Let $(x_n)$ be a sequence of real numbers, such that:  $\lim x_n^{x_n}=4$, prove that $\lim x_n=2$  I'm not sure if my proof is right.  I assumed that $\lim x_n $ isn't 2 and using Cauchy's criterion:  $|x_n-2|>\epsilon$  so $ x_n>\epsilon+2$  or $x_n<-\epsilon+2$  $|x_n^{x_n}-4|<\epsilon $ so $x_n<\sqrt[x_n]{\epsilon+4}$  and then we combine what we've found and get: $\epsilon+2<\sqrt[x_n]{\epsilon+4}$   $\epsilon+4<(\epsilon+2)^2<(\epsilon+2)^{\epsilon+2}<(\epsilon+2)^{x_n}<\epsilon+4$  and it's not true so  $\lim x_n=2$.  Is that okay?  Edit: I just wanted to know if my solution was right but the other post helped as well, thanks.

Given a sequence $\{x_n\}_{n=1}^\infty$ of positive numbers, satisfying $\lim_{n \to \infty} x_n^{x_n} = 4$, prove $\lim_{n\to\infty}x_n=2$. My attampt: from $\lim_{n \to \infty} x_n^{x_n} = 4$ we know $\exists n_0\in\mathbb{N}:\forall n\ \geq n_0: |x_n^{x_n} -4| < \epsilon$ so $|x_n-2| = \frac{|x_n^2-4|}{|x_n+2|} \leq |x_n^2-4| \leq |x_n^{x_n} -4| <\epsilon$ Which completes the proof if correct. Is it?


I just noticed a strange behavior in beamer: if just after the title page, I use a colums environment, in which I put a block, and in which I center the text, the text has the wrong color, namely the title color.     ME:  \documentclass[9pt,hide notes]{beamer} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc}  \usetheme[]{Madrid} \title{The title} \author{The Author}   \institute{The University}   \begin{document}  \maketitle  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \begin{frame}{bla}     \begin{columns}         \begin{column}{0.3\textwidth}             \begin{block}{bla}                 \begin{center}                     bla                 \end{center}             \end{block}         \end{column}         \begin{column}{0.3\textwidth}             \begin{block}{bla}                 \begin{center}                     bla                 \end{center}             \end{block}         \end{column}     \end{columns} \end{frame}  \end{document}

There is a bug in beamer which is quite annoying, and I don't know how to solve it properly. In my theme, the title of a frame is always in white:    However, if the example block is empty, or if it contains only a list, the frame title is black, which makes it hard to read:    Do you know why, and how to solve this problem? I tried to add at the beginning a tilde,but it adds an empty line that I don't like...  Thank you.  MWE  \documentclass[]{beamer} \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage[francais]{babel}      \usetheme{Warsaw}  \begin{document} \begin{frame}{My great title}   \begin{exampleblock}{Exemple}     \begin{itemize}     \item a     \item b     \end{itemize}   \end{exampleblock} \end{frame} \end{document}


A very small and rather simple suggestion... Could you please (pretty please!) prettify the the number of times a question has been viewed, so that at a glance you can figure it out instead of having to decrypt it. Current Look  I mean look at it! It isn't very user friendly. Suggestion Have it output as 296,877 instead of just 296877. I thought I'd ask here so it could be implemented on all the sites network-wide. According to  (comment copied below) comment in this related question, I think anything just to split the numbers up would be better than the current system; spaces would be fine too.  Commas should never happen due to internationalization concerns. The same goes with dots. The only "correct" option is following the ISO standard which calls for spaces. – psubsee2003 Apr 25 '15 at 21:02

For usability reasons, for example in , the 'viewed' counter should show as  ...instead of... . It's much harder to decipher that there are a million views on the question just by looking at it.  Some people in the comments pointed out internationalization concerns with it. I do think that since there might be a problem with it, that spaces would probably be a better idea.


I've tried A LOT of different syntaxes and nothing has allowed me to reach my goal. I want to create a Villager that A) sells spawners (I've been able to do this) and B) have those spawners spawn mobs other than pigs. So like a zombie or something. From there I could name him a "Zombie Spawner Trader" or something like that. Keep in mind, my villager is being created no problem and he's buying and selling things according to what I've programmed, all that's wrong is that the spawner is only spawning pigs. I have tried NBT tags: "Entity", "EntityId" and "SpawnData" with their proper syntaxes according to the wiki, and none of them worked. It proceeded to give me a pig spawner as usual.  Some code:  /summon villager ~ ~1 ~ {CustomName:"Zombie Spawner Merchant",CustomNameVisible:1b,NoAI:1b,Invulnerable:1b,Offers:{Recipes:[{buy:{id:"minecraft:gold_nugget",tag:{display:{Name:"Gold Coin",Lore:["$1"]}},Count:32},sell:{id:"minecraft:mob_spawner",Count:15,tag:{SpawnData:{id:"minecraft:zombie"}}}]}}

I'm trying to use a give command in a Survival world about mob spawners like a blaze spawner. When I place it in Creative, it spawns blazes, but in Survival just pigs! How can I fix this, without mods, or plugins, etc.?  I'm using this command on the moment: give @p spawner{BlockEntityTag:{SpawnData:{id:"blaze"},Spawncount:5,RequiredPlayerRange:100,SpawnPotentials:[{Entity:{id:"blaze"},Weight:1}]}}


How to find an explicit formula for the term $$\sum^n_{k=1}\frac{k^2}{2^k}$$ Then I discovered that $$\sum^n_{k=1}\frac{k^2}{2^k}=1^22^n+2^22^{n-1}+3^22^{n-2}+\cdots+n^22^1-\frac{n(n+1)(2n+1)}{6}$$ But how to write $1^22^n+2^22^{n-1}+3^22^{n-2}+\cdots+n^22^1$ into explicit formula?? $$\\$$ A hint would be grateful.

How to evaluate those infinite series? How are they called?  $$ \sum_{k=1}^\infty \frac{k}{2^k} \quad \text{and} \quad \sum_{k=1}^\infty \frac{k^2}{2^k} $$  I'm really sorry for asking, but I can't figure out how to google such stuff when I even don't know the names/categories.


When you roll with disadvantage is the chance to get a 1 5+5 for 10% or 5X5 for 25%? Just sat down and rolled 100 times with disadvantage got 18 natural 1s and 0 natural 20s. Still don't know.

D&D 5E has an "advantage" concept where instead of rolling 1d20, you roll 2d20 and take the higher. Likewise, disadvantage means rolling 2d20 and taking the lower.  How does this affect the expected average outcome of the roll?


Given the following groups, what is the maximum possible order for an element for   (a) $S_5$ (b) $S_6$ (c) $S_7$ (d) $S_{10}$ (e) $S_{15}$  My book justifies the answer as          (a) The greatest order is $6$ and comes from a product of disjoint cycles of length 2 and 3          (b) The greatest order is $6$ and comes from a cycle of length $6$      The other answers were justified exactly the same way, that is (c) 12, (d) 30, (e) 105  I do not understand how in (a) we even got the number "6" from $S_5$ and what disjoint cycles they are referring to. Could someone at least justify one for me?

If we let $S_n$ denote the symmetric group on $n$ letters, then any element in $S_n$ can be written as the product of disjoint cycles, and for $k$ disjoint cycles, $\sigma_1,\sigma_2,\ldots,\sigma_k$, we have that $|\sigma_1\sigma_2\ldots\sigma_k|=\operatorname{lcm}(\sigma_1,\sigma_2,\ldots,\sigma_k)$.  So to find the maximum order of an element in $S_n$, we need to maximize $\operatorname{lcm}(\sigma_1,\sigma_2,\ldots,\sigma_k)$ given that $\sum_{i=1}^k{|\sigma_i|}=n$. So my question:      How can we determine $|\sigma_1|,|\sigma_2|,\ldots,|\sigma_k|$ such that $\sum_{i=1}^k{|\sigma_i|}=n$ and $\operatorname{lcm}(\sigma_1,\sigma_2,\ldots,\sigma_k)$ is at a maximum?   Example  For $S_{10}$ we have that the maximal order of an element consists of 3 cycles of length 2,3, and 5 (or so I think) resulting in an element order of $\operatorname{lcm}(2,3,5)=30$.  I'm certain that the all of the magnitudes will have to be relatively prime to achieve the greatest lcm, but other than this, I don't know how to proceed. Any thoughts or references? Thanks so much.


To the best of my knowledge, we should capitalize cardinal directions in phrases that refer to a region commonly referred to by that phrase; for example: Eastern Europe and Western Hemisphere.   However, I don't know whether we should capitalize cardinal directions in spontaneously constructed phrases that refer to a region; for example: western Chicago and northern Sumatra. Should the cardinal directions in these phrases be capitalized?

I am trying to capitalize Western Canada or western Canada properly and am wanting a definition for when the "ern" is added as a suffix to a locational distinction of a proper noun.  I believe the capitalization is related to the suffix and am grouping two questions.  After researching on the internet I have found a trend that areas of discrete area become capitalized along with their proper noun   East New York West Hollywood East London (Britain) East Los Angeles   Some locations have "ern" added to their locational modifier.    Web Examples (from government sites):   eastern Canada ( Western Canada ()   All the examples listed contain discrete areas.  The "ern" suffix is used for larger areas, but I am unable to determine when an area becomes large enough.


Let $f$ be $C^1$ in $[-\pi, \pi]$ and satisfies $\int_{-\pi}^\pi f(x)dx=0$, periodic boundary condition.  Then, prove that $\int_{-\pi}^\pi (f(x))^2dx\le \int_{-\pi}^\pi (f'(x))^2dx$.  I try to prove it by Parseval's equality(with $X_n=\sin nx$) and Schwartz inequality,   but then some constants come out. Also why condition $\int_{-\pi}^\pi f(x)dx=0$ needs?  Give some advice.

I have a  basic question  Let $f$ be a $\mathcal{C}^1$  map  from  $[0,1]$ into $\mathbb{R}$ vanishing in $0$ and $1$. I want to prove that   $$\int_0^1 f'^2 \geq \pi^2 \int_0^1 f^2 $$  and to see when we have equality.


I was wondering if anyone had any thoughts on how to iterate through the elements of a vector (or container) when the direction of the iteration is input.   This was the first thing I could come up with:      std::vector<int> vec = {1, 2, 3, 4};     int direction = 1 // or -1;     int start = direction == 1 ?  0 : (int)arrs.size()-1;     for (int i=start; i<(int)vec.size() && 0<=i; i+=direction) {       // do your stuff     }   Does anyone know any better or nicer way to do this?

I'm writing some cross-platform code between Windows and Mac.  If list::end() "returns an iterator that addresses the location succeeding the last element in a list" and can be checked when traversing a list forward,  what is the best way to traverse backwards?  This code workson the Mac but not on Windows (can't decrement beyond first element):  list<DVFGfxObj*>::iterator iter = m_Objs.end(); for (iter--; iter!=m_Objs.end(); iter--)// By accident discovered that the iterator is circular ? { }   this works on Windows:  list<DVFGfxObj*>::iterator iter = m_Objs.end();     do{         iter--;     } while (*iter != *m_Objs.begin());   Is there another way to traverse backward that could be implemented in a for loop?


I accidentally deleted my data in the production database using drop database ... command. I am using InnoDB but I don't enable mysqlbinlog. How to recover the data?

How can I restore a mysql database that was dropped using a "drop database" command? I have access to binary logs which should make this type of rollback possible.


I work as a tutor for an online English school and one student asked me this:  "In this sentence: I have the hiccups  Could it be: I Have hiccups?"  I have done a lot of research on advanced article usage but I haven't found anything even close to that. I have no idea what to say.   Any help will be appreciated. Especially if you can suggest articles about this subject.  Thanks in advance.  Edit:  It is not a duplicate to  because talking about having "hiccups" is not the same as talking about having "flu".

Have you got a cold? Have you got flu? Have you got the flu?  Why can't we say a flu or the cold in the previous examples?


I flagged  on Ask Ubuntu as a duplicate. A comment "Does this answer your question...." was auto-generated. For trying things out, I retracted my flag. Now, I can't delete that comment. Since I'm a low reputation points user, I can't edit my comment as well. Screenshot for reference:  I'm aware of , but that's a bug report that was marked as "by design". The explanation for having it designed that way is because users without privileges supposedly wouldn't be able to restore/repost such automatic comments if they deleted them, and that in the admin's opinion, new users usually aren't aware that they can retract flags. However, this is a feature request to change the design to allow low-reputation users to delete comments created on their behalf. There are also other cases where low-rep users end up with comments posted on their behalf, such as if they trigger the "trivial answer converted to comment" script or if a moderator converts one of their answers into a comment; it doesn't make sense to disallow deletion in those cases, and in the first case, they can repost the comment. Also, just because most users are unaware of the flag retract functionality doesn't mean we should shut it out for users who are aware. This has come up in another interesting way: a new user  an answer that triggered the trivial answer comment conversion feature. For some reason, they didn't see the redirect and notification from the feature (maybe it didn't load for them for one reason or another), and so they thought that their answer went into the void somehow, and tried reposting it two more times, resulting in three duplicate comments which they only noticed later. They were unable to delete the duplicate comments themselves, and couldn't flag the comments since they didn't have 15 rep, which delayed the comment cleanup.

Some preface: I have an alternate account that I'm using to gain rep in order to help test/build bots for the  community on stackoverflow. Bot accounts are essentially users, and they need 20 rep to talk in chat, and 50 in order to add comments.  On this account (with 23 rep), I flagged a question as a duplicate of the wrong post by accident:        When I retracted the duplicate flag, I noticed that the comment was not removed. When I attempted to remove it, there was no [x] icon to the right of the post, and I had no recourse other than to leave the comment up (Which was 100% a wrong duplicate for that post). Additionally, I couldn't even flag it for mod attention, because it was my comment!


My mother was denied a visa to attend my graduation and she has been crying since she received this heartbreaking news. I really want her to attend my graduation. How do I remedy this problem?  After working for an organisation, she started her own business and she attached a document showing her business registration and business account details.  The last application she did was done by an agent as she was feeling poorly during that period. So the agent mentioned that she has no relative or dependent.

Many of the UK visa refusals we see here share a common pattern and the prevailing reasons refer to V 4.2 (a) and (c).    I do understand that, while the applicants may describe very different individual circumstances, there's a consistent pattern and, broadly, fall into specific categories:    Credibility (lifestyle, lack of ties, visit history, lies & omissions) Funding (insufficient funds, provenance of funds, funds parking) Sponsorship (family, friends, employer)   Question: What most commonly triggers a UK visa refusal where V 4.2 (a) and (c) are given as the grounds?  Secondarily: Given that there is a clear pattern, to what extent are these refusals predictable? Does sponsorship make a difference? Is there a set of personal circumstances, however abstract, where a refusal is all but guaranteed? For example, why do those we see here on TSE who sought entry for the PLAB or British Army appear to be refused with a common theme? Is there a uniform shortcoming or is it just discrimination?   PLAB: What is about applications for a visa, for the purpose of sitting the Professional and Linguistic Assessments Board (PLAB) exam, that seem to invite refusals. After all, the test is given so that international medical graduates can show that they qualify to practise medicine in the UK. The first part, PLAB 1, can be taken in centres outside of the UK. However, PLAB 2 can be taken only in the UK. Why can't you can't get a visa just to sit the exam, promising that you'll leave immediately after?    British Army: Since Commonwealth citizens are eligible to apply online to join, even those who don't reside in the UK, why is it so difficult to get a visa just to attend an interview to see whether you are suitable? Even with an invitation from the Army, such visa applications seem to be unsuccessful. Isn't a career in the British Army a valid reason?     Lastly:  After such a refusal, what approaches would increase the chance of a successful application?


I do not know why, but it seem that the tikz and  pstriks packages are in conflict. Using both   \usepackage{tikz} \uspepackage[usenames,dvipsnames]{pstricks}   When compiling, it returns me the following error:     !No room for a   new \dimen   I list below the packages that I used:  \documentclass[a4paper]{article} \usepackage[latin1]{inputenc} \usepackage{color} \usepackage{epsfig} \usepackage{booktabs} \usepackage{MnSymbol} \usepackage{array} \usepackage{makeidx} \usepackage[all,dvips,graph]{xy} \usepackage{hyperref} \usepackage{tikz} \usepackage[usenames,dvipsnames]{pstricks}    Note that without one of tikz or pstricks, it will compile.

I have this error message:  ! No room for a new \dimen . \ch@ck ...\else \errmessage {No room for a new #3}                                                 \fi   which I can not find a cure for.


In a former question, I was suggested to execute:  sudo bash start-dfs.sh   why not  sudo start-dfs.sh   ? I mean, what difference does bash makes?

I'm trying to install VMware Workstation in my Ubuntu 12.04.2 LTS. If I execute the following command:  sudo ./VMware-Workstation-9.0.1-894247.x86_64.bundle   it finishes at once and the installation never starts.  If I execute this command:  sudo sh ./VMware-Workstation-9.0.1-894247.x86_64.bundle   The installer can be launched successfully.  Why does this make a difference?


I have a long file ( 20000+ lines) where each of the lines is a description of a book:   book_number "title of the book" size type author_number   Where the element in quotes is a string with quotes and the others are numbers, except for type which is a single word:   23446 Raising Steam 537724 EPUB 4   I want to extract all the size fields but using cut you cannot use negative numbers to count from the back of the result of splitting with -d " ":   cut -d " " -f -2 books.txt   I cannot count from the front as the books may have any number of spaces in the title (I did not make up this format, I would have used CSV or JSON which require quoting).  Am I missing some option that allows using cut? What else could I use to get the second-before-last field with a one line solution?

I know how to select a field from a line using the cut command. For instance, given the following data:  a,b,c,d,e f,g,h,i,j k,l,m,n,o   This command:  cut -d, -f2 # returns the second field of the input line   Returns:  b g l   My question: How can I select the second field counting from the end? In the previous example, the result would be:  d i n


I installed 12.04. Yesterday I tried installing tomcat server and java. There was some errors in that installation and when I tried to open my system after some time I couldn't login. At that time I found its in loop. When I used terminal using ctrl+alt+f1. I can login there, and after login there shows one error which I incurred while installing java.  it shows like in 31 line.  Syntax error near unexpected token '('   and also in line   export JAVA_HOME=/media/F25ACC3E5ACBFCFB/Program Files (x86)/Java

My Ubuntu is stuck in a login loop when trying to enter my desktop. When I login, the screen gets black and soon after that the login screen comes back.   I've read that the problem might be caused by an error depending on the graphics, here's my graphics card: ATI Radeon 7670M


I have used \listoffigures in my report and the list contains indexing like 2.1 if it belongs to chapter 2 first image and 5.4 for chapter 5 ,fourth image, how can I change this to continuous arabic numeral indexing like 1,2,3,... without taking consideration for the chapter and figure number in that chapter.

Some document elements (e.g., figures in the book class) are numbered per chapter (figure 1.1, 1.2, 2.1, ...). How can I achieve continuous numbering (figure 1, 2, 3, ...)?  And vice versa: Some document elements (e.g., figures in the article class) are numbered continuously. How can I achieve per-section numbering?  \documentclass{book}% for "vice versa" variant, replace `book` with `article`  \begin{document}  \chapter{foo}% for "vice versa" variant, replace `\chapter` with `\section`  \begin{figure} \centering \rule{1cm}{1cm}% placeholder for graphic \caption{A figure} \end{figure}  \end{document}   Bonus question: Is it possible to adjust the numbering of the sectioning headings themselves? Can I, e.g., switch from per-chapter to continuous numbering of sections in the book class?


I need help converting this switch statement from Matlab to something equivalent to Python. Is there a simple way to do it like an if statement? switch nmax     case 0         Tk( 1, : ) = ones( 1, length( x ) )/sqrt(N);     case 1         Tk( 2, : ) = (w ./ w1).*ones( 1, length( x ) )/sqrt(N);     otherwise         Tk( 1, : ) = ones( 1, length( x ) )/sqrt(N);         Tk( 2, : ) = (w ./ w1).*Tk( 1, : );          for m = 3:nmax             ni=m-1;             w2_A = N^2-ni^2;             w2_B = (2*ni+1)*(2*ni-1);             w2   = ni*sqrt(w2_A/w2_B);             Tk(m,:) = w./w2.*Tk(m-1,:) - w1/w2*Tk(m-2,:);                      w1 = w2;             T = Tk(m,:);             for k=0:ni                 Tk(m,:) =  Tk(m,:) - sum(T.*Tk(k+1,:))*Tk(k+1,:);             end             h=sqrt(sum(Tk(m,:).^2));             Tk(m,:) = Tk(m,:)/h;         end

I want to write a function in Python that returns different fixed values based on the value of an input index.    In other languages I would use a switch or case statement, but Python does not appear to have a switch statement.  What are the recommended Python solutions in this scenario?


The rate of Hawking radiation emission increases as the mass of the black hole decreases, what I don't understand is that if the emission method is related to zero-point energy particles appearing and one half of the pair being captured, why is it that when the surface area of the event horizon would be greater for a larger black hole the Hawking radiation doesn't increase?

I am asking for a non mathematical answer. I think I have a pretty good understanding of physics without the maths, which unfortunately eludes my understanding. It may be the answer would be obvious if I understood the maths, but I don't. As I see it, the event horizon has the same property for any size of black hole; it is the point from which light cannot escape. Given that this property is the same regardless of the size of the hole, it seems reasonable to suppose that the intensity of the Hawking radiation would be constant per unit area of the horizon. I know I am wrong, but I don't know why. A non mathematical explanation would be appreciated.


15 persons are arranged in a row. Find the number of ways of selecting  6 persons so that no two persons sit next to each other.   I think we have to select 6 persons from either the group of 8 people sitting 1st, 3rd, 5th.....15th or the group of 7 people sitting 2nd, 4th...14th.  I tried to solve this way but I'm not getting the required answer. Please some one help me.

Let $X=\{1,2,3,\dots,n\}$ where $n\in N$. Show that the number or $r$ combinations of $X$ which contain no consecutive integers is given by   $\binom{n-r+1}{r}$ where $0\le r\le n-r+1$.  I am unable to think of any possible way to prove it.  Please explain the proof and comment on the technique used to help me with problems in the future.   Thanks in Advance!  Thanks for pointing the typing faults!


Every now and then I find one or two of these tiny bugs in my kitchen. They are about 3-4 mm long and seem to be very static on hard surfaces (furniture or walls). They rarely, if ever, more. The one in the picture was found dead on the floor so I was able to take close-up pictures. The insect seems to have a very regular pattern of spots and presumably wings. I tried to look online for Italian websites of "household bugs" but I could not find it. Is it problematic, i.e. does it ruin food or something? Location: Northern Italy, province of Vicenza

I live in Chapel Hill, North Carolina, and recently started seeing a bunch of these little guys in my house. They're about 1/8" long (estimate), with brown/black zigzag stripes; it's possible they're babies, but over the last two weeks their size has remained consistent so this seems unlikely.


Before you mark as duplicate I have read everything I can find, and done the following.  1) I have added myself to dialout group, then logged out, then back in, chmod 0666, even 0777 /dev/ttyUSB0.  2) I have done this, as suggested in :  ~$ esptool.py --port /dev/ttyUSB0 chip_id esptool.py v2.5.1 Serial port /dev/ttyUSB0 Connecting.... Detecting chip type... ESP8266 Chip is ESP8266EX Features: WiFi MAC: 60:01:94:5d:4d:9d Uploading stub... Running stub... Stub running... Chip ID: 0x005d4d9d Hard resetting via RTS pin...   Passing grade there!  3) I have tried 7 different boards that were pulled from new packages.  4) I have tried every baud rate in settings.  5) I have tried every possible combination of settings for NodeMCU v1 and v0.9, just in case.  6) Board temps and wiring pass all checks, this is not a duplicate issue because all the steps in your linked issue have been tested, yet the error persists.  I still get the following error every time I try to upload via Arduino 1.8.5  error: cannot access /dev/ttyUSB0 An error occurred while uploading the sketch  error: espcomm_open failed error: espcomm_upload_mem failed   Why? Is Arduino app 1.8.5 buggy in Ubuntu 18.04?  Frustration level is at smash with hammer. Please tell me there is something I missed.  Oh the kicker, these boards will flash on a Mac Pro perfectly, so I know it's isolated to the Arduino app on Ubuntu only.

Can't force upload sketch from arduino IDE.  warning: espcomm_sync failed error: espcomm_open failed error: espcomm_upload_mem failed error: espcomm_upload_mem failed   dmseg  [ 4980.110605] usb 3-4: new full-speed USB device number 9 using xhci_hcd [ 4980.305550] usb 3-4: New USB device found, idVendor=10c4, idProduct=ea60 [ 4980.305556] usb 3-4: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [ 4980.305561] usb 3-4: Product: CP2102 USB to UART Bridge Controller [ 4980.305565] usb 3-4: Manufacturer: Silicon Labs [ 4980.305569] usb 3-4: SerialNumber: 0001 [ 4980.317468] cp210x 3-4:1.0: cp210x converter detected [ 4980.319521] usb 3-4: cp210x converter now attached to ttyUSB0  lsusb Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 003 Device 009: ID 10c4:ea60 Cygnal Integrated Products, Inc. CP210x UART Bridge / myAVR mySmartUSB light Bus 003 Device 002: ID 24ae:1100   Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub   Settings in Arduino IDE  Board NodeMCULuA 1.0 CPU 80 Mhz Upload Speed 115200 Flash Size 4M(1m SPIFFS) Programmer AVR ISP   Provided access to the ttyUSB0 by command sudo chmod 666 /dev/ttyUSB0  Previously worked on 16.04. What can be the problem and how to solve it? Behavior chip also changed. Earler diode only flashed when sketch was uploading, now is always on till the sketch start uploading and switched off when error is displayed.  Any help will be usefull.


I am trying to use symbolic links with samba to link to a file outside the samba share directory. I've search around and have updated the config file with all the suggestions, but still no luck.   This is my smb.conf file:  [global] workgroup = WORKGROUP log file = /var/log/samba/log.%m max log size = 1000 panic action = /usr/share/samba/panic-action %d server role = standalone server obey pam restrictions = yes unix password sync = yes passwd program = /usr/bin/passwd %u passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* . pam password change = yes map to guest = bad user usershare allow guests = yes  allow insecure wide links = yes unix extensions = no  [Private] path = /media/hdd1/samba/private/ browseable = yes guest ok = no writable = yes valid users = @samba follow symlinks = yes wide links = yes   When I try testparm I get the following output  [global]     log file = /var/log/samba/log.%m     max log size = 1000     allow insecure wide links = Yes     panic action = /usr/share/samba/panic-action %d     usershare allow guests = Yes     unix extensions = No     map to guest = Bad User     obey pam restrictions = Yes     pam password change = Yes     passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* .     passwd program = /usr/bin/passwd %u     server role = standalone server     unix password sync = Yes     idmap config * : backend = tdb  [Private]     comment = House private samba share     path = /media/hdd1/samba/private/     wide links = Yes     read only = No     valid users = @samba   The follow symlinks is inclided in the config file, but not on the testparm output which I think is a bit odd.  The stripped down simple file structure is:  /media |- hdd1    |- datafolder    |  |-- file1    |    |- samba       |-- private           |-- Symbolic link to file1     Permissions are:  file1  root  plugdev link   samba sambashare

This is Ubuntu server 10.04 64 and samba 3.4.7.  I have a shared directory /home/mit/share and another one /home/temp that I link into the shared one:  ln -s /home/temp /home/mit/share/temp   But on windows, after using internet, I cannot open S:/temp, but on Linux it is possible to access /home/mit/share/temp like expected.   This works if I link directories inside /home/mit/share/temp, so I guess samba is restricting to jump with a link outside/above the shared directory.   EDIT:  See also this question titled .  It seems best to put unix extensions = no into the global section and follow symlinks = yes and wide links = yes only into the shares section, where you really need it.  The unix extension flag has to live in the global section and not in the individual shares sections. But for security reasons it is better to use the other options only where you need it, and not globally.


Suppose I have a scanned book with equations, is there a convenient way to obtain latex that reproduces them?

I know that hardly any information is passed to the PDF when a .tex file is compiled.  But is there a tool that can convert a PDF document back to (La)TeX?


So I just watched a video where they explained that the sum of all natural numbers is $-1/12$. However, there was an interesting comment:  S1 = 1 + 2 + 3 + 4 + 5 ... = - 1/12 S1 - S1 =          1 + 2 + 3 + 4 + 5 + 6 ...              - 1  - 2  - 3 -  4 -  5 ... =      1 + 1 + 1 + 1 + 1 + 1 ... Since S1 - S1 = - 1/12 - (- 1/12) = 0 It follows that 1 + 1 + 1 + 1 + 1 .... = 0 Let's name this sequence S2: S2 = 1 + 1 + 1 + 1 + 1 ... = 0 Now let's subtract it from itself: S2 - S2 =          1 + 1 + 1 + 1 + 1 ...              - 1  - 1  - 1  - 1 .... =      1 Given that S2 equals 0, we can also write this as: 0 - 0 = 1   For those who are wondering about the video:  It does the same trick of "shifting". With infinity and stuff things get tricky. What is wrong with this proof? I am a math student, so involved answers with limits is fine.

The staff of  has shown that the sum of all the integers from $0$ to $\infty$ is $-\frac1{12}$. Recently I was looking for the sum of all the (positive) integers from $0$ to $n$ and I found that: $$\sum_{i=0}^n i=\frac{n(n+1)}{2}$$  So I decided to take the limit: $$\lim_{n\to \infty}\frac{n(n+1)}{2}$$ but that tends towards $\infty$ when I expected that to be $-\frac1{12}$! Where did I got wrong? (the result is also confirmed by Wolfram Alpha)


I'm learning how python stores variables and refers it with names in Python and I came across something that I couldn't make sense of. I assigned same value to var1 and var2 and saw that these variables refers same object. And I created another two variable named var3 and var4 and assigned same value (but different from before) and I saw that objects that these variables refers isn't the same. Can someone explain the difference in this?   Python 3.6.4 (v3.6.4:d48eceb, Dec 19 2017, 06:04:45) [MSC v.1900 32 bit (Intel)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>> >>> vars() {'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>} >>> var1 = 100 >>> var2 = 100 >>> var1 is var2 True >>> var3 = 500 >>> var4 = 500 >>> var3 is var4 False >>> id (var1) 491903584 >>> id (var2) 491903584 >>> id (var3) 56573264 >>> id (var4) 87458544 >>> >>> vars() {'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>, 'var1': 100, 'var2': 100, 'var3': 500, 'var4': 500}

Why does the following behave unexpectedly in Python?  >>> a = 256 >>> b = 256 >>> a is b True           # This is an expected result >>> a = 257 >>> b = 257 >>> a is b False          # What happened here? Why is this False? >>> 257 is 257 True           # Yet the literal numbers compare properly   I am using Python 2.5.2. Trying some different versions of Python, it appears that Python 2.3.3 shows the above behaviour between 99 and 100.  Based on the above, I can hypothesize that Python is internally implemented such that "small" integers are stored in a different way than larger integers and the is operator can tell the difference. Why the leaky abstraction? What is a better way of comparing two arbitrary objects to see whether they are the same when I don't know in advance whether they are numbers or not?


I read in another post that kernels are distributed as new releases rather than upgrades. I didn't know this when I was allocating space to my partitions during my initial install of Ubuntu. As a result I ran out of space on my boot partition. Can I increase the size of it using GParted and how do I do this without doing damage to my system?  1      1049kB  512MB   511MB  fat32              boot  2      512MB   768MB   256MB  ext2  3      768MB   1000GB  999GB                     lvm  Model: Linux device-mapper (linear) (dm) Disk /dev/mapper/ubuntu--vg-swap_1: 3712MB Sector size (logical/physical): 512B/4096B Partition Table: loop  Number  Start  End     Size    File system     Flags  1      0.00B  3712MB  3712MB  linux-swap(v1)  Model: Linux device-mapper (linear) (dm) Disk /dev/mapper/ubuntu--vg-root: 996GB Sector size (logical/physical): 512B/4096B Partition Table: loop  Number  Start  End    Size   File system  Flags  1      0.00B  996GB  996GB  ext4  Sorry, don't know how to capture and post the terminal output screen.

My /boot partition is nearly full and I get a warning every time I reboot my system. I already deleted old kernel packages (linux-headers...), actually I did that to install a newer kernel version that came with the automatic updates.  After installing that new version, the partition is nearly full again. So what else can I delete? Are there some other files associated to the old kernel images?  Here is a list of files that are on my /boot partition:  :~$ ls /boot/ abi-2.6.31-21-generic         lost+found abi-2.6.32-25-generic         memtest86+.bin abi-2.6.38-10-generic         memtest86+_multiboot.bin abi-2.6.38-11-generic         System.map-2.6.31-21-generic abi-2.6.38-12-generic         System.map-2.6.32-25-generic abi-2.6.38-8-generic          System.map-2.6.38-10-generic abi-3.0.0-12-generic          System.map-2.6.38-11-generic abi-3.0.0-13-generic          System.map-2.6.38-12-generic abi-3.0.0-14-generic          System.map-2.6.38-8-generic boot                          System.map-3.0.0-12-generic config-2.6.31-21-generic      System.map-3.0.0-13-generic config-2.6.32-25-generic      System.map-3.0.0-14-generic config-2.6.38-10-generic      vmcoreinfo-2.6.31-21-generic config-2.6.38-11-generic      vmcoreinfo-2.6.32-25-generic config-2.6.38-12-generic      vmcoreinfo-2.6.38-10-generic config-2.6.38-8-generic       vmcoreinfo-2.6.38-11-generic config-3.0.0-12-generic       vmcoreinfo-2.6.38-12-generic config-3.0.0-13-generic       vmcoreinfo-2.6.38-8-generic config-3.0.0-14-generic       vmcoreinfo-3.0.0-12-generic extlinux                      vmcoreinfo-3.0.0-13-generic grub                          vmcoreinfo-3.0.0-14-generic initrd.img-2.6.31-21-generic  vmlinuz-2.6.31-21-generic initrd.img-2.6.32-25-generic  vmlinuz-2.6.32-25-generic initrd.img-2.6.38-10-generic  vmlinuz-2.6.38-10-generic initrd.img-2.6.38-11-generic  vmlinuz-2.6.38-11-generic initrd.img-2.6.38-12-generic  vmlinuz-2.6.38-12-generic initrd.img-2.6.38-8-generic   vmlinuz-2.6.38-8-generic initrd.img-3.0.0-12-generic   vmlinuz-3.0.0-12-generic initrd.img-3.0.0-13-generic   vmlinuz-3.0.0-13-generic initrd.img-3.0.0-14-generic   vmlinuz-3.0.0-14-generic   Currently, I'm using the 3.0.0-14-generic kernel.


why the code is un deserlaizable ! cannot read serlaizable file ! it write correctly in file but cannot read it     public ArrayList<customer> read_file(){ ArrayList <customer>file = new ArrayList<customer>(); try {     File f= new File("file.bin");     ObjectInputStream is= new ObjectInputStream (new FileInputStream("file.bin"));     int x=(int) f.length();       while(is.available()!=0){     file.add((customer)is.readObject()) ;      } } catch (FileNotFoundException ex) {     Logger.getLogger(Login.class.getName()).log(Level.SEVERE, null, ex); } catch (IOException | ClassNotFoundException ex) {     Logger.getLogger(Login.class.getName()).log(Level.SEVERE, null, ex); }  return file ;}

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?


How can rotate multi-dimensional List without using the zip function, I have this list (but it can be longer):   testlist = [[1, 2, 3],            [4, 5, 6],            [7, 8, 9],            [10,11,12]]   I want to rotate it 90 degrees clockwise and also 90 degrees counterclockwise. ps: The reason i don't want to use zip is because this is a homework and i must write it in vanilla python .

Inspired by , say you have a 4x4 two dimensional array, write a function that rotates it 90 degrees. Raymond links to a solution in pseudo code, but I'd like to see some real world stuff.  [1][2][3][4] [5][6][7][8] [9][0][1][2] [3][4][5][6]   Becomes:  [3][9][5][1] [4][0][6][2] [5][1][7][3] [6][2][8][4]   Update: Nick's answer is the most straightforward, but is there a way to do it better than n^2? What if the matrix was 10000x10000?


My friend went to a concert of Bob Dylan 3 weeks ago. Today I met him and spoke with him about the concert. I know I can say, "hope you enjoyed the show," because the show is over, but would it be possible to use present perfect in this case instead? (Suppose I had not seen my friend since he went to the concert.)  Could I use the sentence below?     I hope you have enjoyed the show.

I saw a dog.       I have seen a dog.   What are the differences between them? Did these events happen on the same day?


Let $\Bbb D^n$ be n-dimensional ball and $S^{n-1}$ the $n-1$ dimensional sphere realized as boundary of $\Bbb D^n$. Prove that following are equivalent.   There is no retraction $\Bbb D^n\to S^{n-1}$ Every Continuous map $\Bbb D^n \to \Bbb D^n$ has a fixed point.   I can do for the case of $n=2$. For this case, I don't even need the help of 2. to prove 1. just i will show there is  induced homomorphism between them such that $\pi _*(S^{1}) \to \pi _*(\Bbb D^2) \to \pi_*(S^1)$ does not commute. Next direction is also easy for the case of n=2  But I can't do for the case of $n>2$. could u please do for me for higher dimension.

I'm trying to show that they're equivalent statements:  1) $1_{S^1}$ is not homotopic to a constant map.  2) $S^1$ is not a retract of $D^2$ ($D^2$ is the closed unit ball).  3) Every continuous map $f:D^2\to D^2$ has a fixed point.  1)$\to$2) I suppose the opposite, then there exists $r:D^2\to S^1$ continuous such that $r(x)=x$ for every $x\in S^1$. How can we show that $1_{S^1}$ is homotopic to a constant?  2)$\to$3) I suppose that there exists $f:D^2\to D^2$ such that $f(x)\neq x$ for every $x\in D^2$, but I don't know how to prove that $S^1$ would be a retract of $D$.  3)$\to$1) Of course I tried to suppose that $1_{S^1}$ is homotopic to a constant, and show a map without fixed points.  Any hint? Thanks.


Version 1.0.53  Viewing questions with code blocks is fine, until I click on the code to scroll. Crashes every time, even after rebooting the phone.   Example question:   OnePlus One phone, latest CM Stock nexus 5 updated

Steps to Reproduce   Tap faster on the code. or Tap once on a huge code.   but happens only when  setupForGeneric() is called, might be a bug related to   private void setupForCode()   { String str = getIntent().getStringExtra("com.stackexchange.marvin:code_block"); PrettyWebView localPrettyWebView = (PrettyWebView)findViewById(R.id.code); localPrettyWebView.setPostBody("
" + TextUtils.htmlEncode(str) + "
", false); localPrettyWebView.setBackgroundColor("#eeeeee"); }  private void setupForGeneric() { String str = getIntent().getStringExtra("com.stackexchange.marvin:web_url"); PrettyWebView localPrettyWebView = (PrettyWebView)findViewById(R.id.code); localPrettyWebView.getSettings().setBuiltInZoomControls(true); localPrettyWebView.getSettings().setLoadWithOverviewMode(true); localPrettyWebView.getSettings().setUseWideViewPort(true); localPrettyWebView.loadUrl(str); localPrettyWebView.setBackgroundColor("#eeeeee"); }   Log  09-05 03:54:30.312: E/AndroidRuntime(26264): FATAL EXCEPTION: WebViewCoreThread  09-05 03:09:39.522: E/Crittercism(18318): java.lang.NullPointerException: [v0.1.22]  09-05 03:09:39.522: E/Crittercism(18318):   at android.content.ComponentName.<init>(ComponentName.java:75) 09-05 03:09:39.522: E/Crittercism(18318):   at android.content.Intent.<init>(Intent.java:3156) 09-05 03:09:39.522: E/Crittercism(18318):   at com.stackexchange.marvin.ui.ViewPopupActivity.showCode(ViewPopupActivity.java:25) 09-05 03:09:39.522: E/Crittercism(18318):   at com.stackexchange.marvin.ui.question.QuestionFragment$1.onCodeClicked(QuestionFragment.java:67) 09-05 03:09:39.522: E/Crittercism(18318):   at com.stackexchange.marvin.ui.common.PrettyWebView$WebAppInterface.codeClicked(PrettyWebView.java:197) 09-05 03:09:39.522: E/Crittercism(18318):   at android.webkit.WebViewCore.nativeTouchUp(Native Method) 09-05 03:09:39.522: E/Crittercism(18318):   at android.webkit.WebViewCore.nativeTouchUp(Native Method) 09-05 03:09:39.522: E/Crittercism(18318):   at android.webkit.WebViewCore.access$4000(WebViewCore.java:59) 09-05 03:09:39.522: E/Crittercism(18318):   at android.webkit.WebViewCore$EventHub$1.handleMessage(WebViewCore.java:1449) 09-05 03:09:39.522: E/Crittercism(18318):   at android.os.Handler.dispatchMessage(Handler.java:99) 09-05 03:09:39.522: E/Crittercism(18318):   at android.os.Looper.loop(Looper.java:137) 09-05 03:09:39.522: E/Crittercism(18318):   at android.webkit.WebViewCore$WebCoreThread.run(WebViewCore.java:790) 09-05 03:09:39.522: E/Crittercism(18318):   at java.lang.Thread.run(Thread.java:856)


With a film camera it is easy to take infrared photos, just get infrared film.  Is there any way to do this with a standard professional digital camera?  My understanding is that such cameras have a 700-1000nm filter to block infrared light. Can this filter be removed somehow?

I remember taking infrared pictures with a simple filter and black and white film. How can I do something like this with digital cameras? Or is this even possible?


My problem is the following :   I want a reference to another section to be like that :   "See section 3.2"   I tried \textbf{section~ref{section}} but there are two problems :    Only the number of the section is an hyperlink and I want the "section" also to be an hyperlink. This is not automatic ...    How can I do this ?   Thank you.

Inspired by my earlier question , here is another similar question.  There are many different packages for making cross references. Among them , , , , … The  package defines its own cross-referencing command for theorems…  Which collection of packages provides which kind of functionality, and which packages cause conflicts with each other?


First of all I'm trying to disaster scenario for our db. My DB Recovery model is FULL now. And I have full backup. I can do recover from a time point or TransactionID. But I wanna cancel or undo only one TransactionID on SQL Server. How I can do this without third party software? Thanks in advance.

Is it possible to rollback a committed transaction?  I have deleted all the data in a table. The delete statement is inside Begin Transaction and I have committed the transaction with a commit transaction command. Now is it possible to rollback and get the data back?


Below match doesn't work:      import re pattern = re.compile("[\^\/!*\[({%?$]")  param = "f00.*"  if pattern.match(param):     print " I am a regexp" else:     print "non regexp"   But this does:  import re node_pattern = re.search("[\^\/!*\[({%?$]", "f00.*")  print bool(node_pattern)   What's wrong with re.compile()?  Isn't it the valid way to match a string against a regexp?

What is the difference between the search() and match() functions in the ?  I've read the  (), but I never seem to remember it.  I keep having to look it up and re-learn it.  I'm hoping that someone will answer it clearly with examples so that (perhaps) it will stick in my head.  Or at least I'll have a better place to return with my question and it will take less time to re-learn it.


My app craches when i try to update my database it gives me the following problem      attempt to invoke virtual method 'android.database.cursor com.leoni.bd.Gestion_db.FindDate(java.lang.String)' on a null object  reference   i couldn't find the null object i tried many things but it didn't work  ! i need help please !   this is my Gestion_db.java class   private SQLiteDatabase _myDbm;  public Gestion_db(Context pContext) {      SqliteCreator s = new SqliteCreator(pContext, Stat.DB_NAME, null, 1);      _myDbm = s.getWritableDatabase(); }  public void close() {     _myDbm.close(); }  public Cursor FindDate(String Attribute) {         String query = "SELECT * FROM " +Stat.TABLE_NAME +" WHERE ? LIKE '%?%' ";         return _myDbm.rawQuery(query, new String[] {Stat.COL_DATE,Attribute});      }   this is the method from my Controle.java activity wich contain the cursor  //header of the activity  private Gestion_db _myGestionDB; private String _myRecognizedText = null;  // Mise à jour de la base de données quelque soit l'action private void MiseAJour() {      String dateCourante = new SimpleDateFormat("yyyy:MM:dd",Locale.getDefault()).format(new Date());     Boolean existe=false;      Cursor c = _myGestionDB.FindDate(dateCourante);      if (c.getCount() != 0) {          c.moveToFirst();          while (!c.isAfterLast()) {               String ldate = c.getString(c.getColumnIndex(Stat.COL_DATE));             String lMatricule = c.getString(c.getColumnIndex(Stat.COL_TEXTE_OCR));              if (ldate.equals(dateCourante)&& lMatricule.equals(_myRecognizedText)) {                 existe=true;                 break;              }             c.moveToNext();          }        }      if (existe){         UpdateHeure(_myHeure);      }else{         AddVoyage();     }  }   this ic Stat.java class wich contains some Strings  public class Stat { public static final String DB_NAME = "leoni.db"; public static final String URL_CHECK = "http://192.168.1.6/check.php"; public static final String GET_URL = "http://192.168.1.6/getChauffeurs.php"; public static final String COL_ID = "_id";  // Gestion des déplacements public static final String TABLE_NAME = "gestion_des_deplacements"; public static final String COL_TEXTE_OCR = "texte_ocr"; public static final String COL_DATE = "date"; public static final String COL_HEURE_DEPART = "heure_depart"; public static final String COL_HEURE_ARRIVEE = "heure_arrive"; public static final String CREATE_TABLE_DEPLACEMENTS = "CREATE TABLE "         + Stat.TABLE_NAME + " (" + Stat.COL_ID         + " INTEGER PRIMARY KEY autoincrement," + Stat.COL_TEXTE_OCR         + " VARCHAR(40)" + "," + Stat.COL_CHAUFFEUR + " VARCHAR(50)" + ","         + Stat.COL_DATE + " VARCHAR(50)" + "," + Stat.COL_HEURE_DEPART         + " VARCHAR(30)" + "," + Stat.COL_HEURE_ARRIVEE + " VARCHAR(30));";  // Gestion des chauffeurs public static final String COL_MATRICULE = "matricule"; public static final String COL_CHAUFFEUR = "chauffeur";  }

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 had Windows 10 and Ubuntu 14.04 installed in dual boot.  Roughly 125GB each.   After the Windows update the PC only showed me the grub rescue terminal. I could neither use Ubuntu nor use Windows.  I inserted the liveCD and ran boot-repair.  After that Windows appeared normally, but no GRUB and no Ubuntu.  This is what I get when I run sudo fdisk -l:    Ubuntu must be either /dev/sda2 or /dev/sda4, since they are the biggest partitions, but neither of them is recognized as a Linux system.  What should I do?

I installed Windows 7, which ate Ubuntu's boot file. When starting up the computer, it now goes straight to Windows, without giving me the option of booting Ubuntu.   How can I get Ubuntu back?


What if Ginny died in the Chamber of Secrets and Tom was able to come back... Would that mean he would return in his 16 year old self that was preserved within the diary?

As teenager Tom Riddle is speaking to Harry Potter in the Chamber of Secrets, both he and Harry are refering to the real Voldemort in the third person. If Tom Riddle had succeeded in sucking all the life energy out of Ginny and had come back alive, wouldn't that have meant there were two Voldemorts in the world? The wraith one which had lived in Quirrell, and the newly constituted one?  This Tom Riddle clearly doesn't have the memories of the wraith version.   As a bonus: If they both existed, would they have competed against each other?


As the radiation peak of the sun is in the UV region and since at around room temperature materials emit radiation at IR, I wonder why our eyes are not capable of using these wavelengths. I guess there is a reason why we exactly only see the region between these intensity peaks?

Across the electromagnetic spectrum, 400-700 nm is a narrow spectrum of frequencies and focused in the region of short wavelengths. For example, radio waves cover a large range of frequencies unexploited by the visual system. So what biological reason is there that evolved us to use such a small frequency bandwidth for vision?


I've seen conflicting information on this online, but say you have an environment with two domain controllers: one Forest, one Site, one Domain; simple as it gets.  How should each domain controller's NIC be configured with respect to DNS?   Assuming both are running DNS Server, should DC1 should have it's own canonical IP address (i.e. not loopback address) as the primary DNS and the secondary should be DC2? Rinse and repeat for DC2. Seems logical to me. Does this have any impact on replication? I'm assuming forwarders/root hints are irrelevant with respect to Active Directory?

This is a  about Active Directory DNS Settings. Related:     Assuming an environment with multiple domain controllers (assume that they all run DNS as well):  in what order should the DNS servers be listed in the network adapters for each domain controller? Should 127.0.0.1 be used as the primary DNS server for each domain controller? Does it make any difference, if so what versions are affected and how?


If I am commenting and want to reference another user, sometimes when I use @[username], I get a clickable pop-up with their username, other times I do not.  Some Meta questions indicate that @ isn't needed anymore.  Is there old / new / draft guidance on the "correct" way to reference a user in comments?

How do the comment replies (aka "pinging users") work?  Who can I send an @reply to? How do I respond to a specific user when entering my comment? Will they be notified? What do people mean when they talk about "pinging" another user?  Related:


What is the correct usage of however; and however?     I sometimes find myself not really checking my email on a daily basis   but, I do however; find this to be very helpful to keep up with what's   going on. Now that I am in school I will make sure that I check   everyday just to make sure that I stay on top of my work and   schooling.

What is the rule of thumb for using 'however' in the middle of the sentence? For example:         Some people disagree with this theory, however, as it's never been proven right.


I apologize if this is a stupid question, but I cannot find any answers online, so I feel I must ask here.  I do not quite understand exactly what voltage is. I see on batteries, "X Volts", but I do not quite know what that means. I looked online and read sources on volts, amperes, and watts, and it has only confused me more. What exactly is voltage? If it isn't a measure of the electric current, then why is it used on batteries as a measure of their electric power? Why aren't amperes used?

Bit of a strange question, but what is it? My physics teacher said it was kind of like a "push" that pushes electrons around the circuit. Can I have a more complex explanation? Any help is much appreciated.


I have a server and a client connecting using TCP socket. At the client (which is written in C++) I compress a string (str) using the zlib library:  uLongf compressedStringLength = compressBound(str.length()); Bytef* compressedString = new Bytef[compressedStringLength]; const Bytef* originalString = reinterpret_cast<const Bytef*>(str.c_str()); compress(compressedString, &compressedStringLength, originalString, str.length());   Then I send it to the server. This is the line of code where I write the compressed string to the socket:  int bytesWritten = write(sockfd, &compressedString, compressedStringLength);   At the server (which is written in C#) I recieve the stream of the compressed bytes from the socket and decompress it using the DeflateStream class:  NetworkStream stream = getStream(ref server); //server is a TcpListener object which is initialized to null. byte[] bytes = new byte[size]; stream.Read(bytes, 0, size); Stream decompressedStream = Decompress(bytes);   This is the Decompress function:  private static Stream Decompress(byte[] input) {         var output = new MemoryStream();          using (var compressStream = new MemoryStream(input))         using (var decompressor = new DeflateStream(compressStream, CompressionMode.Decompress))         {             decompressor.CopyTo(output);         }          output.Position = 0;         return output;  }   The compressing process and sending the compressed bytes over the socket works, but I get an exception at the line decompressor.CopyTo(output); at the Decompress function above: System.IO.InvalidDataException: Block length does not match with its complement.  Does someone know what the problem is and how can I solve it?  EDIT: I`ve already tried to skip the first two bytes brfore the start of the decompression process.

Are System.IO.Compression.GZipStream or System.IO.Compression.Deflate compatible with zlib compression?


I have samples from a highly skewed dataset about users' participation (e.g.: number of posts), that have different sizes (but not less than 200) and I want to compare their mean. For that, I'm using two-sample unpaired t-tests(and t-tests with the Welch’s factor, when the samples had different variances). As I have heard that, for really large samples, it doesn't matter that the sample are not normal distributed.  My metrics are discrete, they are counts of the number of each user's participation. Of course we have those users who participate much more than the others, but I'm not considering them as outliers. Here are the data description:   My problem: someone, reviewing what I've done, said that the tests I am using were not suitable for my data. They suggested to log-transform my samples before using the t-tests.  I do know that I can't log-transform these, because all of them have zero-values on the samples. My guess is, if I can't use t-test, I should use the Mann Whitney U test.  Are they wrong? Am I wrong? If they are wrong, is there a book or scientific paper which I could cite/show them? If I am wrong, which test should I use?

I have samples from a highly skewed (looking like an exponential distribution) dataset about users' participation (e.g.: number of posts), that have different sizes (but not less than 200) and I want to compare their mean. For that, I'm using two-sample unpaired t-tests(and t-tests with the Welch’s factor, when the samples had different variances). As I have heard that, for really large samples, it doesn't matter that the sample are not normal distributed.  Someone, reviewing what I've done, said that the tests I am using were not suitable for my data. They suggested to log-transform my samples before using the t-tests.  I am a beginner, so it sounds really confusing to me to answer my research questions with "log of participation metric".  Are they wrong? Am I wrong? If they are wrong, is there a book or scientific paper which I could cite/show them? If I am wrong, which test should I use?


Consider $f(x) = 2x$ and $g(x)=4x$. Is there any homeomorphism $h:\mathbb{R}\rightarrow \mathbb{R}$ such that $h\circ f=g\circ h$? Well it means $h(2x)=4h(x)$ but I don't know what to do from here?

Consider $f(x)=mx$ and $g(x) =bx$ in which $m>0$ and $b>0$. Does there exist any homeomorphism $h$ such that $h \circ f$ = $g \circ h$? If exists find the domain of $h$.   Obviously I tried $h(mx)=bh(x)$. But I don't know how to go for solving it! In addition, I have no idea about how to prove homeomorphism existence in such problems.


I'm sorry if this is in the wrong place. I'm an undergraduate majoring in biology. I think, this semester, I'll fail a class on Statistics (the class is titled "Statistics for Life Sciences"). While I have the option this semester to use "Satisfactory/Unsatisfactory" and protect my GPA, this is nonetheless a failure that will show up on my transcript. I know I messed up and I feel really bad... I could have taken an introductory Math class (an option available to those with only an AS Level in Mathematics) before taking this Statistics class and I stupidly chose not to (officially, an AS Level meets the prerequisite for this Statistics class, though most students taking it have a full A Level in Mathematics). But this is no excuse (it's officially allowed, and plenty of AS Math students succeed in this class) and I think in fact reflects worse on my judgement.  :( I fully intend to retake this course (I can't not take it anyway; it's a core class, plus Statistics is important in Biology) and do much better in it. How badly does this hurt my chances at a graduate school program in biology? Assuming my other biology-related classes are okay (A grades). I don't know how I'm going to explain it. I was hoping to take a research Master's, then a PhD. Am I screwed? Thanks for any input and and have a nice day.

I'm currently an M. Phil student in Math and I failed a course last semester because I was not able to hand in a home work assignment (which was worth 40% of my grade) on time (I was 30 minutes late).   Apart from that I'd say I'm a fairly decent student, I got an upper second class honours bachelors degree, I have a B+ and A's for all my other courses in my current programme and I'm almost finished with my first paper to be published.   I've however been deeply worried about this failure as it would reflect poorly on my transcript if I were to apply to a Ph.D or another Master's programme.   Will my failing grade affect my chances of getting into a competitive programme or greatly lower my chances of getting a scholarship?


I am only starting to learn coding. I need to be able to use my custom controller I created for use in a visualforce page in production. I can't get past code coverage failure when I try to deploy from sandbox. I tried all the existing test classes available in production, because I don't know how to create a test class. Below is the code for my controller, please check if there's something wrong with it: public class MyController {  public ApexPages.StandardController sc;  public MyController(ApexPages.StandardController sc) {     this.sc = sc; }  public void quicksave() {     AVTRRT__Job_Applicant__c j = (AVTRRT__Job_Applicant__c) sc.getRecord();     update j.AVTRRT__Contact_Candidate__r; } }

I would like to know the best way to write test methods for controller extension classes that are used by Visualforce.  What is the minimum set code that I need to cover the basic operation of the controller without taking into account any custom functionality that I might add.  Here is my example class with the test method ready to be completed.  public with sharing class myExtension{      private final Account acct;      public myExtension(ApexPages.StandardController stdController){         this.acct = (Account)stdController.getRecord();     }      public static testMethod void testmyExtension(){      } }


How can i open the applications from the folder? Theres an option in mac, where you can access the applications folder and run an app from there. Is there a way in ubuntu?

Under Windows, most applications and application data are stored in a special directory known as C:\Program Files (and occasionally C:\Program Files (x86)). What is the Ubuntu/Linux equivalent to this path? Is there even one?


I tried to install a new Ubuntu Server, but after the installation when I want to configure the network it didn't work using the Interface file. so i tried as per duplicate to set up the network with netplanbut thqt fqils too.  netplan file:  # Let NetworkManager manage all devices on this system network:   version: 2   renderer: networkd   ethernets:     enp3s0:       addresses:         - 193.171.201.236/27       gateway4: 193.171.201.225       nameservers:           search: [pro2future.at, pro2future.eu]           addresses: [140.78.2.62, 140.78.3.62]   How should I proceed?

I've just installed ubuntu server 17.10. During installation, it suggested me to connect to the network through wifi, and so i did. After installation was finished and system was rebooted, computer connected to the wifi automatically (which means, it saved the connection creds somewhere). But in /etc/network/interfaces i found nothing. I need my computer connect to wifi network with static ip, so I've put configuration into the /etc/network/interfaces:  # /etc/network/interfaces -- configuration file for ifup(8), ifdown(8) # Generated by debian-installer.  # The loopback interface auto lo iface lo inet loopback   iface wlp2s0b1 inet static         wpa-driver wext         address 192.168.0.12         netmask 255.255.255.0         gateway 192.168.0.1         wpa-ssid *****         wpa-psk **********         dns-nameservers 8.8.8.8 192.168.0.1 auto wlp2s0b1   When system starts, it doesn't connect using my configuration. It does only after  sudo ifdown wlp2s0b1 && sudo ifup -v wlp2s0b1  and after this command, system getting a SECOND IP! Server is still available by the ip it gets from DHCP, and in the same time, it is available by the static ip!


This morning I went to install an app on one of my Ubuntu machines and found I was locked out by apt.system.daily. This is not in the root cron, so please tell me where it is running from?   root@acer:/home/stephen# apt install htop  E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)  E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?   I found this interesting because I have purged update-manager. I like to take care of updates on my own. So then looking into it I find this :  root@acer:/home/stephen# ps -ef | grep apt root     23463     1  0 06:23 ?        00:00:00 /bin/sh  /usr/lib/apt/apt.systemd.daily install root     23468 23463  0 06:23 ?        00:00:00 /bin/sh  /usr/lib/apt/apt.systemd.daily lock_is_held install

I am trying to understand how automatic upgrades are happening through the unattended-upgrades package. What is described below is what I found on a fresh install of Ubuntu 16.04.3.  /etc/cron.daily/apt-compat has a line exec /usr/lib/apt/apt.systemd.daily at the end which executes the script apt.systemd.daily.  systemd also executes /usr/lib/apt/apt.systemd.daily and it uses a timer. The systemd service definition doing the update can be found in /lib/systemd/system/apt-daily.service. It calls the script apt.systemd.daily with the argument update while the systemd service definition in /lib/systemd/system/apt-daily-upgrade.service calls the same script with the argument install.  As I understand, /usr/lib/apt/apt.systemd.daily is the script used by unattended-upgrades package to do the automatic upgrades. What  I would like to know is why do both cron and systemd execute it?


So we have many issues with the sub-domain that we are using with the marketing cloud. One of them is: If we want to reply to the emails from Outlook, we get an error message that says:  Undelivarable and the content is: reply-fecc157376670c7c-2139_HTML-104564539-100025066-1 wasn't found at hello.ourSubdomain.com.  Also every time a client replies to one of our emails, @hello.ourSubdomain.com is getting appended at the end of their actual email address. We did whitelist our IP address and this was resolved for 2 days. But later, we started getting the same errors.  marketing-cloud


Question Is there any way for the general public to get access to Ubuntu pre-release/beta ISOs or tarballs for testing?  Background I currently help maintain a Linux product, and the bulk of our customers currently use Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. When the next 17.04 and 18.04 LTS releases come out, I would like to be able to test on them before it's released to the general public so that I can confirm that my product works on the latest release. Since I use Gtk and upgrades for it aren't usually backwards compatible (different library version labels), I have to recompile a new version for new distros.  Problem My current issue is that the second a new release of Ubuntu comes out, customers download and install it, test my product on it, then complain that my product is "broken". It would be very helpful to be able to pro-actively handle/test such issues before they arise.  Work Done I've gone through the support forums and the r, but cannot find any info on acquiring/testing pre-releases. Thank you.

I'd love to test the latest Ubuntu alpha/beta (otherwise known as "Ubuntu+1"), but I can't find it.   Where can I find download for the pre-releases of Ubuntu?


I'm using windows 7 and/or 8 64 bit with QGiS 2.01.  I'm wanting to us the pyQGiS tools in a custom python application outside of the QGiS environment (i.e by running a python executable located in C:/Python27.  To do this I have been following the instructions posted at   For the first step (to remove the error "ImportError: No module named qgis.core") i set my pythonpath to "C:\Program Files\QGIS Dufour\apps\qgis\python"  As expected I now get an error: File "C:\Program Files\QGIS Dufour\apps\qgis\python\qgis__init__.py", line 26, in      import sip ImportError: DLL load failed: The specified module could not be found.  The instructions say to add "the directories where the QGIS libraries reside".  I have tried adding a number of paths, with no success.  I also cannot locate the sip.dll file anywhere within the C:\Program Files\QGIS Dufour directory.     Does anyone know which paths I need to set?

First of all, I'm using Python 2.7.3, QGIS 1.8 (Lisboa) on Windows 7 pro 64 bits.  Now let's go to the actual question:  I have written some code (Python) that works well within the QGIS built in Python console, but now I need to run it from outside QGIS (it is too much to ask for the final user to open QGIS, then the python console and to copy and paste the code).  I have been trying to access the QGIS API, but it is missing from my PYTHONPATH. I've tried whatever is on the instructions, plus a bunch of paths like:  C:\Program Files(x86)\QGIS\apps\qgis\python\qgis and  C:\Program Files(x86)\QGIS\apps\qgis\python. My result so far is always the same:  import qgis.core ImportError: No module named qgis.core   Any ideas?


Strangely, using {\color{}} in \lfoot{} is causing my footer parts to misalign.  This code  \documentclass[11pt,a4paper]{article}   \usepackage{fancyhdr} \usepackage[pdftex]{color,graphicx}  \pagestyle{fancy}  \lhead{} \chead{} \rhead{}  %%% \lfoot{{\color{blue}Build}} %%%  \cfoot{\textcolor{blue}{P.\thepage}} \rfoot{} \renewcommand{\headrulewidth}{0pt} \renewcommand{\footrulewidth}{0pt}  \title{Yep.}  \begin{document}      \maketitle     \thispagestyle{fancy}      \section{Blarg} \end{document}   Produces...

this TeX-source  \documentclass[a4paper,12pt]{book} \usepackage[usenames,dvipsnames,svgnames,table,x11names]{xcolor} \usepackage{fancyhdr} \pagestyle{fancy} \fancyhead[LO,RE]{} \fancyhead[LE,RO]{{\large{}\color{DarkRed}\rightmark}} \fancyfoot[C]{\thepage} \fancyfoot[LE,RO]{\color{DarkRed}\large{}\leftmark} \fancyfoot[LO,RE]{xxx} \renewcommand{\headrulewidth}{0.14mm} \renewcommand{\footrulewidth}{0.14mm} \setlength\headheight{6mm}  \begin{document} \markboth{A}{B}  Yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda yadda ...  \end{document}   when compiled with XeLaTeX, will cause this output:    as you can see, the red A is not properly aligned with the rest of the footer. naturally i first assumed that was because of the font size, but, surprisingly, changing  \fancyfoot[LE,RO]{\color{DarkRed}\large{}\leftmark}   to  \fancyfoot[LE,RO]{\large{}\leftmark}   gives me not only (naturally) a black A, but also a properly aligned one:    any hints why that should be so? any fixes?


I have a computer with windows OS and i would create an app for AppleStore. I must have a computer with apple's OS or can i program with windows?

Is there any way to tinker with the iPhone SDK on a Windows machine? Are there plans for an iPhone SDK version for Windows?  The only other way I can think of doing this is to run a Mac VM image on a VMWare server running on Windows, although I'm not too sure how legal this is.


What is Golden Ratio? how do we use it during interface designing?

is just one example of an article promoting use of the golden ratio in design. Over the past few years I've seen quite a few similar articles, but none of them really seem to go into depth beyond just explaining what the golden ratio is. I've been able to find very  that test it and it seems as if the results are inconclusive.   Here are some more web design articles advocating the golden ratio:             Unfortunately, even though the articles above are from some of the more popular design blogs online, not one of them even cites a study. Only  seems to be even questioning its use, but he only questions it for the medium of the web.  At the risk of going against the grain of the design community, is there any objective evidence that the golden ratio actually improves design? Are there any split test studies comparing the effectiveness of a website design based on the golden ratio versus one that isn't? And if, in fact, the golden ratio in design is proved to be more effective, why is that the case? Are there greater principles that we can pull from it that can be applied in different ways? Are there are other golden ratios?


I have this code for creating custom post type  add_action( 'init', 'create_sidebarone' );  function create_sidebarone() {     register_post_type( 'sidebarone',         array(             'labels' => array(                 'name' => 'Sidebar One',                 'singular_name' => 'sidebarone',                 'add_new' => 'Add New',                 'add_new_item' => 'Add Sidebar One',                 'edit' => 'Edit',                 'edit_item' => 'Edit Sidebar One',                 'new_item' => 'New Sidebar One',                 'view' => 'View',                 'view_item' => 'View Sidebar One',                 'search_items' => 'Search Sidebar One',                 'not_found' => 'No Sidebar One found',                 'not_found_in_trash' => 'No Sidebar One found in Trash',                 'parent' => 'Parent Sidebar One'             ),             'public' => true,             'menu_position' => 15,             'supports' => array( 'title', 'editor', 'comments', 'thumbnail' ),             'taxonomies' => array( '' ),             'menu_icon' => get_template_directory_uri() . '/images/ggicon.png',             'has_archive' => true         )     ); }   Now I want to achieve something to cater my needs, I want to create a custom admin screen or setting page for my custom post type, to be precise please refer to the image below:  This is the illustration of the custom post type that i've created from the code above   Now, I want to customize the admin screen or the setting screen of that post type, like the image below:   Now as you can see, the admin screen or the setting screen of that post type has been customize. (the second image is an assume of what im trying to achieve, image edited)  So far, what i tried is the post type base from the first image from the codes above. Anyone, im open in any suggestion, recommendations and idea's. Very much thank you in advance.

Most plugins try to hide the components of the edit.php screen on wp admin and replace it with meta boxes to create the needed layout and fields for the custom post type.  But this means that there is still unnecessary code on that edit.php page not used and increases the page load. Also, Not everything can be done using meta boxes.  Is there is a way where i can create my own edit.php page from scratch for my custom post type? maybe hide the custom post type UI and make a new admin page and use it to insert the custom posts or update it? is this possible on admin pages?


Is there a way to discover the date a schema was last modified? I'm trying to decide if a schema's still being updated and is therefore "active" in my system.  I use PostgreSQL 9.2 under Linux CentOS release 6.4

I'm trying to get when my table was modified by checking its file modification date as it is described in . But the result is not always correct. The file modification date updates in several minute after I update my table. Is it correct behaviour? Does PostgreSQL store table modifications in some cache and then flush it to the hard drive?   So, how do I get the correct last modification date of a table (let's assume that auto vacuum modifications are ok too)?  I use PostgreSQL 9.2 under Linux Centos 6.2 x64.


There is no way to find the square root of a negative number. It just doesn't work. So the answer to the impossible question, "What number squared equals a negative number?" is just said to be $i$, an imaginary number.   So now let's look at a different problem. What is one divided by zero? Of course, you can't answer that question. It doesn't make any sense. Splitting up a chocolate bar to a group of 0 friends isn't possible. It's like being told to walk north when standing on the north pole. So, what if just like $i$, we just say $1/0$ is an imaginary number, referenced by the letter $o$?  What applications would this have? Does it even work? The number $i$ has real life applications, but it can also be used to create abstract designs like the Mandelbrot Set. Could $o$ even be used for an abstract purpose?

Before, the concept of imaginary numbers, the number $i = \sqrt{-1}$ was shown to have no solution among the numbers that we had. So we declared $i$ to be a new type of number. How come we don't do the same for other "impossible" equations, such as $x = x + 1$, or $x = 1/0$?  Edit: OK, a lot of people have said that a number $x$ such that $x = x + 1$ would break the rule that $0 \neq 1$. However, let's look at the extension from whole numbers to include negative numbers (yes, I said that I wasn't going to include this) by defining $-1$ to be the number such that $-1 + 1 = 0$. Note that this breaks the "rule" that "if $x \leq y$, then $ax \leq ay$", which was true for all $a, x, y$ before the introduction of negative numbers. So I'm not convinced that "That would break some obvious truth about all numbers" is necessarily an argument against this sort of thing.


the rapper, stars in  as one of the main characters. However, his name is under "and" in the opening credits. Why is that? Is it because he is also a rapper? I am curious to know.

I've always been curious what decides if a credit is in the opening or closing credits.  It seems loosely that cast (in order of today's "big name" significance), directors and financiers get the front spots, and everything else appears later.  But lately I've been developing some specific curiosities about how cast members are credited on TV shows.  Opening credits seem to follow this rough outline:  Part of "opening credits" video segment   (optional) Major Actors Show Title Core Cast Actors Directors Producers (optional) Episode Title Episode Writers   Subtitles over beginning of show, after opening video   (Episode Title and Writers may appear here, instead) Special Guest Actors   I've probably missed a few things, and mis-ordered a few things.  But, as I said, my main curiosity is about actor credits.  Typically, there is little indication of which characters the core cast actors play.  Sometimes their name is edited to appear along with an image of the character as an indictator, but sometimes there is no indication.  As I've never seen anyone credited in both the opening and closing credits, that leaves the potential for core actors to never be directly associated with their character.  This seems potentially problematic; is there a reason for this?  Are viewers expected to know who's who?  Guest actors sometimes are simply credited by name (and not being part of the opening video, this means they will never be associated with their character in credits).  But often they are credited as "special guest as character name".  This is quite helpful.  The thing I find really confusing is, sometimes the last few regular cast actors will get the guest actor treatment.  I've seen opening video with "and actor as character" paired with an image of that character for an entire season.  Why does this actor get special treatment?  Finally, sometimes guest actors will be credited at the front following the opening video, sometimes they'll be credited in the closing credits.  Are there rules for deciding who get's credited early or late?  I've sometimes wondered if shows deliberately play with actor's name position to obfuscate plot arcs ("you won't think we're killing of this character if their actor is still in the opening credits", or "you won't expect this recurring guest if we place their name in the closing credits") and I've also wondered if there are thresholds for "people appearing in XX number or YY percentage of episodes get placed here."  But it's difficult to build a good sampling base for this.  And season 7 of Stargate SG-1 kinda took a shotgun to my guesses so far.  So...  Are there rules?


The quote in question is one from Shakespeare's Othello, Iago says “I am not what I am” (I.i.71), it references, but alters the words of God in Exodus 3:14, “I am that/who I am”. Is there a name for this kind of language or a literary device of some kind? Where the author takes a popular or famous quote and alters it change the meaning, while still referencing back to the original?

I didn't know how to phrase my title to make it meaningful to anyone, and I can't really explain it now, so I shall use an example:  The opening phrase on the DSGB website is "It's counting, Jim, but not as we know it". This comes from the Star Trek quote "It's life, Jim, but not as we know it". What is it called when someone does this (mainly for comedic effect)?


How can I prove:  If $$a_0=\alpha>0\quad and\quad a_{n+1}=a_n + \frac{1}{a_n}$$, then $$a_n^2<\alpha^2+2n+\frac{1}{\alpha^2}+\frac{1}{2}ln\left ( \frac{2n}{\alpha^2}+1 \right )$$ ?  I'll really appreciate your help. Thanks.

Today, we had a math class, where we had to show, that $a_{100} > 14$ for  $$a_0 = 1;\qquad a_{n+1} = a_n + a_n^{-1}$$  Apart from this task, I asked myself: Is there a closed form for this sequence? Since I didn't find an answer by myself, can somebody tell me, whether such a closed form exists, and if yes what it is?


BACKSTORY  I read today newspaper and made discovery of planet Cygnus (in news paper of course :v) that human can live there! The distance is 1400 Lightyear. Assuming I travel with the world fastest rocket in the planet earth how many days / year would it take me to travel (and rule da planet :v) If that is possible I will surely want to be an astronauts! Yay :v if its not I will consider what would I become.. XD   AND  I have read something about 'TIME DILUTION' that can make me survive the 'TRANSPORTATION'  Heading  The question is how long is it to be exact in my iOS (and bricked android) timer app? Well with that said, non-nerd will understand what kind of time I am asking here.. :v

Suppose I wanted to travel to one of the recently discovered potentially Earth-like planets such as Kepler 186f that is 490 light years away. Assuming I had a powerful rocket and enough fuel, how long would it take me?


When I'm opening a PDF-file in macOS Preview I got some annoying white borders in full-screen mode. Does anybody know how I can get rid of this annoying borders?  It's about the borders you see at the bottom and on the right, there's no scrolling needed they're still there.

Whenever I have a sprite frame, and I open it in Preview app, I can't see the exact edges of the image because the background of an image is transparent. Therefore, I can't see if there is any padding around it. Is it possible to turn on image borders in Preview app?


Hello although this question has been asked several times, I still can't position my figures at the right place. I have installed the float and the here packages. and the code is as follow:  \begin{figure}[H] \centering \includegraphics[scale=0.7]{pictures/pic.png} \caption{The Pulse Co-Oxymetrie} \label{fig: Massimo} \end{figure}    even though there is more than enough space left for the image,a new page is created and the figure goes at the top of this new page,while the caption stays at the bottom meaning I have a lot of blank spaces in my thesis.

How to influence the position of float environments like figure and table in LaTeX?   This is a general question and should collect useful answers for all users. I hope we can use this as a reference


How to disallow one domain path in robots.txt? (there is a module which allows to do that but it is better to avoid it because of performance issues) For example, onedomain.com/path1/* must be disallowed. Is it right to type like this in robots.txt (there is another domain twodomain.com for the same website):  Disallow: onedomain.com/path1/*  Twodomain path must be allowed to be crawled and Onedomain path must be disallowed to be crawled (both of them are pointing to the same path).

Is it possible to exclude a domain name in robots.txt?  I have a single Drupal site with multiple domains pointing on it. For example our dev and staging server are being crawled by Google when our .htaccess password protection is disabled.  I don't intent to block any access in our development server but to tell search engine bots to stop indexing all the contents when the domain is/are dev or staging.   Basically I am seeing some of the links pointing in dev servers when I search some of my content in Google.  Is there any way or any module that could handle this?  EDIT:  Here's how I ended. Inside theme_preprocess_html().  // Avoid search engines to index dev and stage domains.   $restricted_domains = array('dev.mydomain.com', 'stage.mydomain.com', 'editorial.mydomain.com');    if (in_array($_SERVER['HTTP_HOST'], $restricted_domains)) {     $meta_robot = array(       '#tag' => 'meta',       '#attributes' => array(         'name' => 'robots',         'content' => 'noindex, nofollow'       ),     );     drupal_add_html_head($meta_robot);   }


I am having a sort of confusion, whether which of the following statements is/are correct:  "How can I get to watch  a movie for free?"   Or  "How do I get to watch  a movie for free?"

Is it better to say "How do I do something?" or "How can I do something?"


I have Linux mint 14 in my computer.How do I install Ubuntu 14.04 without removing Linux mint and its data? I just need both OS for study purpose.

Just as the question says, I need to install newer version of Ubuntu without messing up the older version. I have looked at the responses to similar questions but it isn't clear to me how to do so (some suggest dual boot using a second hdd and some suggest using virtualization -- both of these are not an option for me).


Adding a text that has the unicode "\u000b" will throw an error when you open the saved docx. I am using docx4j-JAXB-Internal 8.1.6. The same issues occurs with "\u000c" so I assumed it happens with all Control Characters. At the moment I am simply removing them with:         String removeControlCharacters = this.content.replaceAll("\\p{Cc}", "");  and then adding it a Text and it works fine. I am wondering if anyone else has had this issue and what the best way to resolve it is.

The list of valid XML characters is well known, as defined by the spec it's:  #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]   My question is whether or not it's possible to make a PCRE regular expression for this (or its inverse) without actually hard-coding the codepoints, by using Unicode general categories. An inverse might be something like [\p{Cc}\p{Cs}\p{Cn}], except that improperly covers linefeeds and tabs and misses some other invalid characters.


Two days ago I tried to download skype and it says an error occurred it says   end of central directory signature not found  Either this file is not   a zipfile, or it constitutes one disk of a multi-part archive.  In the   latter case the central directory and zipfile comment will be found on   the last disk(s) of this archive.  zipinfo:   cannot find zipfile directory in one of /home/maria/Downloads/SkypeSetup-aoc-jd.exe   or  /home/maria/Downloads/SkypeSetup-aoc-jd.exe.zip, and cannot find /home/maria/Downloads/SkypeSetup-aoc-jd.exe.ZIP   pe...  this happens whenever I try to download anything like games and also i can't watch videoss it's looking for plug ins but it doesn't find them i hate this

Can .exe and .msi files (Windows software) be installed in Ubuntu?


I've tried solving $\sqrt[3]{3} =a + b* \sqrt[3]{2}+c* \sqrt[3]{4}$, but there is no obvious contradiction, even when taking the norms/traces of both sides. I can't think of another approach.  This is part of a proof, it seems obvious, but it's really bothersome I can't prove it.

We all know that $\sqrt[3]{3}\not\in \mathbb{Q}({\sqrt[3]{2}})$ intuitively. We even know that $\sqrt[3]{p}\not\in \mathbb{Q}(\sqrt[3]{q})$ for two distinct primes $p, q$. However, I don't know how to prove these things rigorously. In case of $\sqrt{p}\not\in \mathbb{Q}(\sqrt{q})$, we can just set assume $\sqrt{p}=a+b\sqrt{q}$ for some $a, b\in\mathbb{Q}$ and deduce a contradiction. However, in cubic case, expansion of $(a+b\sqrt[3]{2}+c\sqrt[3]{4})^{3}$ is very complicated and even I expand this I couldn't get any contradiction by this.  To be specific, it gives us 3 diophantine equations  $$a^{3}+2b^{3}+4c^{3}+12abc=3$$ $$a^{2}b+2b^{2}c+2c^{2}a=0$$ $$ab^{2}+2bc^{2}+ca^{2}=0$$  and I don't know how to check solvability of this kind of diophantine equations (over $\mathbb{Q}$). Even if there exists a way to check solvability, I cannot convince that it can be used to prove $\sqrt[3]{p}\not\in \mathbb{Q}(\sqrt[3]{q})$.   So I tried to use Galois theory, but actually I don't know where to go. I assumed $\mathbb{Q}(\sqrt[3]{3})=\mathbb{Q}(\sqrt[3]{2})$ and take a Galois closure, i.e. $K=\mathbb{Q}(\sqrt[3]{3}, w)=\mathbb{Q}(\sqrt[3]{2}, w)$ where $w^{3}=1$ then tried to use field norm maps. We can check that $\beta=\sqrt[3]{3}\cdot\sigma(\sqrt[3]{3})\cdot\sigma^{2}(\sqrt[3]{3})\in \mathbb{Q}$ when $\sigma\in Gal(K/\mathbb{Q}), \sigma(\sqrt[3]{2})=\sqrt[3]{2}, \sigma(w)=w^{2}$. But I cannot get any information from this.   Edit : It would be great if there is a simple algorithm to check whether $\alpha\in K$ or not for a given algebraic number $\alpha$ and a number field $K$.


I have LAS files with code 0 - never classified. I have no other classes other than this.   How do I assign class codes for my LAS file?

I want to load approximately 10 large LiDAR tiles for analysis. I have tried using ArcScene but it appears there is a limit on how much data ArcScene can handle at one time. Each tile is 65-90MB in size. The only returns that I am using (and that are available) are ground returns.  My computer has 8GB ram, an amd 6 core processor, and a really good video card. I am fairly certain that it is more than sufficient to handle large amounts of data.    I am not against using something other than an ESRI product to complete this task. What are other options to visualize multiple large LiDAR tiles?    For visualizing LiDAR/point cloid data in web browsers, see


Any one please suggest commands to install PHP 5.4 instead of PHP 5.5 that comes default with Ubuntu server 14.04  For some compatibility issues i want to install PHP 5.4 not 5.5. I have a fresh server with nothing installed as of now.  Thanks.

I am trying to update to install PHP 5.5, 5.6 or 7.0 in Ubuntu 12.04/14.04/16.04 LTS, and I can only get PHP 5.3.10 for Ubuntu 12.04, PHP 5.5.9 for Ubuntu 14.04 or PHP 7.0.4 for Ubuntu 16.04 using official repositories (using apt-get).  I'm not really sure how to do a manual update – as I need:   to play around with the new(est) PHP features to install older PHP version due support in the software


Is this acceptable to say the following:     I am working on a project in my company   Will 'for' keep the same meaning?   How about 'at'?   Is there any rule of thumb to make such choices more easily?  I looked at   but I have a feeling that my case is slightly different. Because here we have an additional noun before "company". I understand that saying: "I work at XYZ" is preferred but what if we have something else coming before? If somebody is working on a project, is he working for or at company?

Which is the correct way to tell where I'm working?        I'm working in XYZ company.   I'm working for XYZ company.   I'm working at XYZ company.      Or is there any difference in the meaning?


So this is the code:  class Program {     static void Main(string[] args)     {         Type T = Type.GetType("CSharpLearningPurposes.Program");          PropertyInfo[] properties = T.GetProperties();          foreach (PropertyInfo property in properties)         {             Console.WriteLine(property.PropertyType.Name);         }      } }   More specifically, the question is about this line of the code: Console.WriteLine(propert.PropertyType.Name);  You see here that I access property.PropertyType okay I understand that I am accessing the object's member but I don't understand this: property.PropertyType.Name  What's that doing exactly? Can anybody explain me?

This is for .NET. IgnoreCase is set and MultiLine is NOT set.  Usually I'm decent at regex, maybe I'm running low on caffeine...  Users are allowed to enter HTML-encoded entities (<lt;, <amp;, etc.), and to use the following HTML tags:  u, i, b, h3, h4, br, a, img   Self-closing <br/> and <img/> are allowed, with or without the extra space, but are not required.  I want to:   Strip all starting and ending HTML tags other than those listed above.  Remove attributes from the remaining tags, except anchors can have an href.   My search pattern (replaced with an empty string) so far:  <(?!i|b|h3|h4|a|img|/i|/b|/h3|/h4|/a|/img)[^>]+>   This seems to be stripping all but the start and end tags I want, but there are three problems:   Having to include the end tag version of each allowed tag is ugly. The attributes survive. Can this happen in a single replacement? Tags starting with the allowed tag names slip through. E.g., "<abbrev>" and "<iframe>".   The following suggested pattern does not strip out tags that have no attributes.  </?(?!i|b|h3|h4|a|img)\b[^>]*>   As mentioned below, ">" is legal in an attribute value, but it's safe to say I won't support that. Also, there will be no CDATA blocks, etc. to worry about. Just a little HTML.  Loophole's answer is the best one so far, thanks! Here's his pattern (hoping the PRE works better for me):  static string SanitizeHtml(string html) {     string acceptable = "script|link|title";     string stringPattern = @"</?(?(?=" + acceptable + @")notag|[a-zA-Z0-9]+)(?:\s[a-zA-Z0-9\-]+=?(?:([""']?).*?\1?)?)*\s*/?>";     return Regex.Replace(html, stringPattern, "sausage"); }   Some small tweaks I think could still be made to this answer:   I think this could be modified to capture simple HTML comments (those that do not themselves contain tags) by adding "!--" to the "acceptable" variable and making a small change to the end of the expression to allow for an optional trailing "\s--". I think this would break if there are multiple whitespace characters between attributes (example: heavily-formatted HTML with line breaks and tabs between attributes).   Edit 2009-07-23: Here's the final solution I went with (in VB.NET):   Dim AcceptableTags As String = "i|b|u|sup|sub|ol|ul|li|br|h2|h3|h4|h5|span|div|p|a|img|blockquote"  Dim WhiteListPattern As String = "</?(?(?=" & AcceptableTags & _       ")notag|[a-zA-Z0-9]+)(?:\s[a-zA-Z0-9\-]+=?(?:([""']?).*?\1?)?)*\s*/?>"  html = Regex.Replace(html, WhiteListPattern, "", RegExOptions.Compiled)   The caveat is that the HREF attribute of A tags still gets scrubbed, which is not ideal.


I had seen many answers to install MySQL. I had tried everything. It shows: There's no MySQL already installed Unable to locate package MySQL-server For synaptic, there's no keyword found Unable to connect to 172.17.0.1:3128 if I try update.  Am sick of all the errors.  Can anyone guide me from the beginning to install MySQL ?? Please asap since it's urgent ! :) Thanks in advance !

I tried mysql in my command line :   I get:  The program 'mysql' is currently not installed.  You can install it by typing: sudo apt-get install mysql-client-core-5.5   But when I do:  sudo apt-get install mysql-client-core-5.5   But I get:  Reading package lists... Done Building dependency tree        Reading state information... Done mysql-client-core-5.5 is already the newest version. 0 upgraded, 0 newly installed, 0 to remove and 47 not upgraded.   How should I proceed?


Slightly related:  Related:   My  currently syncs with my "oldest profile", which is Physics.SE. Unfortunately, this means that the physics-specific blurb out there is shown to everyone. Also, whenever I create a new account, . I had filled in all my details and the one-line bio on Physics and used "copy to all SE accounts". Then I later filled in the Physics-specific bio. It seems that the site the profile was all-site copied from is kept in memory, and new sites just copy from the current version of that site. I'd like a more intuitive and easy way to manage these profiles. I know profiles aren't a big deal, but currently I have a bunch of Physics-y stuff all over the place. And it's annoying.  Also, one important part of a bio is the expertise level, and that's obviously different for each site. Could we have a better way to manage these profile bios? One idea I could toss out is this: Have a centralized place to manage these bios. Maybe, just have a single text box with something like this: SE.com bio here   <!-- Site:stackoverflow--> <!-- summary: SO summary here --> SO bio here  <!-- Site:physics--> <!-- summary: Phy summary here --> Phy bio here . . . . <!-- Site: alltherest --> <!-- summary: General summary for all the sites not listed above --> Bio for all the sites not listed above  Whenever you save this, the relevant bios are sliced out and copied to each site. I feel that this will be way better than the "copy to all sites".  Update: now that profile images can be uploaded independent of gravatar, we should be able to selectively sync these across sites as well.

I tend to put information on my profiles that's relevant for that particular site.  For example, my profile on Stack Overflow says what languages and technologies I'm familiar with and currently working in, my profiles on ELU and ELL say that I'm a native speaker of English and what dialects, my profile on Pets says what pets I keep and have kept in the past, etc. On sites where there's nothing specific relevant, I leave it blank.  My network profile syncs with my oldest site, which is Stack Overflow. But it just doesn't make any sense for me to have information about programming-specific stuff on the network profile.  It's already been asked , but since there has been no answer in nearly a year, I assume it's not possible. (Further,  to another question says that there is no way to leave the global one blank.)  So I'm requesting it.  Ways it could be done (in descending order of helpfulness):   Allow network profile to be edited independently (already requested ) Allow users to change which site gets synced from Allow users to delete their "about me" on the network profile   The first would be best, but it's already been suggested and not much done about it. The others would at least allow slightly more control.   is also related, but it's talking about manual sync, not automatic sync.