I am trying to convert a old desktop into ubuntu (or Debian) machine. I have already looked up the  but still have following questions. In order to provide details, here is all the info I have collected on the current hardware on this machine:   Dell Dimension 3100/E310 with BIOS version A03 CPU : Processor 80547 Pentium 4 Prescott DT 2.8GHz 800 MHz bus, Hyperthreading capable Intel EM64T (Processor ID 0F49) RAM : 1.25GB 533MHz DDR2.  I have found reports of others successfully running 4GB, and according to 915G specs at  this can take upto 8GB RAM. But,  I am not sure if 915G refers to what i find in BIOS as Intel 82915G/GV/910GL Express chipset. Would like confirmation from someone knowledgable about intel chipsets. The above link also shows couple of things that I do not understand. It says Supported FSBs::   533/800MHz,  but also says Memory Types::     DDR 333/400, DDR2 400/533.  Since I am planning to upgrade RAM, can i buy DDR2 800MHz ?  I see DDR3 is selling for even lower prices now a days, but I am not sure if i can use a DDR3 on this. The above intel link also says under memory specs, Physical Address Extensions::    32-bit and I was wondering if this means that I CAN NOT run ubuntu/debian 64 bit versions. I need the 64 bit version of one of these OS installed because I plan to run mongoDB server on this machine, and mongoDB supports only 64 bit versions of these two OS. My understanding of PAE makes me guess that "32-bit" means that it supports more than 4GB memory space and 64 bit architectures. Hard Drive:  Currently Hitachi 7200rpm SATA 80GB. Under Windows 7 control panel I see that SATA Controller is Intel 82801FB Ultra ATA 2652(and Ultra ATA 266F).  Come thanksgiving, I want to get a SSD, but since I do not see AHCI listed anywhere in BIOS, i wonder if this hardware will support SSD.  Wireless: I currently have 2 wireless N adapters, but not sure if either of them will work under Ubuntu or Debian. First is a Zonet ZEW1642D model PCI card that has RaLink chip RT3062F.  Second is a Linksys N300 USB adapter that has been certified for Windows 7, but i do not see linux listed on the box.  Do i need to buy a wireless card for this machine and if so, where can i find compatible cards for this hardware ? Ubuntu version:  I have already looked up the  but it says only older versions of Ubuntu were tested on this hardware. Will i be ok with installation of latest Ubuntu/Debian ? Goal is to run this machine as a learning machine at home and run simple apps. MongoDB server would be installed but only for learning purposes. Which flavour of linux is recommended - Ubuntu or Debian ? I am mentioning Debian because i read a webpage that said Debian is more suited for server machines. But this is not a industry server, but home machine. Video upgrade : Will i get better performance on this, if i upgrade to a PCI video card ? No gaming on this machine, but potentially internet streaming maybe done for Netflix or Hulu movies. Currently my plan is to upgrade to 8GB RAM and SSD as the basics. In today's market prices, this is going to cost me about $150. I am guessing that if Wireless card is needed that would cost another $25 for Ubuntu. So, if i add $50 for a video card, that would bring upgrade costs to about $225. But a newer laptop with SSD+4GB ram is about $350, here in bay area (Toshiba Satellite Radius 11 L15W-B1120, Pentium N3540, 11.6" Convertible Laptop With 4GB, Memory, 128GB SSD, Windows 8.1). I only have to add a wireless card and reformat it for Ubuntu. The only sacrifice here would be the lower 4GB RAM on the laptop. As i finish writing the question, i am starting to wonder if this machine is worth upgrading, but would like to find answers to my questions anyways. This would become the 5th PC i have at home, and wife would object if she saw me getting yet another new laptop :-)   Thanks a bunch for reading my long post.

I am a bit financially strapped and received a Gateway GT5056 tower. The tower has an AMD dual core 64-bit processor in it. Will Ubuntu 12.04 run on this machine? I will not have any other application other than LibreOffice installed.


I have installed MATE on Ubuntu 14.04 and nm-applet doesn't run on startup despite being set as a startup application and being installed. When I log in, I am able to open up a terminal, type nm-applet, and then it works but not when I restart the computer.

So a couple of weeks ago my network manager icon stopped appearing; I still get automatically connected to my saved networks and the internet works fine, etc. If I go into System Settings and look at the Network settings I can still see all the networks, only the icon that's normal in the top bar is missing.  I have no idea what caused this, I don't remember installing anything. I think it just happened after a regular update.  I tried these commands to make sure I was properly up-to-date, (which I found on another forum post):  sudo apt-get -f install sudo apt-get update sudo apt-get upgrade   That didn't do it so I found this post:  and I followed the instructions in those answers:  sudo apt-get purge network-manager-gnome && \ sudo apt-get install network-manager-gnome   And, quoted from an answer there:     Add nm-applet to the Startup Applications (which may be found by   entering "Startup Applications" in the Dash).   I restarted and then saw no Unity interface at all! So I tried those 3 commands above to update again and thankfully that fixed Unity but I still don't have my network manager.  If I try the command nm-applet in a terminal it says:  nm-applet-Message: using fallback from indicator to GtkStatusIcon   So.... I'm pretty much stumped. Any help would be appreciated.


This is a Questions and Answers site, the actual persons asking and answering is a less important matter. There is hardly any difference between an answer provided by "user155098" and "chx". The profile pages still could serve to link the contributions together, the reputation points and badges would still show, the "top users" ladders would still function etc. Users, I guess, could still opt in to show their user names and profile pictures if they would want for old times' sake or something.  This would nuke the pronoun problem from orbit.  It would also fix a very long-standing bug where an older comment or answer is referenced by @username and the username changed since, making it very hard to understand the reference.  This is not a duplicate of the old question because I do not suggest anonymity, I suggest pseudonimity. Anonymity loses the link between answers of the same author. I also suggested keeping showing reputation and badges because that's important.

It has been discussed before, but in light of some of the , I can't help but wonder what is accomplished by displaying the author of a given question or answer.  There is a , but if anything, I don't think it goes far enough.  If questions and answers are supposed to stand on their own merit, why do we need to show the author at all?  I'm not proposing any change to the way rep works; rep should still be accrued and abilities gained.  The only difference is that questions and answers would appear anonymous.  Does this better reflect the goals of SO?  If so, how far do you think the anonymity should be taken?  If not, what shortcomings am I missing?


I need to work in WGS 84 so I am trying to project my shapefile into WGS 84. Despite changing the default CRS to WGS 84, when I mouse over my shapefile I am still getting a different coordinate system (please see image). Now, if I right-click on my layer and go to properties, and choose WGS 84, the shapefile disappears from the map. So for whatever reason it doesn't seem to want to be this CRS. In ArcGIS you can use the toolbox to define a transformation - is there an equivalent in QGIS?   Changing the CRS makes my image disappear and that's the problem so ideally I need some suggestions beyond the usual steps () as to what might be happening.

I have a series of layers of lines (shapefiles) in My Project. The CRS of some are different and to merge them they all must have same CRS.  When I use Processing/Toolbox/Qgis_algorithims/Reproject_layer the reprojection only works if it is allowed to save to temporary file somewhere (it will not change the CRS when I reproject if I try to save and replace it in My Project directory);   I must remove the original from the layer list and reproject the temp file (without changing the CRS) to get it into my project and name it appropriately.  Is there a better way to reproject a layer in Qgis?


I was browsing my logs on papertail and I saw this.  Jun 03 03:26:01 /USR/SBIN/CRON:  (root) CMD (test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily ))      Jun 03 03:26:04 su:  Successful su for www-data by root      Jun 03 03:26:04 su:  + ??? root:www-data      Jun 03 03:26:04 su:  pam_unix(su:session): session opened for user www-data by (uid=0)      Jun 03 03:26:04 su:  pam_unix(su:session): session closed for user www-data      Jun 03 03:26:04 su:  Successful su for www-data by root      Jun 03 03:26:04 su:  + ??? root:www-data      Jun 03 03:26:04 su:  pam_unix(su:session): session opened for user www-data by (uid=0)      Jun 03 03:26:04 su:  pam_unix(su:session): session closed for user www-data      Jun 03 03:26:04 syslog-ng:  Configuration reload request received, reloading configuration;      Jun 03 03:26:04 syslog-ng:  EOF on control channel, closing connection;      Jun 03 03:26:05 syslog-ng:  Configuration reload request received, reloading configuration;      Jun 03 03:26:05 syslog-ng:  EOF on control channel, closing connection;      Jun 03 03:26:05 CRON:  pam_unix(cron:session): session closed for user root      Jun 03 03:39:01 CRON:  pam_unix(cron:session): session opened for user root by (uid=0)    Isn't it possible breakin attempt? Why is root logged as www-data and syslog-ng reload configuration?  Edit.  Files in /etc/cron.daily  apt  aptitude  bsdmainutils  dpkg  lighttpd  logrotate man-db  passwd  In lighttpd is   #!/bin/sh # Cleanup lighttpd compress cache  cache=/var/cache/lighttpd if test -d "$cache/compress"; then     su -s /bin/sh -c "find $cache/compress -type f -atime +30 -print0  | xargs -0 -r rm" www-data fi if test -d "$cache/uploads"; then     su -s /bin/sh -c "find $cache/uploads -type f -atime +1 -print0 | xargs -0 -r rm" www-data fi

This is a  about Server Security - Responding to Breach Events (Hacking)   See Also:                  Canonical Version I suspect that one or more of my servers is compromised by a hacker, virus, or other mechanism:   What are my first steps? When I arrive on site should I disconnect the server, preserve "evidence", are there other initial considerations? How do I go about getting services back online? How do I prevent the same thing from happening immediately again? Are there best practices or methodologies for learning from this incident? If I wanted to put a Incident Response Plan together, where would I start? Should this be part of my Disaster Recovery or Business Continuity Planning?   Original Version       2011.01.02 - I'm on my way into work at 9.30 p.m. on a Sunday because our server has been compromised somehow and was resulting in a    attack on our provider. The servers access to the Internet   has been shut down which means over 5-600 of our clients sites are now   down. Now this could be an FTP hack, or some weakness in code   somewhere. I'm not sure till I get there.      How can I track this down quickly? We're in for a whole lot of   litigation if I don't get the server back up ASAP. Any help is   appreciated. We are running Open SUSE 11.0.            2011.01.03 - Thanks to everyone for your help. Luckily I WASN'T the only person responsible for this server, just the nearest. We managed   to resolve this problem, although it may not apply to many others in a   different situation. I'll detail what we did.      We unplugged the server from the net. It was performing (attempting to   perform) a Denial Of Service attack on another server in Indonesia,   and the guilty party was also based there.      We firstly tried to identify where on the server this was coming from,   considering we have over 500 sites on the server, we expected to be   moonlighting for some time. However, with SSH access still, we ran a   command to find all files edited or created in the time the attacks   started. Luckily, the offending file was created over the winter   holidays which meant that not many other files were created on the   server at that time.      We were then able to identify the offending file which was inside the   uploaded images folder within a  website.      After a short cigarette break we concluded that, due to the files   location, it must have been uploaded via a file upload facility that   was inadequetly secured. After some googling, we found that there was   a security vulnerability that allowed files to be uploaded, within the   ZenCart admin panel, for a picture for a record company. (The section   that it never really even used), posting this form just uploaded any   file, it did not check the extension of the file, and didn't even   check to see if the user was logged in.      This meant that any files could be uploaded, including a PHP file for   the attack. We secured the vulnerability with ZenCart on the infected   site, and removed the offending files.      The job was done, and I was home for 2 a.m.            The Moral   - Always apply security patches for ZenCart, or any other CMS system for that matter. As when security updates are released, the whole   world is made aware of the vulnerability.   - Always do backups, and backup your backups.   - Employ or arrange for someone that will be there in times like these. To prevent anyone from relying on a panicy post on Server   Fault.


I create a Heap class which uses E general type generics extends from Comparable class. In the isEmpty method it checks whether the first element is empty or not.   But when I implement it, a NullPointerException occurs at isEmpty and add methods. How can I fix it ?  public class Heap<E extends Comparable<E>> { private E[] heapArr ; private int size = 3 ;  public Heap(){  } public Heap(E[] a){     this.heapArr = a;     size = a.length; } public boolean isEmpty(){     if(heapArr[0] == null)         return true;     else     return false; } public void add(E element){     if(isEmpty()){         heapArr[0] = element;     }     else{     int parent = (size-1)/2;     while((int) element > (int) heapArr[parent]){         heapArr[parent] = element;         parent = (parent-1)/2;     }     } }  public E remove(){      heapArr[0] = heapArr[size];      size = (size - 1);       int x = 0;      TricklingDown(heapArr, x);     return heapArr[0]; } public int max(E e1, E e2){     if((int) e1 > (int) e2){         return (int) e1;     }     else          return (int) e2; } public void swap(E e, int x){     heapArr[x] = e;      } public int TricklingDown(E[] heapArr1, int x){      int leftChild = (2*x +1);     int rightChild = (2*x +2);     int largerChild = 0;      while((int) heapArr1[x] < (int) heapArr1[leftChild] || (int) heapArr1[x] < (int) heapArr1[rightChild]){          largerChild = max(heapArr1[leftChild], heapArr1[rightChild]);         swap(heapArr1[x], largerChild);          x ++;      }     if(largerChild == leftChild){         return leftChild;     }     else          return rightChild;  }  }

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


I need to write a regex to target commas that exist only outside a pair of brackets or braces.  Currently I have:  var regex = /,(?![^{]*})(?![^[]*])/g   When the target string is:  var str = '"a":[{"b":2,"c":["d"]}],"b":2'    // OK: only second comma matches   the pattern correctly matches only the second comma.  When the target string is:  var str = '"a":[{"b":2,"c":{"d":9}}],"b":2'    // OK: only second comma matches   the pattern also correctly matches only the second comma.  However, when the target string includes a array and object, the negative lookahead fails and the regex matches both commas.  var str = '"a":[{"b":2,"c":[{"d":9}]}],"b":2'    // BAD: both commas match

I don't really understand regular expressions.  Can you explain them to me in an easy-to-follow manner?  If there are any online tools or books, could you also link to them?


Let n be a positive integer which representation in base 10 is $a_ka_{k-1}a_{k-2}...a_2a_1a_0$. It's not particularly hard to prove that:  $n\equiv a_0\pmod2$  $n\equiv2a_1+a_0 \pmod 4$  $n\equiv 4a_2+2a_1+a_0\pmod8$  However this doesnt seem to hold for $\pmod{16}$, what I mean is:  $n\equiv 8a_3+4a_2+2a_1+a_0\pmod{16}$   For example if we take $n = 54217$  $54217\pmod{16} = 9\;\;$ and $8*4+4*2+2*1+7 \pmod{16} = 1$  Is there anything I can add to this rule to actually make the rule work for $2^m$?

It is easy to calculate small examples like $26\pmod {5}$ but how do you calculate examples like $9801 \pmod {32}$ without a calculator.


If I have two physical cores and hyperthreading enabled, is the CPU load computed against two cores or fours?  In other words, is complete load indicated by 2.0 or 4.0?

lead me to be quite shocked with my current system. The CPU in my workstation is an i7 with hyperthreading enabled, and cat /proc/cpuinfo produces 4 'cpu's.  That all given, my PC can generate over a 16 in all the load average slots from 1 minute to 15 minutes while compiling packages for Gentoo, but still be working perfectly for all other tasks as well. I've even seen it as high as 24, though it was starting to slow down at that point. How does this work, if 1.0 is supposed to represent one core at full utilisation?


I used tikzposter to create a poster and authblk to do my affiliations. My problem is that the first index of the affiliations ( index 1, at Dept. of Alpha Research in the MWE) is a lot larger than the font of the rest of the affiliations. How can I standardize it or fix the font size of my affiliations?  here is my MWE:  \documentclass[25pt]{tikzposter} \usepackage{authblk} %Allows improved author and affiliation design \usetheme{Desert}  %Set title authors and institute \title{\parbox{\linewidth}{\centering ULTRA LONG TITLE NO ONE BOTHERS   TO    READ}} \institute{Alpha University}  \author[1,2]{John Doe} \author[2]{Jane Doe} \author[2]{Jennifer Doe} \author[3,4]{James Doe} \author[3]{Jenna Smith} \author[2]{John Smith} \author[1]{Jennifer Smith}   \affil[1]{\normalsize Dept. of Alpha Research} \affil[2]{\normalsize Beta corporation} \affil[3]{\normalsize Gamma university} \affil[4]{\normalsize Delta Research group}  %Make title customizer \makeatletter \def\maketitle{\AB@maketitle} \makeatother  \begin{document} \maketitle \block{Abstract}{ Tih is an abstract to fill the MWE } % See Section 4.2 \end{document}

I have some problems when customizing author and affiliation using authblk.    The above picture shows the author and affiliation format generated by my MWE.  I want to:   typeset the author names bold face. I use the command \renewcommand*{\Authfont}{\bfseries}. However, it will turn both author names and affiliation boldface. I do not know what the problem is. I want to put XXXXX in affiliation 1 together with 200021 in a new line. How can I achieve this? Thanks.   The following is my MWE:  \documentclass{article} \usepackage[left=3.00cm, right=3.00cm, top=2.00cm, bottom=2.00cm]{geometry} \usepackage{authblk}  \renewcommand*{\Authsep}{, } \renewcommand*{\Authand}{, } \renewcommand*{\Authands}{, } \renewcommand*{\Affilfont}{\normalsize} %\renewcommand*{\Authfont}{\bfseries}    % make author names boldface     \setlength{\affilsep}{2em}   % set the space between author and affiliation  \title{Aa Article Title} \author[1]{Aaaaaa Aa} \author[1*]{Bbbbb Bb} \author[2]{Ccccccc Ccc} \affil[1]{Department of Chemical Engineering, University of AAAAA BBBBBB, CCCCC road, XXXXX 200021, Y Country}  \affil[2]{AAAAAA Laboratory, University of AAAAA BBBBBB, XXXXX 303939, Z Country} \date{}      \begin{document} \maketitle  This is an article. \end{document}


I have a online store with Magento, which means there are a lot of parameters to filter categories. Small example:  www.example.com/chats/distributeurs-fontaine/  www.example.com/chats/distributeurs-fontaine/?limit=12   Since it's bad for SEO, we did 2 things for the 2nd URL not to index: we blocked it via robots.txt and used a canonical.  Robots.txt line: Disallow: /*?limit*  Canonical: <link rel="canonical" href="http://www.example.com/chats/distributeurs-fontaine/" />  Still, the 2 URLs are indexed. I'll admit we didn't set proper URL parameters instructions in Webmaster tools from the start, but I would have thought we did enough.  Do you have an idea why the canonical didn't work? And do you see a potential solution to get the thousands of bad URLs out?

Is there any way we can delete Google URL Parameters? I know in webmaster tools that there is no option to delete the URL parameters that were crawled by Google, but is their any other way we can take them out of the Google search results?  We had no URL parameters in WMT showing last month and we had a good amount of organic traffic to the website.  After few changes on SEO pages, related to rel="canonical" Google has crawled about 20 URL Parameters automatically in the last month. Each URL parameter has around 7,012,505 monitored URLs. We have lost around 50% of the organic traffic.   We made some changes to edit URL parameters, but so far that has not had any effect. We are looking for a way to tell Google to ignore these parameters and forget about all the URLs that it already crawled with them.


I have met with generalized linear model, but I'm confused with the errors and residuals? Can anyone help me out? I have got three questions. (1)what's the difference between error and residual?  (2)what does error distribution refers to in generalized linear models? The distribution of the response variable? Or anything else?  (3)Assuming normally distributed residuals is always needed whether in linear model or generalized linear model?

I was reading about regression. I understand one of the how the variance of each $x_i$ needs to be normal distributed, but why doesn't that related to the $s_b$? It seems like it should. I was reading the AP College Board paper about Inference.      Two more assumptions are that the errors are normally distributed and that they have   the same standard deviation for all x values. Although it is not at all obvious, this is   not the same as saying that the residuals are normally distributed and all have the same   standard deviation. The difference is that the “errors” are the deviations between the   response variables and the “actual” underlying (invisible) linear phenomenon, whereas   the “residuals” are the deviations between the response variables and the least-squares   regression line, which is only an estimate of the “actual” line.   I understand (I think) that just because the error of the regression is normal doesn't mean that the variance of $x_i$ is normal because the sample could just randomly follow normality.  (don't know if I said that statistically correct), but if all the $x_i$ are normal and the variance are equal, then why doesn't that variance equal the variance that one would get for the $\beta$  I have gotten some great answers here that are very clear and I am hoping that I could get another answer to help clear up my confusion.    The kernel of my question is What exactly is the relationship between the variance of the residuals and the $x_i$ and is there any connection to the error, variance of $\beta$


Not sure if this has been suggested before. But does anyone else think that there should be a feature to convert a comment to a answer?   So you are talking to the OP and then suggest what to do and it turns out to be the answer. It would be great if we or the OP can recommend that comment to be the answer then it gets convert to an answer.

Allow converting comments to answers, so they can become accepted answers.  I asked a question. Someone commented on it, and it was an awesome comment that fully answered the question. As the original questioner, I would like to convert that comment to an answer in order to accept it.  Or, if you prefer, I would be okay with being able to simply mark the comment as accepted.


I'm new-ish to Blender. I just built a Ryzen 9 PC for graphic design applications and unfortunately Blender 2.83 LTS does not seem to be functioning properly. What happens, right from the jump, is that objects do not appear in the viewport or in renders, but they appear as normal during modeling, sculpting, and UV editing. Instead, all I see if they are selected is an outline (and in renders what appears to be a black hole). See my photos for examples. I've tried some of the solutions offered elsewhere including: changing the clipping distance, checking that the object's visibility is properly set, various alt-this and alt-thats, nothing is working. Sometimes I can get things to appear in the viewport if I mess around with the object in modeling first, but this is not a sustainable solution. And for just a bit more context, I can get 2.79 to work fine(but as I said, I'm new and still learning, and it's too bid of a difference in layout and function to easily follow along with tutorials), but 2.9 crashes immediately upon startup. Oddly enough, I can also get 2.8 to function in Linux, but this is also not an ideal solution as I was hoping to use downtime during work to get more practice so I can't be switching OS's all the time. Finally, it's definitely worth noting that I'm using a pretty old AMD Firepro 5900 (2GB GDDR5) as I suspect that might be where the issue lies. It's the only card I had lying around, and given that even older GTX cards are going for three times their reasonable market value, I just can't bring myself to spend $$$ on another card until the GPU shortage works itself out. Any help would be appreciated. Thanks!!

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?


Is this statement true?  $$\sqrt{(-5)^2} = -5$$

Are they equal?      -5 = $\sqrt{(-5)^2}$


I believe that the function: f(x,y)=$\frac{x^{2}y}{x^{2}+y^{4}}$ is continuous on the point (0,0) but i can't prove it.  I know you have to choose something like $x=cy^{2}$(with c a constant) to prove this but it doesn't seem to work. Can anyone help me solve this?

Can someone help me calculate the following limits?  1) $ \displaystyle\lim _ {x \to 0 , y \to 0 } \frac{\sin(xy)}{\sqrt{x^2+y^2}} $ (it should equal zero, but I can't figure out how to compute it ) .   2) $\displaystyle\lim_ {(x,y)\to (0,\frac{\pi}{2} )} (1-\cos(x+y) ) ^{\tan(x+y)} $ (it should equal $1/e$).   3) $ \displaystyle\lim_{(x,y) \to (0,0) } \frac{x^2 y }{x^2 +  y^4 } $ (which should equal zero).   4) $\displaystyle \lim_{(x,y) \to (0,1) } (1+3x^2 y )^ \frac{1}{x^2 (1+y) } $ (which should equal $e^{3/2}$ ).   Any help would be great !   Thanks in advance !


I'm trying to convince Ubuntu's init system not to start X11 at boot-up. Removing gdm did not change the fact that each time the machine restarts, X11 with Gnome comes up.   How do I get rid of it? I need to auto-login as root with no Xserver after startup. It's inteded for a very specific automation-purpose to behave like that and not meant for Desktop experience ;)

Is it possible to disable X at boot time? I'm setting up a server so it would be nice if it wouldn't load the graphical interface every time I boot.


I'm trying to achieve a gain of exactly -1, however the output of this circuit isn't the expected waveform (correct gain, just wrong wave).   Is there an issue with the circuit?

I'm getting a non inverted output. The resistors I used were two 100ohm 1/4watts. Signal was 4v peak to peak 600hz.


I shoot raw with a Sony A7sII and I am really satisfied with the results of the image previews, until I import them into Lightroom. Lightroom shows the processing thumbnail which reflects how I perceived the image in camera, but it then immediately processes the RAW in a different way with the colors dramatically off.  I am using Lightroom 2015.3 with Camera Raw 9.3, for reference.  Lightroom has a "Camera Calibration" feature in the Develop Settings which is always set to Profile Adobe Standard by default, with the 2012 process. Some of the other profiles more so reflect what I saw in camera and the thumbnail, but after Lightroom processes a RAW for its own catalogue preview, there is no way to undo it for reference. This is very aggravating and I will probably just shoot RAW+JPG to get around it, but this makes my shooting slow down in the field and is less practical.  Is there any way get the RAW processing more reflective of what I perceived in camera for the Sony A7 files?

I'm a novice shooting in RAW and find that half the time my camera JPEG images come out better than my Lightroom tweaks to RAW files.  So to give myself a better start I'd like to apply the JPEG settings that are applied automatically by the camera to my RAW files in lightroom so that initially my RAW files look exactly like the JPEG files.   How can I do this?


Prove that      $$\sum _{ i=1 }^{ n }{ \frac { i }{ { 2 }^{ i } } = } 2-\frac { n+2 }{ { 2 }^{ n } } \quad { for\quad all}\quad n\in \mathbb N $$   My attempt:  For my inductive step I tried the following:  $$\left(2 − \left(\frac{k + 2}{2^k}\right)\right) + \left(\frac{k + 1}{2^{k+1}}\right) = 2 − \left(\frac{k + 3}{2^{k+1}}\right)$$  But they never equal, this is where I'm stuck.


I just want to change the paper left, right, top and botton margins in LaTex because I think the default margins isn't enough.

I am writing a document for which I need the margin to be exactly as follows: left, right, top and bottom text margin all equal to 1in, distance from bottom of the paper to page number equal to 0.75in (I don't have any footnote or header to set).  I tried to use the fullpage package in LaTeX but it does not give me the 0.75in to the page number. Is there a way to force that? I tried to set manually the margins for a 8.5x11 paper but I am not succeeding.    I tried but after writing:  \documentclass[PhD]{class_file} \usepackage[margin=1in,footskip=0.25in]{geometry}   I get the error message \paperwidth (0.0pt) too short.  I don't see the \paperwidth is set to 0.0pt anywhere though..  Also it seems to me that depending on which machine I use to compile my tex file, I get different margins, even when I set them up manually (without using geometry). Is it possible?    Using the geometry package things seem to work a bit better now (I changed machine and the problem with the paper width previously mentioned disappeared).   \usepackage[margin=1in,footskip=0.25in]{geometry}   gives me without problem upper, right and left margin of 1in. But the lower margin is 1.2in and I can't change it to be 1in even by using bottom=1in or bottom=0.8in. I really don't see how this can happen. Maybe a problem with the spacing between lines? The class files I am using can be fund at   I erased the margin settings of uclath12.clo as the margin I need are different from the ones that this file gives. Thank you.


I need to create closed network for few computers running Windows XP connected to wireless router. Can some one give me some pointers?  I configured the routers wifi and security, set device ip to 192.168.0.1 and dhcp range of 5 addresses (192.168.0.100-104). Computers connect to my wifi network and can ping router but can't see each other in network. I turned on file and printer sharing and shared appropriate folders and set permissions. I added all computers ( with unique names ) to the same workgroup called ABC and restarted them. They should see each other now but they don't, nor I can ping them  (I did this same setup with 5 pc running Windows 7 and they immediately showed on HomeGroup so now I can't figure out what is wrong with this). Firewall is disabled and router is tested and configuration ok.

I have 2 pcs with win xp and a wifi router ( without outgoing internet connection )...my job was to connect them over wifi to share some files. router was properly configured, both computers connected to wifi without problems, but when I tried to network them I could not see them in workgroup...i changed their names and added them to same workgroup but i couldn't connect pc1 to pc2 ( i could ping router from each pc but pinging other computer resulted in ping timeout) ..now i cant figure out why this is not working since I've done this before on more complex networks and it should work but...( maybe I have gremlins hiding somewhere..)    edit1: Firewall is down on both machines( I disengaged it in both control panel and in services) and folder sharing and permissions are ok.. edit2: I know about Ad Hoc network ( wlan-to-wlan, without router/switch ) but that's not what I am trying to accomplish here :)


I am familier with other languages.But i am learning java now. I was reading the access modifiers . I found that only public class can be accessed from outside. And the [default] class cant not be accessed from outside. But as i have written some simple code i cam access the non public class from outside:  Add.java  class Add{     int a(int x, int y)     {         return x+y;     } }   MyClass.java  public class MyClass {     public static void main(String args[]) {       Add obj= new Add();       int sum= obj.a(10,20);       System.out.println("Sum of x+y = " + sum);     } }   OUTPUT>>>     Sum of x+y = 30   So please someone explain this for me? I want to know how this is happening!  Thanxx in advance.

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


Note: I didn't downvote! (yet)  Earlier today, I flagged an answer as it really wasn't an answer at the time. However, the poster later added a JSFiddle example (which didn't really answer the question either but merely repeated the OP's post) but it got a few comments going, and got the OP engaged, which resulted in some useful comments before the answerer bowed out. The OP also commented via their own comments and on other posts.  It is the habit of this particular user, s/he should have used the comments IMHO to extract the extra info needed or make their original observation in the first place, and I shouldn't have been so quick off the mark with a flag! I'm not worried about the wrong flag but what if anything should or can be done in a situation similar to this.  I know it was likely a "FGITW" type answer, where a user was hoping to edit (may still happen) but again IMO it failed this time. If it was me who'd tried it, I would delete but then I wouldn't want to delete what may be useful comments = hence the quandary and my question.  Is there anything that can be done to either retract the flag or explain why the flag in the first place (beyond the original not an answer!)?  My apologies to whoever saw my flag!

I'm wondering (since it just happened to me), is it possible to "cancel" ("undo", "delete", "retract", whatever) a flag I just raised if I misclicked it, so the mods won't waste time?  I looked everywhere, but I can't find such a feature.


I have had this iPhone4 for about over three years now but it suddenly won't charge. It comes on at 1% and than turns straight back off and it keeps doing that whilst on the charger. I don't even have enough time to turn off my phone.  Could someone please tell me if I need a new phone or a new battery ? what is wrong with it it has all my contacts and details in it and I need it fixed.

I have an iPhone 4s running on iOS 8.1.3. I've owned it for about 2-3 years now and have taken good care of it physically and hardware wise. But recently my phone had died. I plugged it in to the charger no problem right? I come back about 20 minutes later to see nothing had changed... I tried adjusting the cord, trying to power down the device, rebooting, safe mode, and just letting it sit without the cord and retrying to charge it. Nothing worked; the phone just kept blinking the red battery logo even of 1 entire day of charging. What is there to do?


I've noticed that userscripts aren't automatically synchronized like (regular) extensions in Google Chrome.   Is there any way to ensure that userscripts are synchronized between Chrome installations?

I use the normal version of Chrome as well as Canary (on both Windows and OS X).  It's kind of a pain that my TamperMonkey scripts are only available in one or the other.  Trying to maintain both, and synchronize changes I made in one to the other, is a ridiculous pain.  I understand that .  Is there a way to share this between browser versions?


Is there a free version of Kingoffice for Ubuntu 12.04?  If not, what are existing alternatives ?

I am an Ubuntu 12.04 user and I want to install Kingsoft Office but I don't know how to install it.   Please tell me the procedure to install Kingsoft Office in Ubuntu 12.04.


How we can print the second last row from the table using SQL query.

I'm interested in learning some (ideally) database agnostic ways of selecting the nth row from a database table. It would also be interesting to see how this can be achieved using the native functionality of the following databases:    SQL Server MySQL PostgreSQL SQLite Oracle   I am currently doing something like the following in SQL Server 2005, but I'd be interested in seeing other's more agnostic approaches:  WITH Ordered AS ( SELECT ROW_NUMBER() OVER (ORDER BY OrderID) AS RowNumber, OrderID, OrderDate FROM Orders) SELECT * FROM Ordered WHERE RowNumber = 1000000   Credit for the above SQL:   Update: See  regarding the SQL standard. Troels, have you got any links we can cite?


I don't understand why the operator "==" will not work for comparing string, but will for comparing int, double, float, etc. from what i understand, "==" determines if two entities are pointing to the same object  int a = 10; int b = 10;  if(a == b){ ... }   a and b are have different reference in memory but this statement returns true. why is that? i thought "==" compares reference?

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?


I was installing Ubuntu 13.10 and chose to replace the old Ubuntu 12.04. The problem is that the new installation also erased my Windows and installed the new Ubuntu using all space available in my HD, instead of keeping the dual boot.  That also happened with my friend, we are both developers that need both OS. Very sad, this should be fixed.  EDIT:  As @oldfred said: "Reinstall says overwrite Ubuntu but it also erases existing Windows. 2"

I have a Toshiba satellite A-200 laptop with a Vista OS on it with 4 NTFS partitions  (C:) Vista  (D:) Entertainment  (E:) Work  (F:) Sources   and I wanted to start using Ubuntu instead. So I tried it first from the live CD and everything was OK and all the partitions were shown and working and so I decided to install Ubuntu to replace Vista on the (C:) drive. After I did that I can no longer find my folders and files on the (D:), (E:), (F:) partitions and the only file system that is shown is one 198 GB although my HDD is 320 GB.  I can't access the lost data on the remaining 120 GB which I hope is still there and not totally lost  I am now working from the live CD but I am unable to install testdisk. Can I recover the Vista partitions by the product recovery CD to get my laptop back to the factory settings? Can I recover the NTFS partitions using a recovery program for Windows or will that make the problem worse?   I need these data badly as I don't have a backup for them.


Find the number of real roots of the polynomial $f(x)=x^5+x^3-2x+1$    ( I think similar questions have already been asked. However, I am not sure whether the exact question has already been raised by some user. I urge the members of this mathematical community to mark my question as duplicate if it has already been asked. I tried an attempt below:-)    What I attempted:-  I know a little bit of theory of equations but not all. While I was in the examination, I did not ponder much more on any theorems relating to real roots. Rather I tried to do it with some intuition. We have $f(1)=1$,$f(0)=1$,$f(2)=1$, $f(\frac{1}{2})=\frac{5}{32}$,$f(-\frac{1}{2})=\frac{59}{32}$,$f(-2)=-35$ It just helped me to trace a root between $-1$ and $-2$. Then I tried to study the nature of the graph.    Here $f'(x)=5x^4+3x^4-2$ Let $f'(x)=5x^4+3x^2-2=0$     $\Rightarrow 5y^2+3y-2=0$  (where $x^2=y$) $\Rightarrow (5y-2)(y+1)=0$ Therefore, $y=\frac{2}{5}$,   or $y=-1$ (It is not of our interest, as we are dealing with real roots)   Therefore $x=\sqrt{\frac{2}{5}},-\sqrt{\frac{2}{5}}$ These two values divides the real line into three disjoint subsets $(-\infty,-\sqrt{\frac{2}{5}})$, $(-\sqrt{\frac{2}{5}},\sqrt{\frac{2}{5}})$, $(\sqrt{\frac{2}{5}},\infty)$    It s quite easy to notice that $f$ is decreasing in $(-\sqrt{\frac{2}{5}},\sqrt{\frac{2}{5}})$ and increasing in $(-\infty,-\sqrt{\frac{2}{5}})$, $(\sqrt{\frac{2}{5}},\infty)$     Again, $f(-\sqrt{\frac{2}{5}})=1.911$ and $f(\sqrt{\frac{2}{5}})=0.089$    Looking at all these details it is clear that $f(x)$ comes close to zero in $(-\sqrt{\frac{2}{5}},\sqrt{\frac{2}{5}})$ but is not equal to zero. There is no possibility for $f(x)$ to be zero in $(\sqrt{\frac{2}{5}},\infty)$   as it is increasing here. Again, we have already discovered one root between $-1$ and $-2$. Apart from that there is of course no root as $f$ is again increasing in $(-\infty,-\sqrt{\frac{2}{5}})$. So, te graph should look something like this  Therefore there is only one real root of the polynomial.    Is my approach correct? Is there any way to do the same thing using some more beautiful as well as advanced method ? (I have just made a rough plot of the graph in my answer sheet). I am not sure if the examiner would expect much better method than this one.

Determine number of real roots of $f(x)=x^{5}+x^{3}-2x+1$.   I used Descartes's rule of sign to determine the number of positive and negative roots; there is only 1 negative (hence minimum 1 real root) and two positive roots. These 2 positive roots can be anything- a complex pair, or two real roots- but what about the other 2 roots? Is there any flaw in my understanding of rule of signs? How can I find the exact number of real roots?  Thanks in advance.


I recently discovered the todonotes package. It would be great to somehow check the notes as done. I know the creator has this on his "todo list" (funny), but right now its not implemented. My idea was to hide it in the document and to strike it out in the listoftodos. Below you see a minimum working example. This is how I do it now.  Thanks for the help in advance!  \documentclass[a4paper,12pt,captions=tableheading,abstracton, %draft, %final, headsepline,bibliography=totoc]{scrreprt}  \usepackage{ulem} \usepackage[obeyFinal,textsize=footnotesize]{todonotes} \newcommand{\addref}{\todo[color=red!40]{Add reference.}} \newcommand{\done}{\todo[disable]{Test} }%this shouldnt show up in document and be striked out in listoftodos    \begin{document} \listoftodos\clearpage \todo{ToDo}  \addref{addRef}  \done{Done} \end{document}   In an older version of the question I also asked for the color in listoftodos. This is not the case anymore.

I'm trying to add a \listoftodos using the todonotes package to a template file I have. I've added two todos with \todo[inline]{Write abstract \ldots} and \todo{Fill in these details \ldots}. I'm using TextMate to render my document on Mac Osx.  My list of todos in my document looks like this:   My table of contents (in Estonian) looks like this (I think it might be interfering with the styling):   And finally, the intended behaviour and styling from todonotes  looks like this with hyperlinks and colors:   Do you have any ideas how to debug the styling issues with rendering todos?


I'm trying to raise an event from my worker thread in the SerialPort.DataReceived event in the main thread.  Background: I have a device connected that can send data by itself to the serial port of my PC. I need to recognize this data and when a telegram is completed, pass it to the UI thread to e.g. show received values. Because the data can arrive spontaneously I used the DataReceived Event of the SerialPort class.  The DataReceived Event creates its own background thread, this I know and this is my problem. When the telegram is complete, I raise an event on the open form of the application e.g. to update a certain text field. The problem is, this event raising is done in the worker thread of the SerialPort received Event.  Is there a way to raise this event on the main UI thread?

Which is the simplest way to update a Label from another Thread?   I have a Form running on thread1, and from that I'm starting another thread (thread2).  While thread2 is processing some files I would like to update a Label on the Form with the current status of thread2's work.   How could I do that?


Can the following sentence be considered as grammatically correct? :  "That(,) he doesn't need any more."

Besides , which are the  that can be found in English? Are there any that are peculiar to dialects such as Singlish or Indian English? Please provide an example sentence for each order along with pertinent information such as tense, mood, voice, etc.


A phrase being used by the "news" media regarding the  is "firearms favored by the Mexican cartels", referring to their purchase of AK47s and other semiautomatics; weapons that are in fact favored by many people who want a good weapon for a reasonable price. I'm trying to name the fallacy, and "guilt by association" and "red herring" come to mind but aren't really a good fit.  I've read , but can't really match it to the situation. I've also looked through many of the fallacies at  and  and can't see a good match. Any ideas?   It could be rewritten for clarity:  Person P bought weapons A and B. A and B are favored by the Mexican drug cartels. Therefore, P bought the weapons with intent to distribute them to the Mexican drug cartels.

Examples, some are ridiculous: Someone refuses to buy a lab grown diamond because 'all diamonds are blood diamonds'.  We cannot buy a sports car because 'the trunks of sports cars are too small', even though this sports car has a larger than average trunk.  Someone refuses to drink wine because 'wine comes from France', even though this particular wine is from Chile.


How can I evaluate $$\sum_{n=1}^\infty\frac{2n}{3^{n+1}}$$? I know the answer thanks to , but I'm more concerned with how I can derive that answer. It cites tests to prove that it is convergent, but my class has never learned these before. So I feel that there must be a simpler method.  In general, how can I evaluate $$\sum_{n=0}^\infty (n+1)x^n?$$


I've been trying to prove this statement by induction; however, in following the steps I normally take I end up utterly stuck. I know that I must be missing something, but I have been stuck on this for a while now and can't seem to figure it out. Does anyone know how I can get to a sum on the RHS of my proof statements? Any other advice on how to find this?  Prove $**2^n > n^2**$ by induction using a basis > 4: Basis: $**n = 5** **2^n > n^2**$                  32 > 25 Assume: $**2^n > n^2**$  Prove:  $**2^(n+1) > (n+1) ^2**$  $**2^{n+1} = 2^n * 2** $    LHS Prove = LHS Assume + Fix  $**2^{n+1} > (n^2) *2**  $   Utilize assumption $**2^{n+1} > 2(n^2)** $      Could utilize assumption again...  $**2^{n+1} > 1(n^2)**  $       ..doesn't seem to help $**2^{n+1} > (n * 1)^2**   $     Basically just$ n^2$

How do I prove the following statement by induction?  $$n^2 \lt 2^n$$  $P(n)$ is the statement $n^2 \lt 2^n$  Claim: For all $n \gt k$, where $k$ is any integer, $P(n)$  (since $k$ is any integer, I assume I have to prove this for positive and negative integers)  So let base case be $P(1)$, and I have to prove $P(n)$ for $n \ge 1$ and $n \lt 1$  $P(1)$ is $1^2 \lt 2^1$ which is clearly true.  Induction hypothesis: $k^2 \lt 2^k$  Inductive step $(k+1)^2 \lt 2^{(k+1)}$  $(k+1)^2 = k^2 + 2k + 1$  $k^2 + 2k + 1 \lt 2^k + 2k + 1$ by inductive hypothesis  Not sure how to proceed. Is my previous intuition that I have to prove this for $n \ge 1$ and $n \lt 1$ correct?


Java supports pass by value (always works on a copy) but when you pass a user defined object then it changes the actual object (kind of pass by reference but no pointer changes), which I understand but why the changeObject2CLEAR method below is actually changing the value of the object ? Instead it has to work on the copy?      import java.util.HashMap; import java.util.Map;  public class PassBy {      class CustomBean {         public CustomBean() {          }          private int id;         private String name;          public int getId() {             return id;         }         public void setId(int id) {             this.id = id;         }         public String getName() {             return name;         }         public void setName(String name) {             this.name = name;         }             @Override         public String toString() {             return id + ", " + name;         }     }      public Map<Integer, String> changeObject2NULL (Map<Integer, String> m) {         m = null;         return m;     }      public Map<Integer, String> changeObject2CLEAR (Map<Integer, String> m) {         m.clear();         return m;     }      public CustomBean changeCustomObject (CustomBean _e) {          _e.setId(_e.getId() + 1);         return _e;     }      public static void main(String[] args) {      PassBy passby = new PassBy();      Map<Integer, String> map = new HashMap<Integer, String>();     map.put(1, "value");      CustomBean bean = passby.new CustomBean();     bean.setId(1);     bean.setName("arun");      // Initial Value     System.out.println(map.toString());     System.out.println(bean.toString());     System.out.println("-------------------------");      // Pass by value works fine     passby.changeObject2NULL(map);     passby.changeCustomObject(bean);      // Custom object value changes since we pass as the object reference but Map remains with actual value     System.out.println(map.toString());     System.out.println(bean.toString());     System.out.println("-------------------------");      // Testing Pass by value - CANT UNDERSTAND why it changed the object since it has to be pass-by-value and not by ref in this case ??     // Why setting to null not chainging the value but clear does ?     passby.changeObject2CLEAR(map);     System.out.println(map.toString());      } }

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


I created a standard table of contents page in Beamer   \AtBeginSubsection[] {     \begin{frame}{Outline}         \tableofcontents[currentsection,currentsubsection]     \end{frame} }   I have a lot of sections and this leads to the contents being cut out.  How can I split the page in two (something like minipage) or in the worst case continue in the next slide ?

In my LaTeX  presentation I have a long Table of Contents, which has been split across two columns by using the  package. The problem is that I have not found any way to control vertical alignment in the multicols environment. Right now the left column starts lower than the right column, which looks weird. Instead, I would like the left column, or both columns, to be vertically aligned to the top.  I've found some related questions but nothing that solves my problem.  Look at the MWE shown below. As you can see right before Section 3, I tried adding a \vfill along a manual column break, but it didn't help... (The manual column break was added in order to keep Section 3's subsections together with the section in ToC).  Do you have any tricks?  Screenshot of the ToC slide:    MWE:  % MWE showing problems with vertical spacing in multicol ToC \pagenumbering{arabic} \documentclass[compress,14pt,t]{beamer} \usepackage[latin1]{inputenc} \usepackage{multicol} \usepackage{charter} \frenchspacing  \begin{document}  \begin{frame}     \frametitle{Outline}     \begin{multicols}{2}         \tableofcontents     \end{multicols} \end{frame}  \section{Section 1} \begin{frame}Test\end{frame}     \subsection{Subsection 1}     \begin{frame}Test\end{frame}     \subsection{Subsection 2}     \begin{frame}Test\end{frame}     \subsection{Subsection 3}     \begin{frame}Test\end{frame}     \subsection{Subsection 4}     \begin{frame}Test\end{frame}  \section{Section 2} \begin{frame}Test\end{frame}     \subsection{Subsection 1}     \begin{frame}Test\end{frame}     \subsection{Subsection 2}     \begin{frame}Test\end{frame}     \subsection{Subsection 3}     \begin{frame}Test\end{frame}  \addtocontents{toc}{\newpage}           % Splits manually the ToC into 2 columns %\addtocontents{toc}{\vfill\newpage}    % No difference \section{Section 3} \begin{frame}Test\end{frame}     \subsection{Subsection 1}     \begin{frame}Test\end{frame}     \subsection{Subsection 2}     \begin{frame}Test\end{frame}     \subsection{Subsection 3}     \begin{frame}Test\end{frame}  \section{Section 4} \begin{frame}Test\end{frame}     \subsection{Subsection 1}     \begin{frame}Test\end{frame}     \subsection{Subsection 2}     \begin{frame}Test\end{frame}     \subsection{Subsection 3}     \begin{frame}Test\end{frame}     \subsection{Subsection 4}     \begin{frame}Test\end{frame}  \section{Section 5} \begin{frame}Test\end{frame}     \subsection{Subsection 1}     \begin{frame}Test\end{frame}     \subsection{Subsection 2}     \begin{frame}Test\end{frame}  \end{document}


I am using maven to build a java project. My project has a lot of dependencies. Now, I need to deploy this project on a server, so I want to create a self-contained executable jar, which includes all the dependencies. I went through an old question, where maven shade plugin was recommended, but I am wondering whether it is possible to do this just with maven. Is there a way I can create a self contained executable jar only by using maven?

I want to package my project in a single executable JAR for distribution.  How can I make a Maven project package all dependency JARs into my output JAR?


Let $u$ be a real harmonic function on $\Bbb C-\{0\}$. I'm trying to show that if $u$ is bounded above, then $u$ must be a constant.   This is my attempt: It is known that there exists constants $a,b\in \Bbb R$ such that  $$\frac{1}{2\pi}\int_0^{2\pi} u(re^{i\theta})~d\theta=a \log r+b$$ for all $r>0$. Since $u$ is bounded above, we must have $a=0$. Then it seems that we should have $u \equiv b$, but I have no idea here.  Any hints?

Let $f(z)$ be a positive harmonic function on $\mathbb{C}\backslash  \{0\}$. Prove that $f(z)$ is constant.   I have no idea to prove this statement.


I know that here  it says spiders always check the robots.txt before going to page. However I have recently been told that Google crawls every single URL that it can find on a site and then looks at the robots.txt file and filters out what is disallowed. Is this true?

I have some pages on my site that I want to keep search engines away from, so I disallowed them in my robots.txt file like this: User-Agent: * Disallow: /email  Yet I recently noticed that Google still sometimes returns links to those pages in their search results.  Why does this happen, and how can I stop it? Background: Several years ago, I made a simple web site for a club a relative of mine was involved in.  They wanted to have e-mail links on their pages, so, to try and keep those e-mail addresses from ending up on too many spam lists, instead of using direct mailto: links I made those links point to a simple redirector /  script running on my own site.  This script would return either a 301 redirect to the actual mailto: URL, or, if it detected a suspicious access pattern, a page containing lots of random fake e-mail addresses and links to more such pages.  To keep legitimate search bots away from the trap, I set up the robots.txt rule shown above, disallowing the entire space of both legit redirector links and trap pages. Just recently, however, one of the people in the club searched Google for their own name and was quite surprised when one of the results on the first page was a link to the redirector script, with a title consisting of their e-mail address followed by my name.  Of course, they immediately e-mailed me and wanted to know how to get their address out of Google's index.  I was quite surprised too, since I had no idea that Google would index such URLs at all, seemingly in violation of my robots.txt rule. I did manage to submit a removal request to Google, and it seems to have worked, but I'd like to know why and how Google is circumventing my robots.txt like that and how to make sure that none of the disallowed pages will show up in their search results. Ps. I actually found out a possible explanation and solution, which I'll post below, while preparing this question, but  in case someone else might have the same problem.  Please do feel free to post your own answers.  I'd also be interested in knowing if other search engines do this too, and whether the same solutions work for them also.


The dragon in LOTR is powerful.  Powerful things can exert lots of power The exertion of lots of power is useful for winning wars one wants to win Gandalf fights in wars he wants to win Gandalf is a more powerful thing than the dragon is. (Evidence: He slays it) So Gandalf can exert lots of power Gandalf does not exert lots of power in the wars he wants to win.    What gives?

We know that the Maiar sent to Middle-earth as Istari are not using their full Maiar power. Gandalf the Gray is more than a human power wise, but not nearly equal to his full real power.  Is it known (from canon) whether there is something explicitly restricting Olorin's power when he's Gandalf the Gray, or is he merely prohibited from using it but still has it at his disposal?  Question arose from  comment. Daniel was using Saruman having greater powers once he turned "bad" as his reasoning.


When Darth Vader killed Obi Wan in Episode IV, he vanished completely into thin air. But when Darth Maul (Phantom Menace) killed Qui Gonn Jinn in Episode I, his corpse just lay there with a big hole in his stomach. Why is that?

Some Jedi disappear when they die:   In Star Wars Episode IV: A New Hope       At the end of his duel with Vader on the first Death Star, Obi-Wan Kenobi let down his guard and concentrated for a moment, disappearing entirely just as Vader's lightsaber passed through his empty robe.   In Star Wars Episode VI: Return of the Jedi      When Luke returned to Dagobah in the Return of the Jedi, Yoda also disappears when he peacefully dies.  In Star Wars Episode VIII: The Last Jedi      When Luke is exhausted after “being” on Crait he looks into the Horizon and disappears.    And others don't:   Star Wars Episode I: The Phantom Menace      When Qui-Gon Jinn's dies after his duel with Darth Maul, he doesn't  disappear and is cremated.  Star Wars Episode VI: Return of the Jedi      When Vader/Anakin Skywalker dies on the second Death Star, he does not disappear and he is cremated by Luke.      Also, they all became a "ghost" after their death.


I have created a service, where I am sending commands to the service via MSMQ.   Now I need to restart the service but when it reaches to the stop command it just throws error or it is not able to read the next line as the service performing this task stops.  The code I am using is :  ServiceController service = new ServiceController(serviceName);             try             {                 int millisec1 = Environment.TickCount;                 TimeSpan timeout = TimeSpan.FromMilliseconds(timeoutMilliseconds);                 ShutdownService(serviceName, timeoutMilliseconds);                  // count the rest of the timeout                 int millisec2 = Environment.TickCount;                 timeout = TimeSpan.FromMilliseconds(timeoutMilliseconds - (millisec2 - millisec1));                  service.Start();                 service.WaitForStatus(ServiceControllerStatus.Running, timeout);             }             catch (Exception ex)             {                 s_log.Error(ex);             }   How can I restart service by itself as logically when the service will stop, it will not execute next line of code.

I need to write robust code in .NET to enable a windows service (server 2003) to restart itself. What is the best way to so this? Is there some .NET API to do it?


I have two geodataframes. One of about 5000 points (geolocated by me using GoogleV3, and one of 25000 polygons (from a govt-provided shapefile). Every point will be in one (and unless only one) polygon. I would like to identify which polygon the point is in. I am struggling to conceptualize how to do this, particularly as I cannot seem to access the 'geometry' column of the geodataframe that was imported by the shapefile. For example, if I call foo = offices.loc[3,'geometry']  I get a point: the coordinates of the 4th item in the GDF. However, if I call bar = zones.loc[3,'geometry']   I get a KeyError bar = zones.loc[3,'geometry'] Traceback (most recent call last):    File "/opt/anaconda3/envs/Geolocating/lib/python3.8/site-packages/pandas/core/indexes/base.py", line 3080, in get_loc     return self._engine.get_loc(casted_key)    File "pandas/_libs/index.pyx", line 70, in pandas._libs.index.IndexEngine.get_loc    File "pandas/_libs/index.pyx", line 101, in pandas._libs.index.IndexEngine.get_loc    File "pandas/_libs/hashtable_class_helper.pxi", line 1625, in pandas._libs.hashtable.Int64HashTable.get_item    File "pandas/_libs/hashtable_class_helper.pxi", line 1632, in pandas._libs.hashtable.Int64HashTable.get_item  KeyError: 3   The above exception was the direct cause of the following exception:  Traceback (most recent call last):    File "<ipython-input-17-8f543fae5979>", line 1, in <module>     bar = zones.loc[3,'geometry']    File "/opt/anaconda3/envs/Geolocating/lib/python3.8/site-packages/pandas/core/indexing.py", line 889, in __getitem__     return self._getitem_tuple(key)    File "/opt/anaconda3/envs/Geolocating/lib/python3.8/site-packages/pandas/core/indexing.py", line 1060, in _getitem_tuple     return self._getitem_lowerdim(tup)    File "/opt/anaconda3/envs/Geolocating/lib/python3.8/site-packages/pandas/core/indexing.py", line 807, in _getitem_lowerdim     section = self._getitem_axis(key, axis=i)    File "/opt/anaconda3/envs/Geolocating/lib/python3.8/site-packages/pandas/core/indexing.py", line 1124, in _getitem_axis     return self._get_label(key, axis=axis)    File "/opt/anaconda3/envs/Geolocating/lib/python3.8/site-packages/pandas/core/indexing.py", line 1073, in _get_label     return self.obj.xs(label, axis=axis)    File "/opt/anaconda3/envs/Geolocating/lib/python3.8/site-packages/pandas/core/generic.py", line 3739, in xs     loc = index.get_loc(key)    File "/opt/anaconda3/envs/Geolocating/lib/python3.8/site-packages/pandas/core/indexes/base.py", line 3082, in get_loc     raise KeyError(key) from err  KeyError: 3  I have no idea where to even begin, since I can't access specific rows to check if the point is within the polygon.

I have two GeoDataFrames: one with 191k address points and another with 18 polygons representing catchment areas for specific schools. Theoretically, every address should fall into one of the zones. When running my code, I get the following error: ValueError: Length of values (191888) does not match length of index (191921)  I suspect that there are 33 points that are not matched to a polygon. import geopandas as gpd import os  from shapely.geometry import Point, Polygon   pointpath = "/path/to/address points/" point_df = gpd.read_file(os.path.join(pointpath,"addresses.shp"))   shapepath = "/path/to/catchment areas/" shape_df = gpd.read_file(os.path.join(shapepath,"catchments.shp"))   school_list = [] for i in range(len(point_df)):     pt = Point(point_df['geometry'][i])     for index, row in shape_df.iterrows():         poly = Polygon(row['geometry'])         if(pt.within(poly)):             school_list.append(row['school_name'])             print(i) point_df['zoned school']=school_list point_df.to_excel(os.path.join(pointpath,'foo.xlsx'))  First off, is this the most efficient way of performing this task? Second, is there a way to loop through the catchment areas and if there is no match, enter something like "no match found" so that the number of list items matches the number of dataframe rows?


suppose I have a string containing substrings  # the substrings and the whole string surrounded by parenthesis string = '((substring1)(substring2))'   I want to get both substring1 & substring2 using regex, but I'm having a problem :(  This is what I have now:  match = re.search('(\(.*\))', string) print match.groups()    The problem is, the result shows:  ('(substring1)(substring2)', )     It seems like the regex matches only the first opening parenthesis and the last closing parenthesis..  In other words, the matching regex is like..  (    match.....    )   instead of   (    (match1)(match2)   )   How do I make the regex catch the INNER parenthesis??  Thanks

Is it possible to write a regular expression that matches a nested pattern that occurs an unknown number of times? For example, can a regular expression match an opening and closing brace when there are an unknown number of open/close braces nested within the outer braces?  For example:  public MyMethod() {   if (test)   {     // More { }   }    // More { } } // End   Should match:  {   if (test)   {     // More { }   }    // More { } }


Question: The coefficients of how many terms in the expansion of (1+x)2018 are multiples of 13?  So, we've to investigate the powers of 13 in ${2018 \choose r}$, where 0 ≤ r ≤ 2018  I tried using the following: $$s_p(N!) = \left \lfloor \frac{N}{p} \right \rfloor + \left \lfloor \frac{N}{p^2} \right \rfloor + \left \lfloor \frac{N}{p^3} \right \rfloor + \cdots$$  where, $s_p(N!)$ denotes the highest exponent of prime p in n!, where n is a natural number.   ${2018 \choose r}$, may be written as $\frac{2018!}{r!(2018-r)!}$. Now, I tried to figure out the exponent of 13 in numerator for several values of r, but couldn't find a pattern that would lead me to the desired answer.   Could someone please give a detailed solution to this problem, and also explain how to approach such problems? Is there any generalisation for the multiples of a prime number p in ${n \choose r}$?  P.S. The answer, to the best of my recollection, is 1395.

Find the number of binomial coefficients in the expansion of $(1+x)^{2018}$ that are divisible by $13$   On searching the internet for a long time I found that these type of questions are relevantly solved using either Kummer 's theorem or the Luca's theorem. But I haven't studied them yet. So can someone please explain some method to solve these problem without using those theorems.


I need to install the imsart package to submit my article to an IMS journal. I downloaded the zip file from the , but I do not know how to install this package. I want to install this package so I can use it in Scientific WorkPlace and Texmaker.

I know how to define a package or a class, but how do I make it available (to myself) at all times?  Say I have the package file commonstuff.sty (or myprettyclass.cls), that I want to be able to include in any .tex file I create on my computer. Where do I put it? Do I need to run some installer on it, or is it enough to keep it in a certain folder?  Note: I know I can just place it in the same folder as the .tex file, but that's not what I'm after here. I'm looking for a way to "install" the package centrally on my computer.


Let $R$ be a nonzero commutative ring, and let $n,m$ be integers. Let $f:R^n\rightarrow R^m$ be an injective homomorphism of $R$-modules.  I'm trying to show that $n\leq m$.  My idea: Assume that $n>m$, let $i:R^m\rightarrow R^n$ be the "embedding in the first $n$ coordinates", and take the composition $g:R^n\rightarrow R^n$ define by $g=i\circ f$.  First, $g$ is injective. Second, we can apply a version of Nakayama's lemma to  get a monic polynomial $p(X)\in R[X]$ such that $p(g)=0$.  Now, I somehow want to use the fact that the image of $g$ consists of elements  which are zero on the last coordinate (at least), but I'm circling around this with no success.  This is an exercise from Atiyah-Macdonald.

I'm trying to prove that if $A\neq 0$ is a commutative ring and there is an injective $A$-module homomorphism $A^m\hookrightarrow A^n$ then $m\leq n$ must necessarily hold.    This is exercise 2.11 from Atiyah and MacDonald's Introduction to Commutative Algebra, but unfortunately all the solutions available online are either very sparse with regard to this question or seem to use (to my surprise) a generalized version of Cramer's rule. Is there perhaps some other "cleaner" approach to solving this problem?


How do i write data from the Command-line into the copy paste buffer? I see the programs xsel, and xclip and they look fine, but i would prefer a command line option. Can i redirect terminal output to the buffer some how? What is the technical name for the copy paste buffer?   I use mate for the desktop environment. The reason I want to be able to do this without installing anything is I want to be able to write scripts to use this function even on systems where i am not an administrator... i know i can compile in my home directory, but i would still prefer a standard output method. I wouldnt mind writing a bit of c-code to do it either.     I am still not certain, perhaps the copy paste buffers are just frame buffers?

Can we copy a string with a command-line and have the ability of pasting it with Ctrl + V shortcut?


I have an object that implements an interface and inherits from another class. However for a function, I can only pass in an interface of the item. Is it possible to get a variable from the parent object or null if they are not there?      public class ProductStamp   {    public int qty;   }    public class TrolleyItem : ProductStamp, ITrolleyItem   {    }    private void foo(ITrolleyItem trolleyItem)   {      trolleyItem.qty;      }   Sorry for the confusing situation. I just want to know if this is possible and if so how I can best go about it.   Note: I have simplified the situation but each of these classes are in very separate places with other attachments relying on them. Due to how it is structured, I cannot simply pass in foo(TrolleyItem trolleyItem)  thank you in advance

In C#, when I have an interface and several concrete implementations, can I cast the interface to a concrete type or is concrete type cast to interface?  What are the rules in this case?


It is well-known that not all complex numbers can be written as a zero to a polynomial with rational coefficients (the transcendental numbers). However, I am wondering if we "extend" polynomials to allow for infinitely many terms (i.e. the power series expansion of a holomorphic function) while still restricting the coefficients to be rational, if every complex number could then be expressed as the zero of such a function?   $\pi$, for instance, is transcendental, but it is a zero of the $\sin$ function, whose power series expansion centered at $z=0$ has only rational coefficients.

I'm wondering if anyone has come across the following ring before. Let $R$ be the ring of complex power series $f=\sum_{n \ge 0} a_n t^n$ such that   $a_n \in \mathbb{Q} \: \: \forall \: n$ The function $f: \mathbb{C} \rightarrow \mathbb{C}$ is entire   Any information about it would be welcome but in order to keep the question specific, I'll list a few things I would like to know in particular.   Is $R$ a unique factorisation domain? Are there any elements of $R$ which are known to be prime/irreducible but are not associates of polynomials? If an element $f \in R$ is prime/irreducible, must all its zeroes (in $\mathbb{C}$) be simple? Is every $\alpha \in \mathbb{C}$ a root of some nonzero $f \in R$ ?


I need to install octave-octcdf package to work with Octave. I tried, sudo apt-get install -y octave-octcdf. But this receives an error as following; user@PowerEdge-R540:~/user/tools$ sudo apt-get install -y octave-octcdf Reading package lists... Done Building dependency tree        Reading state information... Done Package octave-octcdf is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'octave-octcdf' has no installation candidate  Can anyone help to properly install octave-octcdf package?

What does the above Error mean? What is an installation candidate?  I was trying to do  sudo apt-get install munin-memcached     and I get this message:  Reading package lists... Done Building dependency tree        Reading state information... Done Package munin-memcached is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package munin-memcached has no installation candidate   I googled for the problem and someone said to do a apt-get upgrade but it still did not solve my problem.


How do I find a closed expression for $$\sum_{k=1}^n\cos(kA)$$ any idea about how to go about doing this?   Thanks in advance

How can we sum up $\sin$ and $\cos$ series when the angles are in arithmetic progression? For example here is the sum of $\cos$ series:  $$\sum_{k=0}^{n-1}\cos (a+k \cdot d) =\frac{\sin(n \times \frac{d}{2})}{\sin ( \frac{d}{2} )} \times \cos \biggl( \frac{ 2 a + (n-1)\cdot d}{2}\biggr)$$  There is a slight difference in case of $\sin$, which is: $$\sum_{k=0}^{n-1}\sin (a+k \cdot d) =\frac{\sin(n \times \frac{d}{2})}{\sin ( \frac{d}{2} )} \times \sin\biggl( \frac{2  a + (n-1)\cdot d}{2}\biggr)$$   How do we prove the above two identities?


So recently, I decided to change my password and used the provided password ubuntu gave me, which I wrote down in my notebook so I don't forget it. In order to see if it worked, I suspended the laptop and it locked itself. So when I tried to use the password that I wrote down to unlock it, it kept saying "incorrect password, please try again" but I was certain it was right. So I looked up online to see how to change passwords from the outside and I was able to change my password. Here's the problem, ever since I changed my password (from the grub menu and not the settings) the "Authentication required" window keeps popping up, especially when I'm doing school work on my browser. It says that "the password you use to log in to your computer no longer matches that of your log in keyring". Can someone please help me figure out how to get rid of this? I don't want to re-install the software again.

I installed Ubuntu 12.10 and entered a password in SeaHorse. I would like to remove the password of "Default" but I get this error :  GDBus.Error:org.freedesktop.Secret.Error.NoSuchObject: The collection does not exist   Is there a fix or a way to bypass modify the password ?


I need to set a variable in my bash script  #!/usr/bin/env bash  GITNAME= git config --global user.name echo " $GITNAME "   But it doesn't seems to work that way.   How does it work?

What is the difference between below variables assignments?   var=23 var =23 var= 23 var = 23   Is there any difference in space around the assignment operator?


Give examples of four groups of order 12 no two of which are isomorphic.   So far I've thought of $Z_{12}$ and $D_6$.   Thanks!

I'm trying to find 4 groups of order 12, none of which are isomorphic to each other.  Should I be trying external direct products?   So far I have $A_4, \mathbb Z_{12},\,$ and $\,\mathbb Z_6\times \mathbb Z_2.\,$ How do I show all of these are non-isomorphic to each other? And how do I find a fourth? `


I am travelling from India to Oslo, Norway on a resident permit. I have a transit at Stockholm, Sweden. Do I need a transit visa for the same travel?

I found many related questions on this site but I am still not sure about the rules. How can I decide if I need a visa to transit? Schengen members as of May 2021 are as follows:  Austria Belgium Czech Republic Denmark (excluding Greenland and the Faroe Islands - but an open border with the Schengen Area is maintained) Estonia Finland France (excluding overseas departments and collectivities) Germany Greece Hungary Iceland Italy Latvia Liechtenstein Lithuania Luxembourg Malta Netherlands (excluding Aruba, Curaçao, Sint Maarten and the Caribbean Netherlands) Norway (excluding Svalbard) Poland Portugal Slovakia Slovenia Spain (except Ceuta and Melilla) Sweden Switzerland


I want have the item in the chest (the dye) to have a custom name, I have tried very hard to do so.  Here is what I have so far (it works but I need the item to have a name as said before):  /give @p chest 1 0 {BlockEntityTag:{Items:[{Slot:0,id:dye,Damage:2,Count:1}]}}   Also I need the answer in 1.12  Here are things I tried but failed:  /give @p chest 1 0 {BlockEntityTag:{Items:[{Slot:0,id:dye,Damage:2,Count:1,display:{Name:"Name of item"}}]}}   and  /give @p chest 1 0 {BlockEntityTag:{Items:[Slot:0,id:dye,Damage:2,Count:1,tag:{display:{Name:"Name of item"}}]}}

I am making a Minecraft Mini Game adventure map, and one of the levels has a /setblock command, I am using the command in a way to spawn an item in a chest (Wooden Button) I need the wooden button to have CanPlaceOn tag so it can be placed on a log. I have tried this command: setblock 294 5 -1251 minecraft:chest 0 replace {Items:[{Count:1,Slot:0,id:minecraft:wooden_button,CanPlaceOn:[log]}]}`


Can i connect a dc power supply rated 20v,6 A to a system which needs a power supply of 8-32v and 1.5A? My  concern is about current. Will my system only consume max of 1.5A from supply instead of 6A?

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


My friend asked me this question  "Two observers, A and B:  QUESTION : "A is on a train travelling at a constant speed of 0.9c and B is standing on the ground outside. Both observe the motion of a 1m long pendulum swinging (in the direction of the motion of the train), compare the observations made by A and B with regards to the motion of the pendulum. Observer A measures the period of the pendulum to be 2.01 seconds."  I'm not too familiar with Special relativity but, A is stationary relative to the equilibrium position of the pendulum so he will observe the period of the pendulum according to T = 2π√(l/g)  The pendulum is moving relative to B and so B will observe the effects of time dilation, length contraction etc and the period of the pendulum will be greater than that observed by A. But the length of the pendulum is unchanged (I think), but the angle it makes with the vertical is changed and so is the period.   However, according to Special Relativity, the Laws of Physics are the same in inertial frames, so   T = 2π√(l/g) should hold for B's frame of reference as well so the gravitational field observed by A and B should be different.   From what I've read, the period measured by A shouldn't be 2.01 seconds, as the Earth is moving relative to the pendulum, and A on the train and so we can not take g = 9.8 ms^-2, but it is true that time dilation effects will take place and B will observe a longer period? What exactly are the effects at play here that make the period observed by B longer?   Thanks in advance, and apologies I'm not very familiar with Special Relativity at all

I've been pondering the precise mechanism of time dilation for the example of a simple pendulum in two different situations:   The observer and ground are at rest in one frame of reference;  the pendulum is moving at high speed with respect to that frame. The observer is at rest in one frame of reference; the pendulum and the ground together move at high speed with respect to that frame.   user8260 has pointed out that in situation 1, in the pendulum's frame $g$ is greater by $\gamma^2$ compared to $g$ in the observer's frame. Thus in the pendulum's frame the period is less than it is in the observer's frame by a factor of $1/\gamma$, just as one would expect from time dilation.  But what about situation 2? Here, compared to the pendulum frame, the observer sees the pendulum with the same length in a stronger gravitational field, yet observes a longer period. Does the inertial mass of the pendulum change differently than its gravitational mass? Also, does the analysis depend on whether the plane of swing is perpendicular or parallel the direction of motion?


Why increasing lambda parameter in L2-regularization makes the co-efficient values converge to zero?   I have just tried to do the math, but it's a little bit rusted.  Lets say that we have a simple linear model as follows:  $y=w_1\cdot x$  we could write the cost function for ridge regression is to be minimized:   $cost(\hat{w_1}, \lambda)= (y - \hat{w_1} \cdot x)^2 + \lambda \cdot \hat{w_1}^2$  it means that if we consider the problem as min-max:  $\frac{\hat{dw_1}}{dc} = -2 \cdot x \cdot (y -  \hat{w_1}) + 2\cdot \lambda \cdot \hat{w_1} = 0$ so,   $y = (1 + \frac{\lambda}{x}) \cdot \hat{w_1}$  Since the y and x are invariants, it is to be expected increasing $\lambda$ make the co-efficient decrease as the equation holds.   Is that the right way to reason?

I am having some issues with the derivation of the solution for ridge regression.  I know the regression solution without the regularization term:  $$\beta = (X^TX)^{-1}X^Ty.$$  But after adding the L2 term $\lambda\|\beta\|_2^2$ to the cost function, how come the solution becomes   $$\beta = (X^TX + \lambda I)^{-1}X^Ty.$$


Spices create aromatics so it is important when to add them. But what about salt? Is it critical if you add salt to the flavor base instead of adding it to the tomato paste, or adding it to the finished soup?

If I'm preparing a dish for myself and someone on a low-sodium diet, I will withhold adding salt while cooking.  Instead, I'll season my plate after serving.  However, I can't seem to get the same flavor from adding salt after-the-fact as I do when I'm salting while preparing the dish.  Is this all in my head or is there actually a difference in how the flavors are affected depending on when the salt is added?


Define $X$ and $Y$ to be two exponential random variables. The probability distribution functions are $f_{X}(x)=\lambda e^{-\lambda x}$ and $f_{Y}(y)=\delta e^{-\delta y}$. Note that $X$ and $Y$ are independent.  Define $Z=X +\frac{a Y}{Y+b}$, where $a$ and $b$ are some positive constants. My goal is to derive the CDF of $Z$, i.e. I want to calculate $P(Z <z)$.  My approach consists in deriving the CDF of $R=\frac{a Y}{Y+b}$, and then trying to find the CDF of the sum, which will be a function of the CDF of $R$. So I have started as follows: $P(\frac{a Y}{Y+b} < r)=P(Y(a-r) <rb)$. It is clear that here $a$ should be $>r$, because otherwise we get something negative.. Thus, following this approach forces us to assume that $a>r$, something that I don't know if I can assume or not.    Question: is this assumption necessary to be able to derive the CDF? is there any other approach that I can adopt to derive the CDF without making this assumption?

Let $X_1$ and $X_2$ be two independent exponential random variables with the PDFs $f_{X_1}(x_1)=\lambda_1 \exp(-\lambda_1 x_1)$ and $f_{X_2}(x_2)=\lambda_2 \exp(-\lambda_2 x_2)$.   Let $X= \frac{X_1X_2}{X_1+X_2+a}$ be a r.v. for which I want to derive the CDF, where $a$ is a positive constant.  In other words, I need to calculate $\mathbb{P}\{X <x \}$.  Any ideas or hints?  Edit (attempt):  Using a similar approach to that used , we have $X_1 \in [0, \infty)$ and  $X_2 \in [0, \frac{x(x_1+a)}{x_1-x})$. The latter interval results from: $\frac{x_1x_2}{x_1+x_2+a} < x$, thus $x_2(x_1-x)<x(x_1+a)$ which implies $x_2 < \frac{x(x_1+a)}{x_1-x}$; but I am not sure if this is correct since $x_1-x$ can sometimes be negative (?). Based on the above, we can write: \begin{align}  \mathbb{P} \{ \frac{X_1X_2}{X_1+X_2+a} < x \}  & = \int_{x_1=0}^\infty \int_{x_2=0}^{ \frac{x(x_1+a)}{x_1-x}} \lambda_1 \exp(-\lambda_1 x_1) \lambda_2 \exp(-\lambda_2 x_2)  dx_2 dx_1  \\ &= \int_{x_1=0}^\infty \left(1-\exp(-\lambda_2\frac{x(x_1+a)}{x_1-x}) \right) \lambda_1 \exp(-\lambda_1 x_1) dx_1  \\ & = 1-\lambda_1 \int_{x_1=x}^\infty \exp(-\lambda_2\frac{x(x_1+a)}{x_1-x} ) \exp(-\lambda_1 x_1)   dx_1 \end{align} In the last equality: for the integral of $\lambda_1 \exp(-\lambda_1 x_1) dx_1$, I suppose that $x_1 \in [0,\infty)$, whereas for the second term I suppose that $x_1 \ge x$ (since $x_2$ should be positive) (?).  Is my approach correct ?


I try to understand quantum entanglement and especially what it’s called « Action at a distance »  from my understanding, if you have a pair of entangled photon, after measuring the polarization of one photon you will find a correlation between his polarisation and the polarisation of the other photon even if they are very far away from each other.  From there i fail to see the difference between an entangled pair of photon and two magnets in a box (if there are any) , let me explain. What if, we use round magnets in a non-transparent box instead of photons... and use magnetic  polarity instead of photon polarization and then perform that experiment :   we place a magnet in two boxes and shake them in a way that there polarity is random an unknown. Then we make a pair of « entangled » magnet by  approaching the boxes sufficiently.  after “measuring” the polarity (just opening the box and see in which side the magnet is) of one box you will find a correlation between his polarity and the polarity of the magnet in the other box even if they are very far away from each other. (because the two magnets moved in their boxes thanks to the magnetic force when there were close at the ‘entanglement’ step)  The real question is: So is there any difference between my two ‘entangled’ magnet box, and two entangled photons?   As a second question : I suppose, like my magnet box example, that the polarisation (or any quantum property)of two entangled photons is fixed at the entanglement state (still in a random position but correlated), and no real superposition or any 'action at a distance' occurs. Can this statement be false ? Is there any proof or experiment that invalidate this?  Ps : I’ve very limited physic and quantum physic knowledge, and English is not my native language, so some paper may be hard to understand and i apologize for my bad English..

From everything I've read about quantum mechanics and quantum entanglement phenomena, it's not obvious to me why quantum entanglement is considered to be an active link. That is, it's stated every time that measurement of one particle affects the other.  In my head, there is a less magic explanation: the entangling measurement affects both particles in a way which makes their states identical, though unknown. In this case measuring one particle will reveal information about state of the other, but without a magical instant modification of remote entangled particle.  Obviously, I'm not the only one who had this idea. What are the problems associated with this view, and why is the magic view preferred?


I know something like this has asked before  But my question is slightly different.  What should we do when some user just copied the content from another answer from SO or from other web resources, and they never mention it?  After leaving some comment on the post they mention but again they forget to mention the original post while answering a question. What should we do in that cases?

How should I act if I discover a user plagiarizing fellow users' posts? What if I find someone plagiarizing external resources without attribution?  See also:


I am stuck with the this question:     Prove by induction that $2^n > n^3$, for all $n \ge 10$   I got this far:  Base: For $P(10)$: $$ 2^n > n^3 \\ 2^{10} > 10^3 \\ 1024 > 1000  $$ so, $P(10)$ is true  Inductive steps: Need to show $P(k+1)$ is true, assuming $P(k)$ is true.  For $P(k+1)$: $$ 2^{k+1} > (k+1)^3 \\ 2 \times 2^k > k^3 + 3k^2 + 3k + 1 \\ 2^k + 2^k > k^3 + 3k^2 + 3k + 1  $$  We assume $2^k > k^3$, so we only need to show $2^k > 3k^2 + 3k + 1$ ? But I am stuck here.   Any idea/hints? Thanks a lot for the help.

I need to prove that $$ 2^n > n^3\quad \forall n\in \mathbb N, \;n>9.$$  Now that is actually very easy if we prove it for real numbers using calculus. But I need a proof that uses mathematical induction.   I tried the problem for a long time, but got stuck at one step - I have to prove that:     $$ k^3 > 3k^2 + 3k + 1 $$   Hints???


So I have an executable (output of gcc compiling a C program), that I would like to run after login so it is the first thing a user sees upon login. It is a graphical menu that displays system information (read only).  After experimenting around with /.profile, by simply adding the following bash command with the path to the executable:  exec /home/TUI/bin/main   I was able to get my program to run and display the UI after login, but then upon exiting, I am continually prompted to login again in a loop and the process repeats over and over. I believe I am not putting the script in the right location. Would it go in /etc/rc.local? ~/.bashrc ... ?  What would be the best way to go about getting the program to run after a user logs in? (I'm not very experienced with shell scripting and the initialisation process of Ubuntu.)

How can I make an application automatically start when I have logged in?


I'm just downloaded (current available) Blender 2.8 RC2, and little confused: I see NO restriction icons [commands] in Outliner:   Restrict Viewport Visibility  Restrict Viewport Selection  Restrict Rendering   I Have "hide in viewport" only. Is this OK? Or maybe I miss something? How to get back all 3 restrictions?

The selection toggle arrows in the Outliner disappeared. Is there some preference in the settings that has to be turned on?


Ok, I'm studying real analysis and I'm trying to make my homework, but there is a question about real analysis which I can't solve.  If $A \subset \mathbb{R}^n$ is an open and convex set then $A = \operatorname{int}(\,\overline{\!A})$  I've proved that $A \subset \operatorname{int}(\,\overline{\!A})$, because $A$ is an open set. For the other way, I guess I need to use that $A$ is a convex set to prove that $\operatorname{int}(\,\overline{\!A}) \subset A$, but I dunno how to use that assumption.  Can you help me?

Convex set $A$ in $\mathbb{R}^n$ iff for every $ x,y\in A,0\le\lambda\le1$, then $\lambda x+(1-\lambda)y\in A$.  $U$ is regular open set iff $A$ is open and $int(cl(A)) = A$.  Is convex open set in $\mathbb{R}^n$ is regular?


i recently installed ubuntu 12.04 by wubi installer.By giving right details of proxy in firefox i am able to access internet but when i try to download something ,ubuntu gives the error "failed to download package files check your internet connection.". How should this error be resolved?

For the command   sudo apt-get update   I get following error:  W: Failed to fetch http://ch.archive.ubuntu.com/ubuntu/dists/maverick-updates/multiverse/binary-i386/Packages.gz   407  Proxy Authentication Required (The ISA Server requires authorization to fulfill the request. Access to the Web Proxy filter is denied. )   I am running Ubuntu 10.10 installed on Windows XP using VirtualBox. For Internet connections I am using proxy server with an authentication. I tried to use gnome-network-proxy tool to set proxy settings system-wide.   After that /etc/environment has been updated by http_proxy variable with the format http://my_proxy:port/, there were no authentication data.  I checked this with Firefox. Browser asked my for login and password and everything was working fine. It was unfortunately not the case for apt-get. I have also tried to do as described . Unfortunately it does not work.  May it be somehow related to the fact that a proxy is in a Windows domain, any ideas?  My proxy name is http-proxy. Is '-' a special character here?


I have several objects with subdivision surface that I would like to set in optimal display option, because it is annoying to apply that setting in every single object separately.

I have been using the Copy Attributes add-on to copy some properties from active object to selected objects. This add-on is not enabled by default and must be explicitly enabled. But its a very useful workflow enhancing tool.    There is a limitation though. Not all properties can be copied and even those that can be copied are copied in groups (Its hard-coded in to the add-on).  My question is if there is a built-in feature or any another other way to copy any property from the active object to the selected objects?


Every time I get an audit question it drives me crazy.    Can we please ensure that the audit questions have the same correct tags as my filter?  Previously you used to get a question that had the filter tag slapped on randomly so it looked out of place.  Now you seem to have questions that don't match my filter tags at all.  I just get confused when I see these, because I might be looking at php questions and suddenly I'm getting a question which is marked C++ and VBA when I look for further info I get repremanded for being such a fool that I didnt see that this question was fine.  But it wasn't fine it had weird tags.  Can we please review the review questions they don't make me want to keep reviewing!!!!

Just recently the . I've got  this morning which seems to be out of scope for my filtered list. I have filtered my list to only review VBA and Excel-VBA tags while the audit is tagged with perl http pipes which have nothing in common with VBA. I see a problem with the way the system currently works  Since I have a filtered list of tags, once I see a differently tagged question I already know it's an audit. Come on, that's too easy!  Can this please be fixed? update I have ran into  which I decided to edit - the question was tagged VBA and I thought it had nothing to do with VBA so I selected Edit which was the correct action. Now, once the first audit was clearly one to close - nothing to do with VBA and really easy to know that it actually was an audit - the second one was a very good audit. I am just thinking now if this is a proper bug or just a matter of malfunction in the system. I think the first one may have been made an audit for the wrong reason. Let's turn this into a discussion as I can't clearly work the system out.


I'm using Ubuntu 18.10. I have installed Dash to dock gnome extension. But when i click on Activities button, two docks are shown. One at the bottom and one at the left. I want to see only at the bottom. Is there a way to remove the left dock??

What's going on here? I've installed the  on Ubuntu 17.10. Everything was cool, and as I was trying to hone and tweak the look of my desktop, at some point the shortcuts bar (dock?) on the left is duplicated.  (Click image to enlarge) The default, which normally disappears with Dash to Dock, is there underneath the one that usually shows up when I install Dash to Dock. Why? I've tried to go through the options for Dash to Dock, the GNOME Tweak Tool, and the regular Ubuntu settings, but I can't figure it out.


Is there a way to protect a file in such a way that even root cannot delete it or rewrite it after creating it? I have a file which is created by root under /var/log/ and I want to restrict all users (including root) so that they can just read this particular file after it has been created.

While logged in, I can do the following:  mkdir foo touch foo/bar chmod 400 foo/bar  chmod 500 foo   Then I can open vim (not as root), edit bar, force a write with w!, and the file is modified.  How can I make the operating system disallow any file modification?  UPDATE Mar 02 2017   chmod 500 foo is a red herring: the write permission on a directory has nothing to do with the ability to modify a file's contents--only the ability to create and delete files. chmod 400 foo/bar does in fact prevent the file's contents from being changed. But, it does not prevent a file's permissions from being changed--a file's owner can always change his file's permissions (assuming they can access the file i.e. execute permission on all ancestor directories). In fact, strace(1) reveals that this is what vim (7.4.576 Debian Jessie) is doing--vim calls chmod(2) to temporarily add the write permission for the file's owner, modifies the file, and then calls chmod(2) again to remove the write permission. That is why using chattr +i works--only root can call chattr -i. Theoretically, vim (or any program) could do the same thing with chattr as it does with chmod on an immutable file if run as root.


I was in the castle mission, and while travelling to the castle,something went off and the game got stuck for a second. Then everything turned green like in the image below.  Why did this happen? How can I fix it?

I've come across a really annoying visual effect in Fallout 4. It appeared as the vision was green, and the closer to the edges, the more distorted it got. Also, looking through the rifle's sight caused too much light, so much that I couldn't see anything.  At first, I thought it was addiction to chems, so I looked for some , but using it didn't help.   Anyone know what's causing this?


I took out Frozen Perdue chicken breast on Sunday afternoon and put them in the fridge to thaw. They are each pre packaged. Today is Thursday are they still good to cook today?

How do I know if a given food or ingredient I have is still good, or if I should discard it?  How can I best preserve a food or ingredient?     This broad question is intended as a "general reference" question to quickly answer many how long will food keep for? questions. Please feel free to edit this question to expand and clarify as needed.