time = 2  log_warnings = 2  server-id   = 1 binlog-format = row replicate-same-server-id = 0 auto-increment-increment = 2 auto-increment-offset = 1 log_bin = mysql-bin log-slave-updates relay-log=mysqld-relay-bin expire_logs_days        = 10 max_binlog_size         = 100M  innodb_data_home_dir = /var/db/mysql innodb_data_file_path = ibdata1:10M:autoextend innodb_log_group_home_dir = /var/db/mysql innodb_buffer_pool_size = 8G character-set-server = utf8 #innodb_additional_mem_pool_size = 2M innodb_log_file_size = 2047M innodb_log_buffer_size = 32M innodb_flush_log_at_trx_commit = 2 innodb_thread_concurrency = 8 innodb_lock_wait_timeout = 50 innodb_flush_method = O_DIRECT  [mysqldump] quick quote-names max_allowed_packet = 16M default-character-set = utf8  [mysql] default-character-set = utf8  [myisamchk] key_buffer_size = 32M sort_buffer_size = 32M  [mysqlhotcopy] interactive-timeout  [mysqld_save] syslog   My application uses only InnoDB, but there are few database like mysql, which came with the standard mysql installations are only the ones which uses MyISAM engine type, I guess that should not be my concern though.  As you can see I have replication too, the warning is the same one in replicated server too, whose config is identical as this.


VirtualBox - RTR3InitEx failed with rc=-1912 (rc=-1912)

I have installed VirtualBox Version 5.1.18 r114002 (Qt5.5.1) on Ubuntu 16.04 LTS. To virtualize everything (Kali, Windows 10).  I encounter the following error:      RTR3InitEx failed with rc=-1912 (rc=-1912)      The VirtualBox kernel modules do not match this version of VirtualBox.   The installation of VirtualBox was apparently not successful.   Executing      '/sbin/vboxconfig'      may correct this. Make sure that you do not mix the OSE version and   the PUEL version of VirtualBox.      where: supR3HardenedMainInitRuntime what: 4   VERR_VM_DRIVER_VERSION_MISMATCH (-1912) - The installed support driver   doesn't match the version of the user.       What causes this problem?  How can this problem be solved?   When i run dpkg --list virtualbox-* in terminal, I get:   Desired=Unknown/Install/Remove/Purge/Hold    | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend       |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)    ||/ Name       Version      Architecture Description  +++-==============-============-============-=================================   rc  virtualbox-5.0 5.0.32-11293 i386         Oracle VM VirtualBox   rc  virtualbox-5.1 5.1.18-11400 i386         Oracle VM VirtualBox    un virtualbox-gue <none>       <none>       (no description available)  un virtualbox-gue <none>       <none>       (no description available)  un virtualbox-ose <none>       <none>       (no description available)


Extract raster values from point using GDAL

I want to extract raster value from point shapefile geometry. Raster size is 45924 x 61671 and shapefile has 11.000.000 points. I'm using extract function from Raster package in R but is not very fast.  I'd like avoid non-terminal methods like ArcGIS or QGIS and prefer some terminal options like gdal_xx.py mode at prompt.  As a result I need an object with 11.000.000 length in any format (CSV, txt, shp, etc).   I need repeat this procedure over several similar rasters.  Here's a nice  but I don't know how to get or manipulate the resulting object and I'm not sure about their efficiency.


Why can't I see the profile of this user?

I saw something terrible in  site that, i can't able to view the profile of a particular user who posted  answer.    Did the user got deleted?


How can I change ubuntu 16.04 LTS wallpaper to a custom image?

I know that there are some options for wallpapers on Ubuntu, but how to pick up a custom image and set as wallpaper?


Sequences of Real Numbers in a closed bounded interval

Why is it that a sequence in a closed, bounded interval [a, b] is a bounded sequence? What is the formal proof of this proposition from the definition of a bounded sequence?


How do I replace multiple spaces with a single space in C#?

How can I replace multiple spaces in a string with only one space in C#?  Example:  1 2 3  4    5   would be:  1 2 3 4 5


Showing $\{\sin(2^kx): k\in \mathbb{N}\}$ is linearly independent

How would I go about showing that the set $\{\sin(2^kx): k\in \mathbb{N}\}$ is linearly independent without using any integration. I am really stuck on this and I don't know where to begin.


I am not a native English speaker, the source of my learning is books, websites and of course movies and music. In the movie — if I remember the name correctly — The Last Samurai, I heard that they said "I bid you good morning".  Can I use it as a professional way to wish good morning or is it informal? Or did I just hear it wrong?


What is a "viewport"? What about a "workspace"?

Is a viewport different from a workspace? What's the distinction? It seems like the terms get used interchangeably.   I'm trying to accomplish something that other people have been stabbing at for a while -- I have a script that launches a bunch of programs at once and I'd like to launch them in a specific workspace. The question's been asked:      But the answers hop between talking about "viewports" and "workspaces" -- how are they different?


How can orbitals be oriented if the nucleus is symmetrical?

I know very little about quantum physics, but I just can't wrap my head around the fact that non-spherical orbitals appear to be "oriented", constituting a set of fixed "frame of reference axes".  Does it really work like that? Are there for a single atom given directions in which the orbitals "protrude"? And if so, what are they based on? If I understand it right, the nucleus is seemingly spherical - symmetrical with no unique axis of symmetry. What would then decide the orientation of the orbitals in space (with respect to the surroundings)?  Edit: I understand any orientation works to satisfy the wave equation. I was more curious why the atom would choose one direction, instead of any of the others. Is that fundamentally random? And is this setup retained further, or can it change at any time?


Area 51 Reputation not shown on "Your Communities"

The Area 51 Reputation is not shown on "Your Communities" drop down.


There is a story on  that  . I don't understand why they are doing so.  Can someone explain why it makes sense to buy CIBC bonds with negative return? Why would that be preferable to holding the amount in cash?


Ultralimit of an eventually constant generalized sequence

Suppose that $x_{i \in I}$ is a generalized sequence on a compact Hausdorff space $X$, indexed by the directed set $I$, and with the property that $\exists \, j \in I$ such that $\forall i \geqslant j$, then $x_i = k$, where $k \in X$. We then pick a non-principal ultrafilter $U$ on the index set $I$ (so $U \subset \mathcal{P}(I)$).  My claim is that we then have $\lim_{U} (x_i) = k$.  First we notice that $X$ being compact and Hausdorff, the ultralimit, $\lim_U (x_i)$, of this sequence always exists uniquely. Also, we can just assume that such an ultrafilter on $I$ exists ($I$ being an infinite index is actually sufficient and necessary for that).  I have been unable so far to prove that this claim is true and I am starting to think I am missing an assumption for it to be true.


I'm trying to make a Sankey diagram. I know it's possible with Tikz picture but I don't get the hang of it. I'm trying to make something like this:  Is there anyone who has experience with this package?


What is the most efficient way to deep clone an object in JavaScript?

What is the most efficient way to clone a JavaScript object? I've seen obj = eval(uneval(o)); being used, but . I've done things like obj = JSON.parse(JSON.stringify(o)); but question the efficiency.  I've also seen recursive copying functions with various flaws.  I'm surprised no canonical solution exists.


Handling random with unique chance in Python

Okay, let's say you have a handful of enemies, each with their own 'rarity' to spawn. For example:  monsterlist = []  snake = 'snake', 60 wolf = 'wolf', 80 antlion = 'antlion', 30  monsterlist.append(snake, wolf, antlion)   Now I want to spawn one at random:  totalchance = 0  for monster in monsterlist:     totalchance += monster[1] #add each monster's rarity to totalchance chance = random.randint(0, totalchance)  if chance <= targetlist[0][1]: #chance is <= than first entry's rarity     #spawn first monster elif chance <= targetlist[0][1] + targetlist[1][1]: #chance <= second target's rarity     #spawn second monster #etc   Assuming you have a large amount of monsters in monsterlist, this is going to take stupid amounts of code just to calculate chance to spawn, I like to assume there's a less annoying way to do this, right?


I have an apt-get install process that seems to be hopelessly wedged at the processing triggers for python-support step.  My inclination is to kill it, but in the past, simply kill-ing an apt-get install process has caused me much grief.  (IIRC assorted lock files are left behind, etc.)  Is there a safer way to stop this process?


MySQL replication of single DB to same server

I have a DB Server running CentOS 6.4 and MySQL 5.5 from RPMs (not source).  I have dozens of databases but one of them is being hit quite hard with large updates which degrade the performance of other queries.  To alleviate this I would like to replicate one of the databases onto the same server so that the writes can write to the "master" and reads can be done on the "slave". I don't have the luxury of additional hardware.  I have found a lot of guides on the internet describing how to replicate to a different server, and one () describing how to replicate to the same server but it doesn't seem to be geared towards retrofitting this functionality to an existing database with 10s of GB of data in it already.  It also talks about compiling MySQL from source.  Does anyone know how I can retrospectively convert my MySQL 5.5 config to replicate one of my databases on the same server?  My existing DB runs on port 3306 so I feel it should be as easy as firing up another instance of MySQL on port 3307 and making some changes to my.cnf but not sure what changes.  Thanks in anticipation.


The sum of odd powered complex numbers equals zero implies they cancel each other in pairs

Show that if a set of complex numbers $z_1,z_2,\ldots,z_n$ satisfy  $$z_1^l+z_2^l+\cdots+z_n^l=0$$ for every odd $l$, then for any $z_i$ we can always find some $z_j$ such that $z_i+z_j=0$.  The question has been answered  for real numbers but not for complex numbers


Java new BigDecimal generates another number

I'm using BigDecimal data type, when I set   new BigDecimal(21.30);   then, I returned it as xml source, it shows as  21.30000000000710522735760100185871124467578125   Another number   new BigDecimal(23.11)   returned  23.1099999994315658113818187512921995859375   I want to show results with the same decimals as I set on create.


I am trying to figure out what permissions would still be missing if the SPN is created manually for SQL Service account and I am seeing this error message:     The SQL Server Network Interface library could not register the Service Principal Name (SPN) for the SQL Server service. Error: 0x2098, state: 15. Failure to register an SPN may cause integrated authentication to fall back to NTLM instead of Kerberos. This is an informational message. Further action is only required if Kerberos authentication is required by authentication policies.


Pros and cons of python and R for machine learning?

Some people use python for machine learning, other people use R. What are the pros and cons of using Python compare to R for ML?


highlighting vowels using a background color

Is it possible to give the letters a,e,i,o,u,y a different background color in a piece of text by using a loop or package? For instance, give the a's a red background, the e's a blue background, etc. Without changing the background of the other letters in the text.


AWS S3 + Route53: Always redirect to www prefixed domain

I have a domain: example.com.   I've created an A record for www.example.com with an alias targeting the load balancer’s DNS; this works just fine for www.example.com.  Now, I want to redirect all requests to example.com to www.example.com (note the www. prefix).  So I created an S3 bucket named example.com with a redirection to www.example.com, and an A record for example.com with an alias targeting the S3 bucket named example.com I just created. The idea here is to make all requests to example.com go to my S3 bucket and then get redirected to www.example.com.  But when I go to example.com, the browser just keeps loading forever. No redirection seems to be happening.  All I want is to redirect requests to example.com to www.example.com. How can I make this work? Why is my browser loading forever and not giving any error message?


I'd like to have a SoX one-liner that would record 1 hour of audio to mp3. I'm on Windows 7. Is this possible?


pgfplots function x^(0.5) skipping first sample, sqrt is not

In the following example, you will see that the sample at (0,0) is not drawn using x^(0.5) (blue), with sqrt it is (green). How can you explain that?  \documentclass{standalone} \usepackage{pgfplots} \begin{document} \begin{tikzpicture}     \begin{axis}[samples at={0,0.02,...,1.5,2}]        \addplot[green,thick]{sqrt(x)};        \addplot[blue,thick]{(x)^(0.5)};     \end{axis} \end{tikzpicture} \end{document}


How to open a form from a string in C #?

// get the name of the chosen form             string myMenu = Convert.ToString(treeView1.SelectedNode.Tag);             Form frm = new Form();             frm.Name = myMenu;             frm.MdiParent = this;             frm.Show();             frm.BringToFront();  // opens a blank form and not the one in the solution.


A sequence of real numbers such that $\lim_{n\to+\infty}|x_n-x_{n+1}|=0$ but it is not Cauchy

Give an example of a sequence $(x_n)$ of real numbers, where $\displaystyle\lim_{n\to+\infty}|x_n-x_{n+1}|=0$, but $(x_n)$ is not a Cauchy sequence


I am given this equation:  $f^{-1}(B_1 \cap B_2) = f^{-1}(B_1) \cap f^{-1}(B_2)$  I want to prove it: what i did is  I take any $a \in f^{-1}(B_1 \cap B_2)$, then there is $b \in (B_1 \cap B_2)$ so that $f(a)=b$. Because of $b \in (B_1 \cap B_2)$, it is true that $b \in B_1$ and $b \in B_2$, so $a \in f^{-1}(B_1)$ and $a \in f^{-1}(B_2)$.    this means $f^{-1}(B_1 \cap B_2) \subseteq f^{-1}(B_1) \cap f^{-1}(B_2)$.   is it ok?


Is there anyway to transport completed levels on my computer over to my phone?

I am on level 1758 online on my computer and only on level 40 on my phone app.  Is there anyway to transport all the levels on my computer that are completed over to my phone?


Allow me to find companies by zip code - job listings or not

I was not aware that, when searching by zip code, the careers site . (As per the  of the answer to the above bug report, I am opening a feature request to have this changed.)  While I completely understand the reasons for this (I think Stack Exchange deserves to earn a profit), this is a bit limiting for users who want to find out what kinds of companies exist in a geographic area, whether they are actively hiring or not. It's a great networking opportunity!  I'd really like to see these companies whether or not they have job postings available. I have two proposals:   Could we add a difficult-to-find or "hidden" feature of some kind to include all companies in a zip code search? Maybe a non-prominent checkbox on an advanced search screen or a "poorly" documented search criteria (like "include:all" or "onlyjobs:false")? The incentive for paying for a job listing would still be there since users would need to go out of their way to use this feature (thus reducing "hits" on the company's profile). If the first isn't palatable (which I could understand), could you at least give companies the option to pay for placement in zip code searches, job listing or no? Companies with job listings would get priority placement (at the top of the list) and/or companies with no job listing would be grayed out with a notice ("0 job listings"). Any kind of search which includes criteria other than zip code (such as "c#") would automatically filter out companies with 0 job listings.   Example scenarios:   I'm interested in a job listing in another city, but I want to know whether or not there are other companies in the area before I pursue it seriously (you know, in case things don't work in the first couple months). I am fairly content with my current job, but I want to find out what else is going on in my hometown, maybe connect/cooperate with other developers doing similar/compatible things.     I'll add that companies which have no job postings (yet) have very little incentive to list themselves on careers if they can't be discovered. This proposal would provide some additional incentive to list themselves (which would look good in your advertising: "200,000 companies listed and growing...") and, with option 2, also provide a little extra cash to help pay for improvements to the service.


Suppose we have a material point. If it is moving from position $X_0$ with initial velocity $V_0$ and constant acceleration $A$, then from elementary physics course I remember that its movement is described by the equation  $$X(t) = X_0 + V_0t + At^2/2.$$  Now, my question is, what is the equation of the movement of the material point if its acceleration is an arbitrary function of $t$: $A(t)$. Is it simply:  $$X(t) = X_0 + V_0t + A(t)t^2/2,$$  or is it more complicated than that? From the looks of $At^2/2$ I have a suspicion that integrals may be involved.


Wrap C++ code with cython (with templates)

I'm trying to create a cython wrapper from C++ code (it just adds two numbers). I have the following code: myc.cpp: #include "myc.hpp"  template <class T> T add(T a,T b){     return a+b; }  myc.hpp: template <class T> T add(T a,T b);  myc.pxd: cdef extern from "myc.hpp":     T add[T](T a,T b)  mymodule.pyx: # distutils: libraries = myc # distutils: library_dirs = "." # distutils: language = c++ # distutils: sources = myc.cpp  from myc cimport add  cpdef double add2(double a,double b):     return add(a,b)  main.py: from mymodule import add2  a = 32.0  print(add2(a,a))  The files are all in the same folder. Now, if instead of using templates in the 'add' function definition, I use double type, the code works fine. If I change the 'from "myc.hpp":' from the myc.pxd file to 'from "myc.cpp":', the code works fine too. So, why doesn't it work when I define the function from the header file in the myc.pxd? PS: I call cythonize -i mymodule.pyx, and the following error appears at the end of the output:  mymodule.obj : error LNK2001: unresolved external symbol "double __cdecl add(double,double)" (??$add@N@@YANNN@Z) C:\Users\######\Desktop\#######\mymodule.cp37-win_amd64.pyd : fatal error LNK1120: 1 unresolved externals error: command 'C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.28.29333\bin\HostX86\x64\link.exe' failed with exit status 1120


Why 'c[&i]' compiles while 'c[i]' doesn't?

This example compiles without warnings/errors (gcc 4.8.2 -Wall):  #include <stdio.h> int main()  {      char c;     int i;         printf("%p %02x\n",&i,c[&i]);     printf("%p %02x\n",&c,c[&c]);      // important to note that this line DOESN'T compile:     //printf("%p %02x\n",&i,c[i]);     //  which makes sense as c is NOT an array, it is a char.      return 1; }   Why does the syntax c[&i] compile ? Is it intentional or an accident? Is the syntax c[&i] semantically valid ? (Does it have any useful meaning?)  Example of output for me: (pointers change each time)  0xbfb2577c b7718cea 0xbfb2577b 08   This question originated from a strange bit of code 'ch2[&i]' in question here:   NOTE#0 (updated, upon reflection) on duplicates/similar questions: This question is not a duplicate of the linked questions on c array references. It is related so it is useful to refer to them. The related questions discuss the valid a[b] and b[a] case where one of a or b is a pointer and the other is an int. This question deals with the more weird and maybe should be invalid case where one of a or b is a char. With C arrays, why is it the case that a[5] == 5[a]? 14 answers  String as an array index 3 answers   NOTE #1: This happens with compiler as the type of variable c is char and that can be used as index into array when combined with pointer.  NOTE #2: for some reason, type of c[<ptr>] evaluates to type of <ptr>.  E.g.: the resulting types of c[&pi] and c[&pc] cause warnings in the following code:  int *pi; char *pc; pi=&i; pc=&c; printf("%p %02x\n",&pi,c[&pi]); printf("%p %02x\n",&pc,c[&pc]);   Warnings on type 'int *' or 'char *' instead of 'unsigned int':  c/so_cweirdchar2.c: In function ‘main’: c/so_cweirdchar2.c:13:5: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 3 has type ‘int *’ [-Wformat=]      printf("pi %p %02x\n",&pi,c[&pi]);      ^ c/so_cweirdchar2.c:14:5: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 3 has type ‘char *’ [-Wformat=]      printf("pc %p %02x\n",&pc,c[&pc]);      ^


What is the difference between a workflow and a user flow?

I am new to UX just graduated and I was asked to do a design challenge about service accessibility.  They provided assets, personas and a use case scenario. The main problem is to find ways to the user reschedule medical appointments via a mobile app.   However, they asked me to do a workflow which is not a term that I am familiar with…just wondering if I should ping them back asking if they meant user flow?


Can I kill an indestructible creature with damage and -1/-1?

If a indestructible creature is a 3/3 and I block that creature with a 2/2 then I give the indestructible creature a -1/-1 will the indestructible creature die?


What do energy weapons in the Star Wars universe actually fire, and why are they better than projectile weapons?

In the films it's obvious that whatever the blasters and turbolasers are firing, they aren't lasers. The bolts travel way slower than the speed of light. So slow in fact that people with preternaturally high reflexes are able to block and dodge the shots.  This question  mentions a number of these quandaries but doesn't actually answer them, instead wondering if actual lasers exist in the EU.   So what are they firing? And is there any in-universe reason as to why people don't use projectile firearms as a way of taking down these annoying Jedi who seem able to deflect all their blaster bolts?  I am aware that the out of universe reason is "because it looks cool". Which is fine. Just wondering if anyone's ever tried to explain this discrepancy in canon.