Intel i9-9960x Processor with MSI X299 SLI plus motherboard support Ubuntu 16.04 or   Intel® Core™ i9-9960X Processor with ASUS TUF X299 MARK 2 DUAL LAN support ubuntu 16.04  need 16 core /32 threade processor with dual lan supported board with os Ubuntu 16.04

Could you please give me an idea how I should tackle the problem ()? I have looked up for the solution and followed the suggestion to update the Bios to the latest version (). The error retains.  Error:   ACPI Error: [SDS0] Namespace lookup failure, AE_NOT_FOUND (20160930/psargs-359)   ACPI Error: Method parse/execution failed, [\SHAD._STA] (Node ffff...), AE_NOT_FOUND (20160930/psparse-543)   ACPI Error: [SDS0] Namespace lookup failure, AE_NOT_FOUND (20160930/psargs-359)   Info:   Motherboard: ASUS - TUF X299 MARK 2 ATX LGA2066 Motherboard CPU: Intel - Core i7-7800X 3.5GHz 6-Core Processor Memory: G.Skill - Ripjaws V Series 32GB (2 x 16GB) DDR4-3200 Memory Storage: Samsung - 960 EVO 250GB M.2-2280 Solid State Drive Video Card: MSI - GeForce GTX 1080 Ti 11GB DUKE OC Video Card


I've the following PS1 prompt:  export PS1="\e[1m\e[38;5;198m\u\e[0m @ \e[1m\e[38;5;208m\h\e[0m : \e[1m\w\e[0m\e[38;5;226m\$(parse_git_branch)\e[0m \e[1m>>>\e[0m "   what happens is that when typing and it reaches halfway through the terminal, it will send the cursor at the beginning of the line and overwrite itself like:  rossid @ HOST : /Library/Java/JavaVirtualMachines/jdk1.8.0_151.jdk/Contents >>>  oussid @ HOST : /Library/Java/JavaVirtualMachines/jdk1.8.0_151.jdk/Contents >>>  this is just a test to show what happens nothing seri    (the rest of the string serious replaces the beginning)  Any idea why? (I'm using osx standard terminal and IntelliJ terminal... all do the same)

I am using the gnome-terminal with bash, and when I have a command that should go over the line, it just stays on the same line. So instead of:  echo "abcdefghijklmnopqrstuvwxyz"   I would get  opqrstuvwxyz""abcdefghijklmn   Or something similar to that. However, if I press enter the command will still work. I believe it has something to do with my PS1 variable, but I don't know what is wrong with it. Here it is:  export PS1='\e[1;35m[\u:\w]\$\e[0;35m '


Could some one advise me in some ways (or popular ways) of representing population variables in a map? For population variables I refer to: distribution of age among the population, people with elementary school, etc..

I would like to plot the following per zone (30 zones total) data on a printable/non interactive map:   Average age Average household income Number of households Population density Number of people Number of workers   How would you display the above 6 layers effectively on one map?


Does anyone know where my Instance server is located? My organisation is located in Berlin, Europe.

To access chatter rest api using APEX code, I need salesforce instance server url in following format:  https://na17.salesforce.com  Is there any method which works in all cases  Case 1: Any Development Org  Case 2: My Domain Enabled  Case 3: Sandbox  Case 4: Managed Package


How to do connect to Ubuntu machine (remote desktop) from windows machine remotely? I need to add an account on my Ubuntu machine. Maybe through ssh?  Thanks

How to configure Remote Desktop on my office Ubuntu machine and how to connect to it from my Windows laptop at home?


Java has a number of useful and FREE tools for reviewing not just formatting and style but quality of code and bad coding habits.    and  could work but they are not free and open source.   works well for java but there are no official updates to support Apex.  What does static code analysis for apex that is free?

What static code analysis tools are there for apex? The only one I seem to be able to find is the Force.com Security Source Code Scanner but that has the draw back of placing your request into a queue and running it when it can. I would like something I can run locally so I can make refactoring into a number of very short cycles.


I am trying to search all posts by a user to a specific site excluding other sites from my mobile phone.  How do I find all posts by a specific user @JoeDoe to a specific site e.g. SuperUser using the Android SE app?

I know there is a way to view all my questions in reverse chronological order from the PC by going to my profile. But I would like to do the same from the mobile app for Android. On Android in the left upper hand corner I can only see the latest answers to my posts, but I would be able to view all my posts.


If I remember correctly, the 12 series of Ubuntu had some issues with the Asus U46e-bal6 -- how is 13.10 working, anyone know?  I'm starting to have some issues with Windows 7, and I have no desire to upgrade to Windows 8.  Giving serious consideration to returning to a dual boot set up with Ubuntu.  Anything I should know going in with my current hardware?  Thanks!

I have a device on which I would like to install Ubuntu. How do I find out if Ubuntu will work on it?


i have dual boot system! Ubuntu 14.04.3 LTS and Windows Xp! I want to delete the Ubuntu and use only Windows Xp, because my netbook is too old and the wifi does not work with Ubuntu! I searched for a solution for a month and none worked!

I have installed Ubuntu as another OS on my laptop, and my default OS is Windows 7. I just want to know how to remove (or uninstall) Ubuntu without harming the other OS.  PS: Ubuntu and Windows 7 are both installed on one drive.


I'm stuck on this seemingly easy problem in elementary group theory.  Q. Let $(G,\ast)$ be a group and $a,b\in G$. If $a^2=e$ and $a\ast b^2\ast a=b^3$, prove that $b^5=e$. ($e$ denotes the identity element of $(G,\ast)$)  Attempt:  $$a\ast b^2\ast a=b^3\implies a^2\ast b^2\ast a^2=a\ast b^3\ast a\implies a\ast b^3\ast a=b^2\tag1$$  Using $(1)$ and the given two equations in the question, we get,  $$b^5=b^2\ast b^3=a\ast b^3\ast a^2\ast b^2\ast a\implies a\ast b^5\ast a=b^5$$  This is the most progress I think I have done for this problem. I had tried different approaches but they all went in vain.  I'd like hints on this problem rather than a complete solution. Thanks.

Let $G$ be a group and $a,b \in G$ with $a \ne 1$ and $b \ne 1$. Assuming $ab^2 = b^3a$ and $a^2=1$ I need to prove that the order of $b$ is $5$.   I have proved by contradiction that it can't be 2 or 3 but I don't know how to prove that it must be 5 and it can't be 4.


I have Canon lenses and would like to purchase an adapter to use them on the D3200? Is there one available? If so name and model would be appericated. I understand that I will have to shoot on manual mode.


From my reading, $\mathrm{SU}(4)$ has 15 parameters and $\mathrm{SU}(2)$ has 3 paramaters that range differently with certain parameter (rotation angle). And all the parameter is linearly independent to each other.  My question are:   What the characteristic of each of the parameter?   If I choose two of them, what is the reason behind  the theory?   Can anyone explain to me or suggest any book/paper to me to understand the parameter itself.

From my reading, $SU(4)$ has 15 parameters and $SU(2)$ has 3 parameters that range differently with certain parameters (rotation angle). And all the parameters are linearly independent to each other.  My question are:   What the characteristic of each of the parameters? If I choose two of them, what is the reason behind the theory?  Can anyone explain to me or suggest any book/paper to me to understand the parameters themselves?


If $x + \frac{1}{x} = \sqrt{3}$, then find $x^{18}$. This is sorta like . So my question is, do I solve my question the same way as the question in the link?

Given that $x+\frac{1}{x}=\sqrt{3}$, find $x^{18}+x^{24}$  Hints are appreciated. Thanks in advance.


Hi I'm on the verge of getting an eGPU Razer Core X and an AMD 5700 XT on macbook pro 15" 2.6 GHz Intel Core i7 32 G RAM for archviz but I need to make sure it's compatible with Blender

I am considering purchasing a Mac for my godson who will be using it to run Blender 2.8.  I know very little about this program.  All I can find are requirements for a Mac that will run earlier versions of Blender.  Would someone please recommend a list of requirements for a Mac (or a link to a list of requirements) that I could use to find a model that can run 2.8?  Thank you in advance for all your help! Sincerely, M. Lap


(a) I would ask you to forward the document to the associates in New York (b) I would like to ask you to forward the document to the associates in New York  My understanding was that (b) is the only correct form; (a) can only be used if the speaker has a counterfactual premise in mind, as in "If it were me, I would ask you to forward...." I could come up with a number of situations where (a) might sound natural enough, but at least, (a) does not mean the same thing as (b) under normal circumstances. Recently, however, I keep receiving emails asking me to do something using the construction (a), and they seem to be intended to convey the meaning of (b). Granted, most of them are from non-English speaking countries, but I see this usage so often it makes me wonder: Is it acceptable, or at least common, to make a request -- asking someone to do something for you -- using the form "I would ask you to" as in (a) above? Note: A few people have pointed out my question aoove might be a duplicate of this question:  .  But that page concerns Indian dialects of English and I do not see any connection, unless this usage of "would" as in (a) only, or at least mainly, is common in India. Thank you.

My recent trip to India exposed me to many sentences using "would" as a polite substitute for "will", as in  Please make sure to leave on time. The last bus would depart at 8PM. Thanks for checking out early. However, there would be no refund.  I am not familiar with such patterns in AmE or BE. Are they common in particular settings that I'm not aware of? How common are they in India? Note: the following query seems to return a bunch of other examples (among conditional uses of course) inurl:.co.in "would"


I want to list all the files committed under a commit when user sends request in the form of commit id using jgit .

I am looking for a simple Git command that provides a nicely formatted list of all files that were part of the commit given by a hash (SHA-1), with no extraneous information. I have tried: git show a303aa90779efdd2f6b9d90693e2cbbbe4613c1d  Although it lists the files, it also includes unwanted diff information for each. Is there another git command that will provide just the list I want, so that I can avoid parsing it from the git show output?


To read a book like  what are the mathematical prerequisites. I currently know Linear Algebra ( basic course ) , single variable and multiple variable calculus. I want to become a data scientist and for that I require strong mathematical background. Various sites say that courses on optimization like Convex optimization are really important. Now the point is I have no mentor so to say, I have to read on my own. I checked out the stanford course on convex optimization. It said that real analysis was not a prerequisite but if you have done it it will be useful. So my question in a way is, how useful is "real analysis" for a data scientist. And if I know Linear Algebra, single and multivariable calculus, then what are the next things in data science that I should venture into ?

I'm trying to put together a self-directed math curriculum to prepare for learning data mining and machine learning. This is motivated by starting  on Coursera and feeling that before proceeding I needed to improve my math skills. I graduated from college a while ago so my algebra and statistics (specifically from political science/psychology classes) are rusty.  The answers in the thread  only suggest books or classes directly related to machine learning; I have already looked into some of those classes and books and do not know exactly what math subject to study (for instance: what field[s] of math address deriving an equation to "minimize a cost function"?). The other thread suggested ()   only mentions broad categories of skills needed for analyzing data. The thread  does not apply because I do not already have a degree in math; a similar thread  has an incredible list of stats books, but again, I'm looking at starting math from a rusty recollection of algebra and moving up from there.  So, for those that work in machine learning and data mining, what fields of math do you find essential to do your job? What math subjects would you suggest to prepare for data mining and machine learning, and in what order? Here is the list and order I have so far:   Algebra Pre-calculus Calculus Linear algebra Probability Statistics (many different sub-fields here, but don't know how to break them out)   As for the data mining and machine learning, through my current job I have access to records on website/app activity, customer/subscription transactions, and real estate data (both static and time-series). I'm hoping to apply the data mining and machine learning to these datasets.  Thank you!  EDIT:  For posterity's sake, I wanted to share a helpful  for Geoffrey Gordon's/Alex Smola's  class at CMU.


I want to create a spots map for any material, so it looks like this:    Aprreciate the little spots on the front

I have a model, with a node setup that includes a texture. The problem is that the texture isn't showing. How it should look (the little spot distortions are visible):  How it looks:  My node setup Node Setup  The file can be downloaded here:


This question was found in a CSAT entrance exam for Cambridge computer science course, and I had a look at it but I'm not really sure where to start with it:  Given a sequence of zeros and ones of length $n$, let $L_n$ be the number of sequences that have no adjacent zeros. Give a recursive formula for $L_n$

How many $N$ digits binary numbers can be formed where $0$ is not repeated. Note - first digit can be $0$.  I am more interested on the thought process to solve such problems, and not just the answer. If anyone can cite some resources for learning how to solve such problems would be great.


Thanks for taking a look at my question.  How can I get this formatting (shown in image)?    I appreciate your help, this community is great.

If I have a string of equations whose equal signs are aligned and one of the equations is too long and needs to span multiple lines, how do I create a second alignment. For instance, in the following example     \begin{align*}     f(x)&=eqn1\\         &=eqn2_part1+eqn2_part2\\          &           +eqn2_part3\\         &=eqn3\\          &=eqn4\\   \end{align*}   How do I align the equals signs and the plus signs.


$\displaystyle\int_0^1 \dfrac{1}{x^x}dx = 1 + \dfrac{1}{2^2} + \dfrac{1}{3^3} + \dfrac{1}{4^4} + \ldots $ the only idea I have is using the series expansion of $x^{-x} \approx 1 - x\log x + \dfrac{(x\log x)^2}{2!} - \ldots$. But it ends up little complicated, any idea?

I need help with this exercise.  I need to prove $$\int_{0}^{1}x^{-x}\ dx=\sum_{n=1}^{\infty}n^{-n}$$  I think I should use some convergence theorem, but I'm stuck.  Thanks a lot!


I'm writing a OpenGL with NDK example.  My shader code in main.c:  const char vShaderStr[] =       "#version 300 es                             \n"       "uniform mat4 u_mvpMatrix;                   \n"       "layout(location = 0) in vec4 a_position;    \n"       "layout(location = 1) in vec4 a_color;       \n"       "out vec4 v_color;                           \n"       "void main()                                 \n"       "{                                           \n"       "   v_color = a_color;                       \n"       "   gl_Position = u_mvpMatrix * a_position;  \n"       "}                                           \n";  const char fShaderStr[] =       "#version 300 es                                \n"       "precision mediump float;                       \n"       "in vec4 v_color;                               \n"       "layout(location = 0) out vec4 outColor;        \n"       "void main()                                    \n"       "{                                              \n"       "  outColor = v_color;                          \n"       "}                                              \n";  userData->programObject = esLoadProgram ( vShaderStr, fShaderStr );   I had tried this  to convert(I also change the way of create shader in main.c), but failed:  I want use extern shader file by reading them in main.c  .  How can I convert it?

What is the simplest way (least error-prone, least lines of code, however you want to interpret it) to open a file in C and read its contents into a string (char*, char[], whatever)?


I am really struggling to create a multi line equation that incorporates both a matrix and a single equation that lines up the equals signs such as the one below:    So far have done the following:  \begin{equation*}     M =  U\Sigma V^{*} \end{equation*} \begin{equation}              = \textbf{U}\left[ \begin{array}{cccc}       \sigma_{1} & 0 & \ldots & 0\\      0 & \sigma_{2} & \ldots & 0\\      \vdots & \vdots & \ddots & \vdots\\      0 & 0 & \ldots & \sigma_{m}\\         \end{array} \right]\textbf{V*} \end{equation}

A number of related questions have already been asked about this issue:       and even    But I'm still confused by the conflicting suggestions that have been given so far. So I'm trying again.  Which should be the preferred command to produce a displayed equation in my LaTeX documents?  So far the suggestions indicate that one should use \[ ... \], maybe \begin{equation*} ... \end{equation*}, or maybe even the gather* or align* environments from amsmath.  And one should definitely avoid using either $$...$$ or the eqnarray environment.  Now I have to say that, from a language perspective, I have a strong preference for the equation* environment because it is less cryptic than the \[ ... \] notation and it is  the most accurate.  So, is it fine to use equation*? Maybe only after loading amsmath? Or should the equation/equation* environment be redefined to something else so that spacing, package support, or whatever is improved?


While reviewing questions in the review queue, sometimes StackOverflow will change the question dates and hide votes to test if the reviewer is paying attention or not.     While the date of the question is hidden, the date of comments remains the same as the original. So the reviewer can easily spot the mismatch and determine that it is a Test question.    Either we should change the comment date also or hide the comments completely.      In the screenshot, as you can see that question was asked a few mins ago but comments are 10 days old.

I see wrong dates for comments in the Triage review queue. The  is asked 29 minutes ago (today), but the comments are dated 24 May.


Originally, without SMOTE, my ML learning steps go like this:   Feature vectorization  split data into X_train, X_test, y_train, and y_test  use X_train and y_train for machine learning  predict/test on X_test and y_test   I think there are two spots I could inject my SMOTE codes. One is I can inject it before the train/test data split, so that oversampling of minority class takes place in both training and testing data. Like so:   Feature vectorization  SMOTE oversampling  split data into X_train, X_test, y_train, and y_test  use X_train and y_train for machine learning  predict/test on X_test and y_test   I got very good results using the above steps, but I wonder if SMOTE should only be done in the training data, but test on the original testing data set since the latter reflects the real-world distribution of majority and minority class samples. Like so:   Feature vectorization  split data into X_train, X_test, y_train, and y_test  SMOTE done only on X_train and y_train  use X_train_SMOTE and y_train_SMOTE for machine learning  predict/test on X_test and y_test   Which is a better implementation of SMOTE?

I am working on severely imbalanced data. In literature, several methods are used to re-balance the data using re-sampling (over- or under-sampling). Two good approaches are:   SMOTE: Synthetic Minority Over-sampling TEchnique () ADASYN: Adaptive Synthetic Sampling Approach for Imbalanced Learning ()   I have implemented ADASYN because its adaptive nature and ease to extension to multi-class problems.  My question is how to test the oversampled data produced by ADASYN (or any other oversampling methods). It is not clear in the mentioned two paper how they performed their experiments. There are two scenarios:  1- Oversample the whole dataset, then split it to training and testing sets (or cross validation).  2- After splitting the original dataset, perform oversampling on the training set only and test on the original data test set (could be performed with cross validation).  In the first case the results are much better than without oversampling, but I am concerned if there is overfitting. While in the second case the results are slightly better than without oversampling and much worse than the first case. But the concern with the second case is if all minority class samples goes to the testing set, then no benefit will be achieved with oversampling.  I am not sure if there are any other settings to test such data.


For those unfamiliar with the video (and unable to access it), Gandalf basically summons some eagles, they fly over Mt Doom and drop the ring in.  I guess my question is not so much "why they didn't" which implies the characters had an option to, but is there anything in the LOTR canon that prevents this from being an option?  I've read the books (once, ages ago, I'm more familiar with the movies) but can't recall any logic or reason in the stories that would prevent such an approach to disposing of the ring.  It goes without saying that the stories (books and films) are great, but having eagle's available does beg the question.

Why didn't Gandalf use his eagles to fly over Mount Doom and drop the ring? I know he feared what he would do if the ring overpowered him, so why not just give Frodo an eagle? And, if there would be too much risk in flying the ring to Mordor, couldn't the eagles fly them part of the way?  Why risk it with such a long walk; far less risky to fly over most of the journey.


All the Kennedy family is grateful for your support.  Or All the Kennedy family are grateful for your support.

I'd say Microsoft have a way of bending the rules and I know that McLaren have won the championship. While this sounds strange, I believe it is correct English (sorry, I'm not native).   But when it's a small company, would you still use it this way? Is a company always plural, or are small companies singular? I.e., would you say Bakery Johnson makes fine bread or Bakery Johnson make fine bread? Is it My book seller, Woody's, have moved or is it has moved?


Would it be possible on a running system to shrink ext4 partition and create another partition on the available free space such as it is done in Gparted?  I want to shrink /dev/sdb1 which isn't a system partition so unmounting isn't a problem.  I managed to resize /dev/sdb1 with resize2fs but after that I got lost, because fdisk didn't see any free space to create new partition on it.  Running Ubuntu Server 14.04.

I only have access to the server via a terminal and I can't use graphical tools such as GParted! I want to create a new partition from a part of the root (about 768mb) for swap.  # df -h Filesystem      Size  Used Avail Use% Mounted on /dev/vda         20G  1.3G   18G   7% / udev             10M     0   10M   0% /dev tmpfs           199M  4.9M  194M   3% /run tmpfs           100M   12K  100M   1% /run/user tmpfs           5.0M  4.0K  5.0M   1% /run/lock


I have two type of users: admin and user. Here's what I am doing in Login servlet  protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {     PrintWriter out = response.getWriter();     String user=request.getParameter("user");     String pass=request.getParameter("pass");      HttpSession session=request.getSession();       String name="user",type;     try     {         Class.forName("com.mysql.jdbc.Driver");         Connection con=DriverManager.getConnection(url,user,pass);          PreparedStatement ps=con.prepareStatement("select utype from users where email=? and pass=?");          ps.setString(1, user);         ps.setString(2, pass);          ResultSet rs=ps.executeQuery();          if(rs.next())          {             type=rs.getString(1);             if(type.equals("a"))             {                 session.setAttribute("loggedIn", "admin");                 RequestDispatcher rd=request.getRequestDispatcher("admin.jsp");                 rd.forward(request, response);             }             else             {                 session.setAttribute("loggedIn", "user");                 RequestDispatcher rd=request.getRequestDispatcher("home.jsp");                 rd.include(request, response);             }           }         else         {             request.setAttribute("message","Username or password error!");                 RequestDispatcher rd=request.getRequestDispatcher("login.jsp");             rd.include(request, response);         }     }     catch(Exception e)     {         e.printStackTrace();     }  }   And on account.jsp page I am checking is user is logged in or not.Here's the code:  <%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>  <%@ include file="headpl.jsp" %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"  "http://www.w3.org/TR/html4/loose.dtd"> <html>     <head>         <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">         <script>               //have some code here         </script>     </head>     <body>      <%         if(session.getAttribute("loggedIn").equals("admin"))             {                 response.sendRedirect("admin.jsp");           }else            if(!session.getAttribute("loggedIn").equals("user"))         {             response.sendRedirect("index.jsp");          }      %>      //some html code here   </body>   </html>   The code was running fine before I added the session checks. Now, when the admin is logged in and types the URL of the account page, he is redirected to admin.jsp (that's fine), when user is logged in he is allowed t go to account page  , But when no one is logged in I get an exception:    exception  org.apache.jasper.JasperException org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:370) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264) javax.servlet.http.HttpServlet.service(HttpServlet.java:802) root cause  java.lang.NullPointerException org.apache.jsp.account_jsp._jspService(org.apache.jsp.account_jsp:128) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97) javax.servlet.http.HttpServlet.service(HttpServlet.java:802) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:322) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264) javax.servlet.http.HttpServlet.service(HttpServlet.java:802) note The full stack trace of the root cause is available in the Apache Tomcat/5.5.11 logs.   I think that the NullPointerException is due to the fact that no session variable exists since No one is logged in. I saw several answers on SO but none of them worked for me.  Any suggestions?

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 need to detect when the switch SW1 is on and when it is off, and this input has to be sent to a GPIO of a microcontroller. I have no idea how to implement the circuit required to achieve this goal, so I would really appreciate somebody else's help.         – Schematic created using

I want to be able to tell if the mains voltage is on or off with an Arduino.   How could I do this safely with minimal components (or components from Radio Shack)?


I installed Cantor from the software center. (I didn't realize it would install the snap version, which I did not want). I then removed it using snap remove cantor from the command line.  However the Cantor launcher icon still appears in the Gnome-shell "app grid".  I checked ~/.local/share/applications/ and /usr/share/applications/ and there is no *.desktop file for Cantor present in either location.  How can I remove this launcher icon?

When searching for "Skype" I always see these 2 entries.  There is this duplicate blank Skype icon. Both of them seem to run Skype in the same way.    But I've checked both /usr/share/applications, and ~/.local/share/applications, and can't find the extra icon so I can delete it.    Also as described , sometimes similar ghost icons are present even after removing associated applications.


We have a series of monthly data for 20 months (it is not possible to obtain more data). These are the number of medical consultations encoded in a public hospital and we only have monthly data for two years.  We would like to predict some future values for this series since our goal is to see if doctors are adopting the coding system. Which method do you suggest to use to forecast this kind of series?

I have a question related to modeling short time-series. It is not a question , but how. What method would you recommend for modeling (very) short time-series (say of length $T \leq 20$)? By "best" I mean here the most robust one, that is the least prone to errors due the fact of limited numbers of observations. With short series single observations could influence the forecast, so the method should provide a cautious estimate of errors and possible variability connected to the forecast. I am generally interested in univariate time-series but it would be also interesting to know about other methods.


There are five empty boxes. Balls are placed independently one after another in randomly selected boxes. The probability that the fourth ball is the first to be placed in an occupied box equals.

There are five empty boxes. Balls are placed independently one after another in randomly selected boxes. Find the probability that the fourth ball is the first to be placed in an occupied box.   We only need to consider the first 5 balls. The total possibilities are $5^5$. I have been trying various cases but cant seem to pinpoint the crux of the strategy any help?


I have some confusion over dictionaries and hash tables that I wanted to clarify .Suppose I have the current dictionary and the current output of the hashes of the current python run.  Dict = dict() print(hash('a')) print(hash('b')) print(hash('c')) Dict['a'] = 1 Dict['b'] = 2 Dict['c'] = 3 print(Dict)   has the output of  1714333803 1519074822 1245896149 {'a': 1, 'c': 3, 'b': 2}   So to my knowledge a hashtable is simply an array where the hash is the index of the hashtable. For instance, 'a' had a hash of 1714333803, therefore my hashtable index 1714333803 has a value of 'a'. So im confused how many indexes a hashtable has and how the hash function produces the answer? Does it use modulus and have a fixed range of indexes? Because the given print of the dictionary outputs {'a': 1, 'c': 3, 'b': 2}, but is it correct to assume that eventhough it outputs that, the dictionary is actually an array of atleast 1714333803 indexes, because that seems ridiculously overkill to contain 3 elements and not to mention how much of a waste of space it is. Also for the hashtable, what is in the indexes that has no value, null?

Does anyone know how the built in dictionary type for python is implemented?  My understanding is that it is some sort of hash table, but I haven't been able to find any sort of definitive answer.


Prove that if $A,B$ are finite Abelian groups and for every $n$ they have the same amount of elements of order $n$, then $A \simeq B$.  I know I have to use primary decomposition, but am not sure how exactly. Any guidance would be appreciated!

Let $A$ and $B$ be finite abelian groups. Suppose that for every natural number $m$, the number of elements of order $m$ in $A$ is equal to the number of elements of order $m$ in $B$. Prove that $A$ and $B$ are isomorphic.  Idea Given that these groups are finite, I think you have to use the primary decomposition theorem somehow.


Have array like   arr = [1,2,3,4,5,6,7,8,9,10].   How I can get array like this:  [1,2,5,6,9,10]   take 2 elements with step 2(::2)  I try something like arr[:2::2].it's not work

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 was given the hint of using the Mean Value Theorem. I've gone over the definitions but am having a hard time seeing what to do.

Is $f(x)=\ln(x)$ uniformly continuous on $(1,+\infty)$? If so, how to show it?  I know how to show that it is not uniformly continuous on $(0,1)$, by taking $x=\frac{1}{\exp(n)}$ and $y = \frac{1}{\exp(n+1)}$.  Also, on which interval does $\ln(x)$ satisfy the Lipschitz condition?


We all know that the canonical commutation relation give you   $$[x^i,p_j]=i\hbar~\delta^i_j,\qquad i,j=1,2,3.$$   Is there a relativistic version such as   $$[x^a,p_b]=i\hbar~\delta_b^a,\qquad a,b=0,1,2,3~?$$  If so what is the time operator $x^0$?

The question in the title has been asked many times on this site before, of course. Here's what I found:    in 2011. Answer states time is a parameter.  in 2012. Answer by Arnold Neumaier cites surveys in the literature, and very briefly summarizes Pauli's 1958 proof: if a time operator satisfied a CCR with the Hamiltonian, it would imply spectrum of Hamiltonian is unbounded below.  in March 2013. Closed as duplicate without answer.  in Nov 2013. Answer confusingly states there is no time operator, then describes a time operator. Then closed as duplicate.  in Feb 2016. Answer describes an explicit time operator, but points out that multiplication by $t$ does not yield an $L^2(\mathbb{R})$ function since norm is preserved in time.  Let me also link , , , and  which address slightly different questions, but contain related discussions. We also have , where Valter Moretti points out that a sensible construction of coordinate operators in relativistic QFT yields the Newton-Wigner operators, but only for the spatial coordinates, since none exists for the timelike coordinate by Pauli's theorem. And off of physics.se, a great resource is John Baez's website, where he has a note  which mentions that by  a time operator satisfying a CCR with the Hamiltonian would necessitate the Hamiltonian have unbounded spectrum.   Should Pauli's theorem (which is probably a corollary of Stone-von Neumann theorem), as it's referred to in some of the answers, be taken as the definitive answer? Most of the sources seem to agree.  But some of these answers seem to be ignoring an elephant: in a relativistic theory, time and space are treated on an equal footing. If there are spatial operators, surely there must be a time operator. Indeed, some of the comments in the above questions refer to chapter 1 of . Let me quote the relevant passage:     One [option to combine quantum mechanics and relativity] is to demote position from its status as an operator, and render it as an extra label, like time. The other is to promote time to an operator.       Let us discuss the second option first. If time becomes an operator, what do we use as the time parameter in the Schrödinger equation? Happily, in relativistic theories, there is more than one notion of time. We can use the proper time τ of the particle (the time measured by a clock that moves with it) as the time parameter. The coordinate time $T$ (the time measured by a stationary clock in an inertial frame) is then promoted to an operator. In the Heisenberg picture (where the state of the system is fixed, but the operators are functions of time that obey the classical equations of motion), we would have operators $X^\mu(τ)$, where $X^0 = T$. Relativistic quantum mechanics can indeed be developed along these lines, but it is surprisingly complicated to do so.   In a subsequent paragraph, he points out that promoting all the coordinates to operators, including time, is exactly what string theory is, though with the additional complication that there is an additional parameter.  So how do we reconcile these two camps? Is Pauli's theorem incompatible with relativistic considerations? Is it really a problem if your Hamiltonian's spectrum is not bounded below? Why is there no timelike Newton-Wigner operator? Does there in fact exist a relativistic quantum theory which includes an operator whose eigenvalues are time coordinates?   I feel like the existing answers on the site did not address this issue, so I'm hoping for some new answers which look at it from that perspective.


I have used the grep command to match a pattern then the matching row has saved in a file. But when saved the result it's saved with the file directory. But I want to save only the row result not the directory. my command : grep -r 'rs689 ' $TMP_DIR/ >> $GEN_FILE  and output of the genotype file is like that: impute-out/tmp_impute2:SNP1298 rs689 2182224 A T 1 0 0 impute-out/tmp_impute2_info:SNP1298 rs689 2182224 A T 0.000 1.000 1.000 2 0.000 0.000 -1.000 impute-out/tmp_impute2_haps:SNP1298 rs689 2182224 A T -1 -1 impute-out/tmp_impute2:SNP4568 rs12722495 6097283 T A 0 0 1 impute-out/tmp_impute2:--- rs12722495 6097283 T C 0.250 0.500 0.250  I want to save the output in this file like : SNP1298 rs689 2182224 A T 1 0 0 SNP1298 rs689 2182224 A T 0.000 1.000 1.000 2 0.000 0.000 -1.000 SNP1298 rs689 2182224 A T -1 -1  Please suggest me how to remove the directory when saving the file. or Is there any regular expression to use in grep command which will remove directory during save the result?

I am greping a string from multiple files, but the one undesired side effect, is the filename prefacing the output. How can I suppress the filename outputs using only grep?      $ grep -i lp lpNet*      lpNet:This was printed via the internet using the lp command.     lpNet:I believe lp doesnt care what the device is.      lpNet1:This was printed via the internet using the lp command.     lpNet1:I believe lp doesnt care what the device is.      lpNet2:This was printed via the internet using the lp command.     lpNet2:I believe lp doesnt care what the device is.      lpNet3:This was printed via the internet using the lp command.     lpNet3:I believe lp doesnt care what the device is.    I have solved the issue for now using cat lpNet* | grep lp  I am just wondering if there is a more efficient path to have the same effect


I have two figures, 1 and 2. Figure 1 should be placed on top, so a \begin{figure}[t] is the way to go. In the syntax, figure 2 is loaded just after the first one with a \begin{figure}[h] command, so that both figures are placed just below/above each other. But what I get is that a text line from the previous page is forced in between the images. Also [!h] for the second figure does not help. I am sure this problem was already discussed and solved, thus no MWE here. I could not find the solution yet. Any help?

I have two images that I would like to appear on the same page. Each figure should appear as a separate figure with its own caption.  My problem is that LaTeX sometimes places the figures on separate pages.  I currently have achieved this by putting two \psfragfig commands consecutively within the same figure environment. This seems a simple and succesful approach, but I wonder if I am not using the figure environment correctly by doing this. Should I use the subcaption package instead?


When I hit e this is what I see   where do I place nomodeset

I know that editing the boot options line and adding 'nomodeset' solves the problem of my laptop during LiveCD mode, what I don't know is how to set it at boot up through Grub2 after I've installed Ubuntu.  So, my question is; how do I set nomodeset before I boot into Ubuntu?


Is there a "quote words" operator in R, analogous to qw in Perl? qw is a quoting operator that allows you to create a list of quoted items without having to quote each one individually.  Here is how you would do it without qw (i.e. using dozens of quotation marks and commas):  #!/bin/env perl use strict; use warnings;  my @NAM_founders = ("B97",    "CML52",  "CML69", "CML103", "CML228", "CML247",                     "CML322", "CML333", "Hp301", "Il14H",  "Ki3",    "Ki11",                     "M37W",   "M162W",  "Mo18W", "MS71",   "NC350",  "NC358"                     "Oh7B",   "P39",    "Tx303", "Tzi8",                    );  print(join(" ", @NAM_founders)); # Prints array, with elements separated by spaces   Here's doing the same thing, but with qw it is much cleaner:  #!/bin/env perl use strict; use warnings;  my @NAM_founders = qw(B97    CML52  CML69  CML103 CML228 CML247 CML277                       CML322 CML333 Hp301  Il14H  Ki3    Ki11   Ky21                       M37W   M162W  Mo18W  MS71   NC350  NC358  Oh43                       Oh7B   P39    Tx303  Tzi8                    );  print(join(" ", @NAM_founders)); # Prints array, with elements separated by spaces   I have searched but not found anything.

Anyone know if R has quote-like operators like Perl's qw() for generating character vectors?


Is there a reliable to way to check if a particular asset was loaded from cache or from the network?  The only way I found so far is to set a threshold like 10ms and check the loading duration, however it seems that it might not be always accurate.  UPDATE  I need to do that for monitoring/debugging purposes and possible optimizations depending on what I see in the metrics

I want to display from cache for a long time and I want a slightly different behavior on page render vs loading the page from cache.  Is there an easy way I can determine this with JavaScript?


Not sure if anyone here might be familiar with the term "auto income generator," but it's a marketing gimmick where a person/website asks for an investment, sometimes as little as $1, and claims you'll be getting fast returns -- sometimes 200% within the next week I've heard.  As an example, one would claim to take $1 as an investment, and promise 6% returns daily, and 0.25% returns per hour -- better than stocks.  The claim is that all of the money they receive builds interest, and they then pour out more back.  There are very many sites like these online, and I've heard some people swear that they "work."  The idea is that you make a single deposit, and you're "set" -- money keeps coming in at a high return rate and your investment doubles, triples, and more -- supposedly seeming better than anything else.  My question is, does this really happen? I wouldn't give them a penny, but just wondering.

Recently I've been coming across many on-line resources that propose people to pay them in order to to get seemingly gigantic profits. This is what the 'About us' page of such sites normally says:  Extremely-Successfull-Corporation is a new dynamically developing investment project which helps you earn (loads of!) money quickly and easily! Our team manages the funds that you provide us with and invests them in stocks, real estate and lots of other stuff. We are 185.67% professional traders and guarantee that each your investment will result in 125% profit for you! The only thing you have to do is deposit money and wait for the revenue for 24 hours. Join us today and start earning money right away!  They also provide a lot of links to various social networks where people praise that investment company and even post photos of (quite a lot of) money they say they've earned only thanks to it. How this works Basically, they say that you kinda lend them money, they use it in investment and then return that amount multiplied by 1.2. I got curious about this thing and decided to try it out, although I was (and I am) pretty sure that this is  scam. So, I've chosen a random site out of tens of similar sites that provided such 'service'. This is what I had to do to invest into... what?  Creating an account is easy: you supply an e-mail and create a username and a password. It looks like the e-mail is never used after that. I had to create a Qiwi wallet and deposit some money to it as it was the only way to deposit money to the account. After that the site told me to provide it with the number of my wallet and transfer the amount of money I'd like to put onto my account to another Qiwi wallet and supply my username as a comment to the payment. After that I had to put the transaction code into a field on the site to verify the payment. The payment was completed successfully, and I pressed the Deposit button to deposit 100Something. The site immediately accepted it and started the 24 hour countdown constantly showing that after that 120Something will be on my balance. Right now I must wait for 24 hours to see my money lost the revenue.  My concerns The problem is, I don't understand, how such sites work. Is that scam or not? Some of my friends told me that they've actually received the revenue after they deposited a bit of money to similar sites, and I don't have any evidence not to trust them. If such sites really 'work', then how and why? Why would anyone trust them so much to give them money for absolutely no reason? Okay, I'm not so clever, but they can't make profit only because of stupid people, can they? Why there seem to be so many people in different social networks who claim the site has helped them to earn money? If this was scam, the creators of the site would have to pay them so these people wrote their advertisements posts, to my mind: nobody would like to advertise someone's business for free, right? Then, how do the site's owners make profit? Anyway, who will give you 120$ after you gave them only 100$? The question Could someone please explain: are such sites scam or they could be not scam? Update Surprisingly enough, I was able to receive 1.2 times my deposit and transfer it to my Qiwi wallet. What I learned from the answers, Wikipedia and Google is that such schemes allow the 'clients' (actually, victims) to win probably several times and then suddenly disappear with all the investments. So now I'm planning to run away from that site as fast as I can, but another question has arisen: is there any way to determine that today or tomorrow the scammers will disappear with the money? Can there be any signs (except inability to withdraw the money, of course)?


So Comodo wont work properly so I want to uninstall it. I dont want to install other programs that are not legitiment

What are ways to install/uninstall programs in Ubuntu. I will mention only .deb since it is the official package format and for example installing a .sh or .run program can typically be as simple as (In latest Ubuntu) ./program.sh or sh program.run.  Also note that am talking about HOW to install packages IN Ubuntu, not talking about downloading a new installer (Like some Super Cow Software Center Duke Nukem version from sourceforge or something). Only tools that already come in the repositories (In any of the 4 standard ones, main, universe, restricted or multiverse).  Take into consideration all GUI and terminal ways of doing it, with basic format of doing the installation. With this in mind I am talking for example about Software Center, synaptic, apt-get, aptitude, dpkg, etc... a way to show all tools that are available in Ubuntu to install deb packages.  NOTE - Forgot, this should be Community Wiki since it will have all ways a user can install/uninstall something. Like a friendly guide on doing that.  UPDATED question to remove the confusion some are having about sh/run files.


In my book, lots of statements begin with "Let $X$ and $Y$ be jointly continuous random variables." and then some example or a derivation of a formula follows. But can two continuous random variables not be jointly continuous? What does it mean for two continuous random variables to not be jointly continuous? Does it have something to do with the sample spaces on which they are defined on?

When defining jointly continuous, we  are saying: if there exists a function $f(x,y)$ satisfying that   $$ P\{X\in A, Y\in B\}=\int_B\int_a f(x,y)dxdy $$  then $X,Y$ are called jointly continuous.  So not every pair of random variable $X$ and $Y$ are jointly continuous, because such $f(x,y)$ may not exists, right?   Then in Ross's book Introduction to Probability Models, there is something I'm confused:  He proved the formula  $$ E[X+Y]=E[X]+E[Y] $$  for jointly continuous random variables, but then use it for arbitrary pair of random variables.  When $X,Y$ is jointly continuous, it is easy to prove, since $$ E[g(X,Y)]=\int_{\mathbb{R}}\int_{\mathbb{R}}g(x,y)f(x,y)dxdy $$  Then let $g(X,Y)=X+Y$.  To be clear, my question is :  (1) Isn't every pair of random variable $X$ and $Y$ are jointly continuous, right?  (2) The formula $E[X+Y]=E[X]+E[Y]$ is valid for any pair $X, Y$ even if they are not independent, right?  (3) Ross in his book proved $E[X+Y]=E[X]+E[Y]$ under the assumption $X$ and $Y$ is jointly continuous. It is quite easy. How to prove general case?


for example,  1.  public class Something {      public static void main(String[] args){         System.out.print("Hello World");       } }   2.  class Something {       public static void main(String[] args) {          System.out.print("Hello World");        }      }

In Java, are there clear rules on when to use each of access modifiers, namely the default (package private), public, protected and private, while making class and interface and dealing with inheritance?


NOTE: This question has been marked as a duplicate. Well two things.  I don't see an answer there  The interpretation of the user in that question is the count of flags is of available flags instead of those that are not yet handled by myself. Is this the case? If yes, can anyone direct me to a meta/faq link which affirms this? And if you cannot find a meta/faq link then please do not mark it as a duplicate. It is a humble request :) Also  Instead of simply downvoting, I would request you to please let me know what is wrong with this question so that I can improve on it. :)    Please see this screenshot. The numbers never match. No matter how fast I refresh. I thought that maybe there were 7 Not An Answer posts and some of them disappeared because they were actioned so I rapidly refreshed 5 times in a row but that 7 didn't change... nor did the 3 on the left hand side. Same with the total posts to be reviewed (in Orange) vs the total posts 19. The orange total did change after 2 refresh attempts though. Am I missing something? Does the count for individual flags refresh only after some specific time? I assumed it to be dynamic i.e changing with every refresh (Showing the actual count)

I believe this is a new feature so I'm hoping for once I'll have an issue that isn't a duplicate.  I've noticed the review counter is back on the bar, which is great. I have also noticed that it now hides the posts you have made a decision on, even better!  What it does right now is show the total amount of flags that are available instead of those that are not yet handled by myself. Can this be switched?


Every time I try to upgrade ubuntu, it gives me forbidden access. Every time that happens, Ubuntu crashes.  log file :   Do you want to continue [Y/n]? y Get:1 http://archive.canonical.com/ubuntu/ saucy/partner adobe-flash-properties-gtk i386 11.2.202.346-0saucy1 [131 kB] Get:2 http://us.archive.ubuntu.com/ubuntu/ saucy-updates/main libfontembed1 i386 1.0.40-0ubuntu1.1 [47.8 kB] Get:3 http://archive.canonical.com/ubuntu/ saucy/partner adobe-flashplugin i386 11.2.202.346-0saucy1 [6,600 kB] Get:4 http://us.archive.ubuntu.com/ubuntu/ saucy-updates/main lightdm i386 1.8.5-0ubuntu1 [107 kB] Err http://us.archive.ubuntu.com/ubuntu/ saucy/main apturl-common i386 0.5.2ubuntu2   403  Forbidden [IP: 91.189.91.13 80] Get:5 http://us.archive.ubuntu.com/ubuntu/ saucy-updates/main cups-browsed i386 1.0.40-0ubuntu1.1 [44.7 kB] Get:6 http://us.archive.ubuntu.com/ubuntu/ saucy-updates/main liblightdm-gobject-1-0 i386 1.8.5-0ubuntu1 [33.4 kB] Fetched 6,963 kB in 19s (359 kB/s)                                              Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/a/apturl/apturl-common_0.5.2ubuntu2_i386.deb  403  Forbidden [IP: 91.189.91.13 80] E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?   I tried to contact the internet provider but there is no support from their side. I don't have a vpn account.  Is there another solution?

I live in Ethiopia and the government blocks all urls with the word "proxy" in them. I couldn't use that word in the title above because that would make the url contain the word proxy.   When I apt-get upgrade I get errors because some packages like libproxy1, libproxy1-plugin-gsettings, libproxy1-plugin-networkmanager, python-libproxy all contain the p word.  Therefore, it is all blocked. I tried putting the urls into proxy sites, but they all just returned to their home page.   Are there any other solutions?


Since we know the following:  $\lim_{n\to\infty} 1/n=0$  Can we say that the this holds too:  $\lim_{n\to\infty} n*0=1$?  Thank you!

I did a bit of math at school and it seems like an easy one - what am I missing?  $$n\times m = \underbrace{n+n+\cdots +n}_{m\text{ times}}$$  $$\quad n\times 0 = \underbrace{0 + 0 + \cdots+ 0}_{n\text{ times}} = 0$$  (i.e add $0$ to $0$ as many times as you like, result is $0$)  So I thought an infinite number of $0$'s cannot be anything but $0$? But someone claims different but couldn't offer a reasonable explanation why. Google results seemed a bit iffy on the subject - hopefully this question will change that.


I cannot find the exact way to do this.... W is an orthogonal basis...  w ={{1,2,2,4},{4,-2,8,-4},{0,0,0,0}}  vector v = {7,2,2,1}  Anyone know how to project v onto w?

I am trying to understand how - exactly - I go about projecting a vector onto a subspace.  Now, I know enough about linear algebra to know about projections, dot products, spans, etc etc, so I am not sure if I am reading too much into this, or if this is something that I have missed.  For a class I am taking, the proff is saying that we take a vector, and 'simply project it onto a subspace', (where that subspace is formed from a set of orthogonal basis vectors).  Now, I know that a subspace is really, at the end of the day, just a set of vectors. (That satisfy properties ). I get that part - that its this set of vectors. So, how do I "project a vector on this subspace"?  Am I projecting my one vector, (lets call it a[n]) onto ALL the vectors in this subspace? (What if there is an infinite number of them?)  For further context, the proff was saying that lets say we found a set of basis vectors for a signal, (lets call them b[n] and c[n]) then we would project a[n] onto its . We project a[n] onto the signal-subspace formed by b[n] and c[n]. Well, how is this done exactly?..  Thanks in advance, let me know if I can clarify anything!  P.S. I appreciate your help, and I would really like for the clarification to this problem to be somewhat 'concrete' - for example, something that I can show for myself over MATLAB. Analogues using 2-D or 3-D space so that I can visualize what is going on would be very much appreciated as well.   Thanks again.


It's a well known result that the Alternating Harmonic Series : $$1 - \frac{1}{2} + \frac{1}{3} - \frac{1}{4} + ... = \ln(2)$$ But, this is because of "Conditional Convergence". I saw somewhere that if you re-arrange the terms in the series like this : $$1 + \frac{1}{3} - \frac{1}{2} + \frac{1}{5} + \frac{1}{7} - \frac{1}{4} +... = \frac{3}{2} \ln(2)$$ When I first saw it, my mind was blown. I couldn't accept it. How can the result change just by re-arranging the terms? My guess was that it is somewhat related to the $\mathbb{Z^+}$ paradox where the number of even integers is $\frac{1}{2}$ of all the numbers and $\frac{1}{3}$ when you arrange it in some other way(Not the theory but the logic behind it). Can anybody please explain why does the result of the Alternating Harmonic Series change when you re-arrange the terms. Any help is appreciated. Thanks in Advance

$\sum u_n = 1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+\dots$ conditionally converges to $\log 2$; and, when deranged to $\sum u'_n = 1-\frac{1}{2}-\frac{1}{4}+\frac{1}{3}-\frac{1}{6}-\frac{1}{8}+\dots,$ converges to $\frac{1}{2}\log 2$. Why does a deranged conditionally convergent series have a different limit? First Course in Math Anal, p.93, by Burkill, explains that the sums $s_n, t_n$ of the first n terms of the two series are different functions of $n$. This reasoning is incomplete, because different functions of $n$ can converge to the same limit; for example, let $r_n$ be the first $2n$ terms of $\sum u_n$, then $s_n$ and $r_n$ are different functions; besides, by differently defining terms, i.e. clustering pieces of a series, e.g. \begin{align*} 1-\tfrac{1}{2}-\tfrac{1}{4}+\tfrac{1}{3}-\tfrac{1}{6}-\tfrac{1}{8}+\dots = \left(1-\tfrac{1}{2}-\tfrac{1}{4}\right)+\left(\tfrac{1}{3}-\tfrac{1}{6}-\tfrac{1}{8}\right)+\dots \\ = \left(1-\tfrac{1}{2}-\tfrac{1}{4}+\tfrac{1}{3}-\tfrac{1}{6}-\tfrac{1}{8}\right)+\dots,\\ 1-1+1-1+\dots = (1-1)+(1-1)+\dots \\ =(1-1+1-1)+\dots,\\ 1+1+1+1+\dots = (1+1)+(1+1)+\dots \\ = (1+1+1+1)+\dots, \end{align*} one gets the sum of first n terms as different functions, but the series's limit remains. One could view a changed limit from the perspective of the changed number of terms, Denote 'countably many', the size of natural number, as $\lvert\mathbb{N}\rvert$, then $\lvert\mathbb{N}\rvert = \lvert k\mathbb{N}\rvert = \lvert\mathbb{N}\times\mathbb{N}\rvert$. Then two series with different numbers (e.g. $\lvert \mathbb{N}\rvert$, $\lvert k\mathbb{N}\rvert$) of terms– and so having different limits– paradoxically have same number of terms–and so are possibly formed by the same terms. The paradox could be the fundamental reason. Are there other explanations? Is the use here of 'countably many' is proper?


What will happen if someone create a fake account and use it to increase the reputation of his original account by up voting the questions and answers? Is there any mechanism available to find out these kind of accounts?

I've been thinking how easily a user could create a fake account to upvote all his own questions/answers. I didn't think of doing it myself; I like to win my reputation the right way, but I'm sure there are a lot of people who would do that.  Does Stack Exchange prevent this in any way?


I read from this  which explains that to make git to track a folder there must atleast an empty file:  Currently the design of the Git index (staging area) only permits files  to be listed and nobody competent enough to make the change to allow  empty directories has cared enough about this situation to remedy it.  Directories are added automatically when adding files inside them.  That is, directories never have to be added to the repository,  and are not tracked on their own. You can say "git add <dir>" and it  will add the files in there.  If you really need a directory to exist in checkouts you should create a file in it.   I have faced some problems because git not tracking empty folders, i am list a few:  Problem1:  I have a apache/log directory in one of my git repository.  when I pushed it to server and run the website it didn't worked. Where it worked fine in my localsystem. after a lot of research i found out that git push did n't pushed the empty folder /log. the serve checked folder log to create logfiles. since folder log did not exist, it is not possible to automatically create a folder and put these files. That is why the error.  Problem2:   I have lots of branch. Only one of my particular branch say frontend have folder caps.  Sometime one of a folder in the directory my_git_repo/caps/html/home/ will be empty.  branch master doesn't have folder caps  if i make git checkout master it will have empty folder ie caps/html/home/tmp so i want to manually delete the folder caps sometimes it will create confusion.  usually i solve these problems by putting an empty file(README) in the folder.  So I would like to make git to track all empty folders. is it possible by editing .git/config or something?  Any help will be appriciated.:))

How can I add an empty directory (that contains no files) to a Git repository?


What are the steps to remove reimageplus virus manually(as in without using any third party software)? I tried using adwcleaner but it seems to keep coming back or something. How to completely remove it?  I am on Windows 7. I don't know it got contracted.

What should I do if my Windows computer seems to be infected with a virus or malware?  What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware?   This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits.


Is there a way of getting the analysis "create fishnet" to generate a grid of x number of points in ModelBuilder?   For example, I wish to generate a grid consisting of for example 80 points within a polygon (see picture).

Is it possible to create a model in ArcGIS ModelBuilder where you simply state number of points and an area in the form of a polygon to get the model to try and equally space out the points based on the geometry of the polygon and number of points?


When I boot ubuntu then it shows error  [Failed] : "Failed to start network time synchronization" See 'Systemct1 status systemd-timesyncd.services' for details

When I look at  I can see the current time configuration with timedatectl but I always get an error.  $ timedatectl status Failed to create bus connection: No such file or directory $ sudo timedatectl status Failed to create bus connection: No such file or directory  # timedatectl status Failed to create bus connection: No such file or directory   There are no ntp packages installed and the service is running normal.  # systemctl status systemd-timesyncd * systemd-timesyncd.service - Network Time Synchronization    Loaded: loaded (/lib/systemd/system/systemd-timesyncd.service; enabled; vendor preset: enabled)   Drop-In: /lib/systemd/system/systemd-timesyncd.service.d            `-disable-with-time-daemon.conf    Active: active (running) since Thu 2018-03-15 15:37:16 CET; 17h ago      Docs: man:systemd-timesyncd.service(8)  Main PID: 1801 (systemd-timesyn)    Status: "Synchronized to time server 193.190.253.212:123 (1.be.pool.ntp.org)."    CGroup: /system.slice/systemd-timesyncd.service            `-1801 /lib/systemd/systemd-timesyncd  Mar 15 15:37:16 linux-repo systemd[1]: Starting Network Time Synchronization... Mar 15 15:37:16 linux-repo systemd[1]: Started Network Time Synchronization. Mar 15 15:37:21 linux-repo systemd-timesyncd[1801]: Synchronized to time server 193.190.253.212:123 (1.be.pool.ntp.org). Mar 16 08:28:56 linux-repo systemd[1]: Started Network Time Synchronization.


I have two glm, one with a gaussian distribution and identity link and one with gamma family and log link. The predictors are the same, the only thing that change is the response that in the gaussian glm is log-transformed and in the gamma glm is not.  The deviance is lower in the second model, and when plotting the residuals the second model looks much better than the first. However, when looking and the AIC, the first model has half the AIC of the second!  How is that possible? Is it wrong to compare AIC of glm with different distribution families?  summary(mod1)  Call: glm(formula = log_RS ~ DIET + log_Disp + log_II + log_LS + log_SM +      log_AS + log_LONG, family = gaussian)  Deviance Residuals:      Min       1Q   Median       3Q      Max   -5.1050  -0.2672   0.1063   0.3945   1.3012    Coefficients:              Estimate Std. Error t value Pr(>|t|)     (Intercept)  1.061888   0.008574 123.856  < 2e-16 *** DIETOH      -0.077913   0.012762  -6.105 1.07e-09 *** log_Disp     1.529989   0.006960 219.822  < 2e-16 *** log_II      -0.422808   0.006786 -62.310  < 2e-16 *** log_LS       0.325270   0.006093  53.382  < 2e-16 *** log_SM      -0.268292   0.008372 -32.048  < 2e-16 *** log_AS       0.185077   0.010166  18.205  < 2e-16 *** log_LONG     0.067347   0.010494   6.418 1.45e-10 *** --- Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1  (Dispersion parameter for gaussian family taken to be 0.3246263)      Null deviance: 24060.5  on 9345  degrees of freedom Residual deviance:  3031.4  on 9338  degrees of freedom AIC: 16018  Number of Fisher Scoring iterations: 2  > summary(mod2)  Call: glm(formula = RS ~ DIET + log_Disp + log_II + log_LS + log_SM +      log_AS + log_LONG, family = Gamma(link = log))  Deviance Residuals:       Min        1Q    Median        3Q       Max   -2.94338  -0.35264  -0.00239   0.27669   1.40915    Coefficients:              Estimate Std. Error t value Pr(>|t|)     (Intercept)  1.186181   0.006435 184.332  < 2e-16 *** DIETOH      -0.075002   0.009579  -7.830 5.41e-15 *** log_Disp     1.536406   0.005224 294.104  < 2e-16 *** log_II      -0.364580   0.005093 -71.585  < 2e-16 *** log_LS       0.306213   0.004573  66.955  < 2e-16 *** log_SM      -0.233847   0.006283 -37.216  < 2e-16 *** log_AS       0.156994   0.007630  20.575  < 2e-16 *** log_LONG     0.053129   0.007876   6.745 1.62e-11 *** --- Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1  (Dispersion parameter for Gamma family taken to be 0.1828775)      Null deviance: 23484.5  on 9345  degrees of freedom Residual deviance:  2349.8  on 9338  degrees of freedom AIC: 33167  Number of Fisher Scoring iterations: 8  >

What are exactly the prerequisites, that need to be fulfilled for AIC model comparison to work?  I just came around this question when I did comparison like this:  > uu0 = lm(log(usili) ~ rok) > uu1 = lm(usili ~ rok) > AIC(uu0) [1] 3192.14 > AIC(uu1) [1] 14277.29   This way I justified the log transformation of variable usili. But I don't know if I can AIC-compare models when for example the dependent variable is different?  Ideal answer would include the list of prerequisites (mathematical assumptions).


I'd like to run a python script when people log in to the server. I thought editing /etc/motd would be the best approach, but since it's only readable file, that won't work.  I found pretty much identical post:   What would be the best solution here? I'd like to run a script that shows the overview of the server, so the users would see the status immediately.  This was suggested A useful practice is to put the command you want to be executed in a script named /etc/motd.sh and call this script from /etc/profile, usually at about the end of it.  but received this comment Putting output like a MOTD in your profile is likely to break sftp.  Any solution will do. Thanks in advance

Can I put shell commands in the /etc/motd login banner file? I have tried:   $(uptime)   and  `uptime`   Is this possible?


Similar questions have been asked on this site but none of them seemed to help me. I'm asked to compute the Laplacian $$\frac{\partial^2}{\partial x^2}+\frac{\partial^2}{\partial y^2}$$ in terms of polar coordinates.  I did do it, but I don't understand why what I did is correct, and I don't understand the more "brute force" way to do it at all.   Here is what I did:     I calculated $\frac{\partial}{\partial r}$ and $\frac{\partial}{\partial \theta}$ in terms of $r,$ $\theta,$ $\frac{\partial}{\partial x}$ and $\frac{\partial}{\partial y}.$ This gave me a system of linear equations which I wrote as   $$\begin{pmatrix}\frac{\partial}{\partial r} \\\frac{\partial}{\partial \theta}\end{pmatrix} = \begin{pmatrix}\cos\theta & \sin\theta \\\ -r\sin\theta & r\cos\theta \end{pmatrix}\begin{pmatrix}\frac{\partial}{\partial x} \\\frac{\partial}{\partial y}\end{pmatrix}.$$   I inverted to get $$\begin{pmatrix}\frac{\partial}{\partial x} \\\frac{\partial}{\partial y}\end{pmatrix} = \frac{1}{r}\begin{pmatrix}r\cos\theta & -\sin\theta \\\ r\sin\theta & \cos\theta \end{pmatrix}\begin{pmatrix}\frac{\partial}{\partial r} \\\frac{\partial}{\partial \theta}\end{pmatrix},$$   and then I simply wrote \begin{align}\frac{\partial^2}{\partial x^2} &= \frac{\partial}{\partial x} \left( \frac{\partial}{\partial x}\right)\\ &= \left(\cos\theta \frac{\partial}{\partial r}-\frac{1}{r}\sin\theta\frac{\partial}{\partial \theta}\right)\left(\cos\theta \frac{\partial}{\partial r}-\frac{1}{r}\sin\theta\frac{\partial}{\partial \theta}\right)\\ &= \cos\theta\frac{\partial}{\partial r}\left(\cos\theta \frac{\partial}{\partial r}-\frac{1}{r}\sin\theta\frac{\partial}{\partial \theta}\right) -\frac{1}{r}\sin\theta\frac{\partial}{\partial \theta}\left(\cos\theta \frac{\partial}{\partial r}-\frac{1}{r}\sin\theta\frac{\partial}{\partial \theta}\right)\\ &= \cos^2\theta \frac{\partial^2}{\partial r^2} - \frac{2}{r}\sin\theta\cos\theta\frac{\partial^2}{\partial r \partial\theta} +\frac{1}{r^2}\sin^2\theta\frac{\partial^2}{\partial \theta^2}.\end{align}   I similarly got $$\frac{\partial^2}{\partial y^2} = \sin^2\theta \frac{\partial^2}{\partial r^2} + \frac{2}{r}\sin\theta\cos\theta\frac{\partial^2}{\partial r \partial\theta} +\frac{1}{r^2}\cos^2\theta\frac{\partial^2}{\partial \theta^2}.$$ Adding the two yields $$\frac{\partial^2}{\partial x^2}+\frac{\partial^2}{\partial y^2} = \frac{\partial^2}{\partial r^2}+\frac{1}{r^2}\frac{\partial^2}{\partial \theta^2},$$   which Spivak says is correct.   Explicitly, here are my questions:   In my solution, when I found $\frac{\partial^2}{\partial x^2},$ I simply "multiplied" the expressions in the second line of the large aligned equation (treating multiplication of the partial operators as composition). Why am I allowed to do this? Why does the expression on the left not act on the thing on the right, forcing me to do the product rule and other nonsense to get the answer? My original idea was just to compute the Laplacian using the chain rule. That is, write $\frac{\partial}{\partial x}=\frac{\partial}{\partial r} \frac{\partial r}{\partial x}$ and compute $\frac{\partial^2}{\partial x^2}$ from there. My problem with this is that I keep getting confused about in which variables I should be writing everything, and how the partial derivative operators act on these other expressions. For example, I compute $\frac{\partial}{\partial x}=\frac{\partial}{\partial r} \frac{\partial r}{\partial x} + \frac{\partial}{\partial \theta} \frac{\partial \theta}{\partial x} = \frac{x}{\sqrt{x^2+y^2}}\frac{\partial}{\partial r} - \frac{y}{x^2+y^2} \frac{\partial}{\partial \theta},$ but then I don't know where to go. Help understanding this method would be greatly appreciated.   If anything is unclear let me know and I'll make the necessary edits.

Consider the polar coordinates with $x=r\cos\theta$ and $y=r\sin\theta$.  I can show using the chain rule that $$\frac{\partial}{\partial x} = \frac{x}{r} \frac{\partial}{\partial r} -\frac{y}{r^2} \frac{\partial}{\partial \theta}$$   What is the method to compute $\dfrac{\partial^2}{\partial x^2}$? I don't know how to do it.


We know that Vulcans are non emotional most of the time and consider any expression of passion unacceptable. Except from when they experience pon farr every seven years - which apparently the way for them to procreate. We also know pon farr is going same way for males and females (reference T'Pol).   Once they are married how do they synchronize? It seems like a very slim chance for both of partners to come to pon farr at the same period of time.   Do one of the spouse violates the other's good will? Do they make children without waiting for any pon farr state (should be rather technical unemotional act in this case)? Do they somehow synchronize their cycles and then have a chance to procreate only once every seven years?

Since Vulcans are emotionless, how do they get into the mood for sex?  How do they solve the problem of reproduction when sex is not possible?


My application works fine, but sometimes it return "strange" result, I dont't understand why it happens. For ex:   var a = 80.78, b = 83.49, c = 45.33 alert (a+b+c); //209.59999999999997 instead of 209.60   Thanks A.

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


I've updated my Dell XPS 9750 with a fresh install of Ubunty 20.04 LTS (I had to resize the partitions as the Windows 10 partition needed more disc space).  Upon finishing the installation and updating of Ubuntu, I tried installing zoom_amd64.deb.  The following error was produced: dpkg: dependency problems prevent configuration of zoom:  zoom depends on libgl1-mesa-glx; however:   Package libgl1-mesa-glx is not installed.  zoom depends on libegl1-mesa; however:   Package libegl1-mesa is not installed.  zoom depends on libxcb-xtest0; however:   Package libxcb-xtest0 is not installed.  I then tried to update the individual packages specified herein.  However, each one of these packages has a long list of other packages that it is dependent upon.  So, I think my approach is incorrect. Does anyone here have a way to get Zoom's video client to install and function correctly on a machine with an Nvidia GeForce GTX 1050Ti GPU, Nvidia's 450.57 proprietary drivers and Ubuntu 20.04 LTS? Thanks

How do I install a .deb file via the command line?


I have a couple of objects inside of an array :  array1 =[{name : "Cena", age : 44},{job : "actor", location : "USA"}]   is there a way for me to merge these two objects to get something like :   array2 =[{name : "Cena", age : 44, job : "actor", location : "USA"}]   I tried looping through the elements but it is not a good option if the object is a big one, I guess. Any good solution using typescript?

I need to be able to merge two (very simple) JavaScript objects at runtime.  For example I'd like to:  var obj1 = { food: 'pizza', car: 'ford' } var obj2 = { animal: 'dog' }  obj1.merge(obj2);  //obj1 now has three properties: food, car, and animal   Does anyone have a script for this or know of a built in way to do this?  I do not need recursion, and I do not need to merge functions, just methods on flat objects.


This problem , I assume can be proved using induction, however I am trying to find another way.   Is there a simple combinatorial approach? One notices that $(n!)^2$ is equal to the number of permutations of size n squared, and that $n^n$ is the number of redundant combinations where there are n spaces and n choices.   Any help would be much appreciated.  Thanks

Show that if $n>2$, then $(n!)^2>n^n$.     My work: I tried to apply induction. So, at the induction step, I need to prove, $n^n>(n+1)^{n-1}$ Here, I tried to use induction again without any luck. I also took log of both sides, but I did not get anything. Please help!


I installed XAMPP in my Ubuntu laptop and I used to work with it without a problem. Just starting the server with: sudo /opt/lampp/lampp start Then, I tried to install a software that needed an apache server and probably something screwed it. Now, each time I run the command, I have this output: Starting XAMPP for Linux 5.6.3-0... XAMPP: Starting Apache...fail. XAMPP:  Another web server is already running. XAMPP: Starting MySQL...ok. XAMPP: Starting ProFTPD...ok.  What I have to do, is to run the sudo /etc/init.d/apache2 stop and then start the lampp again. This means that the apache2 is running all the time. Is there any way to solve it without destroy the lampp installation too?

How do I stop Apache2 from automatically starting on boot? I can't seem to find an option that disables the automatic start-up when I turn on the machine.


the title is inscribed in the spine or the title is inscribed on the spine? What is right and where is the difference? And is it right to say: Words were inscribed on the sign?

When you write something down is it in or on your notebook?     I wrote it down on/in my notebook.      Please, take notes in/on your notebook.   What about newspapers?     I read the article on/in the newspaper.      It was in/on the newspaper.


I have 2 EverReady 6 volt batteries model number 1209. I also have a 12 volt 1 amp screen that I need to power.  How can I power the screen with these batteries?

Power supplies are available in a wide range of voltage and current ratings.  If I have a device that has specific voltage and current ratings, how do those relate to the power ratings I need to specify?  What if I don't know the device's specs, but am replacing a previous power supply with particular ratings?  Is it OK to go lower voltage, or should it always be higher?  What about current?  I don't want a 10 A supply to damage my 1 A device.


If a series converges absolutely, then any sub-series also converges absolutely.   1) is it true? 2) is there a simple "one line" argument to prove it?

Question:  A subseries of the series $\sum _{n=1}^\infty a_n$ is defined to be a series of the form $\sum _{n=1}^\infty a_{n_k}$, for $n_k \subseteq \Bbb N$. Prove that $\sum _{n=1}^\infty a_n$ converges absolutely if and only if each subseries $\sum _{n=1}^\infty a_{n_k}$ converges.  Suggested solution:  $\Rightarrow$   We assume $\sum _{n=1}^\infty a_n$ converges absolutely $\Rightarrow \lim_{n \to \infty} |a_n|$=0. We know from the definition of series that it's actually the sequence of partial sums so $\sum _{n=1}^\infty a_n = S_n$. Therefore we can treat it like a sequence and say that it converges to L. Since $S_n$ converges to L, each of it's sub sequences also converge to L. Therefore $\sum _{n=1}^\infty a_{n_k} =S_{n_k} \to L$ as well.    $\Leftarrow$    We assume each subseries converges. Specifically the sub series $\sum _{\Bbb N even} a_n = A$  $\sum _{\Bbb N odd} a_n = B$ . Since these two series comprise all of the naturals, then  $\sum _{n=1}^\infty a_n =\sum _{\Bbb N even} a_n+\sum _{\Bbb N odd} a_n = A+B$ . Therefore it converges to A+B.   I would like to verify this proof, because I've given it a lot of thought, and still not 100 percent sure about it. Please hint me, and notify me about any mistakes. Thanks.


I am looking for the best astrophysics book or combination of books given my background. I have a PhD in nuclear engineering and I am still doing research in the nuclear field. I develop mathematical models for radiation transport, hydrodynamics, shock physics and MHD, as well as to study the interaction among these physics. Although these physics play a role in astrophysics, I work with them for nuclear engineering applications. As such, I have a gap to fill as far as astrophysical phenomena are concerned. I am looking for one or more textbooks that can give me a broad overview of the main astrophysical phenomena without being to oversimplifying (details on maths derivation would be a plus). After that, I’d like to go deeper into stellar life cycle and planet formation. I would not dislike if I will be able, in the future, to apply my expertise to publish something in this field.

There are no book recommendations for Astrophysics here. I will write my own answer, but I am also interested in what are others' views on the question (I will NOT mark my own answer as the best one).


If I have a fourth degree polynomial $P_4$, how do I show it is not cyclotomic? Just to be sure, in order for $P_4$ to be cyclotomic, does that mean it can only have roots of unity? So can I just check that $x-1, x^2-1,x^3-1,x^4-1$ doesn't divide $P_4$?

Given a monic polynomial $f\in\mathbb{Z}[x]$, how can I determine whether there is $k\in\mathbb{Z}^+$ such that $f\mid x^k-1$?  For example, $x^2-x+1$ divides $x^6-1$, but $x^2-x-1$ does not divide any such $x^k-1$ (unless I miss my mark!). I would also be interested in finding how to answer this for other parameterized families of polynomials, or working over $\mathbb{Q}[x]$ - I expect the former to be hard and the latter easy.


I have a directory which contains many symlinks which point to other directories.  Now I would like to rename a common ancestral directory of the linked directories by the symlinks, and also have symlinks pointing to the same directories except with renamed pathnames. For example, the symlinks point to /home/Tim/dir1, /home/Tim/dir2, ..., and now I would like the symlinks point to /data/Tim/dir1, /data/Tim/dir2, ....  I would like to automate the process of update the symlinks. But there are several questions:   I heard that symlinks can't be edited. So do I have to create new symlinks and then overwrite the existing ones? how can I get the pathname of the directory pointed to by a symlink, and then use some text processing programs to replace the old name of the ancestral directory  in the pathnames with its new name, and create a symlink pointing to the directory with a new pathname? Thanks.

For example, I'm renaming many files inside a tree like this:  [bash]$ for file in `find . -name "*gsf*"`; do `mv $file ${file/gsf/msf}`; done   That renames all the instances of "gsf" in file names matching gsf to "msf", but softlinks continue to point to now-non-existent files containing "gsf".  For example, this is what happens after the rename:  lrwxrwxrwx 1 trusktr users     20 Apr 25 14:39 libmsf-1.so -> libgsf-1.so.114.0.23 lrwxrwxrwx 1 trusktr users     20 Apr 25 14:39 libmsf-1.so.114 -> libgsf-1.so.114.0.23 -rwxr-xr-x 1 trusktr users 265584 Apr 21 04:41 libmsf-1.so.114.0.23   As you can see, the soft links point to libgsf-1.so.114.0.23 which doesn't exist anymore because it was renamed to libmsf-1.so.114.0.23.  What can I do so that the rename also happens to the soft link pointers?


@Claude Leibovici's answer to this  (it's the second answer) gives an asymptote for the generalised harmonic number $H_n^{(k)}=\sum_{i=1}^n \frac{1}{i^k}$:  $$H_n^{(k)}=n^{-k}    \left(-\frac{n}{k-1}+\frac{1}{2}-\frac{k}{12    n}+O\left(\frac{1}{n^3}\right)\right)    +\zeta (k)$$  Heuristically, this is an excellent fit. But can someone please tell me if this is a published result, and more importantly how it is derived?

Let $H_n$ be the $n$th harmonic number and $H_n^{(k)}$ be the $n$th harmonic number of order $k$ as follows:  $$H_n=\sum_{m=1}^{n}\frac{1}{m}$$ $$H_n^{(k)}=\sum_{m=1}^{n}\frac{1}{m^k}$$  There are several inequalities giving upper and lower bounds on $H_n$, such as this one found on  (eqn 14):  $$\frac{1}{2(n+1)}<H_n-\ln n-\gamma<\frac{1}{2n}$$  where $\gamma$ is the Euler-Mascheroni constant:    Are there any equivalent inequalities for $H_n^{(k)}$? And how does one arrive at them?  Heuristically, the following seems to hold, and offer nice tight bounds:  $$n^{-k}    \left(-\frac{n}{k-1}+\gamma-\frac{k}{12    n}-\frac{1}{n^3}\right)    +\zeta (k)<H_n^{(k)}<n^{-k}    \left(-\frac{n}{k-1}+\gamma-\frac{k}{12    n}+\frac{1}{n^3}\right)    +\zeta (k)$$  For example, this is a plot with $k=1.8$:    Is this inequality valid? And how do I prove it?  NOTE: This is a substantial revision of the original question, which was unclear - and since which, I have found the above potential bounds on my own. The bounty is for validation and proof.


I've wrote a program that it needs to store client usage in MB. The program downloads/uploads files that user sends.I want to save the usage in MB with 2 decimal places.  For example 1.234 >> 1.23  Every client has a usage and I'm having a total usage that is means that I store sum of usages to total usage.The issue is that after using the program a few times, one of the clients usage got too many decimal places! That was 102.39000000000001 instead of 102.39 and also the total. Now what is going wrong?  Note that I don't want to use toFixed because it make the variable string.  These are some parts of the code that I think the problem is: let fileSize=Math.round(res/10485.76)/100 'res' is in bytes user.usage+=fileSize; totalUsage+=fileSize;

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


I heard that many theorems in modern mathematics depend on the unproven Riemann Hypothesis. What are some examples of such theorems, and what will be the impact on these results if the Riemann Hypothesis is proven to be true?

I wanted to prepare a presentation for the students I tutor on the .   This is directed at the  and the Generalized Riemann Hypothesis.  The  is good at showing how many conjectures be come true if RH or GRH is proven to be true:   $GRH \implies Conjecture\;X$.   What am looking for is list of possible solution paths where; if something is true then the GRH (or the RH) is true or something is equivalent to GRH (or the RH):   $Conjecture\;X \;\implies GRH$. $Conjecture\;X \iff GRH$.   The Wikipedia article is a good reference for the first bullet point, but not for the last two.  I am looking for references to fill out a list regarding the last two bullet points for my presentation.


In  Jen jumps off the cliff. Did she die in the novel? What happened?

What happens to Zhang ziyi (Jen) in  when she jumps off the cliff .. she dies? becomes immortal? Just before jumping what does she want Lo to become - a master?  Why does she jump off, guilt?


At what point is the Shield (p. 275) spell put into effect?  The Shield spell description states “Casting Time:  1 reaction, which you take when you are HIT by an attack...”   Does this mean that at the point when an attack is determined to have hit (in other words, after an enemy’s attack roll)  I’m able (should I choose) to use my reaction to cast Shield and thusly add +5 to my AC?   This being the case, I would wait to determine if a strike hit, consider their roll number and engage Shield if the +5 would be helpful.  Otherwise, just take the hit. I can sense that my inexperience is causing me to miss something obvious...

The entry for Shield says that the reaction is triggered by being hit by an attack, which would tend to imply that you can wait to see if your opponent actually succeeds on their attack roll (otherwise they would not be hitting you with their attack) to beat your AC before deciding whether or not to cast the spell. However, wouldn't that be considered meta gaming? After all, my character does not know whether the attack will hit or miss; only that he or she is being attacked.


What is the integer part of the number $$\sum_{k=0}^{44}\frac{1}{\cos (k^\circ)\cos((k+1)^\circ)}$$    I tried to solve it using partial fractions but could not get a result. Please help me out.

Find the sum of the following :   (i) $$\frac{1}{\cos0^\circ \cos1^\circ}+\frac{1}{\cos1^\circ\cos2^\circ} +\frac{1}{\cos2^\circ \cos3^\circ}+......+\frac{1}{\cos88^\circ \cos89^\circ}$$  I tried :  $$\frac{1}{\cos1^\circ}\left[\frac{\cos(1^\circ-0^\circ)}{\cos0^\circ\cos1^\circ} + \frac{\cos(2^\circ-1^\circ)}{\cos1^\circ\cos2^\circ}+...\right]$$  = $$\frac{1}{\cos1^\circ}\left[\frac{\cos1^\circ\cos0^\circ}{\cos0^\circ\cos1^\circ} - \frac{\sin1^\circ \sin0^\circ}{\sin0^\circ\cos1^\circ} + \frac{\cos2^\circ \cos1^\circ}{\cos1^\circ\cos2^\circ} -\frac{\sin2^\circ \sin1^\circ}{\cos1^\circ\cos2^\circ}...\right]$$  For this, as well, I am not getting any pattern to solve further. Please suggest, thanks.


I want to run a plain Ubuntu install, but the BIOS does not easily allow for booting into USB drives. I currently have the Chromebook in developer mode and I found a  on the chromium developer info website, but I not sure how to enter the command in.

I have installed Ubuntu 13.04 on my desktop (runs like a charm). Then I used Crouton to install Ubuntu 12. 04 on my chromebook samsung (ARM). It also works quite well.  Here comes my question. Can we have a true Ubuntu (preferably 13.04) on my ARM chromebook?  It seems that the Crouton/Ubuntu is not 100% the real thing.  The best option would be to have the full Ubuntu 13.04 and remove the Chrome OS.


I'm trying to see if for several cases changing the ring in a tensor product affects the result or doesn't. Now I'm trying to prove  $\mathbb{C}\bigotimes_\mathbb{R}\mathbb{C}\simeq \mathbb{C}\bigotimes_{\mathbb{C}}\mathbb{C}$ if it's true, or to show why it isn't.  I've been unable to find an isomporphism between those two, but I don't know how would I proceed in order to show that there is no possible function that could define one.

Are $\mathbb{C} \otimes _\mathbb{R} \mathbb{C}$ and $\mathbb{C} \otimes _\mathbb{C} \mathbb{C}$ isomorphic as $\mathbb{R}$-vector spaces?   I am having a very hard time at digesting tensor products and I do not know how to "compare" tensor products over different rings. My hunch is that they are not isomorphic. It is easy to see that $\mathbb{C} \otimes _\mathbb{R} \mathbb{C}$ is an $\mathbb{R}$-vector space of dimension $4$. I suspect that $\mathbb{C} \otimes _\mathbb{C} \mathbb{C}$ is also an $\mathbb{R}$-vector space but of lower dimension, but I have no idea how to show this or if indeed this intuition is correct.  Thank you.


By default, \in produces a lunate epsilon that is just a crazy, ridiculous size.  What is the most correct way to make it smaller?

To mean that x is an element of X, we can write x \in X. However, in the standard packages, the membership symbol that results is too big; it draws too much attention to itself. This is especially evident when we're doing set theory and writing sets as lowercase, as in x \in y. Does anyone one how to draw a less attention-seeking membership symbol?


I have an Android 10 phone (Motorola Moto G9 Play) and I want to change the Android ID (I think that's what apps use to identify you sometimes). I have a cell phone with: ROOT + Magisk + EdXposed I always changed my "Android ID" using "Titanium Backup". But there is currently no option to change. Is it possible to change the "Android ID" just using a few tools, command line, applications, something that can modify the "Android ID"? Please, I need it so much. Reason: Some applications when they are going to ban accounts, they block the "Android ID" and I need to modify it and then use it again! (By Google Translator, sorry!) =(

I have an Android 10 phone (OnePlus 5) and I want to change the Android ID (I think this is what apps use to identify you sometimes). I read that either I can do a factory reset or root my phone, both of which probably involve wiping the data clean which I want to avoid, and rooting looks complicated. But I read that it's possible to change the Android ID by just using some command line tools, is it possible?


Today, looking for a package on the CTAN, this window popped up:    Is this for real? Or is it something else?

Today I clicked in this link in TeX StackExchange  and I got this message (screenshot below).  In particular, what does it mean that "Latex Productions International has acquired  the world wide exclusive rights from D.F.Knuth" !?   Obviously ctan.org changed hands or something, what happened to ctan.org?  what would be a good link to use for TeX packages?


I finally reached 3000 reputation. So I can now vote to close questions.  But since I'm able to do this, I can't flag posts anymore. They are automatically close votes.  So I can't get the Marshal badge anymore, where I must raise 500 helpful flags. But when I take a look at the users which were recently awarded this badge, most of them have over 3k rep.   How can I raise flags which are counted for the badge?

I will reach a score of 3000 in coming days in stackoverflow. In privileges section, for 3000, I have seen;     Note that once you gain the reputation to vote to close, you should no longer flag for moderator attention to have questions closed or migrated. It is your responsibility to vote now.   In badges info, it is noted that the requirement of Deputy silver badge is raising 80 helpful flags. How can I track (or how to achieve) this badge after reaching a reputation level of 3000?


I am currently trying to port a python script from 2.7 to 3.4.2. the script should be able to run shellcode from memory.  from ctypes import *  shell = b"\x31\xd2\xb2\x30\x64\x8b\x12\x8b\x52\x0c\x8b\x52\..." createbuffer= create_string_buffer(shell, len(shell)) shellcode = cast(createbuffer, CFUNCTYPE(c_void_p))  shellcode()   This is the closest I have gotten to running shellcode on python 3, and it just leaves me with:  OSError: exception: access violation writing 0x0099....   Bear in mind that this script works 100% fine with 2.7, so i don't see why it can't be ported to 3.

My friend produced a small proof-of-concept assembler that worked on x86. I decided to port it for x86_64 as well, but I immediately hit a problem.  I wrote a small piece of program in C, then compiled and objdumped the code. After that I inserted it to my python script, therefore the x86_64 code is correct:  from ctypes import cast, CFUNCTYPE, c_char_p, c_long  buffer = ''.join(map(chr, [ #0000000000000000 <add>:   0x55,                     # push   %rbp   0x48, 0x89, 0xe5,         # mov    %rsp,%rbp   0x48, 0x89, 0x7d, 0xf8,   # mov    %rdi,-0x8(%rbp)   0x48, 0x8b, 0x45, 0xf8,   # mov    -0x8(%rbp),%rax   0x48, 0x83, 0xc0, 0x0a,   # add    $0xa,%rax   0xc9,                     # leaveq    0xc3,                     # retq ]))  fptr = cast(c_char_p(buffer), CFUNCTYPE(c_long, c_long)) print fptr(1234)   Now, why does this script keeps doing segmentation fault whenever I run it?  I have yet a question about mprotect and no execution flag. It is said to protect against most basic security exploits like buffer overruns. But what is the real reason it's in use? You could just keep on writing until you hit the .text, then inject your instructions into a nice, PROT_EXEC -area. Unless, of course, you use a write protection in .text  But then, why have that PROT_EXEC everywhere anyway? Wouldn't it just help tremendously that your .text section is write protected?


$a_1, a_2,..., a_9$ is an arbitrary permutation of positive integers from 1 to 9. Prove that $(a_1 − 1)(a_2 − 2)...(a_9 − 9)$ is always an even number. So I don't understand what the question is asking by "arbitrary permutation of positive integers". Does that mean consecutive integers or multiples? And also, can someone please help me prove this too? Thank you so much! :)

Let n be an odd integer and let f be an [n]-permutation of length n, where [n] is the set of integers 1, 2, 3,...n  Show that the number   x = (1-f(1))*(2-f(2))*...*(n-f(n))   is even using the pigeonhole principle  In this case, I don't understand what this function f is. What is an [n]-permutation of length n? Take f(2) for example. Permutations of [2] would be 1,2 and 2,1. So the way the problem is worded, f(2) must equal 12 or 21. If that's correct, which one? Will this number x still be even regardless of which [n]-permutation f(n) is?


My laptop has been running pretty slow recently I am trying to fix bugs, and get rid of viruses and I might reset my laptop to start new. Before I do this I wanted to know if my games I bought are saved on Steam, so I can just re-download steam and get all my games back?

I have just bought a new computer and I have everything migrated over except for my Steam games.  I looked in Program Files/Steam/ and I found a folder full of the games I have downloaded, but I do not know if it is safe to just copy these folders from one computer to another (seeing as a lot of other applications will not work if you do this), or is there another recommended way?  I don't really feel like re-downloading all my games. I don't have the time nor bandwidth to download 20GB over a 1.5mbps connection.  Is it possible to contact Valve and get a disk with the games on it?


Today, in my flag dialog box, I got the dreaded message     Attention: some of your recent flags have been declined - please   review them before flagging this post!   I went to the link and I got sent to my flag summary page.  I have 300+ total flags, 7 declined, 13 disputed. I'm sure this is meager compared to a lot of other users. But as it is, it's already tedious to go through the 7 pages of flags at 50 per page just to look for any declined flag.   I suggest that we have a way to sort or filter the flags by status by making the numbers in flagging history links to a filter/sorting query.    This way, users can actually review declined flags without having to go through pages and pages of all their other flags.  The two important ones are declined and disputed, but it is probably trivial to implement the same functionality across the other flag statuses.    I have slightly changed the focus of the question to differentiate it more from    The focus of the two questions are different. This one focuses on the message received from having recent declined flags and suggests a better way to access a user's declined flags. The other question focuses on when a user flag has been acted upon and a better way to see them.

When looking at my flag-responses page, it's not always easy to tell what's new.  Sometimes flags take a while to resolve, so I might have one farther down the page that only now got resolved.  Moderators have always been able to leave messages for declined flags and now can leave them for helpful flags too.  If the moderators took the time to write them, we should try to read them.  But right now all I can do is scan the page and see if anything new jumps out at me.  For other types of responses (comments, edits, reputation changes, even changes in favorites), the new information is highlighted through styling (background color).  Could we do something like that for the flags page too?  Or provide some other way for users to see their newly-handled flags?


homepage of my site is completely de indexed by google.when we search cache of our site,it shows 404 error.Please help me out.

This is a general, community wiki  question and answer pair intended to address any questions   concerning the reasons a site or specific site contents do not appear   in search engine results.      If your question was closed as a duplicate of this question and you   feel that the information provided here does not provide a sufficient   answer, please open a discussion on .   My site (or specific pages on my site) is not appearing in search engine results.  Why isn't my content indexed and what can I do about it?