I'm trying to build my first "serious" webpage. I have just started and I stuck on applying old event listeners on new div section. I would like to apply all old listeners on $(".novo").append("new div ..")  I have tried to use on() functions but it doesn't seem to work.  And also I have issues when adding new list. It adds to every present div. I want to add it only on clicked div.     <button class="novo">Novo</button>

To-Do List
     <input type="text" placeholder="Add New Todo">

 Sabah

       jS:  $("ul").on("click", "li", function(){   $(this).toggleClass("completed"); }); $("ul").on("click", "span", function(event){   $(this).parent().fadeOut(500, function(){     $(this).remove();     });   event.stopPropagation(); }); $("input[type='text']").keypress(function(key){   if(key.which === 13){   var todoText = $(this).val();   $("ul").append("
 " + todoText + "
");   } }); $("#form").click(function(){     $("input[type='text']").fadeToggle(150); }); $(".novo").on("click", function(){   $(".container").append("

To-Do List
<input type='text' placeholder='Add New Todo'>

 Sabah

"); });   Thank You!!


If I found a wrong spelled tag , what should I do ?  ? I think it's JAVASCRIPT . Can I flag to moderator for it ?


Strange color noise in diffuse direct at material edges

I am getting strange color noise in my diffuse direct passes. It shows up at the edges of the model, and at material boundaries on the model. It happens even with basic shaders (just diffuse mixed with gloss) but does not happen when diffuse and gloss are both gray, even with different values (or maybe it happens but just isn't visible.)    I have never encountered this issue before, so I am very perplexed.  Debugging so far: Does not seem to have anything to do with lights or edge settings. Happens with both normal and toon shaders. Only appears in diffuse direct, not glossy direct (or just isn't visible.) Is not visible in the combined pass, but makes problems when working with Diffuse Direct in the compositor.  My main guess is that it has something to do with a render setting in Cycles. Anyone else run into this?  Other render settings:   Happens regardless of resolution Samples: 2,000 Clamp: Happens regardless of clamp value Pattern: Happens with both Sobol and Multi-Jitter Shadows, Reflective Caustics, and Refractive Caustics are all on Filter Glossy: 1.0 Bounces: 5 max/3 min, Diffuse 4, Glossy 4, Transmission 12, Volume 0 Film: Exposure 1, Transparent, Blackman-Harris, Width 1.5 Post Processing: Compositing and Sequence on, Dither 0.00 Turning down the Width for Filter type under Film reduces but does not eliminate the problem.


I am learning a bit of .NET and handlebars, need some help figuring out how to deal with JSON date parsing in this case:  Method in my controller      public JsonResult stats()     {         IQueryable<EnrollmentDateGroup> data = from student in db.Students              group student by student.EnrollmentDate into dateGroup              select new EnrollmentDateGroup()                {                   EnrollmentDate = dateGroup.Key,                   StudentCount = dateGroup.Count()                };          return Json(data.ToList());     }   Template using handlebars             JavaScript             and my result coming from DB into data is a list of /Date(1125547200000)/  How can I parse this date to real date?


After searching for and selecting a tag I am correctly redirected to the "New questions" tab (under questions) with filter: custom tags, the tag I selected in the filter field and its description underneath. Questions are also filtered by the selected tag. If I then navigate to the "popular" tab and select "hot" (which is default) no "filter" drop down exists, and questions are not filtered by the tag I have selected, however I can still see the tag description over the question list.  Steps to reproduce:   Click on a tag from your favorites tags on the right hand screen. Click on the popular tab.     Edit: Another aspect of this issue is that although when I am redirected to the "New questions" tab after a tag selection I get the questions filtered by custom tag, if I navigate to any of the other two tabs and then back to the "new" tab I no longer see the filtered questions and instead only see the selected tag's description. What is more, I don't even see the "filter" drop down in this case.  Steps to reproduce:   Select a tag from the favorite tags or from the tags page. The user is redirected to the "new" questions tab where questions are filtered by the selected tag as expected.  Click the "need answer" tab. The questions that need answer are displayed filtered by the selected tag. Go back to the "new" tab. The selected tag description is still there, however questions are no longer filtered and the "filter" drop down is no longer visible.


On an algebra $F[x]$, defining operators $T,D$ as integration, differentiation, respectively, show that $DT = I$

I am finding difficulty in constructing a proof as requested in the following:  Let $F$ be a subfield of the complex numbers and let $T$, $D$ be the transformations on $F[x]$ defined by  $$ T \left( \sum_{i=0}^n c_i x^i \right) = \sum_{i=0}^n \frac{c_i}{1+i} x^{i+1}$$  and  $$ D \left( \sum_{i=0}^n c_i x^i \right) = \sum_{i=1}^n i c_i x^{i-1}.$$  I am asked to show that $DT = I$, where $I$ is the identity. (Please note the indices on the above sums.)  Clearly, $T$ and $D$ correspond to integration and differentiation, respectively. I felt that this proof should be straightforward, but I'm not able to get it quite right. Here is what I have:  $$ \begin{align} (DT)\left(\sum_{i=0}^n c_i x^i \right) &= D \left(\sum_{i=0}^n \frac{c_i}{1+i} x^{i+1} \right) \\ &= \sum_{i=1}^n c_i x^i \end{align} $$  This uses the definitions of the operators, as given. However, the lower index in the last sum is $i= 1$, which is one higher than the $i=0$ in the original sum that $DT$ was applied to; in loose wording, the constants are gone (i.e., we integrated and then differentiated but the constants in the original expression are now gone). The value of this lower bound makes sense because of the $c^{i-1}$ term; if $i$ can be zero, we would have $x^{-1}$, which is not defined in this contact. To me, resolving this seems impossible, based on the definition of the operator $D$ as given in the text; no matter what the train of logic is, I do not see a way for the lower bound of the final index to be zero, which seems to me to be necessary in order to conclude that $DT =I$.  I do not see how to get around this in order to complete this proof. Where is my error?    A comment on my question suggests that we can simply index the aforementioned sum from $i=0$ since $ic_ix^{i-1}$ can be taken to have value zero for $i = 0$. However, the second part of this exercise asks to show that $TD \neq I$, which does seem to rely on the indices of the sums in the given definitions. Where is the subtlety here?    This is Exercise 9 in Section 3.7 of Linear Algebra by Hoffman and Kunze.


I want to install Ubuntu and totally remove Windows 10.


How to find non-greedy regular expression matching in JetBrains PhpStorm Search and Replace

I'm using PhpStorm and I'd like to find shortest string between {{ and }} by using Regex. An example is like this:     {{$ux['friend']['profile']['firstName']}} {{$ux['friend']['profile']['familyName']}}   I tried this:  \$(.*)(\['.*'\])+   which finds like this   $ux['friend']['profile']['firstName']}} {{$ux['friend']['profile']['familyName']   but I want to make it non-greedy -- only find the string between each match of {{ and }}  like   $ux['friend']['profile']['firstName']


How to reduce many if statements in Python?

I would like to ask if I can reduce many if statements in Python. I've had a problem with many if statements in my budget tracker program. The user for example get money every Month, he have expenses every Week and recurring expenses every Month. But he want to show for example savings for a day. That's many if statements to do every if. If he want to show savings for a day and other things are Month I need divide other things by days of the current Month, then I can count the savings for a day (savings = income - expenses - recurring expenses). I think you can understand me, if not ask me.Sorry if I writed something wrong here, my English isn't perfect.  phases = ['Day','Week','two weeks','three weeks','Month','three months','half a year','Year','two years','five years'] if self.combobox_value_savings == 'Day':     if self.combobox_value_phase_income == 'Day':         if self.combobox_value_phase_recurring == 'Day':             if self.combobox_value_phase_expenses == 'Day':                 # everything the same -> nothing changes             elif self.combobox_value_phase_expenses == 'Week':                 self.expenses /= 7             elif self.combobox_value_phase_expenses == 'two weeks':                 self.expenses /= 14             elif self.combobox_value_phase_expenses == 'three weeks':                 self.expenses /= 21             # ...   Thanks in advance!


Can't use gksudo to run gedit, error copying .Xauthority

I have a battery power issue that I'm trying to resolve. One proposed solution involves adding some boot arguments and then removing the battery, but I'm running into trouble on the first step. To add a boot argument, I'm running   gksudo gedit etc/default/grub   However, I get this response:   Error copying '/home/username/.Xauthority' to /tmp/libgksu-0n0AJS': No such file or directory   New to Ubuntu and not an advanced user.


How to run a function when publish posts?

I have written a PHP function in a php page. This function is not written in function.php. I have written that function in anyname.php file which is located in root directory.  I need to call that function when user click the publish button on WordPress(Only for post submission).  Assume that function name is dothisfunction($name)  Where should I call this function?


I have a problem in beamer (warsaw) each time I create a new section and compile it a slide containing the table of contents is created before it; That slide contains the table of contents with the other sections invisible but this section is visible. How to remove the slide that appears containing the table of contents before each new frame created in beamer ?


Where does the phrase, "to stop on a dime" come from?

I grew up hearing phrases like, "X can stop on a dime," meaning that X, presumably at the controls of some kind of vehicle, can bring that vehicle to a stop in as short a distance as the diameter of a U.S.A. 10 cent piece (a dime, a very small coin little more than a centimeter in diameter). When and where does this phrase come from? As far as I can tell, other questions on this site refer to other uses of the word dime, or they mention this phrase in passing without explaining its origin.


I've seen a similar question on BSE about entering foreign languages into 3D Text, but it doesn't help. I've tried using two different fonts (both of which support Russian). I've tried enabling International Fonts in Blender's User Preferences, but it doesn't work as well. It either types English text with Greek letters or displays empty vertical rectangles.   If anyone has been able to add text in any foreign language, please let me know.  I actually found out that it can be easily done through Text Editor, which would be probably the best way for me since I would prefer to paste my text. Can anyone perhaps guide me through?


Find the minimum of the square of distance between   $a=(u,\sqrt{2-u^2})$ and $b=(v,\frac{9}{v})$   This is a preparation Question PUTNAM contest. The theme of the section is "inequality". I can not make the problem from inequality. Is anyone is able give me a hint (using inequalities)?  Actually I have $(u-v)^2+ (\sqrt{2-u^2}-\frac{9}{v})^2 \geq  (u-v+\sqrt{2-u^2}-\frac{9}{v})^2$ by Arithmetic and Geometric Means Inequalities.


What type of illustration is this with solid colors?

What's this type of illustration called?


I want to excecute the following command over a ssh connection:  tmpValue=$(cat /var/run/jboss-as/jboss-as-standalone8.pid) && top -b -U jboss -n 1 |grep $tmpValue |awk '{print $9}'    This command is working on my target machine.  Now I want to use this command from a different machine and execute it via ssh, so what I have done is this:  ssh jboss@myTargetServer tmpValue=$(cat /var/run/jboss-as/jboss-as-standalone8.pid) && top -b -U jboss -n 1 |grep $tmpValue |awk '{print $9}'    The result is    cat: /var/run/jboss-as/jboss-as-standalone8.pid: No such file or directory Usage: grep [OPTION]... PATTERN [FILE]... Try 'grep --help' for more information.   Whats wrong with my call?


I’m super new to number theory and here is a question from a textbook: Prove this : if $1\le m$ and $2\le n$ ,m and n are natural numbers then we have : $$(n-1)^2|(n^m-1) \iff (n-1)|m$$ I even appreciate a hint or guiding me through the answer.


Additional question on Entire function bounded by a polynomial is a polynomial

I was reading this . Here we are only considering $\frac{f(z)}{z^n}$ to be bounded for large $|z|$, i.e, $\exists R>0 $ such that  $\frac{f(z)}{z^n}$ is bounded for $|z|\geq R$. I was able to understand how we solved this question but I have an additional question.  What will happen if $\frac{f(z)}{z^n}$ is bounded on whole of $\mathbb{C}$?


Time Evolution of a Maximally Entangled State

My question is basically this:     Does a maximally entangled state stay maximally entangled under the time evolution?   Assume our Hilbert space is $\mathcal{H}_A \otimes \mathcal{H}_B$. At the time $t=0$, the states is $\rho_{AB}$ such that $\text{Tr}_A \rho_{AB}=\frac{1}{n_A}id_B$ and $\text{Tr}_B \rho_{AB}=\frac{1}{n_B}id_A$. Now assume at the time $t$, the density matrix is $\rho_{AB}(t)$. Is it right that $\rho_{AB}(t)$ is a maximally entangled state? (If not, under what assumptions one can guarantee this?)  TEMP: Is it right?  $\text{Tr}_A \rho_{AB}(t)=\sum_A \left<e^A_i(t),\rho_{AB}(t)e^A_i(t)\right>=\left<U(t)e^A_i(0),U(t)\rho_{AB}(0)U^{-1}(t)U(t)e^A_i(0)\right>=\left<e^A_i(0),U^{-1}(t)U(t)\rho_{AB}(0)e^A_i(0)\right>=\left<e^A_i(0),\rho_{AB}(0)e^A_i(0)\right>=\text{Tr}_A \rho_{AB}(0)=\frac{1}{n_A}id_B$  So Maximally entangled states remains maximally entangled.


I know this question has been asked in other languages including Java itself.     I just want to clarify that I know how to reverse an array but I would rather appreciate help if any for this particular solution of mine.   So please don't mark it as a duplicate.   import java.util.Scanner; class TestClass { public static void main(String args[] ) throws Exception {     /*          Code for User input     */      /* The problem was with the Swapping Code below */     for(int i=0; i<=n/2; i++)         swap(i,n-i-1,a);    /* Output Code. */      } /*Swap function*/ public static void swap(int x, int y, int[] arr){     int temp = arr[x];     arr[x] = arr[y];     arr[y] = temp; }  }   I have changed my solution according to the links provided in the comments .I am getting alright in some of the test cases but in some, the code fails.I think I have done it correctly.So any help will be appreciated.Thanks


How to support multiple domains on one Web server?

I've set up an Ubuntu 10.04 LAMP server. I am going to set up multiple domains so that they will point to this server's IP. How to configure the server so, that it will serve a specific site (placed in a specific folder) according to a domain name which was used in the request?


E:Problem executing scripts APT::Update::Post-Invoke-Success 'if /usr/bin/test -w /var/cache/app-info -a -e /usr/bin/appstreamcli; then appstreamcli refresh > /dev/null; fi', E:Sub-process returned an error code


Why would Littlefinger want this person dead?

Up until near the end of season four we're led to believe Cersei or Jaime had Jon Arryn — previous Hand of the King — murdered to cover up Cersei's offspring being the product of incest, yet in the episode First of His Name      Lysa Arryn admits to poisoning Jon (her then husband) after being prodded to do so by Petyr Baelish, aka Littlefinger.   The prodder always has a reason for doing something even if it's rarely obvious. What purpose was served by killing Jon Arryn?


Query is slow on AlwaysOn Secondary node

I have two identical servers (same hardware, cpu, memory etc) in an AlwaysOn cluster (sync commit and read-intent enabled), both servers running with SQL Server 2016 SP1 (13.0.4001.0). For some of the queries with identical query plans and statistics, the queries are taking over 10secs to run on the secondary replica where as they finish under 2 secs on the primary replica. I have verified the statistics and query plans are exactly the same and tested executing the queries with no other load on these servers. Not able to find the reason why queries are slow on secondary replica.  Query and Plan from primary replica   Query and Plan from secondary replica   However, when I give a maxdop = 8 hint in the query on the secondary server, the n it finishes in 2secs.  Also, when I switch roles upon failover, the query executes in 2 secs on the new primary server and on the secondary server it again takes around 10secs. So doesn't seem to be a hardware problem as the query executes fast on the server which ever is designated as primary on the AG cluster and it runs slow on the secondary node.


So I have this problem, where on button click it loads a file inside a div. The file contains some text and <button id="loaded_button">TRIGGER EVENT</button> at the end. I have to make a hover for that button with an alert, however I'm doing it wrong somehow. Here's a snippet of my index file with the first button:  <button class="btn" id="btn" testattribute="5">button</button>
FILE SHOULD BE LOADED HERE
   And here's my js:  let url = "files/content.html"; $("#btn").click(function() {     $("#text_container").load(url); });  $("#loaded_button").hover(function() {     alert("123"); });   When I press the "btn" button, the file loads as it should, but the hover button is not working for some reason. I guess it has to do with it being loaded after the js file is loaded, I'm not really sure how to fix that though. Could you please tell me what I'm doing wrong and how to do it? Thanks in advance!


Why do we use the base form of verbs instead of the past form in past tense questions?

In regard to this , my question is similar but that answer is not clear. I want to know why we use base form of verb, e.g. 'go' to form the past tense instead of past form such as 'went'?     Question: Did you go to a bank?  (Why we use 'go' here, rather than 'went'?)   Answer: I went to a bank.   Am I confusing verb forms with tenses? Please note that I'm not a native speaker so some clarification or reference on this would be helpful.


How do I check if a folder has contents?

I'm trying to create a Bash script that will delete everything in my .waste directory. I have a basic script I wrote but I want it to first check if the .waste directory has contents, and if so, to echo out a simple "Folder already empty!" message. I'm not too savvy about if and if else statements, and I don't know what the [ ] equation needs to check for presence.  Basic code:  #! /bin/bash echo "The files have been deleted:" cd /home/user/bin/.waste/ ls rm -rf /home/user/bin/.waste/*   (P.S. not sure if the asterisk is correct at the end, I did try the script with it and I recall it deleted everything in the bin directory as well)


The PE of Minecraft now has like a server name and IP address does that mean we can join computers and play?


Format dates coming from Restful Service in Javascript

I am making a Restful call which is returning me Json and dates are coming in a weird format which looks like following:  /Date(-62135568000000)/   What is easiest way to make it look normal like (January 10, 2016)?  I did come across some of the articles but everything was requiring me to write some regex function. I am thinking that this must be a common problem and there has to be an easy one-liner in Java-script. Any ideas?


I want to install some packages without internet connection.  Please suggest the ways to copy already installed packages on "System1" to "System2" (System2 without internet connection).


Re-checking luggage at connecting airports

I'll be leaving Morocco within the next week, and I'm wondering whether I'll need to re-check my luggage after my connecting flights. I fly from Casablanca to Frankfurt and Frankfurt to London via Lufthansa. From London I fly to Newark, this time with United Airlines. Will my luggage automatically be put onto all of my connecting flights, or will I be responsible for handling this?  I'm somewhat nervous about the Casablanca and Frankfurt airports. In Casablanca, I don't know how easy it will be to check in since I speak no French and only a little Arabic. In Frankfurt, I only have 54 minutes between my flight to London. And that's if the flight is perfectly on schedule. Will things at the Casablanca airport be fine? And is 54 minutes (potentially less) enough time to go through security and board my next flight?


How do you start derby in network server mode and still get an embedded connection?

I just want to know how I can start derby in network server mode and still be able to get an embedded connection?  Thank you.


I'm a beginner on using Ubuntu and I have messed up with partition. I installed Ubuntu over another Ubuntu while the previous Ubuntu had a lot of my important files.  How to recover them?  Disk /dev/loop0: 13 MiB, 13619200 bytes, 26600 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes  Disk /dev/loop1: 42.1 MiB, 44183552 bytes, 86296 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes  Disk /dev/loop2: 140.9 MiB, 147722240 bytes, 288520 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes  Disk /dev/loop3: 2.3 MiB, 2355200 bytes, 4600 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes  Disk /dev/loop4: 3.7 MiB, 3878912 bytes, 7576 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes  Disk /dev/loop5: 87.9 MiB, 92123136 bytes, 179928 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes  Disk /dev/loop6: 14.5 MiB, 15208448 bytes, 29704 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes  Disk /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disklabel type: dos Disk identifier: 0x7dba77fb  Device     Boot Start       End   Sectors  Size Id Type /dev/sda1  *     2048 199999487 199997440 95.4G 83 Linux


So I have a giant object that is completely uv unwrapped. I would like to make areas of the object with a specific area of texture emit light.   The problem is that this object (and it is only one object) only has one material. I would like the lava to emit light, but I cannot move it to a separate material without breaking something.  I'd like to find a method where I can select a part of the texture and tell blender that whatever has that part of the texture emits light.  Is this possible?  Thanks.


I had a bogus charge on my credit card. I called a COMCAST help line and asked for "premium" support ($50) to try to solve the problem with my internet quickly. The help center took my credit card info and charged it, then disconnected me without helping me.  I went to my bank and told them I wanted to do a charge back on the card for $50 and they refused to do it.  What is my recourse here? Should I call the card issuer (Mastercard) and tell them the bank is refusing to do a charge back?


Set "Allow management of content types?" set to "Yes" within a Content Type or List Definition

How do you set "Allow management of content types?" to "Yes" within a Content Type or List Definition?


Python float division "rounding error" on division by 100

When dividing a float by 100 in Python 2.7 I get the following "rounding behaviour":  >>> 3.7e-03/100 3.7000000000000005e-05   I would expect the following:  >>> 3.7e-03/100 3.7e-05   Note that:  >>> 3.7e-03/100 == 3.7e-05 False >>> 3.7000000000000005e-05 == 3.7e-05 False   While probably of not practical difference in most applications I find this behaviour somewhat disconcerting.  Why does this happen and how can I avoid it?  I am using Python: '2.7.5 |Anaconda 1.7.0 (32-bit)| (default, Jul  1 2013, 12:41:55) [MSC v.1500 32 bit (Intel)]'


Unable to access drive with installed ubuntu on dual boot system

I was using windows 8.1 for some days which was installed in C drive. I totally had 4 drives C, F, G, H. I installed Ubuntu as dual boot with windows 8.1. Now my only problem is that, I can't access F drive because I installed Ubuntu on that drive. My question is => am I able to get my F drive(files) back or is it lost. Is there any chance of getting that drive by uninstalling ubuntu?.    If yes, how can I uninstall Ubuntu. Or Even by using ubuntu alongside how can I get my files(F drive) back.


Can an extending component find by aura:id in its base component?

I have a base (abstract) component:  <aura:component abstract="true" extensible="true">     <aura:attribute name="instanceId" type="Object"/>     <aura:handler name="init" value="{! this }" action="{! c.onInit }"/>     {! v.body }     <lightning:workspaceAPI aura:id="workspace"/> </aura:component>   and this works fine in its controller:  onInit : function(component, event, helper) {     component.find("workspace").getEnclosingTabId().then(         function(id) {             component.set("v.instanceId", id);         }     ); }   But when a component that extends this base component calls a helper method in the base supplying it's component reference, the component.find("workspace") fails (for my components - may be an error on my part).  Is this expected behavior i.e. an extending component can only find its own contained components by aura:id and not the base component's contained components?


I made and object in blender with checker texture but when i try to import it in unreal Engine it only imports with object. The texture is not imported


An alternative approach to the close queue

Here's an alternative proposal for the stackoverflow.com close queue. Two queues.  Queue #1 shows only questions that are no more than 24 hours old. The site would use this queue to get attention onto the most important area: the front page. Make it a way to gather community attention onto incoming crud.  Queue #2: older stuff. With an important twist: if you want to have humans slog through 80k of crap, try presenting it to them in batches that they can complete. This queue will never have more than 1000 things in it. The system will only dump the next 1000 things into it when we finish dealing with the previous 1000 things.  Net result: reviewers can visit queue #1 and have real impact on the state of the first page. They can visit queue #2, and have enough positive feedback in the form of progress to motivate them to come back.


$$\frac{1}{i} = \frac{1}{\sqrt{-1}} = \frac{\sqrt{1}}{\sqrt{-1}} = \sqrt{\frac{1}{-1}} = \sqrt{-1} = i$$  I know this is wrong, but why? I often see people making simplifications such as $\frac{\sqrt{2}}{2} = \frac{1}{\sqrt{2}}$, and I would calculate such a simplification in the manner shown above, namely  $$\frac{\sqrt{2}}{2} = \frac{\sqrt{2}}{\sqrt{4}} = \sqrt{\frac{2}{4}} = \frac{1}{\sqrt{2}}$$


Let $0<a_1<a_2<\cdots<a_n$ be real numbers. Show that the equation has exactly $n$ real roots.   $\displaystyle \sum_{i=1}^n \dfrac{a_i} {a_i-x} =2015$  I multiplied out denominators and that was very long, but I don't think descarte's rule will be helpful. Please any help is appreciated.


Normally I use unicodedata to normalize other latin-ish text. However, I've come across this and not sure what to do:  s = 'Nguyễn Văn Trỗi' >>> unicodedata.normalize('NFD', s) 'Nguyễn Văn Trỗi'   Is there another module that can normalize more accents than unicodedata ? The output I want is:  Nguyen Van Troi


Can I choose NTFS when creating a USB bootable device?

In step 5 of , it says to leave all other parameters on their defaults. Could it be a problem to select NTFS rather than FAT?


Is transit Visa required at London and Dublin?

I am travelling to Canada with layovers at London and Dublin ( Mumbai - London - Dublin - Canada) with British Airways. I have an Indian passport and Canadian Student Visa. Both the layovers are below 3 hours. Will I be requiring a transit visa to catch the connecting flights from these airports? Ticket is on same booking id with same airlines.


Are the additive group of rationals and the multiplicative group of positive rationals isomorphic?

This question is a little bit different from  since I was wondering if logarithmic function could solve this or not, thank you.  Consider two groups $(\mathbb Q^+,\cdot)$ and $(\mathbb Q,+)$, does an isomorphism exist between them?  My attempt: Let $\varphi:\mathbb Q^+\rightarrow\mathbb Q$ be the isomorphic function, then the below statement must hold true for all $a,b\in\mathbb Q^+$: $$\varphi(a\cdot b)=\varphi(a)+\varphi(b)$$ So I guess maybe a logarithmic function would be fine here, since it's bijective, too.  But the problem is I can not show for a specific base like $10$ for example, $\log(\mathbb Q^+)=\mathbb Q$.


laptop only has ubuntu, how do i delete it and install windows?

i bought a asus 1015e laptop with ubuntu as it's OS by accident. i want to delete ubuntu partition and install windows. i went to gparted and i dont know which partition to delete. also asus sells this laptop with windows as well, so i think there is a partition with windows on it already. anyway to delete ubuntu and boot into windows? if not do i delete all partitions? thank   so i boot into windows setup and delete all partitions, then i cant format the HD to install windows, it says cannot install windows, the disk is of GPT partition style. please help. if i try to boot to ubuntu it says error: no such partition grub rescue


How to remove TouchWiz and revert to a vanilla Android UI?

Is it possible to remove the TouchWiz UI and have the phone behave like the vanilla Android UI?


I'm trying to write an essay, and I need to embed the structure [Not so much... as...] in it. Alas, all I heard was not so much my music as her piercing screams. I feel not so much frustrated as exhausted. Can anyone tell me if these are grammatically correct, and how exactly does this sentence structure work? Thanks


Which Cloud Region Should I select for my blog site?

I currently have my blog set up with shared hosting(godaddy). After recent growth on traffic, I feel like, its time to get serious by hosting it to a better place, I am thinking about cloud obviously.  However, in amazon/digitalocean etc, I have to select the region where I want to host the site. As part of shared hosting it was hosted in US region, I guess. But as my site's traffic mostly based on Asia, I am thinking to choose a nearby location now, say, Singapore.   Though I know, its probably make sense to do so. But at the same time, I also don't want my North american visitors suffers, rather I want to grow more visitors in this area(I myself currently reside in Canada).  Just wondering if the decision moving the server to singapore region can be very bad for north american visitors or it will be kind of OK for now? Should I stick to a US based server for any reason? For User Experience/SEO perspective?


Hi i'm looking for a payment gateway that can do recurring billing that changes month to month.  Fogbugz do this, they charge based on how many active users there were that month. All of the APIs that i've found only let you set a fixed amount and it's difficult/impossible to vary the subscription amount month to month.  Has anyone come across any services that do this?


Is it possible to install Ubuntu on my Windows 8 computer without any CD or USB drive?

Please read entire post CAREFULLY before answering.  This question will make you confused if you don't.  Information (May skip :P)   OS : Windows NT 6.2 (Windows 8 K) Equipped hard disk   Total 1TB, 1 disk C: (Simple Layout, NTFS, Boot, Pagefile, Crash dump, Main): total 488,039,776,256 bytes, used 93,473,599,488 bytes D: (Simple Layout, NTFS, Main): total 486,859,075,584 bytes, used 8,426,016,768 bytes hidden: Ask if needed  Brand(manufacturer): Samsung Electronics Processor(CPU): Intel(R) Core(TM) i5-3230M CPU @ 2.60GHz RAM: 8GB , 64-bit , OS 64-bit   Question (READ THEM ALL VERY CAREFULLY)   Is there any way to install Ubuntu on this computer without any external disk (CD, USB drive, etc) Note : This computer is 64-bit, so  did not help me. WUBI does not support UEFI, and This computer uses it. No Virtual PC programs like VirtualBox or VMWare, because it takes memory.   EDIT : I already found a USB drive in my home, so now it is installed on my computer xD


Is there a way to force Steam Cloud to sync?

Right now, I have dual boot with Windows 7 and elementary OS(Linux), but my internet connection isn't working on Windows. I used to play Portal 2 a lot on Windows, and now I want to play it on Linux too, as it does have a version for Linux. But, when I ran the game, it didn't load my saved game, but it should, since Portal 2 supports Steam cloud.     Do I have to open Portal on Windows so it can sync? Shouldn't it be stored on the cloud? How do I force it to sync? After I closed Portal on Linux, it was written "Syncing" near Portal 2 on my games library, but nothing changed.


Is this data's mean significantly different from zero?

I need to make a statement regarding whether the mean of this data is significantly different from zero. The data can not be described by a normal distribution.  The population's size is 27, mean is -0.265, and standard deviation is 0.193.  My questions would be:    How would you quantify the compatibility of the data with zero? Can I say with X % confidence that the mean is -0.265 and not 0? What is the typical way to approach this small-sized non-normal population diagnose problems?   Please provide detailed examples and references if possible.


I ran sudo apt-get update in the terminal and got this response:   E: Type 'cdrom://Ubuntu' is not known on line 1 in source list /etc/apt/sources.list  E: The list of sources could not be read.


MongoDB 3.0 - how do I check which storage engine is being used?

I have MongoDB 3.0.0 running on a Digital Ocean droplet.  How can I tell which storage engine it is using?


How can I detect which programs installed malware?

Currently I am attacked by malware.  I try to use Kaspersky Internet Security + manually delete suspicious folders.  However, Whenever I restart my computer, some suspicious folders reappear and my google chrome and firefox are attacked.  That's, I believe there are some files that Kaspersky Internet Security and my bare eyes cannot detected, which continuously install malware into my computer.  Now, I want to trace back which files installed the suspicious folders.  Please help me to do that. Thank you!


Why didn't Doctor Strange use the Time Stone to prevent Thanos from claiming other Infinity Stones?

In the MCU, the Time Stone allows the user to travel through and freeze time.  In Infinity War, why didn't Doctor Strange use it to go back to each stone's location before Thanos got them and take them? Or, at the very least, why didn't he go back before the failed attempt to steal the Gauntlet from Thanos and warn them that they would fail?


Why does my iPhone shift the screen downwards?

My iPhone sometimes shift the view down by about 1/3 of the screen in order to reveal... nothing, just the blurry background image. How can I prevent this from happening?


How do I restore /usr/bin/env after overwriting it with start-tor-browser file

I was installing Tor and wanted to access it directly from the terminal, so I was trying to copy start-tor-browser to /usr/bin. But by mistake, I have replaced the /usr/bin/env file with the start-tor-browser file. What should I do now??


Internet through wireless hotspot, intranet through wired network - can I use both at the same time?

I have been tring this for a while now, without success. I have read online this can be done, either by changing the default gateway (DG) or messing with the DG's metric  The short story is: I need to connect to my company's ERP system (port 80 for some web services and port 22 for sftp and bash) with using my notebook computer's LAN card - but I can't connect to the Internet on this network. So I have my mobile phone's 3g hotspot when I need to go online. But I want to use both at the same time without so much as opening another web browser process.  At the moment, I am using the ERP system regularly - and whenever I need to go online to check a mail or research something related to work, I need to unplug the network cable so the wifi can kick in... which is starting to become annoying especially if I am connected to the ERP system using FTP (Filezilla) or Shell (putty)  Can someone help me with the configurations?  Below are some of the details I can provide:  Wired network - office LAN - for connection to the ERP system: DHCP -    Yes IPv4      10.64.200.245 Subnet    255.255.240.0 DG        10.64.193.254 DHCP Serv 10.64.17.191 DNS       10.68.72.200           10.68.20.200 WINS      10.68.77.200           10.64.20.200   Below are the details for my WiFi internet connection - over my mobile hotspot  DHCP      Yes IPv4      192.168.43.39 <- I'm guessing this changes every time I restart the wifi subnet    255.255.255.0 DG        192.168.43.1 DHCP      192.168.43.1 DNS       192.168.43.1   Finally, here is the tracert results (btw, I'm on Windows 7, 64bit and the remote system should be on Linux) - the target ERP ip address is 10.76.142.39  Tracing route to 10.76.142.39 over a maximum of ...    1    <1 ms    <1 ms    <1 ms  10.64.193.253   2    <1 ms    <1 ms    <1 ms  10.64.4.13   3    <1 ms    <1 ms    <1 ms  10.76.23.124   4     1 ms    <1 ms    <1 ms  10.76.23.93   5     1 ms    <1 ms    <1 ms  2xx-xx-xx-9.adsl...   6     1 ms     1 ms     1 ms  2xx-xx-xx-9.adsl...   7     1 ms     1 ms     1 ms  2xx-xx-xx-10.adsl..   8     2 ms     1 ms     2 ms  10.76.135.125   9     1 ms     1 ms     1 ms  10.76.142.39   sorry, I had to mask out some details above... wasn't sure if they would have any confidentiality issues.  Any help is much appreciated.


comparable price of flash guns for canon 60 compared to 400-500w strobes

After a recent portrait photography session I paid for where I thought all the images were of poor quality I decided that I wanted to be the one taking the studio portraits and getting the emotions/expressions to come out of the subject.  I've been recently more lights (either flash or strobes) for a while now, wanting to get a blown out background look of people but full body portraits not just headshot or body.   I'm not sure of   1) should I go fkash guns like yong nuo or should I get strobes which require mains. Reason being is matt granger did a video showing that 4 X flash guns was about 400w strobe. and this is supported by another video where the person used a light meter on both and a single flash gun metered at f11 while the strobe metered at f22.  if anyone can help me on this argument I'd appreciate it.  from what I can see 1 X4-500w strobe is $500 which is almost the same as 4x95 yong nuo flash gun + triggers for each.  as an example I want to be able to achieve this image - one taken of me in a studio at studio olympia.    It was suggested to me today that 4X4002 strobes could do this in a high key setting with two at front and two at back with umbreallas. the lights would cost 2000.  oh and ive heard you can get 1000 3000 and 5000+ watt seconds strobes, not sure how much power I would need for a photo like below to completely blow away everything. but would love to be able to replicate that image.


I'd like to know the exact word in English for "place or building from which there is an unobstructed view of the surroundings and intended for observation".


For an ellipse with minor radius $b$, show that the product of distances from the foci to any tangent line is $b^2$

Consider the ellipse with equation:   $$\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1$$   How do we prove the product of distances from the foci to any tangent line is $b^2$?        $$F_1A \cdot F_2B = b^2$$


can not get element by id using jquery and d3 but working by native code

console log is below.  -> d3.select("#node1")  <- qa {_groups: Array[1], _parents: Array[1]}  -> d3.select("#node1.1")  <- Uncaught DOMException: Failed to execute 'querySelector' on 'Document': '#node1.1' is not a valid selector.(…)  -> $("#node1")  <- [sdsdg]  ->  $("#node1.1")  <- []  -> document.getElementById("node1")  <- sdsdg  -> document.getElementById("node1.1")  <- asfas  element #node1 has nothing problem. #node1.1 is working well by native javascript but jquery(3.0.0) and d3(4.1.1)  I don't know why. could I know what happened to #node1.1?  I could copy element selector by chrome developer tool. the result is      element #node1 -> #node1      element #node1.1 -> #node1\2e 1


etoolbox and tabularx -- problem with `appto`

I'm trying to print worksheets. I have already implemented an automatic numbering for subtasks. I use tabularx for my subtasks (see the MWE below).  Yesterday, I tried to define a new macro called \task that has one optional argument which is the amount of points you can obtain for this particular question. I would like these optional arguments to be gathered with etoolbox's \appto command so that I can print them with my \credits command.  So far, this seems to be ind of struggling as tabularx is working on the tables several times. Every time tabularx calculates the width of X columns the points are appended to \credits which leads to an incorrect list of points.  Is there any way I can solve this problem? I'm currently stucked with this issue.  Plus, I don't know why my \task command does work. Why is the counter subtask not affected by tabularx's several trials?  \documentclass{scrartcl}  \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc}  \usepackage{etoolbox} \usepackage{booktabs} \usepackage{ltablex} \usepackage{xifthen}  \def\credits{} \newcounter{subtask} \setcounter{subtask}{1} \renewcommand{\thesubtask}{\alph{subtask})} \newcommand{\task}[1][]{%     \ifthenelse{\isempty{#1}}{%         \thesubtask%         \stepcounter{subtask}%     }{%         \thesubtask%         \gappto\credits{(#1)}%         \stepcounter{subtask}%     }% }  \begin{document} \begin{tabularx}{\linewidth}[l]{l@{\hspace*{1ex}}X}     \task[1]    &   TEXT1\\     \task       &   TEXT2\\     \task[3]    &   TEXT3 \end{tabularx} \credits \end{document}       The solution given by David Carlisle below causes a table that is too wide. How can this be undone?  \documentclass{scrartcl}  \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc}  \usepackage[a6paper, showframe=true]{geometry}  \usepackage{etoolbox} \usepackage{booktabs} \usepackage{ltablex} \usepackage{xifthen}  \def\credits{} \newcounter{subtask} \setcounter{subtask}{1} \renewcommand{\thesubtask}{\alph{subtask})} \makeatletter \newcommand{\task}[1][]{%     \ifx\hfuzz\@tempdima% %   % tabularx trial do nothing     \else%         \ifthenelse{\isempty{#1}}{%             \thesubtask%             \stepcounter{subtask}%         }{%             \thesubtask%                 \gappto\credits{(#1 BE)\\}%             \stepcounter{subtask}%         }%     \fi } \makeatother   \begin{document}  \begin{tabularx}{\linewidth}[l]{l@{\hspace*{1ex}}X}     \task[1]    &   Some longer text that exceedes the line width.\\     \task[4]    &   TEXT2\\     \task[3]    &   TEXT3 \end{tabularx} \credits  \end{document}


The int size is 4 byte and when running this program, getting output as 16. May I know the reason why the output is 16?    #include <stdio.h>  typedef struct list {     int data;     struct list *next; } list;  int main() {     printf( "%d\n", sizeof(list) );     return 0; }


Evaluate improper integral $\int_0^\infty \frac{x\sin x}{x^2+1}dx$

How to prove that $$\int_0^\infty \frac{x\sin x}{x^2+1}dx=\frac{\pi}{2e}$$  I've tried several basic approaches like substitution and IBP but can't move forward.


How to convert a drive from the GPT format to the hybrid GPT/MBR format when using High Sierra (macOS 10.13.2)

Previous versons of OS X and macOS automatically converted pure GPT drives to hybrid GPT/MBR format when the 2nd, 3rd, and/or 4th GPT partitions were formatted "MS DOS (FAT)" by the Disk Utility application or the diskutil command. I am not sure when this changed, but this no longer happens under High Sierra (macOS 10.13.2).  My Mac needs the hybrid format in order to BIOS boot the installed Windows operating system.  What is a procedure to manually convert the drive back to the hybrid format?  Below is the output from the command diskutil list disk0.  /dev/disk0 (internal, physical):    #:                       TYPE NAME                    SIZE       IDENTIFIER    0:      GUID_partition_scheme                        *500.0 GB   disk0    1:                        EFI EFI                     209.7 MB   disk0s1    2:                 Apple_APFS Container disk1         249.5 GB   disk0s2    3:       Microsoft Basic Data BOOTCAMP                200.0 GB   disk0s3    4:       Microsoft Basic Data COMMON                  50.0 GB    disk0s4    5:                  Apple_HFS Refind                  200.0 MB   disk0s5   The BOOTCAMP volume is NTFS formatted and the COMMON volume is FAT32 formatted.     Note: The next two commands were executed after starting up from .    Below is the output from the command gpt -r show /dev/disk0.        start       size  index  contents           0          1         PMBR           1          1         Pri GPT header           2         32         Pri GPT table          34          6                   40     409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B      409640  487304680      2  GPT part - 7C3457EF-0000-11AA-AA11-00306543ECAC   487714320        496            487714816  390623232      3  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7   878338048       2048            878340096   97654784      4  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7   975994880        696            975995576     390616      5  GPT part - 48465300-0000-11AA-AA11-00306543ECAC   976386192     176315            976562507         32         Sec GPT table   976562539          1         Sec GPT header   Below is the output from the command fdisk /dev/disk0.  Disk: /dev/disk0    geometry: 60788/255/63 [976562540 sectors] Signature: 0xAA55          Starting       Ending  #: id  cyl  hd sec -  cyl  hd sec [     start -       size] ------------------------------------------------------------------------  1: EE 1023 254  63 - 1023 254  63 [         1 -  976562539] <Unknown ID>  2: 00    0   0   0 -    0   0   0 [         0 -          0] unused        3: 00    0   0   0 -    0   0   0 [         0 -          0] unused        4: 00    0   0   0 -    0   0   0 [         0 -          0] unused


I searched the site for this question but I could not find a solution to my problem.   The code below works without error, but does not work in the function.     When the Program is run, the pairsprocess function must be called with the given parameters and the string and (i + 6) value given as parameters should be written to the screen.   But despite the code work, it doesn't do what I write.  I tried it in Task. Factory. StartNew and it didn't work that method.   static void Main(string[] args)      {         string[] Pairs = new string[] { "EURUSD", "GBPUSD", "EURGBP" };         int totalPairs = Pairs.Count();         Task[] Proc = new Task[totalPairs];         Console.WriteLine($"Pairs Count : {Pairs.Count()}");         for (int i = 0; i < totalPairs; i++)         {             Proc[i] = Task.Run(() => pairsProcess(Pairs[i],6+i));         }      }      public static void pairsProcess(string a,int Counter)     {         for (int i = 0; i < Counter; i++)         {             Console.WriteLine($"Pairs : {a} Counter : {i+1} / {Counter}");         }     }   This is what I normally want.  I add 6 to the value I value.     EURUSD 0 + 6 = 6 times         Pairs: EURUSD Counter: 1/6   Pairs: EURUSD Counter: 2/6   Pairs: EURUSD Counter: 3/6   Pairs: EURUSD Counter: 4/6   Pairs: EURUSD Counter: 5/6   Pairs: EURUSD Counter: 6/6         GBPUSD 1 + 6 = 7 times         Pairs: GBPUSD Counter: 1/7   Pairs: GBPUSD Counter: 2/7   Pairs: GBPUSD Counter: 3/7   Pairs: GBPUSD Counter: 4/7   Pairs: GBPUSD Counter: 5/7   Pairs: GBPUSD Counter: 6/7   Pairs: GBPUSD Counter: 7/7         EURGBP 2 + 6 = 8 times         Pairs: EURGBP Counter: 1/8   Pairs: EURGBP Counter: 2/8   Pairs: EURGBP Counter: 3/8   Pairs: EURGBP Counter: 4/8   Pairs: EURGBP Counter: 5/8   Pairs: EURGBP Counter: 6/8   Pairs: EURGBP Counter: 7/8   Pairs: EURGBP Counter: 8/8      I found the solution to my problem. After running the TASK, the thread had to wait for a little while. My problem is completely solved.  Proc [i] = Task. Run (() = > A. pairsprocess (Pairs [i], 6 + i));             System. Threading. Thread. Sleep (100);


I am building desktop app with pyQT need the the application window to pop-up without the cmd window prompt

I am designing a desktop application using python and PyQT in visual studio IDE and my concern is  after the execution of code ,the command prompt window pops-up and later the application window i need to prevent command prompt window from popping up.How do I do this?


How can I rename the WordPress AJAX URL?

I'm currently looking for a way to change / hide the default WordPress admin-ajax.php URL. I want to do this to remove the admin from it to prevent misunderstandings by my customers when I use the AJAX URL to read for example a file from my server. In this case, the URL has the admin prefix which is a bit confusing.  So in result the AJAX URl should looks like this: ajax.php  I've searched a bit but I can't find any helpful informations. Because of this I can't show you any related code. But when I got it, I'll update my question to help other people.  Maybe there is someone who did this before and can give me some helpful tips so that I can implement this asap? This would be very awesome!


Does software that has been built for older versions of Ubuntu run on newer versions?

On the list of downloads for some software that I want to install they have the options:  Ubuntu 18.04 LTS Ubuntu 16.04 LTS Ubuntu 14.04 LTS  But I am using Ubuntu 20.04. If I download the version for 18.04 will this work on my system? What are things that could go wrong or that I should look out for? I imagine this is dependent on the particular software that I am installing, so I have contacted the support team, but in general how well does this work? Is it likely that most of the time there will be no issues?


In what ways does a Commander in their Command zone influence the game?

has an ability that functions whilst in the command zone. As a newbie to the Commander format, that leaves me unclear about something:  Whilst a Commander is in their Command zone and remains there, what effect do they have on the game?   Are all of a Commander's abilities active? (e.g. ) Can they use their activated or mana abilities? (e.g. ) Can they do anything else (apart from being able to be cast)?   I suspect all their abilities are active and can be used, but I've been told only the ones that specifically mention being in the command zone (e.g. Oloro's ability) are active.


PostgreSQL compare data across different servers

I've one problem regarding manage information from two different Postgres servers.   In the one server I've one table a containing id bigserial and phone varchar(200)  On the other server I've table b that contains id bigserial and tell varchar(200)   Is there a way that I can compare witch rows from table a are present in the rows of table b, comparing by phone = tell?


Prove that $\frac {(m,n){ n\choose m}}{n}$ is an integer for all integers $n\ge m\ge1$

I have a question given to me by a friend.  Prove that $\frac {(m,n){n\choose m}}{n}$ is an integer for all integers $n\ge m\ge1$. Any hint??


Can't open items from the top panel any more

Just updated the iOS app, and now if I click one of the items on the top (horizontally scrolling) panel, the item dims, as if it is waiting for the data to display, but it never opens. I can click other items, and they dim, but nothing ever opens.  The app remains otherwise responsive at all times. This worked fine in the previous version I had.   App Version: 1.6.0.10 Device: iPad 4 (Wi-Fi) OS Version: Version 9.3.5 (Build 13G36)


CAN YOU PLEASE EXPLAIN IN DETAIL. Why are we not checking both condition in "and" of if statement , and in checking both condition in "or" of If condition? Why in first question x= 11, y=20, is printed. While in second question x=11, y=21, is printed.


Find a bijective mapping that shows that [0,1] and [0,1) have the same cardinality

I need to show that the two sets $[0,1]$ and $[0,1)$ have the same cardinality. I know that in order to show this I must show that there exists $f$ such that $f:[0,1]\to[0,1),$ but I am not sure how to proceed.  Any help would be appreciated. Thanks.


Closure of the set of degree $n$ polynomials with $n$ real roots

A very beautiful (but maybe classic) exercise:   Consider the set $\Omega_n$ of polynomials of degree $n$ with real coefficients and $n$ distinct real roots.   What is the closure of $\Omega_n$ in $R_n[x]$?  ($R_n[x]$ denotes the set of polynomials with real coefficients of degree at most $n$)    The answer is the set of polynomials in $R_n[x]$ all of whose roots are real, plus the constant polynomials. Showing that this set is contained in the closure is not too hard, however the reverse implication is more difficult and I'm wondering what is the most elementary method to prove it (without talking about holomorphic functions for example).


I'm trying to solve the second part of the following exercise which is question 32 in Section 1.5 of Real Analysis by Folland.  Suppose $\{\alpha_j\}_{j=1}^{\infty} \subset (0, 1)$. Then:   $\prod_{j=1}^{\infty} (1 - \alpha_j)>0$. if and only if $\sum_{j=1}^{\infty} \alpha_j < \infty$. Given $\beta \in (0, 1)$, exhibit a sequence $\{\alpha_j\}_{j=1}^{\infty}$ such that $\prod_{j=1}^{\infty} (1 - \alpha_j)= \beta$.   How can I prove the second part of the statement? I am pretty sure that it should be solved by induction. But I don't know how to do it.


Can This Matrix Proof Be Done Without the Definition?

The following was taken from Stephen Friedberg's Linear Algebra, 2nd Edition.  Let $A$ be a $m \times n$ matrix, $B$ and $C$ be $n \times p$ matrices.  Show that $A(B+C) = AB + BC$ and, for any $k \in F$, $k(AB) = (kA)B = A(kB)$.  Proof:  $[ A(B+C) ]_{ij} = \sum_{i=1}^n A_{ik}(B+C)_{kj}$  $= \sum_{i=1}^n A_{ik}B_{kj} + \sum_{i=1}^n A_{ik}C_{kj} = (AB)_{ij} + (BC)_{ij} = [AB + BC]_{ij}$  I did the second part myself:  We have $[k(AB)]_{ij} = k \sum_{i=1}^n A_{ik}B_{kj}$  $ = \sum_{i=1}^n kA_{ik}B_{kj} = \sum_{i=1}^n (kA)_{ik}B_{kj}$  $ = \sum_{i=1}^n A_{ik}kB_{kj} = \sum_{i=1}^n A_{ik}(kB)_{kj}$  As a result, $k(AB) = (kA)B = A(kB)$.  I noticed that the proof used the definition of matrix addition and scalar multiplication.  $(B+C)_{ij} = B_{ij} + C_{ij}$ and $(kA)_{ij} = k(A)_{ij}$.  Now is it possible to prove without the definitions?  I became curious because Mr. Friedberg introduced the matrix as a representation of a linear transformation over an ordered basis.  So, I tried proving via the linear transformation over an ordered basis and could not do it.  For example:  Let $\alpha = \{x_1, x_2 ... x_n\}$ be an ordered basis of $V, \gamma = \{z_1, z_2 ... z_m\}$ be an ordered basis of $W$,  and $T: V \rightarrow W$ be a linear transformation.  Elsewhere, Mr. Friedberg already defined that $(kT)(x_j) = kT(x_j)$.  Suppose that $A$ is the matrix representation of $T$.  $k(A) = k *[ \space T(x_1) \space T(x_2) \space ... \space T(x_n) \space ] = [\space kT(x_1) \space kT(x_2) \space ... \space kT(x_n) \space ] = [ \space (kT)(x_1) \space (kT)(x_2) \space ... \space (kT)(x_n) \space]$  But this is possible only because of the definition of scalar multiplication.


Book about future where they use honey instead of money?

I remember reading this about 3 years ago. The main character is a teenage girl who has to learn how to survive in this new world. I think she’s trying to find her brother with the help of some people she met hiding underground in sewers.  It was a newer book when I read it and it’s written in English.


What is the difference between using + to add two strings together or using .conact()

So I know you can do "stringOne" + "stringTwo" to add two strings together. However I saw that you can use the stringOne.concat(stringTwo); What is the difference?


I am trying to put together a LaTeX template that mirrors the following . Does anyone have any recommendations for similar templates that can be my starting code?


re-install Ubuntu software of same version

I updated from v16 of ubuntu to v8.  When I did that all went well. A lot of things were funky (e.g., there is no pip and it won't let me add one).  The best advice so far is to re-install v18 again. 'Software Updater" app runs, but ends up saying "the software on this computer is up-to-date". How do I get it to reinstall the latest version of Ubuntu over the (somewhat messed up) current OS? Addendum: Someone asked for a screenshot.  Here is one from another user who had the exact same problem, but none of the suggested fixes fixed it for me:  BTW, the updater does give me a settings button and pages, but none of them are about the install I want to do.  They control, for example, what the upgrade and patch methodology (daily, automatic, etc.) do.


Compare classification performance of two heuristics

I want to compare the classification performance of two heuristics: $h_0$ and $h_1$. I have around 700 samples for which I know the output class $c$ and the results of the two heuristics $c_{\textit{h_0}}, c_{\textit{h_1}}$.  That is, for each sample I have $\text{sample}_{\textit{id}}, c, c_{\textit{h_0}}, c_{\textit{h_1}}$.   $h_0$ has around ~71% correct predictions of the output class and $h_1$ has around ~77% correct. What I want to calculate now is whether this performance difference is just by chance or if the prediction performance of $h_1$ is statistical significant better than that of $h_0$.  I have found , but I don't know whether I can just put my data in there like the following matrix to calculate a p-value.  $$   \begin{matrix}                                & h_0 & h_1 \\     \text{correct prediction} & 497 & 539 \\     \text{wrong prediction}   & 203 & 161   \end{matrix} $$  I don't know if I can calculate the p-value like that or if I'm completely on the wrong track. I would really appreciate it if someone could point me in the right direction.


Confusion with storage capacity (powers of 10 and 2)

I was taking a look at a HDD and I found a document (from Toshiba, link: ) that says:  "One Gigabyte (1GB) means 10^9 = 1,000,000,000 bytes using powers of 10. A computer operating system, however, reports storage capacity using powers of 2 for the definition of 1GB = 2 ^30 = 1,073,741,824 bytes, and therefore shows less storage capacity."  Then powers of 10 are bigger than powers of 2, OK.   Example 10^2 = 100 and 2^2 = 4.   But I do not understand the document which says for the same storage capacity:  1GB is 1,000,000,000 bytes (powers of 10) and 1,073,741,824 bytes (powers of 2), then: it shows less storage capacity (the powers of 2). Why is it less? If I see for 1GB more storage capacity in powers of 2 than powers of 10.


Are there counterexamples to: $\alpha^\gamma < \beta^\gamma \Rightarrow \alpha < \beta$?

We know that, for $\alpha$, $\beta$, $\gamma$ cardinals, if $\alpha \leq \beta$, then $\alpha^\gamma \leq \beta^\gamma$, and, in general, the usual operations defined on cardinals are compatible with the order relation. I have been given the task to determine if the reversed implication holds, i.e. $\alpha^\gamma \leq \beta^\gamma \Rightarrow \alpha \leq \beta$. I think the answer is no, given that $4^{\aleph_0}=2^{\aleph_0}=\mathfrak{c}$ and $4>2$. But what happens if we have a strict inequality, does this implication hold? $$\alpha^\gamma < \beta^\gamma \Rightarrow \alpha < \beta.$$ I proved that the above implication is true for $\gamma=$ finite. P.S. I am asking this question, because I realize an interesting thing: if we replace the exponentiation operator with multiplication or addition, the implication does hold, that is, $$\alpha+\gamma < \beta+\gamma \Rightarrow \alpha < \beta.$$ $$\alpha\cdot\gamma < \beta\cdot\gamma \Rightarrow \alpha < \beta.$$ Also, there are counterexamples for division and subtraction, $\mathfrak{c}+\aleph_0=\mathfrak{c}\cdot\aleph_0=\mathfrak{c}+1=\mathfrak{c}\cdot1=\mathfrak{c}$, and $\aleph_0>1$.


Who were all the attendees at the Council of Elrond?

Besides the actual fellowship and Elrond, who else attended the meeting in Rivendell? In the movie, it looks like there are around 20 or so attendees. Who were they? How closely does this match the book?


Consolidating multiple rows into multiple columns

I am presented with an issue where we are hitting an API limitation, and its consuming a lot of overhead to get this done.  So I've been tasked with finding a SQL solution. Here is my example data:  Here are my desired result:  I've tried using XML and stuff() but ultimately I just can't figure out how to approach the problem.


How do I redirect in a class sub-classing the EventSubscriber class?

I want to redirect to a specific URL in an EventSubscriber class instead of showing the Page not found page. I followed  but the redirect goes to the home.  This is the code I am using.  use Drupal\Core\Url; use Symfony\Component\EventDispatcher\EventSubscriberInterface; use Symfony\Component\HttpFoundation\RedirectResponse; use Symfony\Component\HttpFoundation\Response; use Symfony\Component\HttpKernel\Event\GetResponseEvent; use Symfony\Component\HttpKernel\KernelEvents;  class PageNotFound implements EventSubscriberInterface {   public function pageNotFound(GetResponseEvent $event) {     $request = $event->getRequest();     $id = '1234';     $scheme_and_http_host = $request->getSchemeAndHttpHost();     $url = Url::fromRoute('myroute', ['id' => $id])->toString(); // this url exist (checked)      $response = new RedirectResponse($scheme_and_http_host . $url, Response::HTTP_MOVED_PERMANENTLY);     $event->setResponse($response);   }    /**    * {@inheritdoc}    */   public static function getSubscribedEvents() {     $events[KernelEvents::REQUEST][] = ['pageNotFound'];     return $events;   } }   mymodule.services.yml  services:   mymodule.page_not_found:     class: Drupal\mymodule\EventListener\PageNotFound     tags:       - {name: event_subscriber}   How do I redirect users from an EventSubscriber class?


I get a lot from Stack Overflow, I want to contribute to others' questions too, but numerous .net, html questions come to the front page, while what I am good at is c and linux. How to filter those questions and just show questions related to my favorite tags?


Is there any problem that is proved not independent of ZFC but the problem itself is not proved yet?

Is there any problem in mathematics that is proved not independent of ZFC but the problem itself is not proved yet?


EXCEL VBA: regEx.Pattern colorize font color between first | and second |

I have an entire macro that searches for every cell in a column and sets the font color of any text between the two parenthesis () or two square brackets []. What i would like to know is what is the regEx.Pattern if i want to set the font color between two vertical bars (pipes) such as "| colored font goes in here |". And while am at it what about a regEx>Pattern that does the same thing but for the less than and greater than symbols, such as < colored font goes here >. Here is the regEx.Pattern for the parenthesis: "\([^)]*\)" Here is the regEx.Pattern for the square brackets: "\[[^]]*\]" I tried replacing the second symbol from the left and the fifth symbol from the right (excluding the quotation marks) with the vertical bars or the less than and greater than symbols but it doesn't work. I searched for a solution on the net but could no find one. All i need is the two regEx.Patterns. Any help would be appreciated. Thank you.


How to describe a fraction with a sentence

I want to describe the fraction x/y, how should I describe it in English?  x divided by y?


Countable additivity implies countable subadditivity?

Suppose $\mu$ is a measure in a ring $R$ of a set $X$. So for any mutually disjoint subsets $A_1,A_2,\ldots$ such that $\sum_{i=1}^\infty A_i\in R$, we have that $\mu(\sum_{i=1}^\infty A_i) = \mu(A_1)+\mu(A_2)+\cdots$. (i.e. countable additivity)  I'm wondering: Does that imply countable subadditivity? I.e. for any subsets $A_1,A_2,\ldots$ such that $\sum_{i=1}^\infty A_i\in R$, is it always true that $\mu(\sum_{i=1}^\infty A_i)\le \mu(A_1)+\mu(A_2)+\cdots$?  I believe it should be true, because you can take the mutually disjoint subsets $A_1,A_2-A_1,A_3-(A_1\cup A_2),A_4-(A_1\cup A_2\cup A_3),\cdots$, each of which is in $R$ (because unions and differences of sets in $R$ are again in $R$), then apply countable additivity, then use monotonicity on the fact that $A_n-(A_1\cup\cdots\cup A_{n-1})\subseteq A_n$.  Is that right? I just want to make sure I didn't make any mistake in my logic.


JAVA how to print out array in main using a method?

So I need to create a method which would take ints and return an array of length 3 with those three ints as they have been input.  This is what I have created, but it returns this [I@7852e922  public class IntsToArray {   public static int[] fill(int a, int b, int c){       int[] array = new int[3];       array[0] = a;       array[1] = b;       array[2] = c;       return (array);   }     public static void main(String[] args){         int a = Integer.parseInt(args[0]);         int b = Integer.parseInt(args[1]);         int c = Integer.parseInt(args[2]);         int[] array = fill(a, b, c);         System.out.println(array);     } }   What am I doing wrong?


Vertically align a multirow text which has been rotated

I know using turn command and a sample code like this:  \usepackage{rotating}  \begin{turn}{90} Supervised Learning \end{turn}}   we can rotate a text inside a cell, however, I couldn't find a way to vertically center this rotated text when we have multirow. Any suggestions is appreciated.  \begin{table}     \centering     \caption{A Classification }     \begin{tabular}{|c|>{\centering\arraybackslash}m{2.2cm}|>{\centering\arraybackslash}m{10.5cm}|}         \hline         \multicolumn{2}{|c|}{Classification} & References \\ \hline         \multirow{2}{*}{{\begin{turn}{90}Supervised Learning\end{turn}}}           % \multirow{2}{*}{\rotatebox[origin=c]{90}{\parbox{.6cm}{\centering{Supervised Learning}}}}            & Bayesian &          \\ \cline{2-3}         & Linear  &          \\ \cline{2-3}         & Decision Trees &          \\ \cline{2-3}         & Neural Networks / Genetic Algorithm &          \\ \cline{2-3}         & Others  &          \\ \cline{2-3}         \hline         \multirow{2}{*}{{\begin{turn}{90} Unsupervised  \end{turn}}}          & Clustering &          \\ \cline{2-3}         \hline         \multirow{2}{*}{{\begin{turn}{90} Others \end{turn}}}          & Reinforcement Learning  &          \\  \cline{2-3}         & Graph-based &           \\  \cline{2-3}         & Statistical Methods &          \\ \cline{2-3}         \hline         %\multicolumn{2}{|l|}{Statistical Methods} &          \\ \hline     \end{tabular}     \label{tab:Machine_Learning_models} \end{table}


What's a good sensor for measuring high voltages

I want to do datalogging on solar strings in the 600V range +-100V.  Would prefer accuracy close to 1%.


I just bought a Schwinn bike with the following codes on the tire. AKR6483 / 40-622 / 700x38c. I have gone to numerous websites to possibly order a solid rubber tire for my bike so I will never have to by a replacement tire or repair a flat due to puncture. Can you tell me which solid rubber tire would be acceptable for this bike  Thank you very much  Ron


Sequence of Polynomials Converging to a Constant Function

I am working on a seemingly bizarre problem and cannot make any progress at all.  I am wondering if anybody has come across a similar problem, and if so just how to start it.  The problem is as follows.  Find a sequence of polynomials $p_i$ on $\mathbb{C}$ such that all of the below are true:  1) On the right open half-plane we have $p_i$ converges to $1$  2) On $i\mathbb{R}$ we have $p_i$ converges to $0$  3) On the left open half-plane we have $p_i$ converges to $-1$  So my idea is that with an appropriate application of Runge's Theorem and the reflection principle we can pretty much just concern ourselves with satisfying the first condition using not polynomials, but some sequence of analytic functions $f_i$.  And then hopefully the sequence of $f_i$ will work out for the rest haha  But basically I have no idea how to start this problem.  Does anyone have any ideas?  Thanks a lot in advance!


How do I know which version of Debian I'm running?

In a tutorial, I'm prompted "If you are running Squeeze, follow these instructions..." and "If you are running Wheezy, follow these other instructions..."  When I run uname, I get the following information:  Linux dragon-debian 3.2.0-4-686-pae #1 SMP Debian 3.2.63-2+deb7u2 i686 GNU/Linux   Is that information enough to know if I'm using Squeeze or Wheezy, or do I get that from somewhere else?


Here is the proof they gave: Start with the statement $a = b$. Multiply both sides by $b$ to get $ab = b²$. Subtract $a²$ from both sides to get $ab − a² = b² − a²$. Factor the left and right sides of the equation to get $a(b − a)=(b − a)(b + a)$. Now divide both sides by $b − a$ to get $a = b + a$. Finally, let $a = b = 1$ in this final result to get the statement that $1 = 2$ but that is not true. What went wrong with the proof?  I'm not sure but is the error that you are not allowed to divide by $b-a$?


$$ \begin{cases} m=&a_1x+ b_1y \\ n =& a_2x + b_2y \end{cases} \qquad\text{and}\qquad a_1 b_2 - a_2 b_1 = 1 $$ I tried to substitute the value of $x$ in eq-1 to eq-2 and got $na_1+ma_2=y$ source: Challenges and Thrills Of Pre-College Mathematics (Exercise 2.2 Q-20)


Linearly expanding vacuum solves cosmological constant problem?

The flat FLRW metric written in terms of conformal time $\eta$ is given by $$ds^2=a^2(\eta)(d\eta^2-dx^2-dy^2-dz^2)\tag{1}$$ where the scale factor $a(0)=1$. The interval of proper time $\tau$ measured by a comoving observer is given by $$d\tau=a(\eta)d\eta.$$ The coordinate system used to describe the metric in Eqn.(1) is that of a stationary observer fixed at the origin $(\eta,x,y,z)=(0,0,0,0)$ with four-velocity $$U^\mu=(1,0,0,0).$$ Assume that he observes a particle moving along a nearby path $x^\mu(\lambda)$ with four-velocity $$V^\mu=\frac{dx^\mu}{d\lambda}.$$ The four-momentum of the particle is $$P^\mu=mV^\mu.$$ The energy $\epsilon$ of the particle as measured by the stationary observer fixed at the origin $\eta=0$ is given by $$\epsilon=U_\mu P^\mu.$$ Now let us assume that the path $x^\mu(\lambda)$ is a geodesic. Using the metric in Eqn.(1) it can be shown that the covariant derivative of the energy $\epsilon$ along $x^\mu(\lambda)$ is given by $$\frac{d\epsilon}{d\lambda}=m\frac{\dot a}{a}V^\mu V_\mu.$$ Consider two types of particle; a massless particle and a stationary massive particle. The massless particle has $V^\mu V_\mu=0$ therefore $$ \begin{eqnarray} \frac{d\epsilon_{\rm massless}}{d\lambda} &=& 0\\ \epsilon_{\rm massless} &=& {\rm constant.} \end{eqnarray} $$ The massive particle has $V^\mu V_\mu=1$ therefore $$ \begin{eqnarray} \frac{d\epsilon_{\rm massive}}{d\tau} &=& m\frac{da/d\eta}{a}\\ &=& m\frac{da/d\tau\ d\tau/d\eta}{a}\\ &=& m\frac{da}{d\tau}\\ \epsilon_{\rm massive} &=& ma. \end{eqnarray} $$ Thus the constant energy $\epsilon_{\rm massless}$ is the energy of a massless particle as it propagates into the future with respect to the stationary observer fixed at the origin at $\eta=0$. The energy $\epsilon_{\rm massive}=ma$ is the energy of a stationary massive particle as it propagates into the future with respect to the stationary observer fixed at the origin at $\eta=0$.  Now, using natural units with $\hbar=c=1$, the Friedmann equation for the vacuum is given by $$\Big(\frac{da/d\tau}{a}\Big)^2\sim \frac{1}{M_{\rm pl}^2}\rho_{\rm vac}$$ where $M_{\rm pl}$ is the Planck mass. The vacuum density $\rho_{\rm vac}$ is given by $$\rho_{\rm vac} \sim P_{\rm pl}^4$$ where $P_{\rm pl}$ is the Planck momentum.  According to the stationary observer fixed at the origin $\eta=0$ $$ \begin{eqnarray} M_{\rm pl} &=& M_{\rm pl}^0\ a(\tau)\\ P_{\rm pl} &=& P_{\rm pl}^0 \end{eqnarray} $$ where $M_{\rm pl}^0$ and $P_{\rm pl}^0$ are the Planck mass and momentum measured at the origin.  Thus, using Planck units where $M_{\rm pl}^0=P_{\rm pl}^0=1$, the Friedmann equation for the vacuum becomes $$ \begin{eqnarray} \Big(\frac{da/d\tau}{a}\Big)^2 &\sim& \frac{1}{a^2}\\ a(\tau) &\sim& \tau. \end{eqnarray} $$ Thus the scale factor $a$ is a linear function of the proper time $\tau$ as measured by a co-moving observer. This is very different from the standard vacuum cosmology which expands exponentially.  In fact we can define the scale factor $a(\tau)=\tau$ so that the scale factor is simply the age of the universe in Planck units.  We can also redefine the energy scale so that by definition a co-moving observer always measures a constant Planck mass. In that case the energy density of the vacuum, $\rho_{\rm vac}$, must vary as $$\rho_{\rm vac} \sim \frac{1}{a^2} \sim \frac{1}{\tau^2}.$$  The age of the universe, $\tau$, is approximately $10^{60}$ in Planck units so that the current density of the vacuum $\rho_{\rm vac}\sim 10^{-120}$. This is consistent with observation.


first of all thank you for answering.  I have a 120GB SSD and a 1TB HDD and I want to dual boot with Windows 10. I tried with this configuration:  SSD  / (ext4 20GB) /usr (ext4 15GB) /boot/efi (ext4 250MB)  HDD  /var (ext4 3GB) /tmp (ext4 8GB) /home (ext4 50GB) swap (none 24GB) (RAM 16GB)  I don't know if I am doing OK, as I tried to install it but installation gets stuck at "Saving installed packages..." and it doesn't continue. I wonder if it could be cause I didn't  partitioned as I had to. I don't find any post where this happens so I ask here.  Thanks!


A fast (and correct) way of finding a common divisor for $1805$, $1991$, $2146$ so that they have the same remainder

A question says:      "Which $n \in \Bbb N$ should the numbers $1991$, $1805$, $2146$ be divided into, so that there will be the same remainders left?"   I arranged them in order: $1805,1991,2146.$ Then did subtraction: $1991-1805=186,$ $2146-1991=155,$ then $186-155=31.$ This last result is the answer. But I am skeptical about my way of finding the answer (and which seems to be a little bit stranger to me), as it wouldn't work in some cases. I would like  1) to know your thoughts on my method, 2) you to provide some hints in order to show the right way of solving this.


If $E(X^2)=1$ and $E(|X|)\ge a >0$, then $P(|X|\ge\lambda a)\ge (1-\lambda)^2a^2$ for $0\le \lambda \le 1$.  I can see from the well known inequality $E(|X|) \le E(|X|^2)^{1/2}$ that it must be the case that $a\le 1$. But what to do next I'm not sure.


Ok, so I know that this question has been asked a million times, but it seems that using the solutions from questions like this has not helped me so far.  How do I set default permissions for new files uploaded through vsftpd?  As of now the files will get the following permissions:  -rw-r--r-- 1 pi   pi      7 Jun 28 13:21 FILENAME   But I need the file to be executable. I could manually chmod the files, but that would not include files in the future. What i have tried:   Setting umask in login.defs - Even after a restart, if I then type umask I will get umask 0022 (not what I set) Setting local_umask=022 and file_open_mode=0644 in /etc/vsftpd.conf   Does anyone have a solution for this? The permissions for future files should be somewhat like:      -rwxr--r--   Hope you understand. I'm new on linux.


Investing in index fund vs. investing to large-cap companies directly

I'm trying to understand the upsides/downsides of investing to an index fund vs. investing directly to stocks of some best-known and well-established large-cap companies. Every single article on investment strategies says that for someone, who does not want to become full-time investor, the best thing is to invest in an index fund and wait 10+ years till your money grows. Let's compare some well-established large-cap companies' performance with performance of well-established index funds. For instance, let's take average yearly growth percentage for the last 10 years for some companies:  Apple - 28.09% Amazon - 33.32% Nvidia - 45.27% Microsoft - 26.66% AMD - 27.94% Mastercard - 31.34% Shopify - 44.50% Square - 32.19% MercadoLibre - 36.98% Netflix - 32.81%  Let's compare them to some well-regarded index funds:  Vanguard U.S. Growth Fund (VWUSX) - 18.54% Vanguard Growth Index Fund (VIGAX) - 16.82% Vanguard Total Stock Market Index Fund (VTSAX) - 14.04%  My thoughts:  There is a huge gap between growth of the stocks vs. growth of the index fund Yes, I know that index funds are created by smart people/algorithms to be more reliable than usual stocks of several companies and they follow some particular indices for a reason. Yes, I know they include other stocks apart from the ones I mentioned above to balance the portfolio and defend against drops in price of the main stocks Interestingly, the lion's share of the cost of each of the growth index funds consists exactly of the companies I listed above Yes, I know that I included mostly companies from tech and finance sectors. But those are the ones, which are expected to grow best of all anyway, because the whole economy is driven by them. If the economy would collapse, then those companies would collapse with it and vice versa. I don't see any single chance that any other sector can in the nearest future outperform the tech and finance sectors, or that those sectors may fall much more than the rest of the businesses.  My question is: what would I get investing in much worse growing index fund vs. investing to some chosen well-established large-cap companies?


Measures of variable importance in random forests

I've been playing around with random forests for regression and am having difficulty working out exactly what the two measures of importance mean, and how they should be interpreted.  The importance() function gives two values for each variable: %IncMSE and IncNodePurity. Is there simple interpretations for these 2 values?  For IncNodePurity in particular, is this simply the amount the RSS increase following the removal of that variable?


how to access my ubuntu, which is present in my partition?

i recently installed ubuntu 16.04,(dual boot with windows 10 using usb drive) i did the disk partition and all and now it is present in my hard disk. but when i restarted after installation, i was not asked to choose ubuntu or windows 10, it directly took me to windows, their was no GRUB bootloader.  and i tried this in windows cmd(admin):  "bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi" . it said successful, but when i restarted again, i was back into windows. now i dont know what to do, and that GRUB loader... should that be installed or something???


VMWare: This host doesn't support VT. Can not play 64-bit VM due to lack of VT flag

I have an Intel E7300 Core2 Duo processor with 2.66GHz speed. I need to run a 64-bit WinXP SP2 VMWare image. My host operating system is Win 7. So I just installed the VMPlayer from www.vmware.com.  The problem is when I run the VM image it says This host doesn't support VT.  If I continue I see Windows shows an error message saying     Attempting to load an x64 operating system, however this CPU is not compatible with x64 mode.   My question is how do I run this VM without buying a new processor? Any other tools or software?


I'm trying to understand the  and came across this paragraph that seems crazy to me:     when the rocket moves, its thrust acts through the distance it moves. Force multiplied by distance is the definition of mechanical energy or work. So the farther the rocket and payload move during the burn (i.e. the faster they move), the greater the kinetic energy imparted.   It makes sense to me that a force acting against an immovable object doesn't impart any change in kinetic energy- the fixed force of gravity can push the stones of Stonehenge into the ground for thousands of years, but if they don't move there's no energy changing hands.  What makes no sense at all to me is that the change in kinetic energy is directly proportional to the distance the object moves. What if the object just coincidentally happens to be moving anyway? Say you have two objects; one is at rest, and the other is coasting through space at 1000km per second. You impart a tiny little 1 newton force on both objects for a second or so. The first object moves a meter so you've increased its kinetic energy by one joule. But just because the second object happens to be traveling at hypervelocity already, you've imparted the kinetic energy of a stick of dynamite? How do those definitions of work and kinetic energy make sense?  Come to think of it, the Earth is moving around the Sun at 30 km/s so if I stand on one of the stones of Stonehenge around sunrise, is the weight of my body dumping 17 megawatts of energy into it? It seems that the definition of work contains some kind of caveat that the distance the object moves has to be related to the force somehow but that's completely unclear to me.  Also, how does the object moving through space at a constant velocity even "know" that it's moving? There is no universal inertial frame of reference that everything moves relative to; who's to say that the fast-moving object isn't at rest and we are the ones moving at 1000 kilometers per second?


Proof that regression residual error is an unbiased estimate of error variance

Consider the least squares problem $Y=X\beta +\epsilon$ while $\epsilon$ is zero mean Gaussian with $E(\epsilon) = 0$ and variance $\sigma^2$. I need to prove that   $\frac{V(\hat{\beta})}{N-(n+m)}$ is an unbiased estimate of $\sigma^2$ with $V(\beta) = ||Y-X\beta||$ .   I wasn't able to find the answer online.  I just got confused by a thousand different ways to write things down.  EDIT: $Y = \begin{pmatrix} y(0)\\ \vdots \\ y(N-1)\end{pmatrix} \quad$ $X = \begin{pmatrix} x^T(0)\\ \vdots \\ x^T(N-1)\end{pmatrix}\quad $  $\beta = \begin{pmatrix} a_1\\ \vdots \\ a_n\\ b_1 \\\vdots \\ b_m \end{pmatrix}$


What is the purpose of @classmethod in Python?

I am currently learning Python. in OOP what is the purpose of @classmethod decorator? What is the difference accessing class variables via @classmethod and accessing it through just normal method? Like I can do that same like this: class A():    _variable = A     def getVariable(self):       return self._variable     or class A():    _variable = A     @classmethod    def getVariable(cls):       return cls._variable     What is the difference between both methods? Why do I need to use when do I use the classmethod and when do I not have to? And what happens if I don't?


I recently wrote  on Stack Overflow.  In order to be nice and in the spirit of our push toward welcoming new users, I began my answer with      Hi, and welcome to Stack Overflow!   When I hit "post", the answer got published with the first word cut off, so the first sentence is just     and welcome to Stack Overflow!   I tried editing it twice to add the Hi, to no avail.  I did not get any warning message, it just didn't save my changes.  I then hypothesized that perhaps Hi, was too few characters, so I tried Hi @username_of_the_OP, which also did not work, and again no error message or indication of an error of any sort, it just didn't save my changes.  I think this is a bug in the site, and am posting here to report it.  I hope this helps.  If this is actually a bug in me (ie, user error) please let me know and I will fix my erroneous ways :D


Is there a Stack Exchange site for Law Questions? If not, why not?

I think a Legal Stack Overflow would be an excellent resource. Why doesn't such a thing exist? If it doesn't, I'd like to create one.


I will be flying to Istanbul from Miami and I have a connection flight in Copenhagen. The flight from Miami to Copenhagen and Copenhagen to Istanbul are not operated by the same airline so I have to claim my baggage and check-in again.    The airlines are SAS and Turkish Airlines, but the website I bought them at says I need to self-transfer.  I am traveling on a Turkish passport.   Do I need a Schengen visa/transit visa for that?


Change the stroke width without changing the width and height of the rectangle

When I change the stroke width of a rectangle the width and and height change also. How can I  prevent this from happening?


Style figure captions and table captions differently

Using the caption package I can set the style for captions for all floating elements in my document:  \usepackage[font={small,it}]{caption}   Now, suppose I want my figures captioned like this, but my tables captioned in bold. How can I achieve this?  The documentation tells me I can define two caption styles, and switch between them manually every time I insert a figure or table using the \captionsetup command. Is there a better way?


My hat falls off when editing tags with keyboard shortcuts

I noticed this when fiddling around on one of my questions.  Steps to reproduce:  Go to a question (this one), and use the T (10k only) shortcut to open the tag editor. Add any tag (although the  one is preferred), click "Save Edits", let it give you the error, then cancel it. Watch your hat fall off!   I also did this on  post, and accidentally pulled Anita's hairdo off.  With apologies to Anita, can we fix that?


Solving a system of equations under modulo

Is there a way that we can solve a system of congruences,  $x \equiv m \, (modp)$   $y \equiv n \, (modq)$  while satisfying the condition $x+y=N$, when $m,n,p,q$ and $N$ are known?  Here $p,q$ are primes, $N=p^2 q$ and   case 1: $m=p, n=q$  case 2:$m=n=0$  Thanks a lot in advance.


Is it still meaningfull to watch the coeffiecent(s) of a regression equation even when it/they is/are not significant?

I am reading the regression analysis resutls in a paper which showed most of the coefficients b2 and b3 are not significant but the R2 is significant. Eventhough there aren't too many variable in this model(see the model below), that happend. How come?   Is it still necessary to watch b2 and b3 and make conclusion like from b2 we can tell that there is a possitiv correlation between X and Y? The author did that but I am not sure whether one should do that if the coefficient is not significant at all.


How do I cherry pick packages from a PPA?

Is there a way to cherry pick packages from a ppa repository you add? That is, to exclude some from updating while including others?  For example, I want just the chromium-browser package from  but not the others. So I don't want my sudo apt-get upgrade to have that ppa's other (besides chromium-browser) packages install over my existing ones, just that one.   I realize this is a license to shoot myself in the foot if I misread dependencies and exclude ones that are needed to ones that I included, but I know for a fact in this case that the other packages are not dependencies for that one.  Is this at all possible? Maybe there is some whitelist/blacklist file or something?


Why in the relativistic quantum mechanics $ \gamma_4$ name is not used instead of $ \gamma_5$?

I have seen in the in the Dirac equation $$\gamma_0,\gamma_1,\gamma_2,\gamma_3.$$ Then I have seen the definition of a new matrix $$\gamma_5=i\gamma_0\gamma_1\gamma_2\gamma_3.$$ Now my question is why the name of the new matrix has not been given as $$\gamma_4.$$ Is there any historical reason behind this or it is simply taken as $$\gamma_5$$ without any special reason skipping $$\gamma_4~?$$


Does your data stay if you buy the full version?

In Geometry Dash Lite on mobile, I made alot of progress, but I am planning to buy the full version. Will my data stay?


How to resolve: Specified key was too long; max key length is 767 bytes

Our server is creating a lot of tables and one of them is the Lock_ table.  We are using MySQL 5.5 on Percona. Also we are using utf8_general_ci and utf8.  It throws the following error when creating the following index on Lock_ table:  ERROR 1071 (42000): Specified key was too long; max key length is 767 bytes   Here is the create-table query:  create table Lock_ (     uuid_ VARCHAR(75) null,     lockId LONG not null primary key,     companyId LONG,     userId LONG,     userName VARCHAR(75) null,     createDate DATE null,     className VARCHAR(75) null,     key_ VARCHAR(200) null,     owner VARCHAR(255) null,     inheritable BOOLEAN,     expirationDate DATE null );   Index query:  create unique index IX_DD635956 on Lock_ (className, key_, owner);   This problem is happening on one of our prod servers (previously it was standalone mysql and then later moved to percona, but the problem was present in both the editions), but this is working fine on our dev environment.  So is there a way we can update the prod environment's index length or something so that it does not throw this error?  Thanks


no wired connection and wirewireless disabled

I am new to Linux kubuntu 14, i tried installing kubuntu 14.04 without internet connection which went smoothly, when i finish installing i was surprise to get a network or connection icon with a red sign showing wireless disable.  Since i have been battling with all kind of solution to fix this problem i can't just find any, i went to internet point and also try to connect ethernet wire it didn't work also can someone help me. when i run   lspci -nn    I get   02.06.1 Firewire (IEEE 1394) [0c00]: Texas instruments PCIxx12 OHCI compliant IEEE 1394 Host Controller [104c:803a] 02.0e.0 Ethernet controller [0200]: Broadcom corporation BCM4401-B0 100Base-TX [14e4:170c](rev 02) 10.00.0 Network controller [0280]: Broadcom corporation BCM4311 802.11b/g WLAN [14e4:4311] (rev 01)


Why does a floating balloon in an accelerated train moves forward but the pendulum moves backward?

If we bring a floating balloon in a accelerated train, the balloon will move forward in the same direction as the acceleration as shown in the following figure.     However if a pendulum is hung on the train ceiling, the ball moves backward. We also get moved backward in the accelerated train.  Could you explain why the floating balloon behaves differently?


SQL Server 2012: query to see queries that are consuming more resources

I'm trying to find/build a query to show me those queries that are consuming more resources in SQL Server so that I can optimize them or at least have a statistical idea of what is really happening.  For now I'm using these queries:  select        er.percent_complete     ,SUBSTRING(text,statement_start_offset/2+1,(CASE             WHEN statement_end_offset = -1 THEN LEN(CONVERT(nvarchar(max), text)) * 2             ELSE statement_end_offset         end - statement_start_offset)/2) AS query_text     ,se.session_id     ,se.login_name     ,se.login_time     ,er.session_id as 'Vitima'     ,blocking_session_id as 'Bloqueador'     ,wait_resource     ,start_time     ,er.status,command     ,db_name(er.database_id) 'Database'     ,SUSER_NAME(er.user_id) 'Usuario de contexto'     ,wait_type,wait_time     ,text     ,query_plan FROM     sys.dm_exec_requests as er     INNER JOIN sys.dm_exec_sessions as se         ON er.session_id = se.session_id     CROSS APPLY sys.dm_exec_sql_text (sql_handle)     CROSS APPLY sys.dm_exec_query_plan (plan_handle) WHERE     se.session_id>50 and se.session_id <> @@SPID   and  SELECT --TOP 10     SUBSTRING(qt.TEXT, (qs.statement_start_offset/2)+1,         ((CASE qs.statement_end_offset             WHEN -1 THEN DATALENGTH(qt.TEXT)             ELSE qs.statement_end_offset         END - qs.statement_start_offset)/2)+1) as vQuery,     qs.execution_count,     qs.total_logical_reads, qs.last_logical_reads,     qs.total_logical_writes, qs.last_logical_writes,     qs.total_worker_time,     qs.last_worker_time,     qs.total_elapsed_time/1000000 total_elapsed_time_in_S,     qs.last_elapsed_time/1000000 last_elapsed_time_in_S,     qs.last_execution_time,     qp.query_plan FROM     sys.dm_exec_query_stats qs     CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) qt     CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp --ORDER BY qs.total_logical_reads DESC -- logical reads --ORDER BY qs.total_logical_writes DESC -- logical writes --ORDER BY qs.total_worker_time DESC -- CPU time --ORDER BY last_execution_time DESC ORDER BY vQuery   They show similar info, but from different places and with different attributes.  The problem with both queries is that they seem to show only late queries. I've added comments to my queries that are being listed, and these comments aren't appearing, which means that latest queries (for about 15 minutes) aren't still being listed by them.  I'm ok with seeing historical data, as long as I'm able to control how historical it is. It's good to have a long run view.  But still, sometimes, I need to see the current situation. In example, all of a sudden the server starts to get slow, then I wanna see what exactly is doing it right now.  I'm still googling more queries, but I still didn't find anything better than these 2, to show more current data.  Anybody can give me a tip?  Another question. Regarding SQL Server optimization and possible caching, is it troubling to add a timestamp to each sent query? Since I can't see how old a query is, I'm thinking in adding in each query the date and time it was sent to SQL Server. But I'm afraid that SQL Server will lose the ability to see that the same query is being requested over and over, and think each query is brand new, and thus stop doing any optimization it might be doing.


How to set the length of a line using openlayers

I'm trying edit a polygon by changing the length of some lines by code. Found  to calculate based on the bearing.  But I didn't find anything on how to calculate the bearing, before I start research my math notes and code this bearing calculation, any recomendations ?  thanks


Make fn the default function key behavior only for some of the function keys

I find myself using the actual F* only for F1 to F6, but for music and sound controls I use the function instead. I've tried using functions by default, and it works great for F7 to F12, but then I need to use fn for the first half. I've also tried disabling the functions by default, but then I end up using fn for the other half of the function keys.  Is there a way to configure the keyboard so they trigger the actual F* only for some function keys, and the function for others?


Cause of hard disk root space utilization

What is the best way to identify the cause of root space utilization. Even after restart my machine it is only showing 2.2G available in my machine.  What are the possibilities   # df -h Filesystem             Size  Used Avail Use% Mounted on /dev/mapper/rhel-root   50G   48G  2.2G  96% / devtmpfs               6.8G     0  6.8G   0% /dev tmpfs                  6.8G  420K  6.8G   1% /dev/shm tmpfs                  6.8G   17M  6.8G   1% /run tmpfs                  6.8G     0  6.8G   0% /sys/fs/cgroup /dev/mapper/rhel-home  408G  210G  198G  52% /home /dev/sda1              497M   96M  401M  20% /boot   I tried this ncdu / and got this       9.1 GiB [          ] /usr     1.2 GiB [          ] /var   806.2 MiB [          ] /root   193.2 MiB [          ] /opt   167.5 MiB [          ] /run    70.6 MiB [          ] /boot    26.8 MiB [          ] /etc   420.0 KiB [          ] /dev   168.0 KiB [          ] /tmp   164.0 KiB [          ]  open.txt    64.0 KiB [          ]  .readahead .   0.0   B [          ] /proc     0.0   B [          ] /sys @   0.0   B [          ]  lib64 @   0.0   B [          ]  sbin @   0.0   B [          ]  lib @   0.0   B [          ]  bin e   0.0   B [          ] /srv e   0.0   B [          ] /mnt e   0.0   B [          ] /media     0.0   B [          ]  .autorelabel   which shows that  total space not exceeding apporx 13G. Still I am getting 49G as total used space.


I having more than 100 computers in my office with old hardware Pentium 4, 1ghz processor, 512mb Ram. Needed software are Google chrome with flash plugins and open office. Kindly suggest me the stable version from ubuntu, that i could get updates for the above mentioned software.  Computers used for only data entry and Internet browsing purpose.  ACUBE.


4K monitor with MacBook Pro 2012 Non-retina not working well in 2K resolution

LG 4K monitor 27 inch (lg-27UK650) Macbook pro 2012 Non Retina 16gb RAM/256 GB SSD  Using 4K monitor with mini DisplayPort. Display works randomly, and sometime stops working while in use. Monitor keeps displaying no signal. I am using external monitor in 2K resolution. Earlier I used to connect full HD monitor on mini DisplayPort and never had this kind of issue. Monitor works fine with my other laptop. Thinkpad x260 over same mini display port. Any suggestions?


Tabular into a .png when compile TeX document?

Do some of you know, whether it is possible or not to make a tabular into a .png when compile into a pdf TeX document?  Best,


In the movie The Avengers (2012), at the end the Hulk smashes Loki to the floor. After that we can see Loki injured with blood on his face.     How can the Hulk hurt a god? Shouldn't Loki be super strong, how can a god bleed?