my puter: 2.3 ghz sempron, 4 g ram, 500gb hd, nvidia 6100 nforce405 chipset/gt240 gc, win xp. I want to know if i can run 14.04 64 bit ubuntu.
For a given hardware configuration, how do I find out if Ubuntu will run on it? What considerations should I take into account when choosing an Ubuntu version and  such as:    with a lighter desktop than the usual Gnome and Unity  with the even lighter LXDE desktop   Obviously Ubuntu does not run on some processor architectures. So how do I go about choosing the right version and derivate. How can I find out the minmal system requirements?
I am trying to prove that:  Let $f$ be analytic in the closed unit disc with $f(z)\leq 1$ for $|z|\leq1$.  For a given $0&lt;r&lt;1$ and $|z_1|,|z_2|\leq r$, $z_1\neq z_2$ then,   $$\left|\frac{f(z_2)-f(z_1)}{z_2-z_1}\right|\leq \frac{1}{(1-r)^2}.$$  My attempt is: part a  of the question asks to prove $$\left|\sum_k^\infty a_nz^n\right|\leq \frac{ |z^k|}{1-|z|}.$$   So, \begin{eqnarray*}  \left|\frac{f(z_2)-f(z_1)}{z_2-z_1}\right|&amp;=&amp; \frac{|\sum_1^\infty a_nz_2^n-\sum_1^\infty a_nz_1^n|}{|z_2-z_1|}\\  &amp;\leq&amp; \frac{\frac{ |z_1 |}{1-|z_1|}+\frac{ |z _2|}{1-|z_2|}}{|z_2-z_1|}\\  &amp;\leq&amp;\frac{1}{(1-r)^2} \frac{   |z_2| ({1-|z_1|})+  |z _1| (1-|z_2|) }{|z_2-z_1|}\\ \end{eqnarray*} But could not prove that the last term is controlled by 1. Evaluation of $ \sum_{k=0}^n \cos k\theta $ I just wanted to evaluate  $$ \sum_{k=0}^n \cos k\theta $$  and I know that it should give  $$  \cos\left(\frac{n\theta}{2}\right)\frac{\sin\left(\frac{(n+1)\theta}{2}\right)}{\sin(\theta / 2)}   $$  I tried to start by writing the sum as  $$ 1 + \cos\theta + \cos 2\theta + \cdots  + \cos n\theta $$  and expand each cosine by its series representation. But this soon looked not very helpful so I need some clue about how this partial sum is calculated more efficiently ... Unable to install Ubuntu on Lenovo Y500 I am totally unable to install any flavor of Linux on my lenovo Y500. TL;DR:  with EFI on -&gt; cannot even access installer with legacy - &gt; installer runs fine, but installed OS never boots  Long Version: It is going to be hard to recap what I did, because I tried so many things, but here is the gist of it: EFI mode (secure boot disabled): Trial #1  ubuntu 12.10 x64 &amp; Mint 14 x64 boot from usb see screen with choices pick &quot;try ubuntu&quot; get black screen  Trial #2  ubuntu 12.10 x64 &amp; Mint 14 x64 boot from usb see screen with choices press &quot;e&quot; to enter edit mode remove &quot;quiet splash&quot; replace with &quot;nomodeset&quot; end up on the command line with an error message from x server: &quot;no screen found&quot; try fiddling around with xorg.conf to no avail  Trial #3  Arch Linux Live USB EFI mode no boot  Trial #4  ubuntu 12.10 x64 &amp; Mint 14 x64 set &quot;e&quot; to enter edit mode in menu add acpi=off end up with &quot;(initramfs) unable to find a medium&quot; message  Trial #5  same as above set SATA mode to legacy (it was AHCI) error loop that says something along the lines of &quot;ata1.00: hard resetting link&quot;  Legacy Mode Trial #1  ubuntu 12.10 x64 &amp; Mint 14 x64 USB boot Everything seems to work Proceed to normal install (picks SSD drive by default) Everything seems to work reboot blank screen reboot with &quot;shift&quot; pressed see message &quot;grub loading.&quot; and nothing As per advised on Ubuntu's community EFI page, run boot-repair same results run boot-repair again same results  Trial #2  ubuntu 12.10 x64 &amp; Mint 14 x64 same as above, but pick 1T HDD as target install same results  Trial #3  create a /boot partition on the SSD install on SSD same results (&quot;grub loading.&quot;) run boot repair twice same results  Trial #4  create a GPT filesystem on HDD create a /boot partition on the HDD install on HDD same results as above  Trial #5  install ubuntu on HDD install boot on all drives (HDD &amp; SSD) same results  Trials #6  install Arch on SSD no boot loader found  Notes:  Every step has been tried with multiple USBs. All isos' MD5Sums have been verified LiveUSBs have been created both through ubuntu's embedded app and unetbootin (save for Arch's live USB which was created by DDing the iso as per advised in the Arch wiki) I have wiped out windows in my first trials, and I don't care, I am never going to use it. I don't want to dual-boot. I just want Ubuntu or Mint or Arch as far as I can remember (it gets hard after 50+ trials), I tried every option with sata mode IDE or normal. Not sure though.  I've also tried numerous other things that I can't recall right now. All in all I've been giving this 3 to 5 hours a day for a week and a half to absolutely no avail. I am extremely disappointed as this is my first Lenovo and word is Lenovo is Linux-friendly...I have never spent more than an hour installing linux on any machine. What's even more frustrating is that it seems to be working for , and I can't find any hint telling me how they managed. I wrote to one guy who posted a serie of youtube videos about how to get everything working perfectly on the Y500, and he told me he just installed mint without any problems. Might be I am a particular case because I have the SLI version of the Y500. If anyone has pointers, incomplete solutions, ideas, black magic, I'll be forever in debt. Thank you P.S: This question, afaik, is not a duplicate of an existing question. I've scoured all questions containing &quot;lenovo&quot; and &quot;install&quot;, and none applies to me. (1)  If $E$ is a subset of $\mathbb R$ with finite outer measure, i.e. $m^{*}(E) &lt;\infty$; and   (2) $E$ is not Lebesgue measurable, i.e. there exists $F$ such that  $m^{*} (F) &lt; m^{*}(EF) + m^{*}(FE^{c}).$  [Claim] There exists an open set $O\supset E$ with finite outer measure, such  that   $$m^{*}(O E^{c})  &gt; m^{*} (O)  - m^{*} (E).$$  My  questions are the following.  (1) Is the above claim correct? I've seen this in Royden's book, but have a bit concern. Note that a set $E$ is Leb measurable if  it satisfies caratheodory condition: $m^{*} (F) = m^{*}(EF) + m^{*}(FE^{c})$ for  all subset $F$. If the claim is yes, it seems that measurability condition can  be reduced from all subset $F$ to Borel set $F$.  (2) If the claim is correct, a proof is needed. How does someone get to cast more than 40 votes in a day? And by someone, I mean that evil feline WesleyDavid:        That screenshot was taken just before 4pm PST, i.e. just before 0000 UTC.  That shows KittehHead's votes for the month, which is the same as for the day since it's March 1st.  Just to be sure it wasn't that SE had the time wrong, I tried upvoting something and got the expected "Daily Vote Limit Reached, Please Vote Again in 6 minutes."  So how did Kitteh^H^H^H^H^H^HWesley get 42 votes in one day?  ADDED: It's getting worse... Now it's March 2nd, and Wesley/Cat has 3 extra votes:        Now I finally got an extra vote (take that evil kitteh!), but it hasn't helped me understand why: How to set up a wi-fi hotspot with an Ubuntu laptop (access point mode)? I've read , and carefully followed the instructions provided. I am sure the wireless card in my laptop supports going into wireless access point mode. But unfortunately, when I use the following command to start hostapd service it throws an error:   $ sudo service hostapd stop  Starting advanced IEEE 802.11 management hostapd                      [fail]    The instructions mentioned above said this could possibly be because my wireless card does not support the g mode, and provided the wiki of hostapd. But what is g mode? I tried to switch to a, or b mode, but it just didn't work.  Can anyone help with this or recommend a tool like connectify in windows ?  ps. I am using Ubuntu 12.04, 32 bit. I have an ADSL wired network, and I want to share it by setting my laptop into a WiFi hotspot with  my windows phone. Using ArcPy to get all database names within server? I am trying to populate a folder with ArcSDE database connection files for all the databases within a server instance.  I need to be able to do this for several of our servers.  Although I know within SQL Server how to get a list of DB names from the sys.databases table, using the arcpy function CreateDatabaseConnection I cannot specify "sys" or "master" to make the connection.  Therefore, I need to know the name of a database currently in the server.  I am not sure how to make the check without hard-coding a name.  import arcpy arcpy.env.overwriteOutput = True  #Input the location where the database connection files will be stored connectionLocation = "F:/FolderName"  #Get the list of servers arcpy.CreateDatabaseConnection_management(out_folder_path= arcpy.env.scratchFolder,out_name= "GIS_USERCONFIG" ,database_platform="SQL_SERVER",\                                           instance = "XXXXXXX" ,account_authentication="DATABASE_AUTH",username="user",password="password",\                                           save_user_pass="SAVE_USERNAME",database= "GIS_USERCONFIG",schema="#",version_type="TRANSACTIONAL",version="dbo.DEFAULT",date="#") sdeConn = arcpy.ArcSDESQLExecute(arcpy.env.scratchFolder + "/GIS_USERCONFIG.sde") serverListSQL = sdeConn.execute("Select name from userservers") serverList = [] for i in range(0,len(serverListSQL)):     serverList.append(serverListSQL[i][0])  #Make a folder for each server instance and build the connection files for all DBs in the server instance for server in serverList:     folder = connectionLocation + "/" + server     if arcpy.Exists(folder):         print server + " folder already created"     else:         try:             arcpy.CreateFolder_management(connectionLocation, server)             print "Created Folder " + server         except:             print "failed to create folder " + server      #     arcpy.CreateDatabaseConnection_management(out_folder_path= arcpy.env.scratchFolder,out_name= server ,database_platform="SQL_SERVER",\                                           instance = server ,account_authentication="OPERATING_SYSTEM_AUTH",\                                           database= "master",schema="#",version_type="TRANSACTIONAL",version="dbo.DEFAULT",date="#")     sdeConn = arcpy.ArcSDESQLExecute(arcpy.env.scratchFolder + "/" + server + ".sde")     dbListSQL = sdeConn.execute("Select name from sys.databases")     dbList = []     for i in range(0,len(serverListSQL)):         dbList.append(dbListSQL[i][0])     for db in dbList:         arcpy.CreateDatabaseConnection_management(out_folder_path= folder ,out_name= db,database_platform="SQL_SERVER",\                                           instance = server ,account_authentication="OPERATING_SYSTEM_AUTH",\                                           database= db,schema="#",version_type="TRANSACTIONAL",version="dbo.DEFAULT",date="#")   Basically my issue is with the 2nd call for the function "CreateDatabaseConnection_management" since it needs a database that exists in the database (and I could not use "master or sys").  If you open this as a tool in arcmap, the input is a drop-down box that populates choices based on the databases in the chosen server instance.  Is there a way to do this in the code? Removing intercept from GLM for multiple factorial predictors only works for first factor in model Is SHA-256 secure as a CTR block cipher? Generate a 256-bit random nonce. XOR it with a 256-bit reusable symmetric key. This is x.  We represent numbers in simple binary instead of a counting function. 0 in dec = [256 zeros] in binary, 1 = [255 zeros]1, 23092348 = [241 zeros]1011000000101110001111100, etc.  For each nth block needed for the length of the plaintext, XOR x with n and hash it with SHA-256 to form b[n].  Let p[n] be the nth 256-bit block in the plaintext and c[n] be the nth block in the ciphertext. Then c[n] := b[n] XOR p[n].  Send the unencrypted nonce along with the ciphertext.  To decrypt c[n], XOR it with b[n] to retrieve p[n].  Is this secure? If so, then why do we need AES-256?  If this is not secure, then is there any mode of operation for which SHA-256 is secure as a block cipher? Specifically, it would need to be used in cipher feedback, output feedback, or any other mode that only uses the cipher in the encryption direction. In any finite graph with at least two vertices, there must be two vertices with the same degree Auxhook warning cannot patch document using AtBeginDocument instead I'm using subfiles within my report (written on sharelatex), when I compile a subfile it produces a warning. Am I doing something wrong or is this normal?  Example  \documentclass[report.tex]{subfiles} % \usepackage{acronym} \begin{document}  some text  \end{document}   Error     /usr/local/texlive/2015/texmf-dist/tex/latex/oberdiek/auxhook.sty   Package auxhook Warning: Cannot patch \document, using \AtBeginDocument instead.   When I compile the main document it does not produce this warning.  The raw log file produces this warning     ......   Package: auxhook 2011/03/04 v1.3 Hooks for auxiliary files (HO)   Package auxhook Warning: Cannot patch \document,   (auxhook)                using \AtBeginDocument instead.   ) (/usr/local/texlive/2015/texmf-dist/tex/latex/oberdiek/kvoptions.sty   Package: kvoptions 2011/06/30 v3.11 Key value format for package options (HO)   ....    Packages  I'm using the following packages:    \documentclass[whitelogo]{tudelft-report}   % Used for referencing   \usepackage{natbib}   % For writing remarks in the text (is this going to be used?)   \usepackage{changes}   % used to write and render different subfiles   \usepackage{subfiles}   % used to draw boxed problems   \usepackage{mdframed}   % for subcaptions in combined figures   \usepackage{subcaption}    % used for Epigraphs of course   \usepackage{epigraph}   % Makes weblinks clickable   \usepackage{hyperref}   % used to display pictures   \usepackage{graphicx}   % used to add urls with strange symbols   \usepackage{grffile}   % used for H command in figures   \usepackage{float}   % used for tickz pictures (Causes a warning)   %\usepackage{pgfplots}   %used for the acronym page [printonlyused,withpage] are options   \usepackage{acronym}    % ######################### open section for code appendix #######################   \usepackage[utf8]{inputenc}   \usepackage{listings}   \usepackage{color}   \definecolor{codegreen}{rgb}{0,0.6,0}   \definecolor{codegray}{rgb}{0.5,0.5,0.5}   \definecolor{codepurple}{rgb}{0.58,0,0.82}   \definecolor{backcolour}{rgb}{0.95,0.95,0.92} I'm using a common charger for both of my laptops.  The charger is specified at 20 Volts and 3.25 Amperes. My other laptop has a specification of 19 V and 3.42 A.  Is it safe to charge my laptop with chargers whose specifications exceed or are not equal to the mentioned specifications?  I have read somewhere that it may cause some damage if the voltage or amperage is not matching the specs. When I run  mkdir ../../bin/Release_Linux/Resources   Im getting an error  $ mkdir ../../bin/Release_Linux/Resources mkdir: cannot create directory ‘../../bin/Release_Linux/Resources’: No such file or directory   Or just   mkdir Release_Linux/Resources mkdir: cannot create directory ‘Release_Linux/Resources’: No such file or directory How to start/stop/restart a thread in Java? It is currently said that MD5 is partially unsafe. Taking this into consideration, I'd like to know which mechanism to use for password protection.  This question,   suggests that hashing multiple times may be a good idea, whereas  suggests using salt.  I'm using PHP. I want a safe and fast password encryption system. Hashing a password a million times may be safer, but also slower. How to achieve a good balance between speed and safety? Also, I'd prefer the result to have a constant number of characters.   The hashing mechanism must be available in PHP It must be safe It can use salt (in this case, are all salts equally good? Is there any way to generate good salts?)   Also, should I store two fields in the database (one using MD5 and another one using SHA, for example)? Would it make it safer or unsafer?  In case I wasn't clear enough, I want to know which hashing function(s) to use and how to pick a good salt in order to have a safe and fast password protection mechanism.  Related questions that don't quite cover my question: In the 70's or 80's I read a short story in which 2 astronauts looking for a nice place to eat lunch choose a spot at the pole of a small desolate planet, overlooking the world's only pool of surface water.  Due to the harsh extremes of heat, and lack of water, this is the home of the planet's single living organism, which has grown slowly over eons,  surviving the daily extremes, moving slowly over the bare rock, dissolving it with acidic digestive juices to get the nutrients it needs for survival. The men watch the organism while eating their lunch, then depart, unknowingly leaving death behind them in their garbage - cigarette butts, tin cans, wrappings - a bonanza that the creature moves over to dissolve and ingest, along with the human-based microscopic organisms that will destroy the alien being. The theme of the story is that although we reach out to the stars to seek life, we are much more connected to the lowest forms of life on Earth, than to any life we may find on other planets. I don't remember the author and title.  Can someone identify the story? How to show $\lim_{n \to \infty} a_n = \frac{ [x] + [2x] + [3x] + \dotsb + [nx] }{n^2} = x/2$? This question came from the prelim exam I took last month. I have a proof that seems a bit unwieldy to me (posted as an answer), so I'm opening it up to ask if there are other ways of showing this.     Let $x$ be any positive real number, and define a sequence $\{a_n\}$ by   $$ a_n = \frac{ [x] + [2x] + [3x] + \dotsb + [nx] }{n^2} $$   where $[x]$ is the largest integer less than or equal to $x$. Prove that $\displaystyle{\lim_{n \to \infty} a_n = x/2}$. Universal Chord Theorem Why do adult insects have 6 legs? Apparently, there is an advantage to having 6 legs in the insect world. What is that advantage, if anything? Why would such an advantage exist for insects, but not for other, larger land animals?  What do those middle legs do that the front and hind legs cannot, if anything? Are they really essential, or do they just generate more muscle power? What is the difference between a field and a property?