Here's the hardware:   P4 2.4ghz (32bit) 2 gigs ram Asus dvd burner MSI GeForce 5200 FX 1 Seagate 60 gig (IDE) 1 WD Black 80 gig (IDE) USB mouse PS2 keyboard 17" NEC LCD   Software:   Ubuntu 13.1   Default install (Full) I let Ubuntu setup disk and Partitions Allow install of updates and 3rd Party Software.  Install goes fairly well maybe a bit slow but otherwise. Get to reboot screen Reboot Hangs after Bios. Reset Very SLOW boot to OS! 12 minutes!! Moving around VERY SLOW! FireFox 3.5 minutes to load. Video drivers loaded are default NOT Nvidia I find the place to load drivers it finds the card and attempts to install and run. After install OS freezes can't recover so did reboot. No video at all now.  I see there are other flavors like Kubuntu and Lubuntu would these be a better choice?

I've  and rebooted my machine and now I get a black or blank screen.   How can I fix this?


Here is the output of the lsblk command my issue was not able to resolve with the above command stated.

I installed Windows on my computer, followed by an installation of Ubuntu. However, now I'm unable to boot into my Windows install.  What can I do to fix this?


I updated my server from 16.04 to 18.04 a few days ago, today I found this:  19 packages can be updated. 18 updates are security updates.   I did:  sudo apt-get update sudo apt-get upgrade  Reading package lists... Done Building dependency tree        Reading state information... Done Calculating upgrade... Done The following packages have been kept back:   libapache2-mod-php7.2 php7.2-bcmath php7.2-bz2 php7.2-cgi php7.2-cli php7.2-common php7.2-fpm php7.2-gd php7.2-intl php7.2-json php7.2-mbstring php7.2-mysql php7.2-opcache php7.2-readline php7.2-xml php7.2-xmlrpc php7.2-zip The following packages will be upgraded:   php7.2 snap-confine snapd ubuntu-core-launcher 4 upgraded, 0 newly installed, 0 to remove and 17 not upgraded. Need to get 12.2 MB of archives. After this operation, 21.5 kB of additional disk space will be used. Do you want to continue? [Y/n] y Get:1 http://archive.ubuntu.com/ubuntu bionic-updates/universe amd64 ubuntu-core-launcher amd64 2.32.8+18.04 [1,644 B] Get:2 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 snapd amd64 2.32.8+18.04 [12.2 MB] Get:3 http://archive.ubuntu.com/ubuntu bionic-updates/universe amd64 snap-confine amd64 2.32.8+18.04 [1,792 B] Get:4 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 php7.2 all 7.2.5-0ubuntu0.18.04.1 [9,240 B] Fetched 12.2 MB in 2s (6,527 kB/s) (Reading database ... 81195 files and directories currently installed.) Preparing to unpack .../ubuntu-core-launcher_2.32.8+18.04_amd64.deb ... Unpacking ubuntu-core-launcher (2.32.8+18.04) over (2.32.5+18.04) ... Preparing to unpack .../snapd_2.32.8+18.04_amd64.deb ... Unpacking snapd (2.32.8+18.04) over (2.32.5+18.04) ... Preparing to unpack .../snap-confine_2.32.8+18.04_amd64.deb ... Unpacking snap-confine (2.32.8+18.04) over (2.32.5+18.04) ... Preparing to unpack .../php7.2_7.2.5-0ubuntu0.18.04.1_all.deb ... Unpacking php7.2 (7.2.5-0ubuntu0.18.04.1) over (7.2.4-1+ubuntu16.04.1+deb.sury.org+1) ... Setting up snapd (2.32.8+18.04) ... Created symlink /etc/systemd/system/multi-user.target.wants/snapd.seeded.service → /lib/systemd/system/snapd.seeded.service. Created symlink /etc/systemd/system/cloud-final.service.wants/snapd.seeded.service → /lib/systemd/system/snapd.seeded.service. snapd.snap-repair.service is a disabled or a static unit, not starting it. Setting up php7.2 (7.2.5-0ubuntu0.18.04.1) ... Processing triggers for man-db (2.8.3-2) ... Setting up ubuntu-core-launcher (2.32.8+18.04) ... Setting up snap-confine (2.32.8+18.04) ...   Now:  18 packages can be updated. 17 updates are security updates.  Reading package lists... Done Building dependency tree        Reading state information... Done Calculating upgrade... Done The following packages have been kept back:   libapache2-mod-php7.2 php7.2-bcmath php7.2-bz2 php7.2-cgi php7.2-cli php7.2-common php7.2-fpm php7.2-gd php7.2-intl php7.2-json php7.2-mbstring php7.2-mysql php7.2-opcache php7.2-readline php7.2-xml php7.2-xmlrpc php7.2-zip 0 upgraded, 0 newly installed, 0 to remove and 17 not upgraded.   How is that possible? What did I miss? Is a web server updated a few days ago, the update is about PHP which is very important for a web server. What can I do?  What should I do?  Will they update later along with other updates? Is this behavior normal after a few days from the version update? My server is in Vultr, maybe something is missing in Vultr?

I just added a PPA repository for the development version of the GIMP, but I get this error:  $ apt-get update && apt-get upgrade ... The following packages have been kept back:   gimp gimp-data libgegl-0.0-0 libgimp2.0   Why and how can I solve it so that I can use the latest version instead of the one I have now?


I've encountered an interview question:  Given several binary labels, each label represents a user will click a certain advertisement or not, we have a trained logistic model and its predicted probability of a user clicking the advertisement. How to evaluate this trained  logistic model?  I answered by using different thresholds on the predicted probability, we can easily plot the ROC curve and then area under the curve should be a measure.  The interviewer said that this is Okay, but can you give me other methods? I'm wondering how to answer this question. By the way, I failed at last.            click or not     predicted user1        1               0.8 user2        1               0.6 user3        0               0.4 ...         ...              ...   usern        0               0.3

I know some well-known measures are $c$ statistic, Kolmogorov-Smirnov $D$ statistic. However, as far as I know, those statistics take into account only of the rank order of the observations, and is invariant under changing the intercept of the logistic regression model (e.g. in oversampling-correction exercise).  In my current application, I need to depend on the accuracy of the logistic regression to predict probability of event. I know only of qualitative way of assessing models for probability prediction ability, namely by plotting "QQ-plot" of the actual vs predicted probability of event:   Score the validation dataset using the developed model. Rank the observations according to the predicted probability and group into $n$ buckets according to their rank of predicted probability. (First 1/n would go to the first bucket, next 1/n would go to the next ...) Calculate the average predicted and actual probability of Event for each bucket. Create a scatter plot of Predicted vs Actual - one point for each bucket.   I am wondering:   Is the "Q-Q plot" I mentioned above a legitimate way to assess predictive performance of models developed from logistic regression? If so, where may I find more reference for that? Is there any known quantitative way to assess the probability prediction ability of this kind of model?


Which is correct,"who/whom do you want to be?" In one book I found that "to be" follows who and not whom, but the sentence should have an objective pronoun whom if we go by the normal rules, as it is the object here.

I can never figure out whether I should use who and whom. Most people use who for both colloquially, but some people say this is not correct.  What’s the rule for using who and whom correctly?


I downloaded the Linux x86_64 file from the link below  and install but get this error  How can I use my graphics card in Ubuntu?

I have 14.04.5/16.04 or newer and an AMD GPU. I'm not getting the performance I want, and some programs say they need things like OpenCL.  I've heard about fglrx, but if I try to install it on my machine, it breaks and I have no GUI.  Is there anything I can do to get my AMD card working to its full potential?


Recently installed 11.04 version of ubuntu. Wanted to create a folder in the root of the fileSystem, but the persmission was denied. Tried with chown and chmod but no result.  Kindly assist me

I copied a set of BlueJ files from /usr/share/doc/BlueJ to a ~/BlueJ directory however the files in folders are set to root permission and read only I need to be able to read/write them.   So in BlueJ folder there are sub folders for each project for example 'shapes' folder.  I found this command here for changing a singular file   user@host:/home/user$ sudo chmod o+x /usr/local/bin/somefile   But how can I change the folder permissions and subsequently all files in folders for every project folder in ~/BlueJ?


I would essentially like communicate that solving a problem, if done through this method, would take way too long to be realistic or practical. This is a common occurrence in computer science where you can solve a problem, but your solution takes too long. I feel like  this problem requires infeasible computational resources  is essentially what I'd like to say. But I'm not sure if  this problem requires infeasibly large computational resources  is more appropriate. Does anyone have any better suggestions than these? Or do any one of these sound better for any reason? A side question: "unfeasibly large" brings up over 300,000 search results, whereas "infeasibly large" only brings up 15,000. They both seem correct, according to , but is there really a preference?

The current version of a sentence I'm writing has the structure:     Computing [such and such] is the most computationally expensive part of [algorithm].   At the moment, I cannot think of a better phrase to replace "computationally expensive".  I know it is legitimate to say this ("computationally expensive" has been published numerous times).  However, it sounds a little informal to me.  What are some alternatives to "computationally expensive" in the above sentence?


I've had multiple problems with commands all involving the new naming system. It just won't work. Only the IDs will. For example, if I were to try     /scoreboard objectives add snow stat.mineBlock.snow Snow   That wouldn't work. But,     /scoreboard objectives add snow stat.mineBlock.80 Snow   would work. I have no idea why, and this has stressed me so much. This won't work in 1.7.10 or the latest snapshots. Does anybody know why this won't work? Please help.

So I wanted to set up something that uses stat.mineBlock.snow, but it wouldn't work. I tried other stat.mineBlock, but they wouldn't work either. I did the command /scoreboard objectives add snow stat.mineBlock.snow Snow But it returns with Usage: Invalid objective criteria type 'stat.mineBlock.snow' So what am I doing wrong, and how do I fix this?


Assume that $W$ and $V$ are two subspace of $X$. Is their union a subspace of $X$ too? I think it is not true unless under certain conditions but I do not know what conditions...

I'm having a difficult time understanding this statement. Can someone please explain with a concrete example?


#include <stdio.h> #include <stdint.h> #include <stdlib.h>  double rand_double() {     return ( ((double)rand())/ ((double)RAND_MAX) ); }  int main(){     double i=rand_double();     double j;     do {         i=(i*0.5);         j=(1+i);         printf("%lf\n", j);     }     while(j>1);     return(0); }

Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


Is it possible to play Sid Meier's Pirates in a windowed mode? I know I need to edit config.ini but otherwise I'm clueless.  I bought the game from the GameStop website if that helps. When I open my config file it says that it is a shortcut and is always blank no matter how I save it.   Do I have to make a copy and save it? Is there an original copy that I have to edit? Can I not edit it because I bought it from the GameStop website? Does it matter what type of computer you have?

I remember seeing a lot of cool Counter Strike videos back in the day. How do you go about recording your gameplay (any game) into an easy to edit format? Do you need special software? How much does it cost?


I'm working up to building a small script which will allow me to import and render 2D views of several OBJ models, but I'm struggling at the moment with the very basic first step, which is importing a model from a folder on my computer. I attempted to follow the code in the script in , but even if I directly copy-paste the code and just change the directory path to where my model is located, when I press Run Script, nothing happens. I don't see any errors, I don't see anything happen, just nothing. I'm fairly new to both Blender and Blender scripting, so I'm not very sure what's going on and any help would be appreciated! This is my code at the moment (copied and pasted from the link above, but modified to have a Linux file path): import bpy import os import glob  # Model directory model_dir = '/home/yuerno/Downloads/test'  # Specify OBJ files model_files = glob.glob(model_dir + "*.obj")  for f in model_files:     head, tail = os.path.split(f)     collection_name = tail.replace('.obj', '')     bpy.ops.import_scene.obj(filepath=f)     myCol = bpy.data.collections.new(collection_name)     bpy.context.scene.collection.children.link(myCol)     for ob in bpy.context.selected_objects:         myCol.objects.link(ob)

Is it possible to batch import Wavefront .obj to blender? I'm working on 2.69. If I select multiple .obj files, only one gets imported. Also if I hit A on file selection window to select all files (.obj and .mtl) I get an error, nothing gets imported. I have to import several hundreds of .obj into the blender file, is this possible?


I am trying to get my head around numpy's fancy indexing. While trying to approach the following I am currently unable to solve the problem: Given the following np.array t. t = np.array([[6, 1, 8],            [4, 3, 7],            [9, 5, 2]])  I want to achieve the following pattern using fancy indexing array([[8, 1, 8],        [1, 8, 1],        [8, 1, 8]])  With my closest approach getting to array([[8, 1, 8],        [8, 1, 8],        [8, 1, 8]])  Using t[:,[2,1,2]][[0,0,0]] how to tackle such problems?

I need a good explanation (references are a plus) on Python's slice notation.   To me, this notation needs a bit of picking up.   It looks extremely powerful, but I haven't quite got my head around it.


I have some 40 machines in our company. They are running Ubuntu 14.04 with 4Gigs of RAM. Very recently I noticed that almost on all machines Firefox browser is using around 1.2 to 1.5 GB of RAM and making my computer freeze. Can someone help me in resolving the issue?

I have firefox version 11.0 and am running ubuntu 11.10. Firefox takes upto 850MB RAM with only six or seven tabs opened and all the tabs loaded with light weight websites only. I wonder why would a browser consume so much memory. It keeps increasing its memory consumption over time. I have 3GB RAM and most of the times firefox consumes upto 30% of my memory. How do I fix this?   EDIT:   The output of the command sudo iotop -oPa as asked by @Jippie


I'm trying to find how to check if particular SSD disc can be used on my motherboard:  Motherboard: Gigabyte EX58-UD3R  SSD: Samsung Electronics 840 EVO-Series 250GB 2.5-Inch SATA III Single Unit Version Internal Solid State Drive MZ-7TE250BW  What do I need to look, or search in order to be sure if I can install SSD drive in my PC.  Thanks in advance.

How can I determine whether a given SSD and motherboard are compatible?  For example, I have an OCZ Vertex 2 OCZSSD2-2VTX50G 2.5" 50GB SATA II MLC Internal Solid State Drive and a GIGABYTE GA-H67A-UD3H-B3 LGA 1155 Intel H67 HDMI SATA 6Gb/s USB 3.0 ATX Intel motherboard.


I would like to submit a manuscript which has 5 co-authors. But one of the co-author is presently not working anywhere. So what could be the affiliation of this author? Is it Okay, if I provide the author's last affiliation address?

Recently my paper is reviewed (by a professor from independent third party) and accepted by a journal. But, my employer allows me to publish this paper only without its name there.  Publishing house is expecting affiliation for each author, i.e. I can not leave affiliation as blank.   What should I write as the affiliation?


Hi I need help with the method that follows: var ages = [3, 10, 18, 20]; function checkAdult(age) { return age >= 18; } function myFunction() { document.getElementById("demo").innerHTML = ages.findIndex(checkAdult); }

I need to set a constant value as true or false for the particular scenario not sure correct working or not const test = data.findIndex(d => d.Fname === '' && d.Lname === '') < 0 ? false : true;  if fname and Lname both are blank then i want to set test as false not sure what is happening here.


The Alien Queen made first appearance in the Aliens movie. Although originally, it was intended for xenomorph individuals to convert victims into eggs, this idea was cut from the Alien movie and was later replaced by the Queen and the Hive concepts.  It's however unclear to me how a Queen is produced. As the concept is heavily inspired by social insects I would expect that some facehuggers are made to carry the queen breed. But then this sounds quite risky given how weak facehuggers are alone and how much they rely on chance when looking for victims.  Was the origin of Xenomorph queen ever explained? In the AvP games, a very successful Alien would become a Queen, but I doubt that was canon.

Some of the comments on the question  got me thinking. I've always assumed that after Newt's father got infected, all of the following happens off-screen:   He makes it back to the colony with an alien inside him. That alien "hatches" and kills a few people.   Some more people go back to the original ship looking for answers, and bring back more eggs to experiment on. Something goes wrong (probably due to the first alien), and more people get infected. At some stage the aliens go back to the ship and bring back a queen. Or perhaps the colonists do, but I always thought it was the alien.   User Beta has a different view. Beta says:     I assumed that the colonists in "Aliens" brought only a few parasites   (or one) from the derelict ship, one of them became a queen, and most   of the adults we saw were from her eggs   This seems perfectly valid to me, perhaps making more sense than my original assumptions.    Does anyone know for a fact where the queen came from?


I'm trying to create a loading animation for when a user submits a form before it informs them whether it was successful or if there was an error. My problem is that the loading icon and text is not aligning vertically to the center of the div it is in (col). I wish to have this in the center so that I can replace the column content (loading icon and text) with the response of the form submission after a certain time. I am using Bootstrap 4 and I have tried various different code such as align-items-center and my-auto on the column to no avail.

Loading

   .formSubmitLoad {   position: fixed;   z-index: 1;   left: 0;   top: 0;   overflow: auto;   color: white;   background-color: rgb(0, 0, 0);   background-color: rgba(0, 0, 0, 0.9); }   Snippet:

I have a div with two images and an h1. All of them need to be vertically aligned within the div, next to each other. One of the images needs to be absolute positioned within the div. What is the CSS needed for this to work on all common browsers?

testing...


I have written code to save cookies in JavaScript. Now I need to clear the cookies irrespective of values that I assigned. Are there any script modules to delete all cookies that were generated by ? My Sample Code: document.cookie = 'ppkcookie2=another test; expires=Fri, 3 Aug 2001 20:47:11 UTC; path=/'  function createCookie(name,value,days) {     if (days) {         var date = new Date();         date.setTime(date.getTime()+(days*24*60*60*1000));         var expires = "; expires="+date.toGMTString();     }     else var expires = "";     document.cookie = name+"="+value+expires+"; path=/"; }  function readCookie(name) {     var nameEQ = name + "=";     var ca = document.cookie.split(';');     for(var i=0;i < ca.length;i++) {         var c = ca[i];         while (c.charAt(0)==' ') c = c.substring(1,c.length);         if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);     }     return null; }  function eraseCookie(name) {     createCookie(name,"",-1); }  How else could I clear all of the cookies? Will there will be any problems when I test the code on the webserver?

How do you delete all the cookies for the current domain using JavaScript?


I will have a flight from Boston (USA) to Hanoi (Vietnam) via Toronto (Canada). My first flight will be from Boston to Toronto with Air Canada (2h 45m transit), the second flight will be from Toronto to Tokyo with Air Canada (1h transit) and the last one will be from Tokyo to Hanoi with Vietnam Airlines.    I want to know if I need a Canadian visa just to transit in Canada without going out at the airport?    I have my US visa but it expired six months ago. My nationality is Vietnamese.

I know that in the US foreigners must have a US visa if they have a connection in the US, even if they fly from a different country to a different country. That is because in the US you have to go through passport control regardless of your final destination.  What is the situation in Canada? Does a person who would need a visa to enter Canada need a visa to connect through Canada without exiting the airport?


Let $(M,d)$ be a metric space, $A\subset M$. Prove that $$f(x)=d(x,A)=\inf_{y\in A}d(x,y)$$ is continuous on $M$.   I have tried the following  Let $\epsilon>0$, $x_0\in M$. I have to find $\delta>0$ such that if $d(x,x_0)<\delta$, then $|f(x)-f(x_0)|<\epsilon$.  For that,   $$|f(x)-f(x_0)|<\epsilon\iff \big|\inf_{y\in A}d(x,y)-\inf_{y\in A}d(y,x_0)\big|<\epsilon \iff \big|\inf_{y\in A}\{d(x,y)-d(y,x_0)\}\big|<\epsilon$$ and I do not know how to continue.  Note: My teacher has not defined Lipschitz continuity.

Let $(X,d)$ be a metric space and $A\subset X$ and $x\in X$. Then  $x\to d(x,A)$ is a uniformly continuous function.  If $\partial A=\{x\in X\,:\,d(x,A)=0\}\cap\{x\in X\,:\,d(x,X-A)=0\}$, then $\partial A$ is closed for any $A\subset X$.  If $A,B$ are subsets of $X$  then $d(A, B)=d(B,A)$. If the function is uniformly continuous then $d(x,y)<\delta $ implies $d(d(x,A)-d(y,A))<\epsilon$ , I can not handle the last expression. Difficulty continues for 3rd choice also. At least give me some hints. And for the 2nd choice I think it is true, as it is intersection of two closed sets. As finite intersection of closed sets closed $\partial A$ closed. And logic for former two sets closed is that the sets are preimage of closed set (singleton $\{0\}$ is closed as $\mathbb R$ is $T_1$) under continuous map. I am not very much sure about my ideas and want a verification.


In the current canon, the success of Order 66 was assured by an inhibitor chip implanted in all clones to ensure total compliance when Order 66 is issued, overriding all conscious control by the clone to prevent any attempt to resist the Order, an otherwise highly likely reaction due to the respect, friendship and loyalty the clones have developed with the Jedi over the course of the war.  How did Palpatine ensure that Anakin would be an exception? Clearly, Palpatine planned to execute Order 66 after Anakin is turned to the dark side. But how did he manage to get the inhibitor chip to not include Anakin in the list of targets without Dooku (who was responsible for running the whole cloning operation while still an apprentice to Palpatine) finding out?

. When activated, troopers would immediately perceive Jedi as a threat and kill them.  Since Anakin was a Jedi until around the time of the Order, how did the troopers know not to kill Anakin?


's text reads:      When The Scarab God dies, return it to its owner's hand at the beginning of the next end step.   If I have  in place and my opponent attempts to exile The Scarab God, can I in response, make Mirage Mirror a copy of it, then select the original Scarab God to be put into the graveyard, and finally return it at the beginning of the next end step?  The Legendary rule reads:     If a player controls two or more legendary permanents of the same name when state-based effects are checked, that player chooses one of those permanents and immediately put the others into their owners' graveyards, without any player having an opportunity to respond.   Is that "put the others into graveyard" considered "dying"?

UPDATE  Latest version of diagram, based on feedback in Answers below.    Original Question  Considering a creature card that is currently on the battlefield, is the following diagram accurate?    "Accurate" in the sense of determining triggers etc.:   Indestructible doesn't prevent Sacrificing, or dying from reducing toughness, but does prevent death from damage. "Destroy Target Creature" doesn't require dealing damage. Everything mentioned so far does count for a "when dies" trigger. etc. etc.   Are there anything missing that would fit nicely into the diagram? Are there other ways to leave the Battlefield?  Suggested Text representation for use in answers:  > Left the Battlefield >> Exiled >> Entered the Graveyard >>> Died >>>> Sacrificed >>>> Toughness-Damage <= 0 >>>>> Dealt Lethal Damage [#1] >>>>> Toughness = 0 >>>> Destroyed [Includes #1]


Anyone seen this panel? Essential for precise modeling.

I need this desperately but can't find it. Am I doing something wrong?


Sequence $a_n$ has a property that for every real $x > 1$, sequence $a_{\lfloor{x^n}\rfloor}$ converges to $0$. Does that mean that $a_n$ converges to $0$? I have tried to find a counterexample, but failed at it, so I think it might be true, but I don't know how to prove it.

Problem  One of my best friends asked me to think about the following problem:     Suppose a sequence $\{a_n\}_{n=1}^\infty$ satisfies $\lim_{n\to\infty}a_{\lfloor\alpha^n\rfloor}=0$ for each $\alpha>1$. Is it true that $\lim_{n\to\infty}a_n=0$?   He told me that the preceding proposition (if true) implies Kolmogorov's strong law of large numbers in probability theory. I don't know how, but it's irrelevant.   Thoughts  Suppose $E\subseteq(1,+\infty)$ is countable (for example, $E=(1,+\infty)\cap\mathbb Q$) and $\lim_{n\to\infty}a_{\lfloor\alpha^n\rfloor}=0$ for each $\alpha\in E$, we cannot conclude that $\lim_{n\to\infty}a_n=0$. In fact, we can choose an infinite set $S\subseteq\mathbb Z_{>0}$ such that $S\cap\{\lfloor\alpha^n\rfloor\colon n\in\mathbb Z_{>0}\}$ is finite for each $\alpha\in E$ as follows:  Suppose $E=\{\alpha_1,\alpha_2,\dotsc\}$. We choose $S$ inductively. Suppose $T_0=\mathbb Z_{>0}$. Given $T_{n-1}$, we set $s_n=\min T_{n-1}$ and $T_n=(T_{n-1}\setminus\{\lfloor\alpha_n^k\rfloor\colon k\in\mathbb Z_{>0}\})\setminus\{s_n\}$. By a density argument, it's easy to see that $T_n$ are infinite therefore the process doesn't terminate. Let $S=\{s_n\colon n\in\mathbb Z_{>0}\}$. It's apparent that $\#(S\cap\{\lfloor\alpha_n^m\rfloor\colon m\in\mathbb Z_{>0}\})\le n$.  Given $S$, we set $a_n=1/n$ if $n\not\in S$, and $a_n=1$ if $n\in S$, then $\lim_{n\to\infty}a_{\lfloor\alpha^n\rfloor}=0$ for each $\alpha\in E$, but $\lim_{n\to\infty}a_n$ doesn't exist.  Here we choose $S$ by a diagonal process, therefore we cannot mimic the construction when $E$ is uncountable. In fact, the falsehood of the original statement is equivalent to the existence of $S$, therefore it's essential combinatorial, or related to some topological structure of $\mathbb Z_{>0}$ (say, compactness or Baire category, etc). I have no idea on the general case. Any idea? Thanks!


I'm using a slight variation of the solution indicated  to insert a picture of a signature next to the name of the person who signs in a document with the following code:  \documentclass[11pt]{article} \usepackage{lipsum} \usepackage[a4paper]{geometry} \usepackage{graphicx} \vspace{5mm}  \hspace*{\fill} \begin{tabular}{c c} Name Surname & \includegraphics[scale=0.35]{image.pdf}  \end{tabular} \end{document}   which gives the following result   However I would like to align vertically the text of the left column to the top of the image in the right column. I tried all the solution I found here without any success.

I am facing some problem in aligning (top-aligned) image and text in a table.  \documentclass[11pt,table,a4paper]{article} \usepackage{array,ragged2e} \usepackage{graphicx} \usepackage[top=2cm, bottom=3cm,right=1cm, left=1cm, headsep=26pt]{geometry} \usepackage[T1]{fontenc} \usepackage{fancyhdr} \usepackage[table]{xcolor} \usepackage{sidecap} \usepackage{longtable} \usepackage{helvet} \renewcommand{\familydefault}{\sfdefault} \begin{document}                          % End of preamble and beginning of  text. \arrayrulecolor{gray} \begin{center} \newcolumntype{M}[1]{>{\arraybackslash}p{#1}}  \renewcommand{\arraystretch}{2.0}\begin{longtable}{M{5cm}|M{6cm}|M{6cm}} \hline \rowcolor{gray}    \textbf{ Col1} &  \textbf{Col2} &  \textbf{Col3} \\ \hline  \vspace{0pt} \large{ABC} & \includegraphics[width=0.15\textheight, width=0.15\textwidth]{Europe_regions.png} \hspace{.1cm}    \includegraphics[width=0.15\textwidth]{male-female.png} &  \vspace{0pt} XYZ.   \\ \hline    \end{longtable} \end{center} \end{document}             % End of document.     How can i top-align image and text?


I'm trying to show that $\mathbb{Z}[\sqrt{11}]$ is Euclidean with respect to the function $a+b\sqrt{11} \mapsto|N(a+b\sqrt{11})| = | a^2 -11b^2|$  By multiplicativity, it suffices to show that $\forall x \in \mathbb{Q}(\sqrt{11}) \exists n \in \mathbb{Z}(\sqrt{11}):|N(n-x)| < 1$  For the analogous statement for $\mathbb Z [\sqrt6]$, it worked by considering different cases, so I tried to do the same thing here. Here is what I did so far:  Let $x+y\sqrt{11} \in \mathbb Q (\sqrt{11})$  Case 1: Suppose there exists a $b \in \mathbb Z$ s.t. $|y-b| < \frac{1}{\sqrt{11}}$, then we can choose such a $b$ and a $a \in \mathbb Z$ s.t. $|x-a| \leq \frac{1}{2}$, then we have $|N(x+y\sqrt{11}-(a+b\sqrt{11}))| < 1$  From now on suppose $\forall b \in \mathbb Z: |y-b| > \frac{1}{\sqrt{11}}$  Case 2: Suppose there exists a $b \in \mathbb Z$ s.t. $|y-b| < \sqrt{\frac{5}{44}}$ Then we have $1 < 11 (y-b)^2 < \frac{5}{4}$, so we can choose $a \in \mathbb Z$ such that $\frac{1}{2} \leq |x-a| \leq 1$, then we have $|N(x+y\sqrt{11}-(a+b\sqrt{11}))| < 1$  From now on suppose $\forall b \in \mathbb Z: |y-b| > \sqrt{\frac{5}{44}}$  Case 3: Suppose there exists a $b \in \mathbb Z$ s.t. $|y-b| < \sqrt{\frac{2}{11}}$ Then we can choose $a \in \mathbb Z $ s.t. $1 \leq |x-a| \leq \frac{3}{2}$, then we have $|N(x+y\sqrt{11}-(a+b\sqrt{11}))| < 1$  From now on, we may suppose that $|y-b| > \sqrt{\frac{2}{11}}$.  This is where I'm stuck. I tried choosing $b \in \mathbb Z$ s.t. $\frac{1}{2} \geq |y-b| > \sqrt{\frac{2}{11}}$, but then I run into problems, whether I choose $a \in \mathbb Z$ s.t. $1 \leq |x-a| \leq \frac{3}{2}$ or s.t. $ \frac{3}{2} \leq |x-a| \leq 2$

I am trying to generalized, for which integral values of $d$,   $\mathbb{Z}[\sqrt{d}] = \{ a + b\sqrt{d} \vert a,b\in\mathbb{Z}\}$ is an Euclidean domain?   I am interested specially in positive integral values of $d$.


Orbitals fill in the following order, 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, etc.  Its a nice pattern that many elements follow, but there are exceptions to.  For example:  V:  1s2 ... 4s2 3d3 Cr: 1s2 ... 4s1 3d5  And not: (which would seem to be breaking pattern)  Cr: 1s2 ... 4s2 3d4  This can also be seen on other elements, where a higher shell 'steals' from one below it in a seemingly random order.  Is there a reason behind this, and if so,  even if complex, what pattern is there to it?  I am new to the world of the very small, new to chemistry.  Any help is greatly appreciated.

Why do electrons not fully fill up all the orbitals sequentially? By this I mean: why don't the electrons fully take up the previous orbit first and then move onto the next orbit? Take calcium for example, it's electron config is 2, 8, 8, 2. Why isn't it 2, 8, 10? Why does another orbit need to be created when there are still many spots to fill up?  (I know that this is a chemistry question in a physics forum, but I really could not find a chemistry or even a broader science type forum here )


How can i enable user to have reboot privileges without sudo? Need to keep sudo password enabled.  ssh user@server "sudo reboot" does not work because it requires a password to be entered.    Want this to work: ssh user@server "reboot"  i have tried /etc/shutdown.allow but  reboot: Need to be root

On one particular machine I often need to run sudo commands every now and then. I am fine with entering password on sudo in most of the cases.  However there are three sudo commands I want to run without entering password:   sudo reboot sudo shutdown -r now sudo shutdown -P now   How can I exclude these commands from password protection to sudo?


When a thermodynamic system gains heat if the heat gain is irreversible then there is a entropy generation along with the entropy transfer..so is there a similar entropy generation associated with irreversie heat loss too? This is the second time i am askng this question so can somebody give me a good answer..?

Consider a heat reservoir which gains heat $Q$ irreversibly at temperature $T$ from the surroundings which is at temperature $T_0$. The entropy change of reservoir is then given by $\frac{Q}{T}$, while that of the surroundings is $-\frac{Q}{T_0}$.  My question is, how is this possible? According to the Clausius inequality, the entropy change of a irreversible process is greater than that due to heat transfer. Please help, thank you!


I lost my USB bluetooth dongle (from DEll) which I used for a wireless  mouse. kindly provide solution

I lost my USB bluetooth dongle (from HP) which I used for a wireless keyboard and mouse. They came together in a set when I bought my last HP computer.  Are the keyboard and mouse useless now? or will any bluetooth dongle allow them to work? If I can just buy a new one - any recommendations on a replacement (good price, and perhaps works with Windows and Ubuntu out-of-the-box?   Forgive me if this is an easy question. I'm just not that familiar with wireless mice/keyboards.


For some problem sheets I have been using the shortenumerate package with hardcoded widths for the columns so far and I wanted to use multicols instead which is a lot easier to use. However the enumerate items on the left are not aligned with the ones on the right - in my example below there is a fraction on the right which takes more height than the left (a) equation and the interval in (e) takes a lot more space than the equation (f) simliarly to the second line with (c) and (d). As such I was wondering whether there is a possibility to use the same height throughout the enumeration to align everything properly.  \begin{multicols}{2}     \begin{enumerate}         \item[(a)] $\displaystyle f(x)=2x^7-x^5+6x+1$, $D=\mathbb{R}$                    \item[(c)] $\displaystyle f(x)=\sqrt{x}$, $D=[0,\infty)$                     \item[(e)] $\displaystyle f(x)=\tan(x)$, $\displaystyle D=\left(-\frac{\pi}{2},\frac{\pi}{2}\right)$                     \item[(b)] $\displaystyle f(x)=\frac{x+1}{x^2+x+7}$, $D=\mathbb{R}$         \item[(d)] $f(x)=\sin(x)\exp\left(\left (x+1\right )^2\right)$, $D=\mathbb{R}$         \item[(f)] $\displaystyle f(x)=2^x$, $D=\mathbb{R}$     \end{enumerate} \end{multicols}

Do you have a simple, minimal template to type Exercise sheets with exercises enumerated with two columns (please check image).    Thank you.


I have the following code  \usepackage{tikz} \usepackage{pgfplots} \usepgfplotslibrary{dateplot}  \begin{figure} \begin{tikzpicture} \begin{axis}[     height=9cm, width=10cm,     title={title},     date coordinates in=x,     xticklabel=\month, ] \addplot[blue] table[x=x1,y=y1] { x1    y1   name 2009-01-01  40  name1 2010-01-01  50  name2 2011-01-01  70  name3 2012-06-01  70  name4 2013-06-01  100 name5 }; \end{axis} \end{tikzpicture} \end{figure}   What I want is to label every point on the plot with labels from 'name' column. I would appreciate any help.

I was wondering how to remove arrow from pgfplots pin option. I do not want any line and want only text.   Many Thanks in advance!    Edit: Added MWE:    I would like to remove the two arrows but want to keep the text only. I am also attaching the output.     \documentclass{standalone}     \usepackage{amsmath, amssymb}     \usepackage{pgfplots}     \usepackage{tikz}     \usepackage{lmodern}     \usepackage[T1]{fontenc}     \begin{document}     \begin{tikzpicture}[every mark/.append style={mark size=1pt}]     \begin{axis}[xmin=0, xmax=0.2, ymin=-0.01, ymax=1, width = 8cm, height = 7cm, xtick align =inside, ytick align =inside, ytick distance=0.2, xtick distance = 0.05, minor x tick num={1}, minor y tick num={1}, xlabel = Volume fraction , ylabel= {Area disorder (AD)}, legend style= {nodes={scale=0.5, transform shape}, legend pos= north east, legend cell align={left}}, y tick label style = {/pgf/number format/.cd,             use comma,             1000 sep={}, set decimal separator={.}, fixed,                 fixed zerofill,                 precision=1,             /tikz/.cd}, x tick label style = {/pgf/number format/.cd,             use comma,             1000 sep={}, set decimal separator={.}, fixed,                 fixed zerofill,                 precision=2,             /tikz/.cd}]      \addplot [only marks, red, mark=square*,mark options={solid, scale=0.6}] coordinates{(0.056,0.3759)};%\addlegendentry{6 wt\% CTBN};     \addplot [color= red, mark=square*,mark options={solid, scale=0.6}] coordinates{(0.097,0.4418)}; %\addlegendentry{9 wt\% CTBN};     \begin{scope}[       every pin edge/.style={<-,>=latex},       pin distance=1.5 cm,       every pin/.append style={font=\small}     ]     \node[coordinate, pin={[fill=white, pin distance = 5 mm, inner sep=2pt]90:{9R}}]                 at (axis cs:0.097,0.4418) {};     \node[coordinate, pin={[fill=white, pin distance = 5 mm, inner sep=2pt]90:{6R}}]                 at (axis cs:0.056,0.3759) {};     \end{scope}     \end{axis}     \end{tikzpicture}      \end{document}


My materials section (the bottom one) is far different from what  the top section looks like. I need help in how i could change it to look like that.

Complete beginner here.  I'm trying to follow  tutorial on Anisotropic shaders, but my property panel looks nothing like the property panel in the tutorial.  For example, when creating a material, this is what his property panel looks like:    But this is what mine looks like, if I follow the same path:    I'm sure I'm missing something obvious.  How can I see the property panel shown in the tutorial?


The question says it all. When using Xamarin this pattern comes up :   public string Property         {             get             {                 return this.propertyField;             }              set             {                 if (value != this.propertyField)                 {                     this.propertyField = value;                     NotifyPropertyChanged();                 }             }         }   And it seems like I I have to do this for each property I have. Any way to avoid repetion?

Is there any way to automatically get notified of property changes in a class without having to write OnPropertyChanged in every setter?  (I have hundreds of properties that I want to know if they have changed).    Anton suggests .  I've actually used the "Castle" library for something similar in the past, and while it does reduce the amount of code I've had to write, it added around 30 seconds to my program startup time (ymmv) - because it's a runtime solution.  I'm wondering if there is a compile time solution, maybe using compile-time attributes...    Slashene and TcKs give suggestions which generates repetitive code - unfortunately, not all my properties are a simple case of m_Value = value - lots of them have custom code in the setters, so cookie-cutter code from snippets and xml aren't really feasible for my project either.


I am new to machine learning and I would like to know whether my trained CNN is overfitting. So I have drawn the curves training and testing losses versus the training epochs.  I have trained my CNN for about $50$ epochs with a learning rate equal to $10^{-3}$ that decreases every $3$ epochs by a factor $0.5$.  I found an answer to this question  but I couldn't find an exact similarity measure between the testing and training error/loss to make a decision.  I have attached the figure of these curves below and I would appreciate any comment.

I understand that dropout is used to reduce over fitting in the network. This is a generalization technique. In convolutional neural network how can I identify overfitting? One situation that I can think of is when I get training accuracy too high compared to testing or validation accuracy. In that case the model tries to overfit to the training samples and performs poorly to the testing samples. Is this the only way that indicates whether to apply dropout or should dropout be blindly added to the model hoping that it increases testing or validation accuracy


How can we check the mount points for partitions listed in /dev/sd*? For example, I would like know if the partition for my home is /dev/sda4.

I used mount to show mounted drives, I don't want to see the not so interesting ones (i.e. non-physical). So I used to have a script mnt that did:  mount | grep -Ev 'type (proc|sysfs|tmpfs|devpts) '   under Ubuntu 8.04 and showed me ext3 and reiserfs mount points only. That line is actually commented out and now I use (for Ubuntu 12.04):  mount | grep -Ev 'type (proc|sysfs|tmpfs|devpts|debugfs|rpc_pipefs|nfsd|securityfs|fusectl|devtmpfs) '   to only show my ext4 and zfs partitions (I dropped using reiserfs).  Now I am preparing for Ubuntu 14.04 and the script has to be extended again (cgroup,pstore). Is there a better way to do this without having to extend the script? I am only interested in physical discs that are mounted and mounted network drives (nfs,cifs).


I want to create a recursion pseudocode that will executed in O(logn) complexity and i want it to find the lower f(i) < 0 and f[1....n] which f(1) >0 and f(n)<0  prodedure fanc(A[n] , p , q )  //(this is my array,first digit of A ,last digit of A) if A[n/2] >= 0      return fanc(A[n/2] , A[n/2] , A[n-1]) else      return fanc(A[n/2] , A[0] , A[n/2 -1]) if p<q    print p else    print q   I know that somehow i have to end the recursion. Also i would like to know if i am in the correct path and if u have any good thoughts for this problem!    Better text of assignment copied from :     Let an integer function f:{1,2,3...n} be monotonic and defined in {1,2,3...n} and suppose that f(1) > 0 and f(n) < 0. We would like to find the smallest integer i with f(i) < 0. Design an algorithm for this purpose that run in O(logn).

How would I implement a binary search using just an array?


document.getElementById('btn1').addEventListener("click", function() {  document.getElementById('div2').innerHTML = document.getElementById('hidden-div').innerHTML; }); document.getElementById('btn2').addEventListener("click", function() {  document.getElementById('div-main').innerHTML = ""; });
  <input type="button" name="button1" value="button1" id="btn1">

      <input type="button" name="button2" value="button2" id="btn2">

     i want to add a button2 on click button1, button2 initially is in a hidden div when i click button1 then button2  comes in div2 but when i click button2 its event doesn't work.

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


I am looking for a word or phrase for the following: friends who contact you only when they need something or assistance

Looking for a word to describe a person who only makes friends to benefit themselves.


I was thinking of buying a Canon EOS Rebel T6 to start of with DSLR. Is it a good option? Previously I have used Canon EOS 1200D and Nikon D3300 from some of my friends. And also should I buy the f/1.8 prime lens simultaneously? I want to click some portraits as well.

I am thinking of buying a digital SLR camera. What things should I be looking for?


I am wondering something. In the XML file of a lightning message channel I can specify lightningMessageFields or I can omit this. Either way messages on the channel function correctly whatever you put into them. Example one with no fields: <LightningMessageChannel xmlns="http://soap.sforce.com/2006/04/metadata">     <masterLabel>TestChannel</masterLabel>     <isExposed>true</isExposed>     <description></description> </LightningMessageChannel>  If i create a payload like this, it works: let message = {request: true}; publish(this.context, TESTCHANNEL, message);  Example two with a field called 'success': <LightningMessageChannel xmlns="http://soap.sforce.com/2006/04/metadata">         <masterLabel>TestChannel</masterLabel>         <isExposed>true</isExposed>         <description></description>         <lightningMessageFields>                <fieldName>success</fieldName>         <description></description>     </lightningMessageFields> </LightningMessageChannel>  The same payload still works: let message = {request: true}; publish(this.context, TESTCHANNEL, message);  So why bother with fields? If any one has any insight into this, Id be very interested. Thanks. Dane

I was thinking - while publishing or subscribing to a LightningMessageChannel, the payload has to be in some way match exactly to the names or fields defined in the lightningMessageFields  XML definition of the channel. Found out my code/components are working without any consideration to the actual names used in the lightningMessageFields.  Whatever I send to the channel( by any name ) I can get back and process in the subscribing component. Am I doing something wrong here or is there any special benefit sticking to the fields defined? if so where can I find details of usage patterns for this specific aspect of LightningMessageChannel fields?


Given database of the website "eMovies" that manage data about cinema movies.      Write in SQL query that finds the names of the directors that played in movies that they directed     My attempt:   SELECT Directors.FirstName, Directors.LastName  FROM Directors, DirectorsMovies,ActorsMovies  WHERE Directors.DirectorID=DirectorsMovies.DirectorID=ActorsMovies.ActorID  GROUP BY FirstName,LastName;   My code does not work well.

Given database of the website "eMovies" that manage data about cinema movies.      Write in SQL query that finds the names of the directors that played in movies that they directed     The tables:  Actors      ActorID      PK     Firstname      LastName  Directors      DirectorID   PK     Firstname      LastName  Genres      GenreID      PK     GenreDescr   Movies      MovieID      PK     MovieName      Year  ActorsMovies      MovieID      PK     ActorID      PK   DirectorsMovies      MovieID      PK     DirectorID   PK   GenresMovies      MovieID      PK     GenreID      PK    My attempt:   SELECT Directors.FirstName, Directors.LastName  FROM Directors, DirectorsMovies,ActorsMovies  WHERE Directors.DirectorID=DirectorsMovies.DirectorID=ActorsMovies.ActorID  GROUP BY FirstName,LastName;   In the output I see an empty table, someone can tell me why and how can I improve my code? or any other working code please?.


When reviewing edits, I often find minor changes which simply remove the name from the original question. So the user wrote something like   Thanks,     myname   at the end of the question and somebody edits this out.  OK, the greetings is not really necessary for a posting so it doesn't hurt. If I see that the original poster wants to remove it, it's also fine for me. However if somebody else removes this, without any other changes I'm a bit torn.  For privacy reasons I would personally agree, as I feel that the name of the person shouldn't matter, and it just makes tracking easier for cross referencing with other information about a given person in the internet. However, if the person added his name, then he should know what he is doing, so why should I disrespect that by removing his name?  So, should such a change be rejected as a minor edit, or should it be approved?

I edit a lot of posts every day. I often run across posts with 'Hi' and 'Thanks' on the top and the bottom of the post respectively. I also run across things like:     --User   Should these items be removed during the editing of the post by an editor?


I have some list tag in my HTML page .I want to find the text and id of list tag separately. Since my list is created in the run time so I cant figure out how to get the id and text value.  I have tried this  $("#users li").click(function(e)  {       console.log($(this).text());      console.log($(this).id); });   But it is not triggering any click event.  HTML part

Online Users

   jquery part  $(function () {     var socket =io.connect();     var $users =$('#users');      socket.on('get users',function(data){     var html='';     for(var i=0;i<data.length;i++){          html+='
'+data[i]+'
';     }     $users.html(html);     });      $($users).click(function(e)     {      console.log($(this).text());     console.log($(this).id);    }); }


While studying confidence intervals, every example I have gone through assumes that the sample data comes from the normal distribution of the population. So, for the confidence interval, do I have to assume that the data comes from the normal distribution?

Which visualization libraries (plots, graphs, ...) would you suggest to use in a standalone application (Linux, .Net, Windows, whatever). Reasonable performance would be nice as well.


VADER: The Rebels are alerted to our presence. Admiral Ozzel came out of light-speed too close to the system. VEERS: He felt surprise was wiser... VADER: He is as clumsy as he is stupid. General, prepare your troops for a surface attack.  Even if Admiral Ozzel came out of light-speed at an optimal distance from the system, how did they plan to approach (land to capture Luke Skywalker) Hoth without alerting the Rebels? Also, didn't Darth Vader's ultimate plan to capture Luke Skywalker on Hoth require a surface attack anyway?

From the :  Alarms sound throughout the hidden Rebel base.  In the control room, a  controller urgently gestures for General Rieekan to check a computer  scan.              CONTROLLER     General, there's a fleet of Star      Destroyers coming out of hyperspace      in sector four.              RIEEKAN     Reroute all power to the energy      shield.  We've got to hold them till      all transports are away.  Prepare      for ground assault.  Rieekan exits hurriedly.   [...]               VADER     What is it, General?              VEERS     My lord, the fleet has moves out      of light-speed.  Com-Scan has      detected an energy field protecting      an area around the sixth planet of      the Hoth system.  The field is      strong enough to deflect any      bombardment.              VADER         (angrily)     The Rebels are alerted to our      presence.  Admiral Ozzel came out      of light-speed too close to the      system.              VEERS     He felt surprise was wiser...              VADER     He is as clumsy as he is stupid.     General, prepare your troops for a      surface attack.              VEERS     Yes, my lord.   Why exactly was this a bad idea, and what was Vader's preferred strategy? The Rebels can apparently raise their shield instantly, so it seems like they would do that anyway, surprised or no. In fact, since being surprised gives them less time to prepare, it seems like this is a good strategy on the Empire's part.  Is the issue that the Imperial forces didn't have enough time to prepare, and it would have been better to come in farther out and spread out, as  says? If so, why wouldn't forming up while already in the system also give the Rebels warning, and give them even more time to escape? All I can really think of is that they would have somehow known the range of the Rebel sensors, dropped out of hyperspace just past them, formed up, then quickly flown into range, but that seems hard to infer from the exchange between Vader and Veers.


If really long tags are selected for a question, it pushes the user info down:    Windows 7 Chrome Version 31.0.1650.63 m  Wrapping the tags would look better:

I know this isn't a big deal, but I thought I'd bring it up anyway.  When a question has a particularly long set of tags, it causes the user name to drop below the tag list:   This is a bit ugly IMO, so I recommend adding this CSS (or something similar):  .tags {     max-width: 450px; }   Which causes the tag list to wrap more gracefully:   Since the .tags class already has float: left, this might have been the intended behavior, but I'm tagging this as a feature request rather than a bug because it's so minor.  Update  After playing around with a user style sheet, I realized that in 'mini' question lists, , this tweak is not appropriate. The user style sheet I'm using right now is:  .tags { max-width: 450px; } .narrow .summary .tags { max-width: none; }   Although there's probably a better way to do this.


I have been wondering to find the answer of some fundamental questions in quantum mechanics and the answer to the above question will help me to clear doubts of quantum world

Linear operators and vector spaces form the backbone of the operator formulation of quantum mechanics. I want to ask are there operators in classical physics too? Are these operators defined on some vector space? Examples can also be helpful.


I have a Bulgarian Blue Card, and I know that it is not valid for countries in the Schengen area. But, I can go, for example, to Romania (I was there last week) with the blue card.  There are others countries like Romania in Europe where I can go with my Blue Card for vacation?

I am a Ukrainian citizen and recently moved to Bulgaria for work. I have received a Blue Card as a high-skilled professional. Does this Blue Card allow me to travel without receiving additional visas to:   Schengen states? EU states?   I can't find this information online. Any links/references will be much appreciated.


I want to install Ubuntu on a USB flash drive. There is Windows 10 installed on my internal SSD. My SSD mode is Intel Obtane, not AHCI. That is why, I cannot install Ubuntu alongside Windows 10 on my SSD. This is the reason why I want to install Ubuntu on a USB flash drive.  I once attempted to do so. But there are two issues that I need to clarify:  a) Can I select "Erase disk and install Ubuntu" as the installation type? Please note that since the SSD mode is not AHCI, the Ubuntu installer does not detect neither my SSD nor Windows 10. It only detects the two USB flash drives: The one that the Ubuntu installer runs on and the one that I want to actually install Ubuntu on. Since it does not detect any operating system and drives other than the USB ones, I think I can safely select this option. But I am not sure. I need your advice.  b) If on the other hand, I select "Something else", I encounter a problem. As before, it only detects my USB flash drive and I create a partition on it. I select "use as Ext4 journaling file system" and "mount point /". The problem arises when I select the device for boot loader installation. Again, there is only my USB flash drive there. I just select it and when I press "install now", I receive the message that "No EFI system partition was found, the system will likely not be able to boot successfully and the installation may fail". I do not know what to do. Do I have to create another partition on the USB drive? Actually, why should such message appear, since the installer only detects the USB flash drive? There is no SSD that it can mess up.   Please answer my question as detailed as possible, because I could not find relevant advice in other questions and their answers.

If you are hurrying to reply, System → Administration → StartUp Disk Creator -- no, that's not what I'm talking about.   I want to try Ubuntu 11.04's Unity without touching my existing Ubuntu install.  To do this, I need to install the nVidia drivers first (sigh).  To do this, I need changes to persist a reboot.  To do this, I need to really install Ubuntu on a USB key.  How do you do that?    What I tried   I tried to make a USB key from , then boot from it, then choose "Install Ubuntu." The installer refused to install to the installation media itself. I tried, from my installed copy of Ubuntu:  sudo kvm /dev/sdb --cdrom .cache/testdrive/iso/ubuntu_natty-desktop-i386.iso   ...but the installer didn't detect the disk properly.


I have one input field with type text and jQuery Datepicker. A weird thing happening is that when I click on that input field, chrome shows a password suggestion.  <input name="registration" type="text" placeholder="MM.JJJJ">   When I remove the name then it stops suggesting passwords.

How do you disable autocomplete in the major browsers for a specific input (or form field)?


I was trying to write a mockito test case (spring boot java rest) for a rest API in controller Class. I was getting a Null pointer exception, Thanks in advance. TestController @RestController @RequestMapping("/heloo") public class TestController {      @GetMapping     public String HellooWorld()     {         return "hello world";     } }  JunitTestCase class @SpringBootTest @RunWith(SpringRunner.class) class EmployeeApiTest {      private MockMvc mockmvc;      @Autowired     WebApplicationContext context;     @InjectMocks     private TestController testcontroller;     @InjectMocks     private EmployeeApi employeeapi;     @Before     public void setup()     {         mockmvc=MockMvcBuilders.standaloneSetup(testcontroller).build();         //mockmvc = MockMvcBuilders.webAppContextSetup(context).build();     }      @Test     void getMockitotest() throws Exception {         mockmvc.perform(MockMvcRequestBuilders.get("/get"))         .andExpect(MockMvcResultMatchers.status().isOk())         .andExpect(MockMvcResultMatchers.content().string("hello world"));              }  }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I have a doubt on https connection -  In TLS/SSL handshake,  browser/http client requests to server. Server responds with digial certificate. That means any one can get digital certificate.' This way a hacker can get a valid digital certificate, this digital certificate hacker can put in his server and use for successful https connection with browsers pretending his server is the  valid server.  Can anyone please explain what actually happens here?

What is the series of steps needed to securely verify a ssl certificate?  My (very limited) understanding is that when you visit an https site, the server sends a certificate to the client (the browser) and the browser gets the certificate's issuer information from that certificate, then uses that to contact the issuerer, and somehow compares certificates for validity.     How exactly is this done?  What about the process makes it immune to man-in-the-middle attacks? What prevents some random person from setting up their own verification service to use in man-in-the-middle attacks, so everything "looks" secure?


This is maybe a duplicate like , but the error still appears.    When I try to click "mark as duplicate" a HTTP 404 error occur.  I'm using Firefox 16.0.2 with Firebug on Mac OS X 10.5.8

I attempted to flag ...        ...as "off topic". Although the initial flag dialog loads correctly, every time I selected the "it doesn't belong here, or is a duplicate" option, the next pane would fail to load:        Request URL:https://christianity.stackexchange.com/flags/questions/18136/close/popup?_=1375739403107 Request Method:GET Status Code:404 Not Found   The account had 46 reputation. I tested this on other sites, but found that it only occurred on Christianity.SE. This was my only account that has the for the  but not enough for the .     I have now earned the commenting privilege on Christianity and am no longer able to reproduce this error, confirming its cause.


If Biff takes the time machine and goes back in time to deliver the Almanac to young Biff, how does old Biff return to his original time line if in the future he altered he became rich? Wouldn't he end up in the rich Biff future? Chronologically... he comes back from the past to his original time after altering the future.

In Back to the Future Part II, there is a scene where old Biff exits the DeLorean. Here he seems to be in a lot of discomfort. He breaks his cane too. He just made himself a rich man, shouldn't he been seen coming back happy?


I have always assumed that you doubled the consonant when the vowel preceding it is short.   bet and betting for example; Why is this different for market and marketing?

Example of such words are:     As far as I know, at least in American English, words that have single syllable double their ending consonant letters when modified.  Such as:  hop - hopping cut - cutting map - mapped   Another part of my question is, are there any exemptions to this rule? Does this rule also apply in British English? If yes, what are the exemptions? If not, what rules apply in regard to this specific matter?  If there are no such rules, perhaps the only way to go is by memorization. Could anyone cite me a real good exhaustive list of such words?


I've been playing D&D 4e for a while, and I've been considering n getting 5e or 3.5, and what are the main differences between 4e and 3.5e? I know 4e is more combat orientated, is 3.5e that same way? Or is it more roleplay oriented?   Thanks!

I have a small group of players who don't play often and we've been playing D&D 3.5.  I wanted to know if there are any significant differences between D&D 3.5 and D&D 4e? Do they use a different style of game? Is one better suited for certain groups? Or is D&D 4th edition just an 'update' of D&D 3.5?  I'd like to know about the major differences (the bard class was removed?) and about any small differences that people have noticed whilst playing.


I don't have an ethernet adapter.   If I go to Settings > Wifi there is "No Wi-Fi adapter Found".  lspci | grep Network Network controller: Intel Corporation Device 02f0   lspci -knn | grep Net -A3; rfkill list Network controller[0280]: Intel Corporation Device [8086:02f0] Subsystem: Intel Corporation Device [8086:0030] Kernel driver in use: iwlwifi Kernel modules: iwlwifi 0: hci0: Bluetooth   Soft blocked: no   Hard blocked: no   Can anyone help me, please?

I have a Lenovo Yoga 13 and I was running 14.04 on it and I've since upgraded to 16.04. I applied the fix descibed here () with 14.04 and it worked but no longer seems to with 16.04. I know that the way Realtek drivers work was reorganized in Linux kernel 4.4 () however I don't know enough about what was changed to know if that was the problem. Has anyone else experienced this issue or know how to fix it?


I didn't  even know there was a daily reputation limit until I earned this badge today, and I appear to have exceeded it already.  Curious.

I've found some questions and those two badges "Epic" and "Legendary" regarding the "daily reputation cap". What is it and how can I hit it?


In the man of find the -ctime is said to be :  -ctime n            File status was last changed n*24 hours ago.  See the comments           for -atime to understand how rounding affects the interpretation           of file status change times.  -atime n           File  was  last  accessed n*24 hours ago.  When find figures out           how many 24-hour periods ago the file  was  last  accessed,  any           fractional part is ignored, so to match -atime +1, a file has to           have been accessed at least two days ago.   I know from  that the ext4 file system stores the creation date , and you can get it using stats , is the status change times they are talking about in the manual the same as the one given by stats ? or precisely , is the ctime the date of creation of a file ?

In what order are the dated ordered by? Certainly not alphanumeric order.  ls -lt sorts by modification time. But I need creation time.


I have convinced myself that this true, however I'm at a loss of where I should start with this proof. Looking at a similar proof with 3 instead of 9, I saw the use of the basis representation theorem, but I'm not 100% comfortable with that, so it was hard for me to follow. Is there a way to do this with mod?

Suppose we have a natural number $N$ with decimal representation $A_kA_{k-1}\ldots A_0$. How do I prove that if the $\sum\limits_{i=0}^kA_i$ is divisible by $9$ then $N$ is divisible by $9$ too?


I'm at the end of my doctoral degree in mathematics. As far as I'm aware, I've been using the symbol $\implies$ effectively for 10-years of higher education (for example, effectively enough to get research papers in mathematical physics through peer review). I thought I would brush up on my formal logic, and it turns out that my intuitive understanding of what $\implies$ means is not enough to understand the logic table of $\implies$; $$     \begin{matrix}     A & B & A \implies B\\     T & T & T \\     T & F & F \\     F & T & T \\     F & F & T     \end{matrix} $$ Suppose I have the following three propositions: $$ A: 2^2 = 4 $$ $$B: \sin(n\pi) = 0 \;\forall \; n \in \mathbb{Z}$$ $$C: \sin(0) = 0$$ All of these statements are true. B is a more general version of C, and A is unrelated to B and C. I see that B is true, and C is true, and if I know B then I will know C. So I agree with the truth table if I apply it to B and C. However, A and B are both true, but if I know A it doesn't tell me anything about B. So I don't see why I would want to say that A $\implies$ B is true in this case. My intuitive understanding of $\implies$ in relation to A and B is then that A doesn't imply B, and I'd say that  A $\implies$ B is false. Can anybody give me some intuitive explanation about why I would want to assign this truth table to $\implies$, preferably with some examples? The lecture notes I've been reading seem to think that "snow is black implies grass is red" is a good example for understanding this truth table. Apparently from the fact that "snow is not black" and "grass is not red", it should be intuitively obvious to me that "snow is black implies grass is red" is true. I run into the same problem here; as far as I can see the colour of snow doesn't tell me anything about the colour of grass. I think my confusion is coming from the fact that I'm assigning some kind of causality to $\implies$, when I'm not supposed to do that? That's what my reading told me anyway, but I don't understand it. Any explanation about what operation what my intuitive understanding may be referring to would also be helpful for me. I think this is probably some concept from probability or information theory (if you guessed that my research so far hasn't been too closely related to these fields, you'd be correct). Edit; I'm looking for some explanation about what concept from probability or information theory captures the intuitive understanding of the word implies that I've tried to express here, additionally to the explanation of the formal logic

I am trying to understand the fundamentals of mathematical logic in order to be able to study discrete mathematics and computer science soon.  I have a big problem understanding Implication. I understand the idea intuitively very well; for example:  $$ x >0  \implies 2x>0 .$$  Or  $$ x \text{ is a prime number} \implies x \geq 2 .$$  I notice that there is always a (connection) between the hypothesis and the conclusion; they seem to be related and fall in the same context.  What I don't understand is: according to the truth table, any two propositions can be linked through an implication even if they are not related at all, or they belong to different contexts.  For example :  $$ \text{A day is 24 hours} \implies \text{A cat has four legs and a tail} .$$  which is logically or mathematically TRUE, because both statements are true and according to the truth table when when both inputs are true for any two statements then the implication is true.  How can that be true?  Another example:  $$ 2 \text{ is a prime number} \implies \text{An hour is 60 minutes}.$$  again, which is logically or mathematically TRUE, because both statements are true and according to the truth table when when both inputs are true for any two statements, then the implication is true.  How can that be true? That's my first question.  The second question could be the same:     How can we use truth tables with implication anyway?   What I understand is truth tables are used to list the probabilities of the output based on the logical values of the inputs. So the value of the output of any line in the truth table depends (only) on the logical values of the inputs in that line and has nothing to do with the conditional connection between the two inputs.   How can we display a conditional statement in a truth table the same way we display a logic gate or so? In other words, how can I tell only from the values of $P$ and $Q$ that $P \implies Q$?


When I have a nested directory find . -name "*.py" -print command gives me all the python scripts beneath current directory. However, find . -name *.py -print returns only the python scrips in current directory.   Is this expected behavior? What makes this difference? I use Mac OS X 10.7.

Using find with grep, one can locate files that match a pattern:  # find | grep error ./solr-modifiedSolr4/SolrPhpClient/phpdocs/errors.html ./error_log ./includes/classes/error_log   However, using find alone the first file is not found:  # find . -name error* ./error_log ./includes/classes/error_log   Why doesn't find locate the errors.html file when not used with grep? How is find used to show this file as well?


I'm new to JS. I try the function closure, just as in the documentation example and I get an uncaught reference. Why?  function fetchData(filter) {     return $.ajax({         type: "GET",         contentType : "application/json; charset=utf-8",         dataType: "json",         url: "my_url"+route,         data: filter       }); };  function fetchDataSource(filter) {   var route = "data_source";   return fetchData(filter); };   And now, when I call the function:  var filter; fetchData(filter);   I have the following error:     Uncaught ReferenceError: route is not defined       at fetchData (:6:49)       at fetchDataSource (:3:10)       at :1:1   Why is route not visible in my function?  Thanks

What is the scope of variables in javascript? Do they have the same scope inside as opposed to outside a function? Or does it even matter? Also, where are the variables stored if they are defined globally?


I have known that the only finite group which has only one automorphism is the cyclic group with order less than $2$. But what's the infinite situation? Is there any infinite group which also satisfies  this condition?

Well, this is an exercise problem from Herstein which sounds difficult:   How does one prove that if $|G|>2$, then $G$ has non-trivial automorphism?   The only thing I know which connects a group with its automorphism is the theorem, $$G/Z(G) \cong \mathcal{I}(G)$$ where $\mathcal{I}(G)$ denotes the Inner- Automorphism group of $G$. So for a group with $Z(G)=(e)$, we can conclude that it has a non-trivial automorphism, but what about groups with center?


I need to recursively append a Node to a linked list, not sure why my code doesn't work public void RecursiveAppend(Node example, Node add){    if(example == null){        example = add;     } else {        RecursiveAppend(example.next, add);    } }  Method to print list public void IterativeTraversal(){        Node example = m_head;        while(example != null){            System.out.print(example.data + " ");            example = example.next;        }    } public class LinkedListDemo {     public static void main (String [] args){         LinkedList example = new LinkedList();         Node A = new Node(10);         Node B = new Node(30);         Node C = new Node(50);         Node D = new Node(70);         example.append(A);         example.append(B);         example.append(C);         example.RecursiveAppend(D);         example.IterativeTraversal();     } }  Result: 10 30 50

I always thought Java uses pass-by-reference. However, I've seen a couple of blog posts (for example, ) that claim that it isn't (the blog post says that Java uses pass-by-value). I don't think I understand the distinction they're making. What is the explanation?


Given positive integers $a$, $b$ and $c$, I'd like to ask whether we may adopt some variant of the Euclidean algorithm to calculate $\gcd(c^a+1,c^b+1)$ fast?

I know that $$\gcd(a^b-1,a^c-1)=a^{\gcd(b,c)}-1$$ which can be seen by expanding both terms into geometric series. Is there any such simplification for $$\gcd(a^b+1,a^c+1)=?$$  EDIT: When working with polynomials instead of whole numbers, it is $$gcd(x^n+1,x^m+1)=\begin{cases}a^{\gcd(n,m)}+1 & \nu_2(n) =\nu_2(m)\\1 &\text{else}\end{cases}$$ But this gives only a lower bound for the whole-number case.


Recently I bought "asus k55vd-sx313r". Earlier I am using Lenovo G570. I installed Ubuntu 12.04 in Lenovo by choosing "Something Else" option, Keeping 2 Gb for Swap 10Gb for Root And 5Gb for Home. After Restart normally windows is opening, but Ubuntu is not detected. Even though hard partitions remain a new drives 10gb and 5gb.

I installed Windows 8 and after that I installed Ubuntu. This are my partition now:   70Gb --> Windows 8 50Gb --> Ubuntu 12.10 100Mb --> UEFI 300Mb --> Recovery   I installed the GRUB on /dev/sda. Then, after GRUB not showing up and booting directly into Windows 8, I turned the laptop off and booted again into Ubuntu LiveCD and ran the Boot-repair utility, it give me  but it didn't solved the problem.  My Laptop still boots directly into Windows 8, without GRUB or Ubuntu even showing up.


I was ripping off a . The basic functionality is to sense the temperature and display it on an LCD. The LCD turned out to have no interface to the controller. The PCB had 3 LEDs which were focused onto the LCD to provide backlight. Other than that there was no other active component(/connector) that can transmit the data to the LCD.  How is this interface done?  I tried googling and tried searching for connectors/interfaces without electrical contact. But, I got no idea how it works.  Attached

I found a component attached to a PCB inside one of my old $5 devices. There are pink, rubbery things attached to either side of the LCD that can bend and were firmly attached (glued?), and there are a lot of exposed conductive traces where the pink things were attached on the PCB.  I would like to know what these pink things are. Pictures are shown below.    The front side of the LCD ^    The back side of the LCD ^    The front side of the PCB. This is where the LCD is connected to. ^    The back side of the PCB ^  Again, I would like to know what the pink things are.


Why is it going into his if when the check is if its not undefined    if (this.table !== undefined || this.table !== null) {             this.table.destroy();         }   Console error : Uncaught TypeError: Cannot read property 'destroy' of undefined  Ive tried   if(this.table)   But no luck either

What's the best way of checking if an object property in JavaScript is undefined?


I think it is necessary to do the replacement. That's just what?  $$\int \frac{3\cos x+7\sin x}{5\sin x+2\cos x} dx$$

Indefinite Integral with sin/cos  I can't find a good way to integrate: $$\int\dfrac{3\sin(x) + 2\cos(x)}{2\sin(x) + 3\cos(x)} \; dx $$


In my problem, I am having a lot of variables - easily 10-15 If this was a 2 dimensional data then I would plot these and visualize the plots to identify certain abnormalities.   But with so many variables, I don't know how to visualize so many variables.  Any suggestions how to think about so many variables?

Please pardon my ignorance, but...  I keep finding myself in a situation, where I'm faced with a bunch of new data I managed to find. This data usually looks something like this:  Date     Number1  Number2  Category1  Category2 20120125      11      101        Dog      Brown 20120126      21       90        Cat      Black 20120126      31      134        Cat      Brown (...)   Usually at first glance I can't really tell if there are any trends here. The correlations between the various columns may not be very significant, but I would be delighted if I didn't have to manually create a plot for every possible combination of columns/categories.  Is there a tool out there which would accept a table of data along with information which columns should be treated as numbers, dates and categories and then proceed to plot:   correlations between each two numerical columns correlations between each two numerical columns, with separate trend lines for each category each number column as a time series, each number column as a time series, separated by category, etc.   In the end this would generate a large number of plots, most of which would show only noise. Ideally, the tool could score the plots by correlation and in the end display a slideshow starting with the highest scoring plots. This would be a very imperfect, but useful first glance at the dataset.  So? Is there a tool everyone uses for this and I just don't know about it, or is this something we need to make?


We know that Superman does eat "human" food. However, is it really necessary for him to eat, i.e. can he starve to death? If yes, would he take the same time to die as an average human?  Also the same question goes for water.

I see related questions such as:   and  But does Superman need to eat?   And if so, what happens if he doesn't?


This is my first question here. I don't know the difference between"only" and "just". Can anyone help me please?  Thanks.

'Just' and 'only' carry a similar meaning, and while my feel for language usually helps me decide which one to use, there are times when I'm at a loss.  From my understanding, 'just' is used as a softener, to add flexibility and politeness. 'Only', on the other hand, is a relatively sharp exclusion. 'Just' also has a wider range of meanings, for instance to denote time.  While this sounds simple enough, it can get messy in practical usage. The sentence that made me stumble was "Not only airports are part of the target customer group, but also other large infrastructures".  Would the meaning of this sentence change when using 'just' instead? The way I see it, there is no difference in this case, except 'just' would make it sound a tad more colloquial.


$a$, $b$, $c$ and $d$ belong to natural numbers (no fractions). Is it possible to find four integers for which two of the square would be equal to the other two? I intend to come up with a special number by operation of two natural numbers that can not be represented by that same operation of any other pairs of natural numbers. I want to find them by algebraic expression. I could find them by using possible numbers.

In the diophantine equation: $ a^2+b^2=c^2+d^2 $, I know that the solutions are parametrized by $ (a,b,c,d)=(pr+qs, qr-ps,pr-qs,ps+qr) $ where $p,q,r,s \in  {Z}$ are arbitrary. I have been having a hard time solving $(p,q,r,s)$ meaning writing them as a combination of the integers $a,b,c,d$).Can you please help me find the solution?


Find the limit of the following expression:      $$\lim_{n \to \infty} \frac{\log n}{\sqrt n}$$   As I plot this function, it seems that this goes to $1$. Is it correct?

How do take this limit:  $$ \lim_{n\to\infty} \frac{\sqrt{n}}{\log(n)}$$  I have a feeling that it is infinity, but I'm not sure how to prove it. Should I use L'Hopitals Rule?


Suppose I need to evaluate the following sum:  $$\sum_{k=2}^n \frac{1}{k(k+2)}$$  With partial fraction decomposition, I can get it into the following form:  $$\sum_{k=2}^n \left[\frac{1}{2k}-\frac{1}{2(k+2)}\right]$$  This almost looks telescoping, but not quite... so at this point I am unsure of how to proceed.  How can I evaluate the sum from here?

How can I use the telescoping technique to compute the following sum? I'm having issues getting started. I know the basic steps but I don't know how to perform them. I know I have to separate the fraction into A and B. After that I have to perform the sum but I'm not sure what comes next.   $$\sum_{i=3}^n \frac{1}{i(i+3)} $$  Thanks for any help!


I had a question in my school exam.  Will the average surface temperature of the Earth be lower or higher, if there was no atmosphere?  Now, the answer expected is "The avg temp will be lower, because of no greenhouse effect."  Isn't this an extremely myopic view of the whole situation? Places where it's night, the temperature will be sub-zero, and places where it's daytime, the temperature will be unbearably high, somewhat like on the moon, right? So the thing is, what's the correct answer? I know my education board is not something to be trusted, so please don't worry about their answer.

An ageing gent says he does not accept this statement:  It's a fact that greenhouse gases, predominantly water vapour, keep the Earth  from being hostile and cold; that CO2 albeit in trace quantities is also a  greenhouse gas and therefore helps keep the planet warm...   I know no more about why he rejects this statement - maybe it is that water vapour alone would do the job. The gent in question has a first class degree and a doctorate in physics.    Is there a debate within the physics community over this or am I misunderstanding?


I want to download a 64 bit Ubuntu version for a Toshiba, not a Mac.  When I download what the download site says is a 64 bit version (NOT the MAC version), its properties still read as 64 bit AMD.  What do I do to get the right version?

I was told that computers with more than 2 gig's memory need a 64 bit operating system to utilize all RAM.  Is the 64bit Ubuntu download really JUST for AMD processors? I am asking because the disk image I downloaded says AMD64.  So will my new Intel 2.3Ghz Core i3 Dual Core processor work with 64 bit Ubuntu?  It runs the 64bit version of Windows without any qualm.


Fire and forget method in C#  I refered different issues for 'Fire and Forget in C#'  i.e.  . . and few several,  but i have an another issue with the same.i wrote following code  static void Main(string[] args)     {         for (int i = 0; i < 5; i++)         {             //fireAway(i);             Task.Factory.StartNew(() => fireAway(i));         }         Console.WriteLine("Main Finished");         Console.Read();     }  public static void fireAway(int i)     {         System.Threading.Thread.Sleep(5000);         Console.WriteLine("FireAway" + i);     }   where i am expecting output like  Main Finished  FireAway0  FireAway1  FireAway2  FireAway3  FireAway4  but output is  Main Finished  FireAway5  FireAway5  FireAway5  FireAway5  FireAway5  very honestly i am new to threading concept, i need help. How can i meet with expected output..?

I met an interesting issue about C#. I have code like below.  List<Func<int>> actions = new List<Func<int>>();  int variable = 0; while (variable < 5) {     actions.Add(() => variable * 2);     ++ variable; }  foreach (var act in actions) {     Console.WriteLine(act.Invoke()); }   I expect it to output 0, 2, 4, 6, 8. However, it actually outputs five 10s.  It seems that it is due to all actions referring to one captured variable. As a result, when they get invoked, they all have same output.  Is there a way to work round this limit to have each action instance have its own captured variable?


While trying to install Ubuntu 14.04 I have this message:  this kernel requires a x86-64 CPU but only detected an i686CPu. Unable to boot  use a kernel appropriate for your CPU.   What should I do?

I was trying to install Ubuntu 12.04 in VirtualBox 4.2.12r84980. I see    this kernel requires an x86-64 CPU, but only detects an i686 CPU, unable to boot   But I am using a 64 bit Windows 8, and trying same .iso for trying Ubuntu. Then what is the problem?


I am on 64-bit Windows 8.1. I'm trying to install Ubuntu on VirtualBox. However, I get the error:   this kernel requires an x86-64 CPU, but only detected an i686 CPU Unable to boot - please use a kernel appropriate for your CPU.   But my OS is 64-bit! I have 12GB DDR3 RAM, Intel Core i74700MQ CPU. So why is this happening and how can I fix it?


I have to prove $$\frac{\sin(n\theta)}{\sin(\theta)}= 2^{n-1}\prod_{k=1}^{n-1}\left(\cos(\theta)-\cos\left(\frac{\pi k}{n}\right)\right)$$  $$\sin(\theta) = \frac{e^{i\theta}-e^{-i\theta}}{2i} ,\qquad\sin(n\theta) = \frac{e^{in\theta}-e^{-in\theta}}{2i}.$$ So \begin{align*} \frac{e^{in\theta}-e^{-in\theta}}{e^{i\theta}-e^{-i\theta}} & =\frac{e^{2in\theta}-1}{e^{2i\theta}-1}\cdot e^{-i\theta(n-1)} \\ & =\frac{(e^{2in\theta}-1)(e^{-2i\theta}-1)}{(e^{2i\theta}-1)(e^{-2i\theta}-1)}\cdot e^{-i\theta(n-1)} \\ & =\frac{e^{i\theta(n-1)}+e^{-\theta(n-1)}-e^{i\theta(n+1)}-e^{-i\theta(n+1)}}{2-e^{2i\theta}-e^{-2i\theta}} \\ & =\frac{\cos((n-1)\theta)-\cos((n+1)\theta)}{1-\cos(\theta)}. \end{align*} Can I get my desired result from here or I made a mistake?

Can somebody help me to prove this identity?     $$\prod_{k=1}^{n-1} \left(\;\cos\theta-\cos\frac{k\pi}{n}\;\right) = 2^{1-n}\sin(n\theta)\csc\theta$$   I was thinking of using the properties of the complex numbers and the binomial theorem, because I found this problem in the Complex Variables book from Schaum's, but it did not solve my problem.  Does anyone have an idea?  Thanks in advance!


I want to find 3 natural  numbers  a, b and c such that  $\frac{4}{193}=\frac{1}{a}+\frac{1}{b}+\frac{1}{c}$. Also I want the see the decomposition  of 4/313 too.  I need to see these decompositions for my research on E-S problem.

Find all positive integers $a, b, c$ such that $1/a + 1/b + 1/c = 4/3999$.  The contest is just ended, so you may freely answer. (I did not attend the contest: it is an Italian contest for schools and the groups may ask other people for hints. This is how I got involved, but of course asking on MSE would have been cheating)  I found three solutions: I am explaining below what I did. I would like however to know if there is a more general approach.


I have an EditText in which I get numbers and need to convert them to a float but still get the same eror - Null Pointer Exception.  This is my code:  public class Basic extends Fragment implements AdapterView.OnItemSelectedListener {      @Nullable     @Override     public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {           View view = inflater.inflate(R.layout.basic, container, false);         Spinner spinnerLenght = (Spinner) view.findViewById(R.id.spinnerLenght);         spinnerLenght.setOnItemSelectedListener(this);         ArrayAdapter<String> lenghtAdapter;         lenghtAdapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, getResources().getStringArray(R.array.basic_string_lenght));         lenghtAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);         spinnerLenght.setAdapter(lenghtAdapter);          return view;     }       @Override     public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {         String itemLenght = parent.getItemAtPosition(position).toString();         EditText editTextLenght = (EditText) view.findViewById(R.id.editTextLenght);         float floatLenght;         floatLenght = Float.parseFloat(editTextLenght.getText().toString());         float result_mm = 0;         if (itemLenght.equals("mm")){               result_mm = floatLenght * 1000;         }           Toast.makeText(parent.getContext(), (int) result_mm, Toast.LENGTH_LONG).show();     }         @Override     public void onNothingSelected(AdapterView<?> parent) {      } }   This is logcat :   E/AndroidRuntime: FATAL EXCEPTION: main                                                                       Process: com.example.dusan.unit, PID: 5181                                                                       java.lang.NullPointerException                                                                           at com.example.dusan.unit.Basic.onItemSelected(Basic.java:46)                                                                           at android.widget.AdapterView.fireOnSelected(AdapterView.java:956)                                                                           at android.widget.AdapterView.access$200(AdapterView.java:49)                                                                           at android.widget.AdapterView$SelectionNotifier.run(AdapterView.java:920)                                                                           at android.os.Handler.handleCallback(Handler.java:733)                                                                           at android.os.Handler.dispatchMessage(Handler.java:95)                                                                           at android.os.Looper.loop(Looper.java:157)                                                                           at android.app.ActivityThread.main(ActivityThread.java:5356)                                                                           at java.lang.reflect.Method.invokeNative(Native Method)                                                                           at java.lang.reflect.Method.invoke(Method.java:515)                                                                           at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)                                                                           at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)                                                                           at dalvik.system.NativeStart.main(Native Method)   I tried it on a double too. I also had problem with null = "" I read a lot about this but can`t find solution.

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


Let's assume we have a CNC machine cutting an aluminium block and we are monitoring its RMS power consumption at a constant sample rate e.g. 1Hz (see figure below for example). Can this considered to be a time-series signal?  link states that time-series should show some internal structure, others could argue that any signal observed over time can be described as time-series.    If the example above is not a time-series, what else could you call that signal?

A stochastic process is a process that evolves over time, so is it really a fancier way of saying "time series"?


I have 2 cron jobs that were running fine but now stopped running. I looked through my crontab and everything looks OK. How can I tell if these jobs are running? is there a place where cron stores errors? Where do I look for cron specific errors, or even a record of the cron jobs that ran prior.

I want to verify that my cron job is executing and at what time.  I believe there is a log for my sudo crontab -e jobs, but where?      I searched google and found recommendations to look in /var/log (in which I do not see anything with 'cron' in the name) and to edit the file /etc/syslog.conf which I also do not have.


I have a list with different strings. Sometimes they are in cp1251, ASCII or something else. I need to process them (convert to Unicode), because I got an error (UncicodeDecodeError), especially when I tried to dump this data to JSON.  How can I do this?

I received some text that is encoded, but I don't know what charset was used. Is there a way to determine the encoding of a text file using Python?  deals with C#.


In BibDesk I introduced a book reference and I added in the publisher the character & and this is the message after compiling document  ! Misplaced alignment tab character &.  I removed the & from BibDesk and saved but the message of error remains. I tried to remove the citation at all, but still the error remains, I don't know what to do

I need to output the below text but since \ is a special character, I cannot:  [RegularExpression(@"\d+")]   Also sometimes I need use dollar sign $ as well but it seems to be a special char, too.  What is the way to escape those in LaTeX?  UPDATE:  I used \verb as suggested but I am unable to run commands inside it. Also, in the output the font and the opacity of the text is different than the default one:  \verb|[RegularExpression(\newline @"\d+")]|


Today I got 7 messages, unfortunately after I looked to see what I got, it marked them all as seen.  Can you change it, so when I review one message it will not mark all the rest as seen? It's hard to remember each time what is new and what is not.

Currently, when receiving notifications in the inbox, you get a number in the top bar on the inbox button. But when you open the inbox that number is gone and everything is marked as read. I don't think this is good behaviour.  I would suggest that only the messages that were clicked are marked as read and the number simply decrements. This would make it easier to follow-up on them. Also there can be buttons for marking individual messages as read, marking them as unread too, and a big button to "mark all as read".  A humble attempt at propagating my suggestion into a design:        I had to fake one of my notifications being unread and sorry, it's badly done. Notice the "mark all as read" conveniently placed in the top right. Notice to the bottom left of each notification the individual mark as read button, in the shape of a bold checkmark for "unread" and a lighter one for "read". This could also be an o for read and a ● for unread or anything else that the designers see fit.  Question history about this here   was already asked here but this was declined simply because it asked for a setting and SO doesn't do preferences. I'm asking to modify the default behaviour.  Then there's  but the so-called duplicate is not a duplicate at all. Also this was before the entire top bar was re-done and it was still the Stack Exchange MultiCollider SuperDropdown thing.  Related (other people want this):


How can we show that any automorphism of $\mathbb{Q}$ under addition is of the form           $x \to qx$ ,for some q in $\mathbb{Q}$.  edited- I found the same question was asked by @tattwamasi-amrutam tagged automorphism from $\mathbb{Q}$ to $\mathbb{Q}$.there is some useful answer.

Any automorphism of the group $\Bbb Q$ under addition is of the form $x\to qx$ for some $q\in \Bbb Q$.   I don't know how to proceed in this. Even if i say that $1\to q$, I can't claim that $x\to qx$ since $\Bbb Q$ is not cyclic.


Graphically, it is easy to see but to analytically derive the following inequality,   $$|e^x-e^y| \le |x-y| \ \ \ \ \forall x,y \in (-\infty,0]  \ \ \ \ (1)$$  do I just apply the MVT and show that the derivative of at a certain c between x and y equals $0$ hence the ratio is less than 1 and thus we derive $(1)$

Came across this problem on an old qualifying exam: Let $a$ and $b$ be complex numbers whose real parts are negative or 0. Prove the inequality $|e^a-e^b| \leq |a-b|$.  If $f(z)=e^z$ and $z=x+iy$, then $|f'(z)|=e^x\leq 1$ given that $x \leq 0$. I played around with the limit definition of the derivative, but wasn't able to get anywhere. Not sure what else to try; a hint would be very helpful!


How do i get those 52 packeges updated?  i give a sudo apt-get update but still it all remains.  Welcome to Ubuntu 16.04.5 LTS (GNU/Linux 4.4.0-138-generic x86_64)   * Documentation:  https://help.ubuntu.com  * Management:     https://landscape.canonical.com  * Support:        https://ubuntu.com/advantage    Get cloud support with Ubuntu Advantage Cloud Guest:     http://www.ubuntu.com/business/services/cloud  52 packages can be updated. 9 updates are security updates.

I am wondering what sudo apt-get update does?  What does it update?


I don't know if gravity or the speed of the drop would prevent us from jumping, but would something like this be possible?  If it's not possible on the ground, is it possible in the ocean?  I'm sorry in advance if I used the wrong tag. I had a hard time figuring out which tag out of the physics tag to choose. If someone can kindly correct me, that would be awesome.

Imagine you're trapped inside a free falling elevator. Would you decrease your impact impulse by jumping during the fall? When?


I understand that PCA and SVD are similar - PCA removes the mean and SVD doesn't?  I think I have an understanding of PCA - you would use it to reduce dimensions of data and separate it out into linear combinations of variables that explain the largest variance of the SS.  But I can't grasp that same concept for SVD - and especially can't understand when you would use SVD over PCA if they are supposed to be very similar.    Can someone explain in very basic terms why I would pick SVD vs PCA, and how SVD works?  What is a real world application where SVD is better than PCA?

I know how to calculate PCA and SVD mathematically, and I know that both can be applied to Linear Least Squares regression.  The main advantage of SVD mathematically seems to be that it can be applied to non-square matrices.  Both focus on the decomposition of the $X^\top X$ matrix. Other than the advantage of SVD mentioned, are there any additional advantages or  insights provided by using SVD over PCA?  I'm really looking for the intuition rather than any mathematical differences.


is there a simple way to morph object along a bezier curve? For example: a rope with one square end and one round end.  Example:   If it can’t be done, that is helpful too. I’ll stop trying to find a way.  Thank you.

I want to model a tube-like structure, which slowly changes from rectangular to circular along a pre-defined path. Below is an example created with bridge:    There are two problems here. The first is that the tube does not have consistent thickness, and the second is that it is not possible to control the exact path of the tube this way.  Is there a technique, or an addon, that can help me out with this? I do not want to lay lots of manually half-morphed shapes along the way and use skin modifier. I have already tried lofting with LoopTools and did not get any usable results.