I have tried to install qt-5 but I got  E: Malformed entry 11 in list file /etc/apt/sources.list (Component) E: The list of sources could not be read. E: Malformed entry 11 in list file /etc/apt/sources.list (Component) E: The list of sources could not be read.   My sources.list  #------------------------------------------------------------------------------# #                            OFFICIAL UBUNTU REPOS                             # #------------------------------------------------------------------------------#   ###### Ubuntu Main Repos deb http://55.archive.ubuntu.com/ubuntu/ xenial main   ###### Ubuntu Update Repos deb http://55.archive.ubuntu.com/ubuntu/ xenial-updates main  deb-src http://55.archive.ubuntu.com/ubuntu/ xenial-updates   ###### Ubuntu Partner Repo deb http://archive.canonical.com/ubuntu xenial partner deb-src http://archive.canonical.com/ubuntu xenial partner  #------------------------------------------------------------------------------# #                           UNOFFICIAL UBUNTU REPOS                            # #------------------------------------------------------------------------------#   ###### 3rd Party Binary Repos  ## Run this command: sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys C6DAEA80 deb http://ppa.launchpad.net/boomaga/ppa/ubuntu xenial main # Boomaga PPA - https://launchpad.net/~boomaga/+archive/ubuntu/ppa  ## Run this command: wget -q -O - http://dano.cu.cc/1Aci9Qp | sudo apt-key add - && sudo apt-get update deb http://repo.daniil.it lenny main # Daniil's Bash Video Download - http://daniil.it  ## Run this command: sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 614C4B38 deb http://ppa.launchpad.net/otto-kesselgulasch/gimp/ubuntu xenial main # Gimp PPA - https://launchpad.net/~otto-kesselgulasch/+archive/gimp  ## Run this command: sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 3B1510FD deb http://ppa.launchpad.net/gnome3-team/gnome3/ubuntu xenial main # GNOME3 Extra Apps PPA - https://launchpad.net/~gnome3-team/+archive/gnome3  ## Run this command: wget -q https://dl.google.com/linux/linux_signing_key.pub -O- | sudo apt-key add - deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main # Google Chrome Browser - http://www.google.com/linuxrepositories/  ## Run this command: wget -q https://dl.google.com/linux/linux_signing_key.pub -O- | sudo apt-key add - deb [arch=amd64] http://dl.google.com/linux/earth/deb/ stable main # Google Earth - http://www.google.com/linuxrepositories/  ## Run this command: sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys  247510BE deb http://ppa.launchpad.net/ubuntu-mozilla-daily/ppa/ubuntu xenial main # Mozilla Daily Build Team PPA - http://edge.launchpad.net/~ubuntu-mozilla-daily/+archive/ppa  ## Run this command: sudo wget -O - http://apt.mucommander.com/apt.key | sudo apt-key add -  deb http://apt.mucommander.com stable main non-free contrib   # muCommander - http://www.mucommander.com/  ## Run this command: sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys F24AEA9FB05498B7 deb [arch=i386] http://repo.steampowered.com/steam/ precise steam # Steam for Linux - http://store.steampowered.com/about/  ## Run this command: curl -s https://syncthing.net/release-key.txt | sudo apt-key add - deb http://apt.syncthing.net/ syncthing release # Syncthing - https://syncthing.net/   Content of /etc/apt/sources.list.d  canonical_partner.list       google.list.save     staticfloat-ubuntu-julia-deps-xenial.list          vivaldi.list.save canonical_partner.list.save  hexinator.list       staticfloat-ubuntu-julia-deps-xensave google.list                  libdvdcss.list.save  vivaldi.list ial.list.save     webupd8team-ubuntu-java-xenial.list google-chrome.list           hexinator.list.save  staticfloat-ubuntu-juliareleases-xenial.list       webupd8team-ubuntu-java-xenial.list.save google-chrome.list.save      libdvdcss.list       staticfloat-ubuntu-juliareleases-xenial.list.

I have unistalled and reinstalled the Ubuntu Software Center as per info I found in a similar thread and I got the same response about line 91 or something like that.  I just tried to upload a screen shot but since I'm new it won't allow me to.  I also can not figure out how to cut and paste anything so I have to hand type what the error screen says, both when I attempt to open the software center and nothing happens, when I try to enter commands into the terminal to uninstall, reinstall, whatever I get the same following:  COULD NOT INTITIALIZE THE PACKAGE INFORMATION An unresolvable problem occured while initializing the package information Please report t:his bug against the 'update-manager' package and include the following error message: 'E: Malformed line 91 in source list/etc/apt/sources.list (dist parse)  E: The list of sources could not be read.,  E: The package list of status file could not be parsed or opened.   How do I report bugs?  What can be done about this.  I have searched and everything everyone says to do leads me back to the same line error message.  So, I don't know how to get to line 91 in the source list; to tell you what it says. Sorry, I'm really new to this. That is what I need is to find out how to get there and fix what it says. I would really like to NOT have to re partition my hard drive and start from scratch, so I'm really looking forward to getting this problem solved. I need to be able to install new software.


As per this , which says that:  No all 127.0.0.1 traffic never hits the physical network, it gets processed by a loop back adapter in the kernel.  The poster has a high reputation. I think all 127.0.0.1 traffic never hits the NICs! Which is the correct answer? The answers with references to some official documents are preferred.

I wonder if it is tied to my NIC at all or if the OS or driver intercepts and immediately returns data sent to the loopback address?  Does the signal actually travel to my NIC then the NIC returns it?


Does anyone know how/if you can use in-line variable substitution for an input path name in ModelBuilder for ArcGIS 10?    I used "get field value" to retrieve a code from one feature class, and I want to substitute that text string in two places in another input variable pathname.    For instance, if I used "get field value" to retrieve the code "ABC123", I would use that to call up a raster (make raster layer) with this path name: "D:\Data\Rasters\%ABC123%\el_%ABC123%  Does anyone know if this will work?    ModelBuilder won't recognize this as a valid path name right now.

Is there any way to add arbitrary code snippets to an ArcGIS model?   I envision something similar to the "show code block" the expression builder in advanced labelling or .  For example my project of the moment could benefit greatly from fetching the username of the person running the tool. I know in python this is a simple import os; os.environ.get('USERNAME'). I think I could write that snippet to get_username.py, add it to a toolbox in Arccatalog, then add that tool to the model and use it as per-requisite model parameter for my current tool. That's a lot of work for such a small thing, and next time I might want something else, like  or a .  I think a code snippet tool or similar could be address all of these needs in a generic, broadly helpful manner.


I have java program like this   public class Distribution {      private LinkedList<Integer > group[];          public Distribution() {         group[0] = new LinkedList<>();         group[0].add(1);         group[0].add(2);         group[0].add(3);          group[1] = new LinkedList<>();         group[1].add(4);         group[1].add(5);         group[1].add(6);     }      public static void main(String args[])     {         Distribution distribution = new Distribution();     } }   but the compiler says Exception in thread "main" java.lang.NullPointerException.

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?


For example: A situation needs both Fact A and Fact B to be explained, but a person accepts Fact A and rejects Fact B, misconstruing the situation?     Do you think this is just ignorance or deliberate _____?

Does anyone know what it's called when you interpret evidence to reach the conclusion you want?


I have implement Get() for http get requests. And I am making a rest call to that function with some authentication headers. When supplied with valid authentication headers, it works. But When I use invalid header, I should get "No Response" in my rest client. This needs to implement. Could anyone say what should do for this.  I am using DHC ReST client chrome extension as my Rest client. Given below the GET implementation  public stream Get() {   if(WebOperationContext.Current.IncomingRequest.Headers.AllKeys.Contains("Authorization"))   {     //Validating the header     ...     if( valid header)     {        WebOperationContext.Current.OutgoingResponse.ContentType = "application/xml";        byte[] bytes = Encoding.UTF8.GetBytes(xml);        var stream = new MemoryStream(bytes);         stream.Seek(0, SeekOrigin.Begin);        return stream;     }      if(invalid header)     {       //I need to generate no response codes from here.       //I tried, throw exception, change status code, return null stream but nothing worked.     }   } }

If something goes wrong in a WCF REST call, such as the requested resource is not found, how can I play with the HTTP response code (setting it to something like HTTP 404, for example) in my OperationContract method?


I find myself yearning to spend the last few minutes of my time in the country to be with the people I love.   Given that I'm already in the airport up to the point where non passengers are allowed, how much time should I give myself to go through the processes?  I understand that this might be a question that is very dependent on the airport, but I hope anyone can shed some light.  I notice that if the flight is 9pm, they request the passenger to be at the boarding gate on 8:40pm. How far can I push this?  It would be nice to discuss both cases with and without check in luggage. I'm also not looking for an exact answer like 1 hour. I'm looking for a comprehensive answer like "enough time to go past all checks to arrive 10 minutes before flight departure".

Generally airlines suggest that you be at the airport around 3 hours from the time of departure. Flying from the US, I've often found this to be unnecessary and I generally end up waiting and getting bored at the airport.  I've also found airports outside the US, where they would not let you in before 2 hours from the actual departure time of an international flight. Often this happens to be a pain, waiting outside the airport.  Is there a reliable way to find out the right time to be at the airport depending on the country and the specific airport anywhere in the world?


I tried the below code i assigned a float value to variable and i compared it with a floating point value but it did not gave the desired output. Here as a==13.30 is true i thought it will print "a" instead it prints "5"  #include<iostream> using namespace std; int main() {     float a=13.30;     if(a==13.30)     cout<<a;     else     cout<<"5";  }   output is "5" not "a"

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


I was editing the source code of a program I had written few days back, and observed an interesting thing.  I had below two statements:  newNode->data = 5   and  newNode->next = NUll   And there was a comma (,) instead of a semi-colon (;) separating above two statements. I was surprised because, I always thought this should result in an error.  Below, I have written a short C program to show what I mean to ask.  #include<stdio.h> #include<stdlib.h>  /*node structure definition*/ struct node {     int data;     struct node *next; };  /*----------main()------------*/ int main(int argc, char *argv[]) {     struct node *newNode = NULL;         newNode = malloc(sizeof(struct node));      /*Below is the interesting statement*/      /*LABEL: QUESTION HERE*/      newNode->data = 5,     newNode->next = NULL;      printf("data: %d\n",newNode->data);      while(newNode->next != NULL)     {         printf("Not Null\n");     }      return 0; }    Please see below compilation and sample run of the above program.  Lunix $ gcc -Wall testComma.c -o testComma Lunix $ ./testComma data: 5 Lunix $   As you see, the program compiles and run with no issues.   Using comma (,) instead of semi-colon (;) should not result in an error here ? Why ?   I thought I knew what C statements are but looks like I don't! Could someone explain the reason why there is no error in this case?


\section{Proof of Theorem~\ref{thm:main}}   doesn't produce the correct pdf bookmark (using the hyperref package).  \section{Proof of \texorpdfstring{Theorem~\ref{thm:main}}{Theorem 3.1.7}}   would give the wished result (), but since "3.1.7" is hard coded I have to change this line of code every time when I rearrange my text.  I understand that many mathematical forumalas cannot be used as pdf strings (pdf bookmarks) since they don't have a Unicode representation ().  But "Theorem 3.1.7" only contains plain ASCII symbols. So at least theoretically it should be possible to implement an automatic solution for that.  Ideally I would like to have code that allows me to just write:  \section{Proof of \Cref{thm:main}}   (by using the cleveref package, but a solution for \ref would already be very helpful too)  Example:  \documentclass{article} \usepackage{hyperref} \usepackage{cleveref} \newtheorem{theorem}{Theorem}[section]   \begin{document}      \begin{theorem}\label{thm:main}         text     \end{theorem}  many pages  \section{Proof of \Cref{thm:main}}   \end{document}   (this code does not give the correct pdf bookmarks)  (PS: I think this would be a really great to include such a code in the hypperref or in the cleveref package)

I'm making pdf bookmarks with hyperref and cleveref packages. However, the pdf bookmarks show the label I defined, rather than the theorem name the label refers to. Here's the code:  \documentclass{article}  \usepackage{hyperref} \usepackage{cleveref}  \newtheorem{theorem}{Theorem}  \begin{document}  \section{Section 1} \begin{theorem}\label{some label}     This is a theorem. \end{theorem}  \section{Proof to \Cref{some label}}  \end{document}   And here's the pdf:   Any idea how to change the label to "Proof to Theorem 1" instead of "Proof to some label"?


Is virtual box as effective as dual booting windows? If I am able run windows in linux and do everything I can in windows I might as well as get rid of win 8.

I would like to set-up a PC to run ubuntu most of the time, but also need to run XP for specific applications and testing. In the past I would have simply set up a dual boot machine and then restart and boot into windows XP as needed.    However since the machine has multiple cores and significant memory, I think I can use Virtual Box, Xen, or VMWare hypervisors. I am thinking of making Ubuntu the "host" VM and having XP as a guest VM. This would be especially nice for testing/debug/development since it is possible to run applications in both OS's simultaneously. I've never setup a virtual machine before and think that by asking the questions below I can avoid some trial-and-error.  Basically, I need to decide if a dual boot or VM setup is more appropriate for what I want to do.  Here's my questions:   I do not always need to have XP running. Do the hypervisors allow me to shut the guest VM down so that the host VM can then immediately use all memory and processor resources? When I then bring up the guest VM, is it easy to provision how much memory and other resources are used by it? Ideally, I'd like to pre-configure this in advance and then toggle the guest VM off/on without thinking about it. Is it possible or advisable to have the host OS be 64bit and the guest OS be 32bit? Alternatively, if both VM's are 32 bit and I have 8G of RAM, can the hypervisor provision each VM with 4G of RAM when they are running simultaneously? Which hypervisors are best for set-ups such as I described?


After I upgraded to Ubuntu Gnome 16.10, typing in Nautilus no longer searches through the folder structure recursively, but rather just skips to a file in the folder (the old "type-ahead" mechanism).  Why is this? Is the Ubuntu version of Nautilus patched to do this? How can I enable the standard Nautilus search behavior?  NOTE: This question is the opposite of  -- I'm trying to enable global search, disable local search.

Until now I was using a "traditional" version of Nautilus: that that comes with Ubuntu 10.10. Now I'm using 3.6.3, included with Ubuntu 13.04 (most likely any recent version is equivalent for the scope of my question, anyway).  One major difference between the two is the search-as-you-type behavior: in classic versions of Nautilus, when you typed an input, the file with the closest alphabetical match would become the selected one, the eligible files/folders being restricted to the current directory.  The new behavior is to perform an optionally-global search instead.  Can one configure Nautilus to provide the previous functionality ?


I think I read that a few decades ago borrowed in a public library, a story about a world with floating islands orbiting an axis, not really on a planet.  I think people were flying dragons between those islands. I remember something about geography of the world, or directions given, being described in terms of the orientation with respect to that axis, and the word used (read that in French, probably a translation) was something like "orbitàdroite" or 'orbitàgauche", which would be "on the right of the orbit" or "on the left of the orbit". Any ideas?

I'm trying to identify fantasy book series I encountered some time ago. Here are things I remember:   it was a fantasy setting but with some s-f elements; with many worlds and possibility to travel between them; resembling  setting a little, the two main races were non-human and probably hostile to each other,  a labyrinth (?), which somehow played an important role in the plot, a protagonist was some kind of emissary and was sent on a mission to another worlds  time period: 80s - 90s    Does anyone know what it is the name of the series?


Assuming we have a very powerful telescope, and a huge mirror 1000 light years away from earth, is it possible to look at this mirror to see what people did on earth 2000 years ago?  Is it even possible to build such telescope, are there anything discovered in the universe that can act like a mirror?

Earth reflects light from Sun into Space; are there any "mirror like" objects which reflect back to Earth this light? Has anyone been able to use this method to recover some information on how was the Earth in the past (how it looked, what was it temperature, etc)?


I am considering buying a macbook pro and have the budget to upgrade either the RAM to 16 gb or get the faster processor, but not both. So I wonder: In what sort of tasks is the performance improved if I upgrade RAM vs. if I upgrade the processor?  Ps: My only really heavy weight application which I use is Lightroom and sometimes Photoshop

I'm zeroing on buying the 2012 MacBook Air. My usage of the machine will be mostly for development work (MySQL, Eclipse, Xcode, Android, etc.). I will also be running Windows 7 with SQL Server in a virtual box or by using Boot Camp. My question is which upgrade will result in the most bang for the buck: more RAM or a faster processor? Does putting higher memory/processor make the machine run hotter?


Is it possible to define $x+x+x+x...x $ times? I need to compute its derivative. It differs from the derivative of $x^2$. It evaluates to $x$ via sum of derivatives.

Consider the following:   $1 = 1^2$ $2 + 2 = 2^2$ $3 + 3 + 3 = 3^2$   Therefore,   $\underbrace{x + x + x + \ldots + x}_{x \textrm{ times}}= x^2$   Take the derivative of lhs and rhs and we get:   $\underbrace{1 + 1 + 1 + \ldots + 1}_{x \textrm{ times}} = 2x$   Which simplifies to:   $x = 2x$   and hence    $1 = 2$.     Clearly something is wrong but I am unable pinpoint my mistake.


Consider the following code:  foo=None def bar():     print(foo, flush=True) # UnboundLocalError     print('MARK')     del foo  print(foo) bar() #print(foo)   Basically I have a function that calls del in it. However, when I run the program, I get UnboundLocalError for that 'foo' referenced before assignment. If I comment out the del line, the exception is gone. I suppose the del should be called exactly on the line it is on, so that the variable is invalidated only after that. But it doesn't seem to be the case.  Is this expected behavior? (Specifically, I'm using Python 3.6.2)

The following code works as expected in both Python 2.5 and 3.0:  a, b, c = (1, 2, 3)  print(a, b, c)  def test():     print(a)     print(b)     print(c)    # (A)     #c+=1       # (B) test()   However, when I uncomment line (B), I get an UnboundLocalError: 'c' not assigned at line (A). The values of a and b are printed correctly. This has me completely baffled for two reasons:   Why is there a runtime error thrown at line (A) because of a later statement on line (B)? Why are variables a and b printed as expected, while c raises an error?   The only explanation I can come up with is that a local variable c is created by the assignment c+=1, which takes precedent over the "global" variable c even before the local variable is created. Of course, it doesn't make sense for a variable to "steal" scope before it exists.  Could someone please explain this behavior?


What is the difference between defining classed in the following ways?  1)  var parentCls = {     name:'John',     callMe : function (){         alert('Method gets called');     } } parentCls.callMe();   2)  function parentCls(){     this.name='John';     this.callMe = function (){         alert('Method gets called');     } } parentCls.CallMe()   Thanks

I've recently started maintaining someone else's JavaScript code. I'm fixing bugs, adding features and also trying to tidy up the code and make it more consistent.  The previous developer used two ways of declaring functions and I can't work out if there is a reason behind it or not.  The two ways are:  var functionOne = function() {     // Some code };     function functionTwo() {     // Some code }   What are the reasons for using these two different methods and what are the pros and cons of each? Is there anything that can be done with one method that can't be done with the other?


What is the difference between feature selection and feature reduction?   When do we use feature selection and what happens when we don't use it? How is this different than feature reduction?

From wikipedia:  dimensionality reduction or dimension reduction is the process of reducing the number of random variables under consideration, and can be divided into feature selection and feature extraction.  What is the difference between feature selection and feature extraction? What is an example of dimensionality reduction in a Natural Language Processing task?


I have Apple M1 MBP and want to use two external display monitors but out the box it is not possible. Is there a workaround them as I need 2 screen?

The Apple Silicon based  supports Thunderbolt version 3 and I'm wondering if anyone has tried connection one to an ? Of course you'd need to use one of Apple's Thunderbolt 3 to Thunderbolt 2 converters. I also understand that this version is limited to supporting only a single 4K or 6K display, but since the original Apple Thunderbolt Display is only 2K I’d want to try and daisy chain these. Can I run more than one external display from the Apple Silicon M1 CPU/GPU based MacBook Pro (or Air)?


-- the all subtab by default, empty, shows no activity found, why?  -- likewise, empty, shows no activity found, after a somewhat long delay, why?  -- not empty, as expected

For some users, the activity tab is empty ("no activity found") if "all" is selected, even though the tabs other than "all" are non-empty.  Also, the "all" tab is loading much slower than usual for the users with an empty "all" tab. As of now:  - Empty  - Empty  - Working normally


I replaced a 2 conductor NM wire running from a light fixture to the switch with a 3 conductor 12/3 wire, to bring a neutral line to the switch box for a smart switch. Then I pulled out the old wire and realized that it actually was 14/2, not 12/2. I thought it was 12/2 so I picked up 12 gauge from the store, and this of course was after I already fished the line through the wall. Is there potentially a problem switching out a wire for a higher gauge? Theoretically a 12 gauge wire can conduct more amps than a 14, so my assumption is that it’s not a problem because it can handle more current than the old wire, not less. But I thought I’d double check.

My father-in-law is a builder. He has put in 20 amp and 15 amp breakers, and ran 12-2 as the home runs to the switch's and the first plug to make them hot. He then ran 14-2 to feed the rest of the plugs, lights, and ceiling fans.   Is it okay that he used different gauge wires on the same circuit?


So i'm a newbie, just started watching Blender Guru's "donut tutorial" and i'm on part 6 level 1, when you try to render the thing that you've made. i made a donut, and when i pressed "Viewport Shading" my donut is gone.. This is the mesh i've made  And this is the mesh when i clicked "Viewport Shading  i can't find anything on the internet, or i just couldn't understand...

I don't know why but now, when i go in material preview or rendered (in solid mode it works fine), my object is entirely gray, or invisible idk, because it has the same color of the background. I've been working for days on this project without having this issue, it suddenly showed up. I tried opening other old projects and suddenly they all do the same so i guess it is some blender program setting that applies for all the projects, but idk how it happened cuz i didn't change anything :/, anyone got any tips?


There are various definitions of fixed and random effects in linear mixed-effects models in the statistics literature, and even in the fixed-effects models from econometrics. The data I have now represent the entire consumption of some products in a country. I aggregated them to annual level for 6 years by each state. A longitudinal analysis was planned.   The primary question here is for the population data by every state in the country, whether fixed-effects models (N states fixed-parameters) or mixed-effects models (1 fixed-effect parameter, N states random-effects) should be used?  Personally, I prefer the definition by Fitzmaurice et al. (Applied Longitudinal Analysis), where a fixed-effect represents the population-average, while random-effects represent subject/state-specific effects. Therefore even the data is based on a fixed number of states in a country, each state will have its own growing trajectories over time, which is regarded as random-effects.   Some authors argue that for individual patient or small unit data, where an individual or unit was drawn from a large population, mixed-effects models or random-effects models are appropriate. But state-level data for a country can hardly be considered as a subset, then fixed-effects models is more appropriated.   Please correct me if any of the statements above is wrong. I wish to hear more opinions on this.

In simple terms, how would you explain (perhaps with simple examples) the difference between fixed effect, random effect and mixed effect models?


It was probably asked multiple times before which is about basic logic. But I couldnt find any.  let X a set and I is index set. for $i\in I$, $A_i$ is a subset of X. if $I=\emptyset$, how can we show   $$\bigcup_{i\in \emptyset} A_i=\emptyset\quad\text{and}\quad\bigcap_{i\in \emptyset}A_i=X$$  is it because from the definition if $x\in\bigcap_{i\in \emptyset}A_i\iff\forall i(x\in \emptyset\Rightarrow x\in A_i) $ which equals to $\forall i(x\notin \emptyset \lor x\in A_i)$ which is true for all $x\in X$ because  $x\notin \emptyset$ is always true.  similarly if $x\in\bigcup_{i\in \emptyset} A_i\iff\exists i(i\in \emptyset \land x\in A_i) $  right statement is wrong because $i\in \emptyset$ is wrong always. that is, for all $x \in X, x\notin\bigcup_{i\in \emptyset} A_i$ so $\bigcup_{i\in \emptyset} A_i=\emptyset$  is this sufficient?

If $A_\alpha$ are subsets of a set $S$ then   $\bigcup_{\alpha \in I}A_\alpha$ = "all $x \in S$ so that $x$ is in at least one $A_\alpha$"  $\bigcap_{\alpha \in I} A_\alpha$ = "all $x \in S$ so that $x$ is in all $A_\alpha$"  It is the convention that $\bigcup_{\alpha \in \emptyset}A_\alpha = \emptyset$ and $\bigcap_{\alpha \in \emptyset} A_\alpha = S$.   But if $x$ is in $\bigcap_{\alpha \in \emptyset} A_\alpha = S$ then $x$ is in all $A_\alpha$ with $\alpha \in \emptyset$ and therefore $x$ is certainly in at least one $A_\alpha$ with $\alpha  \in \emptyset$. But then $x \in \bigcup_{\alpha \in I}A_\alpha$.  Can someone help me and tell me what is wrong with this? Thank you.


Is it possible to have a invertal function that stop and starts if a variable is too high or too low  How can I make moneymaker stop when it reach 300?  I Tried with this code, but didn't get any results...  Code ex.   var money = 0; var maxmoney = 300;  var moneymaker = window.setInterval(function(){      money = money + 1;     document.getElementById('money').innerHTML = money;     }, 1000);  function stopInter(){     if(hp >= maxhp)     clearInterval(regen);     }else{     setTimeout(function(){}, 1000);      } }

I am using setInterval(fname, 10000); to call a function every 10 seconds in JavaScript. Is it possible to stop calling it on some event?   I want the user to be able to stop the repeated refresh of data.


What is the difference between  String name1 = "some name";   and  String name1 = new String("some name")   Which is better and good for use?  thanks

While looking at online code samples, I have sometimes come across an assignment of a String constant to a String object via the use of the new operator.  For example:  String s; ... s = new String("Hello World");   This, of course, compared to  s = "Hello World";   I'm not familiar with this syntax and have no idea what the purpose or effect would be.  Since String constants typically get stored in the constant pool and then in whatever representation the JVM has for dealing with String constants, would anything even be allocated on the heap?


I'm making a tool that finds folders with specific name and I want to compress those folders using the zip command   How can I run the zip command from my tool to compress the folders?

Is there a compression API available for use on the iPhone? We're building some RESTful web services for our iPhone app to talk to, but we want to compress at least some of the conversations for efficiency.  I don't care what the format (ZIP, LHA, whatever) is, and it does not need to be secure.  Some respondents have pointed out that the server can compress its output, and the iPhone can consume that. The scenario we have is exactly the reverse. We'll be POSTing compressed content to the web service. We're not concerned with compression going the other way.


Im a green card holder. I wanted to know if Puerto Rico is considered as USA state for us. Green card holder can’t be out of USA country for more than 6 months. If I stay in Puerto Rico is it considered as being in the USA?

I am currently waiting for my green card in the USA. I was wondering if I could travel to Puerto Rico since it is a territory. Under my green card application I'm not allowed to leave the USA, if I do it is seen as abandoning my application. However if the flight is domestic I assume there would be no problem as there is no immigration.


I have my access token session set to expire every 24 hours, but if someone uses that token (say through a rest API call) at some point, does it last for another 24 hours or does the session not restart?

I have read many places that the access token session length is controlled by the client application and will expire "from time to time", but I cannot find a way for my application to calculate the expiration date/time.  I have used other non-Salesforce systems and they pass along an expires_in value to help determine the expiration.  Salesforce does pass along an issued_at value, which doesn't help me much.  Is there a way to determine when the access token will expire, or is it only based on trial and error?


I created a table with a SERIAL column but I also manually inserted some rows. I need to update the SERIAL so it goes to the next one.

I ran into the problem that my primary key sequence is not in sync with my table rows.   That is, when I insert a new row I get a duplicate key error because the sequence implied in the serial datatype returns a number that already exists.  It seems to be caused by import/restores not maintaining the sequence properly.


I Erased my hard drive from mac utilities from the recovery mode, but now i am not able to install Mac OS Mojave as it doesn't shows my mac hard drive to install and when i checked it in utilities, it shows the drive as UN-formatted. So now i cannot install mac os and my ssd has been erased. What can i do for it ?  I am attaching a image that it is showing in the disk utilities.

I wanted to do a clean install and booted from OS X recovery partition. In disk utility I selected "erase" option. SSD was working correctly before that.  Now, if i startup, the only way to proceed is with Internet Recovery  since I cannot boot from hidden recovery partition. After I wait several hours for the recovery image download, I cannot see the SSD either in disk utility or OSX reinstallation.   In terminal   diskutil list   Shows only recovery image 1.8 Gb or so.  So did erase option destroy my ssd?


Before anyone comments about it, yes I already searched for this thing but I couldn't find the answer I needed. Here's the problem:  I want to output a few random words from a list. The output I get is [Ljava.lang.String;@2e5c649  Here's the code:   import java.util.Random; public static String[] GenerateRandomWords(int n) {     String[] list = {"random" , "school", "game", "habit", "window", "animal", "hidden", "puzzle", "coding", "gaming", "programmer", "box", "laptop", "swing", "jungle",             "house", "picture", "program", "table", "cookie", "project", "mathematics", "think", "graphics", "interface", "innovation", "analysis", "reduce", "screen",             "company", "cow", "banana", "apple", "milk", "tea", "coffee", "job", "cake", "collection", "movie", "toolkit", "tree", "speaker", "microphone", "workshop",             "progress", "story", "article", "music", "script", "language", "instruction,", "key", "sun", "age", "joy", "volume", "orange", "hotdog", "museum", "career",             "radical", "outside", "brother", "balance", "reserve", "action", "notebook", "research", "complete", "remember", "teenager"};     String newarr[] = new String[n];   for (int i=0;i<n;i++)     {         int rand = new Random().nextInt(list.length);         newarr[i]=list[rand];      }      return newarr;  }  public static void main(String[] args) {     System.out.println(GenerateRandomWords(5)); }   }

In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the  of the array, as defined by Object.toString():  int[] intArray = new int[] {1, 2, 3, 4, 5}; System.out.println(intArray);     // prints something like '[I@3343c8b3'   But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:  // Array of primitives: int[] intArray = new int[] {1, 2, 3, 4, 5}; //output: [1, 2, 3, 4, 5]  // Array of object references: String[] strArray = new String[] {"John", "Mary", "Bob"}; //output: [John, Mary, Bob]


/tmp/cc8VVSeG.o(.text+0x122): In function `main': : undefined reference to `TemperatureList<double>::TemperatureList(int)' /tmp/cc8VVSeG.o(.text+0x13d): In function `main': : undefined reference to `TemperatureList<double>::add_temperature(double)' /tmp/cc8VVSeG.o(.text+0x158): In function `main': : undefined reference to `TemperatureList<double>::add_temperature(double)' /tmp/cc8VVSeG.o(.text+0x173): In function `main': : undefined reference to `TemperatureList<double>::add_temperature(double)' /tmp/cc8VVSeG.o(.text+0x18e): In function `main': : undefined reference to `TemperatureList<double>::add_temperature(double)' /tmp/cc8VVSeG.o(.text+0x1a8): In function `main': : undefined reference to `TemperatureList<double>::get_last() const' collect2: ld returned 1 exit status   This is the code:  templist.h:  #ifndef TEMPLIST_H_ #define TEMPLIST_H_  #include <iostream>  using namespace std;  template <class T> class TemperatureList{ public: T* list; long size; long MAX_SIZE; TemperatureList(int n); void add_temperature(T temperature); bool full() const; long get_size() const; T get_temperature(long position) const; void output(ostream &outs) const; T get_last() const; void detele_last(); };  #endif   templist.cpp:  #include "templist.h"  template <class T> TemperatureList<T>::TemperatureList(int n){ list = new T[n]; MAX_SIZE = n; size = 0; }  template <class T> void TemperatureList<T>::add_temperature(T temperature){ if (full() == false){ list[size] = temperature; size += 1; } }  template <class T> bool TemperatureList<T>::full() const{ if (size == MAX_SIZE) return true; return false; }  template <class T> long TemperatureList<T>::get_size() const{ return size; }  template <class T> T TemperatureList<T>::get_temperature(long position) const{ if (position >= size || position < 0) return 0.0; return list[position]; }  template <class T> void TemperatureList<T>::output(ostream &outs) const{ for (long i = 0; i < size; i++) outs << list[i] << endl; }  template <class T> T TemperatureList<T>::get_last() const{ if (size == 0) return 0.0; return list[size-1]; }  template <class T> void TemperatureList<T>::detele_last(){ if (size > 0); size -= 1; }   main.cpp:  #include "templist.h"  int main(){ TemperatureList<double> temp(50); temp.add_temperature(4.0); temp.add_temperature(7.0); temp.add_temperature(8.0); temp.add_temperature(9.6);  cout << "Last element is : " << temp.get_last() << endl; return 0; }

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


On , none of the images show up for me. Several others .  I can still click the broken image links and they open on imgur normally.  The images in  I've checked seem to work fine. This includes  which are broken according to .

On the  blog post, nearly all the images are broken. I assume this is because they are all hosted on stackoverflow.blog/wp-content/uploads/ rather than zgab33vy595fw5zq-zippykid.netdna-ssl.com/wp-content/uploads/, and they got destroyed in the removal of Blog Overflow. I looked around at a few other blog posts, and this post seems to be the only one having an issue.


Running $ sudo apt install  Results in this error. $ The package linux-hwe-5.4-headers-5.4.0-51 needs to be reinstalled, but I can't find an archive for it.  Any ideas how to resolve? Details for $cat /etc/apt/sources.list mike@MikeUbuntu3:~$ cat /etc/apt/sources.list # deb cdrom:[Ubuntu 18.04.3 LTS _Bionic Beaver_ - Release amd64 (20190805)]/ bionic main restricted  # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to # newer versions of the distribution. deb http://us.archive.ubuntu.com/ubuntu/ focal main restricted # deb-src http://us.archive.ubuntu.com/ubuntu/ bionic main restricted  ## Major bug fix updates produced after the final release of the ## distribution. deb http://us.archive.ubuntu.com/ubuntu/ focal-updates main restricted # deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-updates main restricted  ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team. Also, please note that software in universe WILL NOT receive any ## review or updates from the Ubuntu security team. deb http://us.archive.ubuntu.com/ubuntu/ focal universe # deb-src http://us.archive.ubuntu.com/ubuntu/ bionic universe deb http://us.archive.ubuntu.com/ubuntu/ focal-updates universe # deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-updates universe  ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu  ## team, and may not be under a free licence. Please satisfy yourself as to  ## your rights to use the software. Also, please note that software in  ## multiverse WILL NOT receive any review or updates from the Ubuntu ## security team. deb http://us.archive.ubuntu.com/ubuntu/ focal multiverse # deb-src http://us.archive.ubuntu.com/ubuntu/ bionic multiverse deb http://us.archive.ubuntu.com/ubuntu/ focal-updates multiverse # deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-updates multiverse  ## N.B. software from this repository may not have been tested as ## extensively as that contained in the main release, although it includes ## newer versions of some applications which may provide useful features. ## Also, please note that software in backports WILL NOT receive any review ## or updates from the Ubuntu security team. deb http://us.archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse # deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse  ## Uncomment the following two lines to add software from Canonical's ## 'partner' repository. ## This software is not part of Ubuntu, but is offered by Canonical and the ## respective vendors as a service to Ubuntu users. # deb http://archive.canonical.com/ubuntu bionic partner # deb-src http://archive.canonical.com/ubuntu bionic partner  deb http://security.ubuntu.com/ubuntu focal-security main restricted # deb-src http://security.ubuntu.com/ubuntu bionic-security main restricted deb http://security.ubuntu.com/ubuntu focal-security universe # deb-src http://security.ubuntu.com/ubuntu bionic-security universe deb http://security.ubuntu.com/ubuntu focal-security multiverse # deb-src http://security.ubuntu.com/ubuntu bionic-security multiverse deb http://archive.ubuntu.com/ubuntu bionic main universe restricted multiverse deb-src http://archive.ubuntu.com/ubuntu bionic main multiverse restricted universe #Added by software-properties

There are now errors when updating and I cannot install most software due to a corrupted  /etc/apt/sources.list   file. Is there a copy I can download to replace it?  The file would be for Ubuntu 12.04 (Final Beta) in the United States.


I recently tried to install npm and nodejs and got some errors and was suggested to run sudo apt-get update.  After running sudo apt-get update I get the following error:   Failed to fetch http://archive.ubuntu.com/ubuntu/dists/trusty/Release  Unable to find expected entry 'universe/binary-amd64/Packages' in Release file (Wrong sources.list entry or malformed file)   E: Some index files failed to download. They have been ignored, or old ones used instead.   The output of cat /etc/apt/sources.list is :  deb http://archive.ubuntu.com/ubuntu trusty main universe restricted multiverse

I have unistalled and reinstalled the Ubuntu Software Center as per info I found in a similar thread and I got the same response about line 91 or something like that.  I just tried to upload a screen shot but since I'm new it won't allow me to.  I also can not figure out how to cut and paste anything so I have to hand type what the error screen says, both when I attempt to open the software center and nothing happens, when I try to enter commands into the terminal to uninstall, reinstall, whatever I get the same following:  COULD NOT INTITIALIZE THE PACKAGE INFORMATION An unresolvable problem occured while initializing the package information Please report t:his bug against the 'update-manager' package and include the following error message: 'E: Malformed line 91 in source list/etc/apt/sources.list (dist parse)  E: The list of sources could not be read.,  E: The package list of status file could not be parsed or opened.   How do I report bugs?  What can be done about this.  I have searched and everything everyone says to do leads me back to the same line error message.  So, I don't know how to get to line 91 in the source list; to tell you what it says. Sorry, I'm really new to this. That is what I need is to find out how to get there and fix what it says. I would really like to NOT have to re partition my hard drive and start from scratch, so I'm really looking forward to getting this problem solved. I need to be able to install new software.


There is a question on the complex analysis of Conway "Functions of one complex variable" (pg.57 #28) about the mapping properties of $(1-z)^i$. Can anyone describe me what does the exponent '$i$' mean? What does it do to $(1-z)$? I am confused. Can i write in the following way?  $(1-z)^i=e^{i \log (1-z)}=\cos (\log (1-z))+i \sin (\log (1-z))$

There is a question on the complex analysis of Conway "Functions of one complex variable" (pg.$57\ \#28$) about the mapping properties of $(1−z)^i$. Can anyone describe me what does the exponent '$i$' mean? What does it do to $(1−z)$? I am confused. Can i write in the following way? $$(1−z)^i=e^{i\cdot\log(1−z)}=\cos(\log(1−z))+i\sin(\log(1−z))$$


When trying to install Proton VPN using the terminal, I get the following error: W: GPG error: https://repo.protonvpn.com/debian unstable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 71EB474019940E11 E: The repository 'https://repo.protonvpn.com/debian unstable InRelease' is not signed. N: Updating from such a repository can't be done securely, and is therefore disabled by default.  I'm following the install instructions provided on the official Proton VPN website:  Any help resolving this is appreciated. I'm not an experienced command line user, but I'm comfortable using the terminal provided I'm given the commands required and a brief overview of their function.

I added some extra repositories with the Software Sources program. But when I reload the package database, I get an error like the following:     W: GPG error:  trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8BAF9A6F   I know I can fix it using apt-key in a terminal, according to the official Ubuntu documentation. But I would have liked to do it graphically. Is there a way to do this without using a terminal?


I am developing a game that gets the user to crack a vault code.   int [] vault = {1,2,3,4,5};   I currently just have per-determined values for the vault code (above) but I think it would be best if they changed with each play-through of the game.   I have seen the math.random method but I'm unsure how to make it only display integer values.

How do I generate a random int value in a specific range? I have tried the following, but those do not work: Attempt 1: randomNum = minimum + (int)(Math.random() * maximum);  Bug: randomNum can be bigger than maximum. Attempt 2: Random rn = new Random(); int n = maximum - minimum + 1; int i = rn.nextInt() % n; randomNum =  minimum + i;  Bug: randomNum can be smaller than minimum.


Currently we have 2 custom fields on Lead. Lead Number, which is just an auto incrementing number. And then a Round Robin ID which is an equation.   MOD(VALUE({!Lead_Number__c}) ,3) +1   We use this Round Robin ID to assign the lead to a specific salesperson with our Lead Assignment rules.   Only problem is we have one lead source that is the best and hottest leads. The sales guys want those leads to be assigned Round Robin independant of the other leads.   And that is the problem. Their turn in the Round Robin is being used up on an ok lead. So what is currently happening:   Best Lead Source - assigned to Salesguy 1 Ok Lead Source   - assigned to Salesguy 2 Ok Lead Source   - assigned to Salesguy 3 Best Lead Source - assigned to Salesguy 1   But we want this to happen:  Best Lead Source - assigned to Salesguy 1 Ok Lead Source   - assigned to Salesguy X (doesn't matter) Ok Lead Source   - assigned to Salesguy X (doesn't matter) Best Lead Source - assigned to Salesguy 2   Is it possible to make another auto-incrementing field that only increments when the Lead Source is set to something specific?   Or is there a way to setup a workflow to increment a field when another field is set?   I found this  at asks for something similar but it doesn't even need to be auto-incrementing. Just need it to count up only a certain type of lead.

Our customer number ranges are different for each company we acquire. For example, company A has a customer number range that falls between 100,000-199,999. Company B has a number range that may fall between 200,000-250,000.  What we need is a way to automatically set the customer number for the correct company based on a field called Company Code.  Example: We have a new customer for company A. Company A's last customer is #127,002. The new customer number would be #127,003 and company B's number series would remain unchanged.  For right now, we would have this customer number stored in a separate field than the traditional Account Number field, as we are currently transitioning between ERP systems.  Any help would be greatly appreciated. Thank you!


Let $f:(-a,a) \rightarrow \mathbb{R}$, with $a>0$. Assume $f(x)$ is continuous at 0 and such that the limit   $$ \lim_{x \rightarrow 0} \frac{f(x)-f(kx)}{x} = l $$   exists, where $0<k<1$. Show that $f'(0)$ exists. What happens to this conclusion when $k>1$?   Someone can explain me how to prove the last one?

Problem:   If $f(x)$ is continous at $x=0$, and $\lim\limits_{x\to 0} \dfrac{f(ax)-f(x)}{x}=b$, $a, b$ are constants and $|a|>1$, prove that $f'(0)$ exists and $f'(0)=\dfrac{b}{a-1}$.   This approach is definitely wrong:    \begin{align} b&=\lim_{x\to 0} \frac{f(ax)-f(x)}{x}\\ &=\lim_{x\to 0} \frac{f(ax)-f(0)-(f(x)-f(0))}{x}\\ &=af'(0)-f'(0)\\ &=(a-1)f'(0) \end{align}  I will show you a case why this approach is wrong:     \[f(x)= \begin{cases} 1,&x\neq0\\ 0,&x=0 \end{cases}\]   $\lim_{x\to0}\dfrac{f(3x)-f(x)}{x}=\lim_{x\to0} \dfrac{1-1}{x}=0$   but $\lim_{x\to0}\dfrac{f(3x)}{x}=\infty$,$\lim_{x\to0}\dfrac{f(x)}{x}=\infty$   Does anyone know how to prove it? Thanks in advance!


I'm trying to make a number guesser that starts from 000001 and counts up all the way to 999999 how can I do that?

Given: a = 1 b = 10 c = 100  How do I display a leading zero for all numbers with less than two digits? This is the output I'm expecting: 01 10 100


Good day.  SELECT * FROM banners WHERE seet='$seet'   Structure table banners here   Tell me please how get random one row from table?

How can I request a random row (or as close to truly random as is possible) in pure SQL?


folks--    The following throws an error, shown below  \documentclass{book}   \usepackage{Sweave}    \begin{document}    \begin{verbatim}   data ds;      infile 'dir_location\filename.csv" delimiter=",";      input varname1 ... varnamek;   run;   \end{verbatim}    \end{document}     Error:  ! Undefined control sequence.   infile '                   dir_location\filename.csv' delimiter=",";   l.362 \end{verbatim}     Occurs with any ' or ` character in verbatim environments.    Any idea what could be causing this?  Or a workaround?  Thanks!

\begin{verbatim}      infile 'dir_location\filename.csv' delimiter=",";   \end{verbatim}   throws an error on the first '.  What the H?


Considering Arnor was made up of men descended from Númenoreans, one would think they would be a match for the forces of Angmar, or did Arnor not simply have enough numbers?

I recently found out about the war between Arnor and Angmar, and was pretty shocked to learn that the Witch-king basically wiped the floor with the Dúnedain kingdom... I mean he's basically the sole reason Aragorn wanders around like a homeless person.  So with which army did the Witch-king defeat Arnor? Orcs? Men? Sorcery? Did he ever go to battle himself? Did he do this for laughs or by Sauron's orders?   How powerful was the Witch-king at this point, compared to in the Fellowship of the Ring and Return of the King? Were the other Nazgul with him in this war?   And it doesn't even matter to me if all of the eight Nazgul were with him, even if they all had their Rings of Power, and even if they had the largest of armies of Orcs, Men, Elves, Dwarves or even dragons (yes I'm exaggerating at this point), but just how do you defeat a kingdom full of Dúnedain?   We have all seen what Aragorn is capable of doing, so how do you defeat a kingdom worth of Aragorns?   And if it is not much to ask, does anyone know where I can read all about this war and more about the Witch-king? so far all I read about it was from the Internet, wikis, forums and alike, I'd like to read it from the source.


For every element $g$ in a group $G$ of order $23$, prove that there is $h\in G$ such that $g=h^2$.  I am not sure how to prove this. I think that, since $G$ has prime order is isomorphic to a cyclic group and therefore abelian. I can use that property to prove that $g=h^2$ but i am not sure how. Any help will be appreciated.

Let $G$ be a finite group having order $n$, prove that $n$ is odd if and only if for each $a\in G$, there is $b\in G$ such that $a=b^2$. I first assume $n$ is odd, then let $a$ be an element in $G$, since $a^n=e$, we have $$a=a^{n+1}=(a^{(n+1)/2})^2$$ which tells $a$ is the square of $a^{(n+1)/2}$.  To prove the converse, I use contraposition, which I assume $n$ is even, then I want to find $a\in G$ such that it is not a square. My intuition is, "assume" we can always find an element $a\in G$ such that the smallest positive integer $k$ satisfy $$a^k=e$$ is $k=n$. Then it is not true that $a$ can be expressed as a square, indeed if $a=b^2$ for some $b\in G$, then the smallest $k$ satisfy $b^k=e$ will be $k=2n$, but this contradicts the smallest $k$ cannot exceed $n$.  My problem is, is the assumption I made always true? If it is true then it should be in the very beginning of the textbook, but I have forgotton it. Any help?  Source: Apostol Analytic Number Theory.


I am working at a university project with Qt version 4.7.2(I am using an old version because our teacher will use this version to review the project) on a Windows x86 machine but I have some problems while linking some function from the class Container to the class QListModelAdapter.  I've already tried running qmake again, clean and rebuild the project and deleting the build folder for building it from scratch but nothing of this worked, also checked my .pro file but seems like nothing wrong there.  qlistmodeladapter.h  #ifndef QLISTMODELADAPTER_H #define QLISTMODELADAPTER_H  #include <QAbstractListModel> #include "container.h"  class AddLayout;  class QListModelAdapter : public QAbstractListModel { private:     Container<articolo>* model;     const AddLayout* insert; public:     QListModelAdapter(QObject* = nullptr, const AddLayout* = nullptr);     ~QListModelAdapter() override;     bool insertRows(int, int = 1, const QModelIndex& = QModelIndex()) override;     bool removeRows(int, int = 1, const QModelIndex& = QModelIndex()) override; }; #endif   qlistmodeladapter.cpp  #include "qlistmodeladapter.h" #include "container.h" #include "addlayout.h" #include <QFont>  QListModelAdapter::QListModelAdapter(QObject* parent, const AddLayout* ins) :     QAbstractListModel(parent),     model(new Container<articolo>()), insert(ins) {}  bool QListModelAdapter::removeRows(int begin, int count, const QModelIndex& parent) {     beginRemoveRows(parent, begin, begin + count - 1);     model->removeEl(begin);     endRemoveRows();     return true; }  bool QListModelAdapter::insertRows(int begin, int count, const QModelIndex& parent) {     beginInsertRows(parent, begin, begin + count - 1);     articolo art = articolo(new Computer(insert->getNome()));     model->insertEl(art);     endInsertRows();     return true; }   container.cpp  #include "container.h" template<class T> void Container<T>::insertEl(T& p) {     if (maxSize == size)     {         increaseSize();     }     iteratore it = end();     *(it) = p;     size++; } template<class T> void Container<T>::removeEl(int j) {     if (j <= size)     {         iteratore it = begin();         for(int i = 0; i <= (j-1); i++)         {             it++;         }         delete it.punt;         iteratore aux = it;         it++;         for(int i = j; i < size-2; i++)         {             aux = it;             aux++;             it++;         }         size--;     } }   container.h  #ifndef CONTAINER_H #define CONTAINER_H #include "items.h"  template<class T> class Container {     friend class iteratore; private:     T* vector;     int size;     int maxSize; public:     class iteratore { // is defined correctly     };     Container(T* p = nullptr, int s = 0);//it is defined but not included     void removeEl(int);     void insertEl(T&); }; #endif // CONTAINER_H    The incriminated function is removeEl and is where is get this error:  qlistmodeladapter.obj:-1: error: LNK2019: riferimento al simbolo esterno "public: void __cdecl Container<class articolo>::removeEl(int)" (?removeEl@?$Container@Varticolo@@@@QEAAXH@Z) non risolto nella funzione "public: virtual bool __cdecl QListModelAdapter::removeRows(int,int,class QModelIndex const &)" (?removeRows@QListModelAdapter@@UEAA_NHHAEBVQModelIndex@@@Z)   sorry but the language is set on Italian, the strange thing is that it works properly with insertEl so i don't know what to think.  I've already checked the .pro file so I'm not including it right now because there is a lot of code already.  Every help will be really appreciated, thank you a lot.

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


I think this is not appropriate, but as the given video in the link, the youtuber name Bisqwit creates his own 3d engine from scratch in C and SDL2. How much is this advantageous is real 3d game development and following his idea can a first practice project? (rather than just starting with OpenGL)?

I have been studying SDL for a few weeks and I have succeeded in making a 2D Ping-Pong game, but  I want to get started in 3D development, and I'd like to know if SDL is capable (and suitable) for 3D game development, or I must use OpenGL?


Could someone explain what is the reasoning behind the following equality? Or maybe direct me to a proof of the following equality?  $$\sum_{n=0}^{\infty}p(n)x^n = \prod_{k=1}^{\infty}(1-x^k)^{-1}$$ where $\sum_{n=0}^{\infty}p(n)x^n$ is the generating function for the partition function.

I don't understand at all why:  \begin{equation} \sum\limits_{n=0}^\infty p_n x^n = \prod\limits_{k=1}^\infty (1-x^k)^{-1} \end{equation}  Where $p_n$ is the number of partitions of $n$. Specifically how can the sum of positive numbers ever be factored into a fraction or factors to the $-1$ power? Is this something purely notational or am I missing something big?  Thanks for all the help!


public class A {     public delegate void D();     public event D E;      ... }  class B {    void Test()    {        A a = new A();        a.E += () => { ... };         a = null;    } }   Can a be garbage collected when Test() is over or because of event subscription there is still reference to it somewhere?

UPDATE   I have combined various answers from here into a 'definitive' answer on a .  Original question  In my code I have an event publisher, which exists for the whole lifetime of the application (here reduced to bare essentials):  public class Publisher {     //ValueEventArgs<T> inherits from EventArgs     public event EventHandler<ValueEventArgs<bool>> EnabledChanged;  }   Because this publisher can be used all over the place, I was quite pleased with myself for creating this little helper class to avoid re-writing the handling code in all subscribers:  public static class Linker {     public static void Link(Publisher publisher, Control subscriber)     {          publisher.EnabledChanged += (s, e) => subscriber.Enabled = e.Value;     }      //(Non-lambda version, if you're not comfortable with lambdas)     public static void Link(Publisher publisher, Control subscriber)     {          publisher.EnabledChanged +=              delegate(object sender, ValueEventArgs<bool> e)              {                   subscriber.Enabled = e.Value;              };     } }   It worked fine, until we started using it on smaller machines, when I started getting the occasional:  System.ComponentModel.Win32Exception Not enough storage is available to process this command   As it turns out, there is one place in the code where subscribers controls are being dynamically created, added and removed from a form. Given my advanced understanding of garbage collection etc (i.e. none, until yesterday), I never thought to clear up behind me, as in the vast majority of cases, the subscribers also live for the lifetime of the application.  I've fiddled around a while with , but it doesn't work with anonymous delegates (not for me anyway).  Is there anyway out of this problem? I really would like to avoid having to copy-paste boiler-plate code all over the shop.  (Oh, and don't bother with asking me WHY we are creating and destroying controls all the time, it wasn't my design decision...)  (PS: It's a winforms application, but we've upgraded to VS2008 and .Net 3.5, should I consider using the ?)  (PPS: Good , but if anyone can come up with an equivalent to the WeakEventHandler which avoids me having to remember to explicitly UnLink/Dispose, that would be cool...)  EDIT I must admit that I worked around this problem by "recycling" the controls in question. However the workaround has come back to haunt me as the 'key' I was using is apparently non-unique (sob). I've just discovered other links  (tried this - seems to be a bit too weak - GC clears delegates even if target is still alive, same problem with  below),  (forces you to modify publisher, and doesn't really work with anonymous delegates) and  (cited-as-incomplete by Dustin Campbell).   It occurs to me that what I'm looking for may be semantically impossible - closures are designed to 'hang around even after I'm gone'.   I've found another workaround, so I'll stick with that, pending a .


While debugging a program that other people wrote I encountered a strange string assignment. At first I was surprised that it even compiles. Here is an example, which compiles without warnings on Linux (Ubuntu, CentOS).  #include <string> #include <stdio.h> #include <string.h>  using namespace std;  int main () {   string a;   char b[40];    a = "Constant value", strncpy (b, a.c_str (), sizeof (b));   printf ("a = %s\n", a.c_str ());   printf ("b = %s\n", b);     a = "Constant value";   strncpy (b, a.c_str (), sizeof (b));   printf ("a = %s\n", a.c_str ());   printf ("b = %s\n", b); }   Can someone explain, what exactly does the first string assignment in the example, and where can I find any reference describing this behaviour? As you can see a is assigned a constant string, but after that there is a comma (,) and strncpy function call, which returns char *. Why is comma accepted there? According to output it does not make a difference if I use ; or ,.


Hello Physics StackExchange!  I will put the TL;DR in the beginning: I need a self contained, relatively hand-holding sequence of textbooks that covers up from the end of Griffith's Intro to QM to relativistic QM/particle physics to QFT.    This will be my first post. I'm a medical physics grad student who majored in biomedical engineering for my undergrad, with serious regrets about not doing math/physics double major in hindsight. Oh well. I've made it my goal to eventually understand QFT.  My background in relevant subjects is Calc 1 to 3 and Diff EQ, 2 part freshman physics, an E&M course that used Griffiths Electrodynamics, a summer of self studying Griffith's QM (got most of the way through). I will also be officially taking a class in QM using Griffith's textbook this next spring. I am aware of the Lagrangian and Hamiltonian approaches to mechanics as well. In addition I have familiarity with special and basic general relativity using tensors and all this. What would be the best way for me to get from where I am now to a strong understanding of QFT autodidactically? I have no aversion to studying pure maths where I need to.  EDIT: My question is much different than simply asking for a handholding explanation of QFT. Generally these textbooks assume a certain amount of physics/math background, and I was asking for a sequence of textbooks leading up to QFT from the end of a specific textbook, Griffith's QM. Did you even read my question? Did you read the thing you linked me to?

I found Sean Carroll's "A No Nonsense Introduction to General Relativity" (about page .  pdf ), a 24-page overview of the topic, very helpful for beginning study.  It all got me over the hump of learning the meaning of various terms associated with GR, most of which I had heard before without understanding.  It also outlined the most important examples.  Is there a similar document for quantum field theory, which presents the main equations, briefly describes the main ideas, and summarizes the most important applications and results so that the reader can feel the lay of the land before studying in depth?


And yes: for a few days i have problems with one of systems on my PC -LMDE. Recently i got repaired there one thing as shown here : (). Now i have yet bigger problem - system ask me password for non-existing user (root) error code is here: Give root password for maintenance (or press Control-D to continue):  When i press these button it shows me: Reloading system manager configuration Starting default target You are in emergency mode. After logging in, type “journal -xb” to view system logs, “systemctl reboot” to reboot, “systemctl default” or “exit” to boot into default mode. Give root password for maintenance (or press Control-D to continue)  When i chrooted into this OS (with live-boot) i saw that there are problems with sudo and pkexec, so i cant use root even in chroot (and modify system files, etc...) is there any way to boot PC normally or i need to always use “initramfs error” and boot only to busybox cli (i can do that because i accidentally uninstalled grub and now i have cli when booting up pc)? Ps: I didnt setted up root (su) account (no password, user, etc) and i was really messing up with sudo so now i think that this also doesnt exist. ———————————————- Edit: i’ve done it with passwd as @cas said. Now i have bigger problem. My second problem is that all my partition is r/o. Even with modified /etc/fstab to open all partitions as writable. My system didn’t exited cli to the now - system doesn’t load without writable permission and my current (logged-in) user looks like root (have # before command and whoami shows me as root) but it isn’t. When i try mount command they said that i need to have root permission ( how i cant have them when currently i am root?!). Is there something i forgot, all my PC is corrupt or im a real n00b?

I need to manually edit /etc/shadow to change the root password inside of a virtual machine image.  Is there a command-line tool that takes a password and generates an /etc/shadow compatible password hash on standard out?


How to create a PDF document from a batch of images ?  ===  Belowis what I tried before posting this question:  The ImageMagick way, but the PDF document generated is too big:  convert *.ppm book.pdf   The Preview tool way, the created document is much smaller but it creates margins.  The sips way, not working for some reason:  sips -s format pdf *.ppm --out 'book.pdf' 1>/dev/null 2>&1   There also img2pdf which looks good but I couldn't install it on mac (it's not in brew's list of packages).

Is there any way to batch convert .jpg files into single .pdf files?


I am running Ubuntu desktop 16.04 I tried to get the kernel sources using the command  apt-get source linux-image-$(uname -r)   as recommended in the Ubuntu wiki. I got the error   E: You must put some source URIs in your sources.list   I searched the web and found advice on editing sources.list, but don't know what specifically I need to do to get the kernel sources. I am new to this; can someone help?

I'm trying to install PIL a python module on ubuntu   I first need to install a package called python-imaging using the following command    sudo apt-get build-dep python-imaging   When I try and do this I get the error   E: You must put some 'source' URIs in your sources.list   I saw  question whihc shows how to fix via the GUI but I'm using the command line. Does anyone know how I can fix this error..?    UPDATE: Based on the below answers I've updated my package list but I now get this error. Not sure if it is related, if not I'll start a new question as I can't find reference to the error anywhere.   E: Build-Depends dependency for python-imaging cannot be satisfied because candidate version of package python-all-dev can't satisfy version requirements


Is there a difference in Ubuntu OS when I buy it on Amazon and the free version available in Ubuntu official site?

I need to upgrade my existing Ubuntu system, and I also want to install Ubuntu on a new laptop.  I would like to have an installation CD or DVD to do both of these.  Where exactly I can order or request an Ubuntu installation CD/DVD/USB?


Our physics teacher told us that a car moving in a circular track experiences static friction whose perpendicular component to the tangential velocity acts as centripetal force. But how can static friction act on a moving body? Shouldn't it be kinetic?

Static friction : Static friction opposes relative motion between two surfaces. The car is moving at some tangential velocity relative to the road. Thus, static friction should act in the opposite direction. Yet it acts down the incline rather than parallel to the motion of the car. If it acts down the incline, it's essentially helping the car maintain the same relative velocity w.r.t the incline rather than opposing this relative motion.   Kinetic friction :  Consider a block placed on a long, rough plank which is moving to the right at some constant speed, and the block is moving to the right, but slower compared to the plank, so relative to the plank, the block is sliding towards the left. Will kinetic friction act to the left to reduce the kinetic energy of the block, or will it act towards the right to oppose the relative motion of the block and plank? If it acts to the right, doesn't that increase the kinetic energy of the block, which is something kinetic friction should not do?


i done compile file makefile.am and i need shared link for my lib, for example after compile i see /usr/lib64/libtest.a but i need libtest.so because i need my lib to other C source file,   example :g++ -llibtest test.c  i read about this  but i not sure how to work and how to use ranlib or ar,there is any way for create *.a to *.so?

I have a third-party library which consists mainly of a large number of static (.a) library files.  I can compile this into a single .a library file, but I really need it to be a single .so shared library file.  Is there any way to convert a static .a file into a shared .so file?  Or more generally is there a good way to combine a huge number of static .a files with a few .o object files into a single .so file?


As I said in the title, keep inventory is not working. I have cheats on and no mods and I know for sure it is on.

I once played a vanilla Minecraft adventure map (called "Herobrine's Mansion") that prevented the player from losing their items on death. Which commands can be used to prevent the player from losing their items on death (in vanilla Minecraft)?


i have Ubuntu version 13 on my system now i want to install ubuntu 14. the problem is that i installed GEDIT and Aptana studio and some other software from ubuntu and installed on my device. the question is that should i have to download them again????

I'd like to output a list of all installed packages into a text file so that I can review it and bulk-install on another system.  How would I do this?


My Variable c is always zero. I dont understand why its not updating. can anyone please explain why this is happening. what should i do to avoid this  public static int linearSearch(Exam[] marks, String name) {     int c =0;     if( marks==null)     {          return -1;      }     else{          for(int i=0;i<marks.length;i++)         {              //System.out.println(a[i]);             if(performances[i].getName()==name)             {                 c= i;              }          }     }     return c;       //to be completed }

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


Running echo "This is a test" | wc -w > num_words results in the contents of the file num_words being "4". This could also be accomplished with a shell script count_words_and_record.sh:  #!/bin/bash wc -w > num_words   Running echo "This is a test" | ./count_words_and_record.sh has the same outcome.  The trouble is, I am a terribly impatient person, and I want to get on to other tasks without waiting for the words to be counted. So I run echo "This is a test" | wc -w > num_words &, everything happens in the background, and I can run other commands immediately. Eventually, when the counting finishes, I get a message, and the contents of num_words is then "4". However, if I instead modify the script  #!/bin/bash wc -w > num_words &   and run echo "This is a test" | ./count_words_and_record.sh, then the contents of ``num_words'' is "0" instead of "4".  What's going on here? Is there a way to modify the script to get the correct behavior?

I wonder why some similar bash commands behave the way they do.  I have a bash script foo:  #!/usr/bin/env bash  while true do     echo "reading"     read data     echo $data     echo "stderr msg" >&2     sleep 1 done   It's an infinite loop which reads one line at a time from stdin and outputs that same line. I also have a bash script bar:  #!/usr/bin/env bash  ./foo &   The following commands were run in bash (v. 4.4.19) in a terminal on Ubuntu 18.04 (let's assume the scripts reside in the working directory):   ./foo &   Stops when it tries to read from stdin, in accordance with . Killed when controlling terminal is killed, as expected.  (./foo &)   Appears to be automagically continuously fed with new input from stdin. Shouldn't it too stop when attempting to read from stdin? Whatever it's getting it doesn't show when echoed, thus I'm guessing it's EOF characters.  Continues running even after the controlling terminal is killed. Looking at the output of ps, the controlling terminal changes from pts/x to ?. How did this happen without the use of either disown or nohup? (However, after killing the originally controlling terminal, it yields a "write error: Input/output error" on every write, which I suppose is because its stdout was tied to the now closed terminal. Correct?)  bash -c "./foo &"  Appears to behave exactly like 2). ./bar  Appears to behave exactly like 2) and 3). Adding bash -c "~/foo" (no &) as a startup application  Behaves similarly to 2), 3) and 4), with the differences:   Its controlling terminal is the desktop ttyx. You can't (can you?) kill its controlling terminal.   None of those differences seem odd to me, just the fact that it's continuously fed with new input.   My guess is that 2) - 5) all use a subshell of sorts whose stdin is redirected to something like /dev/null, though I'm very unsure and seek a more exact answer.


Consider the random walk $S_n$ given by: $$ S_{n+1}=  \left\{  \begin{array}{ll}   S_n + 2  & \mbox{w.p } p\\   S_n -1   & \mbox{w.p } 1-p  \end{array} \right. $$ Assume that $S_0=n > 0$ with certainty. What is the probability of eventually reaching the origin (the point 0) ?  Now I know the derivation for the same problem but when it's symmetric and unbiased namely the additions are $1,-1$ with probability $\frac{1}{2}$ for each. Can I use this result or that I need to make the derivation from the start?

Consider the random walk $S_n$ given by $ S_{n+1} =  \left\{   \begin{array}{l}     S_n+2 & \text{with probability $p$}\\     S_n - 1 & \text{with probability $1-p$}   \end{array} \right. \ $  Assume that $S_0 = n >0 $. What is the probability of eventually reaching the the point $0$?  Seems that the probability for this must be less than one; since it is not symmetric, it is not guaranteed to reach the origin if $p>0.5$. It also seems like the positive starting value not being at the origin matters too, but I'm not sure how to compute the probability of eventually reaching the origin.


As I understand general relativity theory (please correct me if I'm wrong), time becomes dilated and space becomes compressed around mass, and this is responsible for gravity. I'm struggling with precisely how that results in gravitational force between masses. Can someone explain that to me (please keep any required math understandable to a lay person).

I understand that people explain (in layman's terms at least) that the presence of mass "warps" space-time geometry, and this causes gravity. I have also of course heard the analogy of a blanket or trampoline bending under an object, which causes other objects to come together, but I always thought this was a hopelessly circular explanation because the blanket only bends because of "real" gravity pulling the object down and then pulling the other objects down the sloped blanket. In other words, to me, it seems that curved space wouldn't have any actual effect on objects unless there's already another force present.   So how is curved space-time itself actually capable of exerting a force (without some source of a fourth-dimensional force)?  I apologize for my ignorance in advance, and a purely mathematical explanation will probably go over my head, but if it's required I'll do my best to understand.


My report requires page numbers to start from 1st chapter 1st page. So I use   \pagenumbering{arabic}   just before I do   \include{tex_files/chapter1)Introduction}   Now I want the page counting to start from 1st page, but I dont want the page numbers to appear on the first page of each chapter.  How to do this?  Answer : Quick (and dirty?) solution: \thispagestyle{empty} just after \chapter{...}.

Here's a minimal case of the problem:  \documentclass{book}  \pagestyle{empty}  \begin{document}  \chapter{The first}  This page has a page number\ldots  \newpage  \ldots but not this one.  \end{document}   I've surmised (by removing it) that the problem has something to do with the \chapter line.  But what caused this issue and how do I correct it?


I am integrating with an external API which expects client certificate in the request. They had provided .p12 file. I have converted it into .jks and imported in Salesforce. I have tried to use it two ways and both failed.  req.setClientCertificateName('certname') named credentials with this certificate  The error that is displayed on dev console when I execute the code is System.CalloutException: PKIX path building failed:   sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target  Has anybody faced such issue or have any idea of potential reason for this error? Thanks.

I am trying to make a apex callout from salesforce to external system which is hosted inside in corporate firewall. Firewall sends the request to load-balancer which sends the request to appropriate web server.  I am getting below exception when trying this call from salesforce while I can getting correct response while making a callout from SOAP UI.  As per my client they don't provide any certificate. I am not sure what is happening and how to resolve the issue. As per log it seems like I need to install the certificates.  Any help would be appreciated.  Log -   [51]|System.HttpRequest[Endpoint=https://someURL/servlet/request, Method=POST] 07:51:12.268 (268755208)|CALLOUT_REQUEST|[51]|System.HttpRequest retrying request in response to handshake failure: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target 07:51:12.423 (423017546)|EXCEPTION_THROWN|[51]|System.CalloutException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target 07:51:12.423 (423110461)|SYSTEM_METHOD_EXIT|[51]|System.Http.send(ANY)


I've got an iPhone with ~500 open tabs (500 is the limit). I'd like to bookmark all of the tabs so I can review/read them later on other non Apple devices and potentially in non-apple browsers.  Is there any app or solution (like a pinboard client) that will allow me to bookmark and close those tabs in mobile safari then, at a later time, view the bookmarks in another browser or on a desktop?

On macOS, I can choose Add Bookmarks for These 108 Tabs... which let's me save all open tabs to a bookmarks folder.  Is there an equivalent on iOS?     My workaround is to use iCloud tabs to copy the tabs from iOS to macOS and then do the above.   edit: as of iOS 13 this function is built in. See answer below.


Latex documents often come with a number of different files. What does a .dtx file usually specify? Please assume that the person reading your answer has next to no experience with using LaTeX. I don't care about the syntax used inside of a .dtx, or how to write a .dtx, I just want a short explanation of what it does.  As an example, inside of a .dtx file put out by the association of computing machinery, I found the following:  % \begin{macro}{\if@ACM@screen} %   Whether we use screen mode %    \begin{macrocode} \define@boolkey+{acmart.cls}[@ACM@]{screen}[true]{%   \if@ACM@screen     \PackageInfo{\@classname}{Using screen mode}%   \else     \PackageInfo{\@classname}{Not using screen mode}%   \fi}{\PackageError{\@classname}{The option screen can be either true or     false}} \ExecuteOptionsX{screen=false} %    \end{macrocode} % % \end{macro}   EDIT: Originally I said that a .dtx was a "configuration file," and then asked what a .dtx did. However, others have informed me that a .dtx is not a "configuration file." I have subsequently edited the question.

I am confused on how docstrip/ltxdoc really runs. It seems that LaTeX runs twice when called on such a simple dtx file.  % \iffalse %<*installation> \expandafter\begingroup \input docstrip.tex \keepsilent \askforoverwritefalse \nopreamble \nopostamble \generate{\file{\jobname.cls}{\from{\jobname.dtx}{latex}}} \expandafter\endgroup %</installation> %<*documentation> \ProvidesFile{\jobname.dtx} \documentclass{ltxdoc} \begin{document}   \DocInput{\jobname.dtx} \end{document} %</documentation> %<*latex> % \fi %    \begin{macrocode} \newcommand{\mystuff}{mystuff} %    \end{macrocode} % \iffalse %</latex>  % \fi   I understand the first pass easily: docstrip is read and produces the .cls file as asked by the \generate command (the installation block).  But then a second pass seems to be done with the first group (from \begingroup to \endgroup) being ignored and the rest of the file (the documentation block) being used as normal LaTeX code thus producing the expected .pdf (or .dvi file).  If the \expandafter\begingroup and \expandafter\endgroup lines are removed only the first pass is done and an error is raised.  I read the docstrip documentation (and code but certainly not seriously enough) but did not find any allusion to this double execution.  So I am looking for answers to the following sub-questions:   Am I right (two passes)? Did I miss something in the docstrip documentation (if yes where)? Is the code read twice or once? Why do we need the first group to exist in order for LaTeX to produce the two expected files?


I have 30 flags on Pokemon-Oras. How am I supposed to upgrade my rank?

In secret bases you can collect a flag of each new secret base you find. I've noticed some bases have different color flags, which I assume means a different rank. How many flags to you need to get a new rank (silver rank, etc.)?


What protects The Flash from air friction? At the speed at which he moves, he should be affected by air friction.

The Flash goes from zero to ??? in an eye blink.  As he does not have a Saturn 5 rocket on his back, how do you explain the acceleration?  How do you explain his ability to stop on a dime and turn corners without the effects of inertia?  How do you explain his alternate effect on the world around (lack of friction heat)?  How do you explain his ability to perceive so fast that he does not bump into things, can calculate where to turn flawlessly at such speed, etc?   Does he move normally in a massively slowed time-warp? Do his muscle fibers twitch at an impossibly high rate? Would his brain have to process incoming information at a speed far beyond normal consciousness, and wouldn't that make him a super-genius by normal standards? Why doesn't at least his suit heat up and burst into flame from air friction? Same for his boots and normal friction?   Or is it all "magic" and we are just supposed to accept that it "just happens?"


I am asked to calculate a complex integral. how to compute $\displaystyle \int \limits_{-\infty}^{\infty}\frac{x^4}{1+x^8}dx$ with residue theorem?

I found the method of partial fractions very laborious to solve this definite integral : $$\int_0^\infty \frac{\sqrt[3]{x}}{1 + x^2}\,dx$$  Is there a simpler way to do this ?


I am trying to load the active users information into a new activity and display it. I have done similar things in different activities and they have worked fine, but for some reason this is not and I am not sure. Whenever android studio tries to invoke a method on user, it throws a NullPointerException.  I have tried everything I can think of, reformatting the way its written, nesting in different methods, passing data through to it in different ways. Nothing is working and every article I've found on the subject doesnt help at all  @Override protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_user_edit);     int userID = getIntent().getIntExtra("sessionUser", 0);     tuckBoxDao = TuckBoxDB.createTuckBoxDB(this).tbDao();      Email = findViewById(R.id.email);     Username = findViewById(R.id.username);     Password = findViewById(R.id.password);     Mobile = findViewById(R.id.phoneNumber);     Notifications = findViewById(R.id.notificationBox);     Emails = findViewById(R.id.emailBox);     registerButton = findViewById(R.id.registerButton);     registerButton.setOnClickListener(new View.OnClickListener() {          @Override         public void onClick(View v) {             registerUser(user);         }     });      backButton = findViewById(R.id.backButton);     backButton.setOnClickListener(new View.OnClickListener() {          @Override         public void onClick(View v) {             goBack();         }     });      user = LoginActivity.tuckBoxDB.tbDao().searchById(userID);      String username = user.getUsername();     Username.setText(username);     String email = user.getEmail();     Email.setHint(email);     String mobile = user.getMobile();     Mobile.setHint(mobile);     Boolean notifications = user.getNotifications();     Notifications.setChecked(notifications);     Boolean emails = user.getEmails();     Emails.setChecked(emails);  }   I would have expected this to work fine and update and display the right information, as it has done exactly that in a fragment I made earlier, but for some reason it is throwing as soon as it gets to user.getUsername();

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 run ubuntu 15.04 64 bit on a lenovo y50 and am trying to figure out how to perform a system cleanup. i have very frequently received messages from the OS that there are software updates required, but the latest software update is unable to be installed bc theres not enough space on the disk, which is weird bc i hardly download files on this laptop. i have looked into a few different details, like computer janitor, but the ubuntu software center says the program doesnt exist. and whenever i try downloading ubuntu tweak it says that some files failed to download and i see a wall of error messages

Not to long ago I was using only 35% of my HD. Just recently it shot up to 54% and my diskspace is 16gb so that's more then 3gigs that have been taken.  From what I remember I failed to build mysql, I installed gitolite which required me to build git from source which had a tons of dependencies (I think it was for building docs, I think I saw latex and other packages but I was drowsy when I was installing). I suspect that is what is taking the diskspace.  Anyways so far I deleted source folders I know I had and ran these commands. What else can I do? (3gigs is mighty)  sudo apt-get autoclean sudo deborphan | xargs sudo apt-get -y remove --purge     After doing the above i did ncdu and found that   Git itself was actually using 502mb in 152 files all in '/usr/local/libexec/git-core'. Who knew. I found it strange that most of those files are 4.6mb each... MySql was taking up 1+gb in my /tmp folder I accidentally made a copy of my mono src folder which has two builds of mono and is 1.7gb together.    After deleting the copy of src and an extra mono build (thats 2.6gb together) + the mysql in my temp folder df now reports 28% instead of 54% which makes me feel a lot better.  I'm still surprised git uses 502mb. On windows it uses 57mb (thats about 10xless). And the equivalent folder (C:\Program Files (x86)\Git\libexec\git-core) has all those apps as shortcuts to git. and git is only 1.2mb (not 4.6). Also i checked if the linux git-core folder were all links, i know they arent softlinks (i used the cmd find . -maxdepth 1 -type l -print0 | xargs -0 ls -ld)  I tried stat git, stat git-add and saw they had the same innode. So most of these files are hardlinks (i assume) of git. So git doesnt actually take up that amount of space.


I have a list of figures and one line goes outside the page. I tried to break the line in the caption, but this not happens in the list of figures  caption{blabla \\ blabla}

I'm writing a pretty long document, and at some point this happened with the table of contents:        I would like to be able to force a line break between 'complex' and 'space', either directly or by imposing suitable limits on line lengths or the separation between the lines and the numbers, or any such relevant lengths.  A minimal working example is below,   \documentclass[pdftex,11pt,twoside,a4paper]{report}  \usepackage[a4paper, left=3cm, right=3cm, top=3cm, bottom=2cm]{geometry} \usepackage[T1]{fontenc} \usepackage{lmodern} % load a font with all the characters \usepackage[colorlinks,linkcolor=blue,final]{hyperref} \usepackage{tocloft}  \usepackage{lipsum}   %%% Headers \usepackage{fancyhdr} \pagestyle{fancy} \fancyhf{} \setlength{\headheight}{14pt}  \fancyhead[LE]{\thepage} \fancyhead[RE]{Electron dynamics in complex space and complex time} \fancyhead[LO]{\nouppercase{\leftmark}} \fancyhead[RO]{\thepage}  \renewcommand{\chaptermark}[1]{\markboth{\thechapter.\ #1}{}}   \begin{document}  \tableofcontents   \setcounter{page}{100} \chapter{Quantum orbits as trajectories through complex time and complex space} \lipsum[1-16]  \end{document}   including the headers in use in the document; obviously all of the non-lipsum packages are necessary in the larger document. How can I fix this ugliness?


I have seen The Dark Knight Rises quite a few times and I am unable to understand the significance of Bane raiding the stock exchange. Miranda Tate is already known to be a billionaire so why does Bane need any more money?  The relevance is not explained in the movie after the scene. Was it just set up to set a grand entrance for Bruce?  The program was anyway running through wireless medium, why didn't they just rob the exchange remotely?  Neither did Bane know Batman is to return, the cops would've chased them to the tunnels and the show would've been over before it began.

I recently saw The Dark Knight Rises and I don't remember the goal of the stock exchange robbery.  I remember that:   Selina Kyle steals Bruce Wayne's fingerprints and gives them indirectly to Bane. Bane use them to rob the stock exchange. There are some announcements that economy (and the city) would be perturbated due to the economic losses. But that's nothing compared to the attack by Bane and the bomb threat.   So I don't understand how do this serves the plot of the movie.  Did Bane want to steal the money? It doesn't look like he needs it since his project is funded by Bruce Wayne's economic rival.  The usage of the fingerprints suggests that it targeted Bruce Wayne directly, but I find it extraneous.


I have a very simple AWS Java Lambda function that can be uploaded to an Amazon S3 Instance and successfully run. My code is based on an Eclipse workspace documented by  tutorial. Now I am trying to setup debugging for my Java Lambda function. For that, I am following  tutorial called "AWS Toolkit for Eclipse: Locally Debug Your Lambda Functions and Amazon API Gateway Using AWS SAM Local". It instructs me to install Docker, AWS SAM Local and AWS Toolkit for Eclipse. I have successfully installed all the pre-requisites. Now I am able to run my Lambda function in the Amazon Cloud servers with the context menu item (right click in the source) "AWS Lambda/Run function on Aws Lambda.."  So far so good. But when I choose the menu item "AWS Lambda/Run on AWS SAM Local" things do not work. The build occurs succesfully, the unit tests pass, but running under the debugger fails. I get the following eror details. This occurs for any AWS Lambda java project I create. Can anyone help me diagnose this problem. What part of my setup is incorrect?  Update  After further investigation, it may be the case that the null pointer exception is caused by the lack of a "serverless.template" file in the project. Because creation of an empty one makes the null pointer exception go away but I am on to the next error. So maybe my new challenge is to figure out what the contents of serverless.template are supposed to be for a Lambda function. And I'm not sure why the AWS tutorials do not address this very well.


Physicist Richard Feynman said in his lectures     "It always bothers me that according to the laws as we understand them   today, it takes a computing machine an infinite number of logical   operations to figure out what goes on in no matter how tiny a region   of space, and no matter how tiny a region of time. How can all that be   going on in that tiny space? Why should it take an infinite amount of   logic to figure out what one tiny piece of space/time is going to do?   So I have often made the hypothesis ultimately physics will not   require a mathematical statement, that in the end the machinery will   be revealed and the laws will turn out to be simple, like the chequer   board with all its apparent complexities. But this is just   speculation." (The Character of Physical Law - Ch. 2)   what does he mean by "in the end, the machinery will be revealed and the laws will turn out to be simple". what machinery is he referring to? Is he asking for example what machinery "solves" the endless mathematics? or perhaps how the mathematics unfolds seemingly by itself.  also, these were given in 1965. have we come anywhere closer to answering his question since then?

Watching one of Feynman's lectures, I came across something that puzzled me. What was Feynman referring to when he said the following?     What goes on in no matter how tiny a region of space and no matter how tiny a region of time, according to the laws as we understand them today, takes a computing machine an infinite number of logical operations to figure out. Now, how could all that be going on in that tiny space? Why should it take an infinite amount of logic to figure out what one stinky little bit of space-time is going to do?   —    To be clear, my question is: Why would Feynman say it would take an infinite amount of logic to simulate even a small region of space-time?


I have Trek 1.1 with currently 700*23C tyres.  I need to replace them but the one available in market are 700*28  Can I use this size as replacement?  If yes, what'll be advantage and disadvantages?

We often get questions on bicycles.stackexchange about fitting wider or narrower tires to bicycles. We have a large number of these with answers suiting the specific bike or style of bicycle in question, but I have been unable to find one that provides a generic answer covering off all things that need to be considered. For most bicycles, the answer is the same regardless of the specific style and sizes of tires in question.   This is intended as a canonical question that we can point closed questions to.


I am stuck on how to characterize the elements in $(5,x+7)$ in the polynomial ring $\mathbb{Z}[x]$. I seriously can't even figure out if $x$ is in this ideal. I know that elements in the ideal look like $5h(x)+(x+7)g(x)$ for $h(x),g(x)\in \mathbb{Z}[x]$, and then I tried to expand this out, but I got some huge mess that I didn't know how to work with. In particular I am trying to figure out whether this ideal is maximal or prime or neither, and I thought the best way to do that was to find some elements that are not in the ideal so I could maybe find some zero divisors in $\mathbb{Z}[x]/(5,x+7)$.

I'm currently considering the ideal $(2,X+1)\subset\Bbb{Z}[X]$. I'm trying to figure out if this is a prime ideal, a maximal ideal, or neither. So far I have attempted to look at the quotient ring $\Bbb{Z}[X]/(2,X+1)$. I know that if this quotient ring is a field, then our ideal is maximal, since $\Bbb{Z}[X]$ is commutative. However I'm stuck on how I should be viewing this quotient ring.