Suppose we have a simple discharge tube with two electrodes connected externally through ammeter and battery and evacuated internally.Now we shine radiation of suitable frequency on emmitter so that electrons are emmitted and photocurrent flows.Now my doubt, is the current flowing in external circuit measured by ammeter the same as that flows in the vacuum between the two electrodes due to photoelectric effect?Suppose 100 electrons are emitted per second from emitter plate.Will 100 electrons pass through any cross-sectional area in between the two electrodes and is the expression I=neAv valid for photocurrent?

Consider a Photoelectric effect experiment apparatus as shown in Figure 11.1    The variation of photocurrent with the voltage applied across $\mathrm{A}$ and $\mathrm{C}$ is as shown in Figure 11.3.    My question –     Why is the current non-zero even if the voltage is zero?    Consider a situation in which the voltage across the plates is zero. Photons of sufficient frequency strike the outermost surface of the cathode, emitter plate $\mathrm{C}$. Electrons become free from the attraction of nucleus as their net energy becomes positive.  Why I think that there should be no net current?  As soon as photons strike the outermost surface of the cathode(assumed to be $1$ to $10$ atomic diameters thick), electrons become free. Now, as the electrons have kinetic energy, they'll come out of that outermost surface. Now, the electrons(with kinetic energy) should have an equal probability of going in every direction of the surface. So, around half of the electrons should go in the right direction towards the anode and strike it and half should go to the left, trying to penetrate the inner surfaces of the cathode plate.   Now, the electrons which will go to the right will face some field due to the space charge present in the tube but nevertheless, some electrons will definitely reach the anode plate. After they strike with the anode plate, they'll face some resistance but still, some electrons will reach the low resistance copper wires connected to the anode plate and milliammeter.  Now, consider the electrons which go towards left. They'll definitely face resistance from cathode plate but some will still reach the copper wire.  Now, as there is no potential difference applied between $\mathrm{A}$ and $\mathrm{C}$, there is no need of commutator and voltmeter. So, the ammeter is connected in series with the anode plates and cathode plates with copper wires.  Now, if there is steady state current in the circuit, electrons emitted to any one of the sides should dominate over the other. But the number of electrons emitted on both the sides is same, and all the electrons should face the same resistance as the current(electrons) should flow in a closed loop. But if the number and velocity of electrons coming from both the sides are same, there should be no net current. But there is. Why?  Edit –  From the answers of anna v and mmainville, it can be seen that the emission of electrons is dependent on the angle of emission of light.  But still, the question remains. If the electrons emitted towards anode have enough energy to complete the circuit and again reach the holes in cathode despite the resistance in between, the electrons emitted to the left should have enough energy to come to anode plate via copper wires and again get ejected through anode plate by the virtue of their kinetic energy and reach the cathode plate. In this case too, the current should be zero which is not true. Why?


I do not understand why not works my programm.  I get  only this [I@6af62373 I know it's a very simple problem but I have no Idea.  if someone speaks german can answer me to german.  public class InsertSort {     public static void main(String[] args){     int [] myAr = {8, 9, 7, 5, 6, 4, 3, 2, 1};      for(int i = 0; i < myAr.length; i++){         System.out.println(sort(myAr));     }  }   public static  int[] sort(int[] myAr){          int m,j;         for (int i = 1; i < myAr.length; i++){               j = i;               m = myAr[i];               while (j > 0 && myAr[j-1] > m) {                      /*verschiebe myAr[j-1] nach rechts */                       myAr[j] = myAr[j-1];                       j--;                }                myAr[j] = m;                }     return  myAr;   } }

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


I am confused, Classical wave theory says that Intensity of the light(wave) is the proportional to square of the amplitude. How intensity is proportional to the square of the amplitude?

I often see $I(t)\propto |E(t)|^2$. What is the exact form ? Which constants are missing to make this an equality and why are they so often omitted ?


i am using ubuntu 18. Its getting stuck or freezed very often. i do force shutdown to get out of this issue. can somebody help me to sort this out

All operating systems freeze sometimes, and Ubuntu is no exception. What should I do to regain control when...   just one program stops responding? nothing at all responds to mouse clicks or key presses? the mouse stops moving entirely? I have an    In what order should I try various solutions before deciding to pull the power plug?  What should I do when starting up Ubuntu fails?  Is there a diagnostic procedure I can follow?


How is this issue dealt with, in practice?

I'm training a neural network and the training loss decreases, but the validation loss doesn't, or it decreases much less than what I would expect, based on references or experiments with very similar architectures and data. How can I fix this?    As for question        to which this question is inspired, the question is intentionally left general so that other questions about how to reduce the generalization error of a neural network down to a level which has been proved to be attainable, can be closed as duplicates of this one.  See also dedicated thread on Meta:


Since today, when I go to stackexchange.com and click the login button, I am being redirected to the login at meta.stackexchange.com.  When I login there, I am again being redirected to the main stackexchange.com site. This is new, why was it added?

As of today,  and  no longer have separate login and signup pages. When you log in or sign up on either site you will be sent  through meta.stackexchange.com flow. Currently,  is still on the internet, but we are in the process of completely removing it.  As a part of our removal of OpenID. Learn more here:


I've installed fresh Ubuntu 14.04 on Dell Lattitude E6440 and i've encountered two strange issues when doing full system start/restart: - mouse scroll when full restart is working very fast. One turn of the wheel cause very large change of value (window scroll, sound change etc.) But when i suspend and resume laptop it starts working correctly (one turn of the wheel and small change of value - the same as in previous versions of Ubuntu) - sound from speakers - the same issue. When full restart the sound does not come from internal laptop speakers. It works though through headphones. After suspend/resume internal speakers starts to work.  What can be a cause of these issues ?

I have done a clean Natty install having bought a new SSD and find that in applications (ahem) such as Minecraft, and in the default web browser Firefox, the mouse scrolls too far .  So for example in Minecraft the mouse wheel jumps multiple items rather than one with each mouse wheel roll. With Firefox the page leaps quite a distance with each mouse wheel roll.  Any ideas where I might adjust this?


I want to login in different machine in the network and copy a file from that machine to my machine.I want to do this using python.Any idea how can i do this .I have python 2.5 a nd ubuntu 8.10

What's the most pythonic way to scp a file in Python?  The only route I'm aware of is   os.system('scp "%s" "%s:%s"' % (localfile, remotehost, remotefile) )   which is a hack, and which doesn't work outside Linux-like systems, and which needs help from the Pexpect module to avoid password prompts unless you already have passwordless SSH set up to the remote host.  I'm aware of Twisted's conch, but I'd prefer to avoid implementing scp myself via low-level ssh modules.  I'm aware of paramiko, a Python module that supports SSH and SFTP; but it doesn't support SCP.  Background: I'm connecting to a router which doesn't support SFTP but does support SSH/SCP, so SFTP isn't an option.  EDIT: This is a duplicate of .  However, that question doesn't give an scp-specific answer that deals with keys from within Python.  I'm hoping for a way to run code kind of like  import scp  client = scp.Client(host=host, user=user, keyfile=keyfile) # or client = scp.Client(host=host, user=user) client.use_system_keys() # or client = scp.Client(host=host, user=user, password=password)  # and then client.transfer('/etc/local/filename', '/etc/remote/filename')


Anyone has any idea how Angela cast the spell beneath Dras Leona, that took out the group of soldiers?  The one with time being movement and movement being warmth, while warmth and energy is but the same thing.  I've thought alot about this, and can't come up with an answer

Eragon and Arya asked Angela how she killed twenty men at once she said  What is time but motion? What is motion but heat? And are not heat and energy but different names for the same thing? When you understand the implications of that, you'll understand how and what I did.  What does she mean and how does this explain what she did?


I just realized that answers that have 0 scores are ordered before other answers that have one or more votes. Is this a new feature to promote new answers or a bug?  Examples        Pictures

I have noticed that now the answers to questions are not sorted by votes anymore. Is this a new feature?  For example,  (though you may need to refresh... random, you know..)  I assume it is related to some meta question, but I didn't find such.


What is the area of the largest equilateral triangle which fits inside a square of side a?  so area of trinagle is $\frac{a^2}{2}$, however it is wrong, why ?

How can I find the maximum area possible of equilateral triangle that inside a square whose sides have length a. And how does that triangle look like? Can we construct it (with compass and straightedge)?


Find $$\int \frac{dx}{x^4+1}$$  I found a possible solution to this question   However, I was wondering if there is a "nicer" solution, that would more understandable to a person who isn't advanced in complex numbers.  Thank you!

I am trying to evaluate the integral  $$\int \frac{1}{1+x^4} \mathrm dx.$$  The integrand $\frac{1}{1+x^4}$ is a rational function (quotient of two polynomials), so I could solve the integral if I can find the partial fraction of $\frac{1}{1+x^4}$. But I failed to factorize $1+x^4$.   Any other methods are also wellcome.


I recently received an email which had a sentence:     "Let us know if you would rather we have the meeting next week with   just Alisa and Bob."   This grammar ("you would rather we have") looks weird to me. I would just say "Let us know if you would rather like us to have a meeting...". Yet the person who wrote is a native speaker and insisted that people actually use it all the time. Can anyone explain how to use it and give more examples?

I am just curious, how often this form of Subjunctive mood is used  and what alternatives are available to express the very same thing.  Examples:   I suggest that he implement a budget cut in March. It’s essential that they be heard   and so on.


Can anyone provide some hint on how to proceed with the proof of the following:      The characteristic polynomial and minimal polynomial of a linear operator $T$ coincide if and only if for a certain vector $y$ in $V$ ,vectors $y,Ty,\ldots \ldots ,T^{n-1}y$ are linearly independent i.e. the set $\{y,Ty,\ldots,T^{n-1}y\}$ forms the basis of $V$

I have been trying to compile conditions for when characteristic polynomials equal minimal polynomials and I have found a result that I think is fairly standard but I have not been able to come up with a proof for.  Any references to a proof would be greatly appreciated.  Let $M\in M_n(\Bbb F)$ and let $c_M$ be the characteristic polynomial of $M$ and $p_M$ be the minimal polynomial of $M$.     How do we show that $p_M = c_M$ if and only if there exists a column vector $x$ such that $x, Mx, \ldots M^{n-1} x$ are linearly independent ?


Here's what happens in Ubuntu (Linux ubuntu 5.3.0-53-generic #47~18.04.1-Ubuntu SMP Thu May 7 13:10:50 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux, bash 4.4.20(1)):  In Terminal, open a window (let's call it "window_1") and type:  trap "echo something;" SIGTERM  then  echo $$  9781  then  kill -TERM $$  as expected, something is printed in window_1 and the window stays open.  Now open another "window_2" and type:  kill -TERM 9781  and window_1 is closed (no time to see whether something is printed).  Do the same with SIGINT and everything works as expected.   Do the same with SIGUSR1 and everything works as expected, but only after the Enter key is pressed.  Also, in macOS 10.13.6 everything works as expected (with SIGTERM, SIGINT and SIGUSR1).  Is anybody able to explain this apparent anomaly?  Thanks in advance.

Comparing bash, ash and dash, only bash can be terminated by SIGTERM  kill -TERM <pid>   For ash and bash, I need SIGHUP or SIGKILL  kill -HUP <pid> kill -KILL <pid>   What's the reasoning behind this? Furthermore, the behavior seems to be system-dependent:   bash is terminated by SIGTERM on Ubuntu 14.04 Trusty, Ubuntu 16.04 Xenial, Ubuntu 18.04 Bionic, Ubuntu 19.10 Eoan, Ubuntu 20.04 Focal, Debian 8 Jessie, Debian 9 Stretch, Debian 10 Buster, CentOS 8 bash is not terminated by SIGTERM on CentOS 6, CentOS 7


I am using the commercial fonts "Flexo" and "Brix Slab" with XeLaTeX:  \documentclass{book} \usepackage{fontspec} \defaultfontfeatures{Mapping=tex-text} \setmainfont{HVD Fonts - BrixSlab-Light.otf} \setsansfont{Durotype - Flexo-Medium.otf} \usepackage{blindtext}  \begin{document} \blindtext  \sffamily \blindtext \end{document}   The generated PDFs look good with every PDF viewer except for Adobe Reader X and XI where the "Flexo" font is a mess.    The output of "pdffonts" yields:  name                                 type              emb sub uni object ID ------------------------------------ ----------------- --- --- --- --------- YCEXOQ+BrixSlab-Light-Identity-H     CID Type 0C       yes yes yes      5  0 JAZBMS+Flexo-Medium-Identity-H       CID Type 0C       yes yes yes      7  0   The problem occurs under Linux (TeXLive) as well as under Windows (MiKTeX).  What is the problem?

The following example must be compiled with XeLaTeX to reproduce the issue.  % arara: xelatex \documentclass{article} \usepackage{fontawesome} \begin{document} Text Text \faMobilePhone\ Text Text \end{document}   Normally I am using TeXworks to compile and view the output. With the internal viewer I am getting the desired result. The following image demonstrates it:    However if I open the pdf with Preview (viewer of Mac) the scaling of the icon fails.     If I open the pdf file with Adobe Acrobat Reader the icon is still scaled correctly. If I print the page my printer is also not able to scale the icons correctly.   If I use LuaLaTeX everything seems to work correctly.   Can you reproduce the issue and do you know a solution?


$\newcommand{\lcm}{\operatorname{lcm}}$ Just a quick one. I have to prove that the lcm of two consecutive numbers is its product. Using the identity $\gcd(a,b) \cdot \lcm(a,b) = a \cdot b$, you can find $\lcm(a,b) = \frac{a \cdot b}{\gcd(a,b)}$ I can prove separately that the gcd of consecutive numbers is 1 (coprime) -- which leaves $a \cdot b$ and thus proving the statement. I'm pretty sure this is complete but for the sake of clarity is there something I'm missing?

Can anyone help me out here? Can't seem to find the right rules of divisibility to show this:  If $a \mid m$ and $(a + 1) \mid m$, then $a(a + 1) \mid m$.


I think to remember that if $p_1, ..., p_n$ are the first $n$ prime numbers, then $$   p_{n+1}^2 < p_1 \cdot p_2 \cdot ... p_n $$ for all $n \ge 4$, but I can't find a reference for it. If true, is it obvious (something like Euclid's trick) or more like Bertrand's postulate, etc.?

I wanted to prove the following question in an elementary way not using Bertrand postulate or analytic estimates like $x/\log x$. The question is  $$ p_{n+1}^2<p_1p_2\cdots p_n,\qquad(n\geq4) $$  I made the following argument. Does anyone have some opinion or simpler ideas to complete.  We consider two cases: Case 1: $N=p_1p_2\cdots p_n-1$ is composite: then there will be a prime factor  $q\leq\sqrt{N}$, and of course $q$ is not any of the $p_i$'s. therefore $p_{n+1}\leq q\leq\sqrt{N}$. So $p_{n+1}^2<N+1$.  Case 2: $N=p_1p_2\cdots p_n-1$ is prime. Then???


How do I prove that the function  $$f(x)= \begin{cases}  1-x &,\text{when}\; x \;\text{is rational} \\ 1/x &, \text{when}\; x \;\text{is irrational} \end{cases}$$ is not integrable on every interval $[a,b]$?

Prove that the bounded function $f$ defined by $f(x)=0$ if $x$ is irrational and $f(x)=1$ if $x$ is rational is not Riemann integrable on $[0,1]$.  I was given the hint to use the inverse definition of Riemann integrable and consider the cases of the partition being all rationals, and all irrationals between $[0,1]$, but I'm not too sure how to go about it.


In the book I am reading the author left some excersises for the reader, I happend to be stuck at this sum $$\sum_{n=1}^k{n!(n^2+n+1)}$$ So far I have tried to factorize the polynomial, and also tried to split the  sum. I know how to compute $n\ n!$, but I have no idea on the other terms, any help is accepted!

How to find the sum $$\sum^n_{k=1} (k^2+k+1)k!$$  What I tried as follows :   $$\sum^n_{k=1} (k^2+k+1)k!$$  =$$\sum^n_{k=1} (k^2)k!+ \sum^n_{k=1} (k)k! + \sum^n_{k=1} (1)k!$$  Now we can write $\sum^n_{k=1} (k^2) $ as $$\frac{n(n+1)(2n+1)}{6}$$ but what to do with $k!$ please guide thanks.......


Let $N_i=\{0,1,\dots,\bar{n}_i\}$ and define $N=N_1\times \dots \times N_I$. I want to maximize $f$ on $N$. $f$ has the following form $$ f(n) = \sum_i A_i n_i -\sum_i \sum_{j\neq i} B_{ij} (n_i-n_j)^2 $$ where $A_i\geq 0$ and $B_{ij}\geq 0$ for all $i,j$. Note that $f$ is concave when defined on $\mathbb{R}^I$.  I know that integer programing is in general a hard problem but I would like to find nontrivial conditions on $A$ and $B$ such that this problem is easy to solve. By easy to solve I mean that there is a procedure that is fast and that is guaranteed to find the global maximum.  What I have tried  I have tried the following way of solving the problem. Define the mapping $T$ for which the $i$th element is defined as $$(Tn)_i=\arg\max_{\tilde{n}_i\in N_i} f\left( \left\{ n_1,\dots,\tilde{n}_i,\dots,n_I\right\}\right)$$ and iterate on $T$ until convergence. This is essentially a  algorithm but in a discrete space.   A few remarks:   We can look at the fixed points of $T$. The vector $n^*$ that maximizes $f$ is obviously a fixed point of $T$ (can't improve by deviating in any dimensions) but there might be multiple fixed point. The mapping $T$ is monotone in the sense that $n\geq n'$ implies $T(n)\geq T(n')$. As a result we can use Tarski's fixed point theorem to show that the (non empty) set of fixed point is a lattice. We can find the lower bound of that set by iterating on $T$ from $(0,\dots,0)$ and the upper bound by iterating from $(\bar{n}_1,\dots,\bar{n}_I)$. If both iterations end up on the same vector then there is a unique fixed point and it must be $n^*$. When it works that procedure is quite fast numerically but I don't know what conditions on $A$ and $B$ are needed for it to work. Under some conditions, $T$ might be a contraction mapping which would guarantee uniqueness but I haven't made much progress along that path yet.   Any helps is appreciated! In particular, if somebody has a good reference on these problems that would be useful.

Let $N_i=\{0,1,\dots,\bar{n}_i\}$ and define $N=N_1\times \dots \times N_I$. I have a minimization problem of the form $$ \min_{n\in N} \sum_i A_i n_i +\sum_i \sum_{j\neq i} B_{ij} (n_i-n_j)^2 $$ where $A_i\geq 0$ and $B_{ij}\geq 0$ for all $i,j$. This problem can be written as a convex quadratic integer program.   What are the standard algorithms to solve these problems numerically? Are they guaranteed to find a global solution? How fast are they?


I know this question has already been adressed in several posts like here:  or there . And I'm willing to use the fixparts software, but it says on every answer that I should be very careful using it and I don't really understand careful about what exactly.  I have a dual boot Ubuntu 14.04/Windows7 and recently freed some space in the Windows partition to extend the Ubuntu one (using easeus). After that I used the Boot repair tool to fix the boot. Finally, I can't reallocate it since Gparted is seeing the whole SSD as unallocated...  Here's my gparted error message:   Here's the fdisk -l return  Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x56251d6b    Device Boot      Start         End      Blocks   Id  System /dev/sda1              63       80324       40131   de  Dell Utility /dev/sda2   *       81920    25710591    12814336   27  Hidden NTFS WinRE /dev/sda3        25710592   253602089   113945749    7  HPFS/NTFS/exFAT /dev/sda4       376176639   500117503    61970432+   f  W95 Ext'd (LBA) /dev/sda5       376176640   433166335    28494848   83  Linux /dev/sda6       433166336   500117503    33475584   82  Linux swap / Solaris  WARNING: GPT (GUID Partition Table) detected on '/dev/sdb'! The util fdisk doesn't support GPT. Use GNU Parted.   Disk /dev/sdb: 3000.6 GB, 3000592982016 bytes 256 heads, 63 sectors/track, 363376 cylinders, total 5860533168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0xcbcc2d95     Device Boot      Start         End      Blocks   Id  System /dev/sdb1               1  4294967295  2147483647+  ee  GPT Partition 1 does not start on physical sector boundary.  WARNING: GPT (GUID Partition Table) detected on '/dev/sdc'! The util fdisk doesn't support GPT. Use GNU Parted.   Disk /dev/sdc: 3000.6 GB, 3000592982016 bytes 256 heads, 63 sectors/track, 363376 cylinders, total 5860533168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0xcbcc2d94     Device Boot      Start         End      Blocks   Id  System /dev/sdc1               1  4294967295  2147483647+  ee  GPT Partition 1 does not start on physical sector boundary.   I read on some posts that there should be some space (usually 1 or 2 Mb) between each logical partition to store the EBR. Unfortunately I don't know if this is really my problem nor how to fix it safely without Gparted.  I don't really know what more to add. Please, let me know if I'm missing something here and if "Fixparts" is the way to go.  Thanks!

I have dual booted Windows 7 & Ubuntu 14.04 with EasyBCD, i.e. I have installed grub on the Ubuntu root partition & added entry of linux to Windows bootloader using EasyBCD. So effectively i am using Windows Bootloader to boot into either of them. Working perfectly.  As i already had 4 primary partition on HDD, i converted one of  that (NTFS-Windows 500 GB) to Logical using EaseUs Partition, so that around 70GB of uncollected space on HDD could be used.  NOTE: Before that the 500 GB partition was Primary & i was able to see all partition in Gparted. "What i mean to say is all was working properly".  The problem (i.e. after conv. of primary to logical) is i am getting this message after starting Gparted & shows entire partition as Unallocated.  Unable to satisfy all the constraints on the partition  $ sudo fdisk -l  Disk /dev/sda: 1000.2 GB, 1000204886016 bytes  255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors  Units = sectors of 1 * 512 = 512 bytes  Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0xe6bfc2a4     Device Boot       Start         End      Blocks   Id  System   /dev/sda1   *        2048      206847      102400    7  HPFS/NTFS/exFAT   /dev/sda2          206848   427624447   213708800    7  HPFS/NTFS/exFAT   /dev/sda3       427624449  1805438975   688907263+   f  W95 Ext'd (LBA)   Partition 3 does not start on physical sector boundary.   /dev/sda5       427624512  1532823551   552599520    7  HPFS/NTFS/exFAT   /dev/sda6      1532825600  1780301823   123738112   83  Linux   /dev/sda7      1780301824  1805438975    12568576   82  Linux swap / Solaris   So what is the cause of this problem.  I know there might be duplicate for this at "" (that was bug probably & was for old version of Ubuntu 13.04) & ""  Also, if there is any chance that both errors are related or complementary to each other?  So, is this problem caused because of Sector Size (512 bytes/4096 bytes) or my mistake of converting a Primary partition to logical using EaseUs rather than some of the Ubuntu Tools. How can i rectify this?  If any further info needed, feel free to ask.  UPDATE  @psusi, sudo parted -l says same as what gparted said. (Unable to satisfy..) @oldfred, i have started chkdsk, will update you with the same.  (Thanks to both)  @rod smith, I will try your suggestion after i done with chkdsk.Thanks !


I attempted installing QGIS Server following .  Installation was successful with no errors reported.  However, when I try to use GetCapabilities I am getting this error:     Internal Server Error      The server encountered an internal error or   misconfiguration and was unable to complete your request.      Please contact the server administrator, admin@local.domain and inform   them of the time the error occurred, and anything you might have done   that may have caused the error.      More information about this error may be available in the server error   log   I looked for the error in Apache's logs and found this entry:  [Mon Oct 28 16:02:40 2013] [error] [client 127.0.0.1] Premature end of script headers: qgis_mapserv.fcgi.exe  Can anyone suggest how to troubleshoot this issue?

I followed this tutorial:  but nothing happens.    And when I try to open it this error message appears   So I tried to follow httpd_qgis.conf edition step from  but it gives me the same error.    I think I didn't need that step because I can see "mod_fcgid" in my apache modules directory    What am I doing wrong?


I have recently learned (discovered) that the exponent law $b^{mn} = {(b^m)}^n$ is not universally applicable. To demonstrate, if it were we could conclude that $(-1)^{\frac{3}{2}}$ (or by extension -1 to any power) is equal to 1.  $(-1)^{\frac{3}{2}} = (-1)^{2*\frac{3}{4}}$  = $((-1)^2)^{\frac{3}{4}}$  = $1^{\frac{3}{4}}$  = $1$  Under exactly what circumstances (natural/integer/rational/real bases or exponents) are the various exponent laws applicable? For example, can I use the above law ( $b^{mn} = {(b^m)}^n$ ) with a negative base when the exponents are required to be integers?

I know there must be something unmathematical in the following but I don't know where it is: \begin{align} \sqrt{-1} &= i \\\\\ \frac1{\sqrt{-1}} &= \frac1i \\\\  \frac{\sqrt1}{\sqrt{-1}} &= \frac1i \\\\  \sqrt{\frac1{-1}} &= \frac1i \\\\  \sqrt{\frac{-1}1} &= \frac1i \\\\  \sqrt{-1} &= \frac1i \\\\  i &= \frac1i \\\\  i^2 &= 1 \\\\  -1 &= 1 \quad !!? \end{align}


I'm getting emails for a different email ID which is similar to mine but without a dot . I'm flooded with the emails meant for someone else. I'm not able to resolve it, can anyone help , or connect me with someone who works in Google and help resolve this issue. Can't believe Google could do such a blunder.

E.g.: If your Gmail ID is abc.xyz@gmail.com, it considers this the same as abcxyz@gmail.com.  Why is this so?


admin@mac:/app/$ fetch=$(zsh -c 'zmodload zsh/datetime; strftime "%b %d %R" $((EPOCHSECONDS - 5*60))')  admin@mac:/app/$ echo $fetch Nov 21 08:22 admin@mac:/app/$ sed -n '/$fetch/,$p' test.log  admin@mac:/app/$(Not showing result)  My test.log input file below, Mon Nov 21 08:22 MYT 2020,Test 1  Mon Nov 21 08:22 MYT 2020,Test 2  Mon Nov 21 08:22 MYT 2020,Test 3

I want to do:  cat update_via_sed.sh | sed 's/old_name/new_name/' > new_update_via_sed.sh   in my program.  But I want to use variables, e.g.  old_run='old_name_952' new_run='old_name_953'   I have tried using them but the substitution doesn't happen (no error). I have tried:  cat update_via_sed.sh | sed 's/old_run/new_run/' cat update_via_sed.sh | sed 's/$old_run/$new_run/' cat update_via_sed.sh | sed 's/${old_run}/${new_run}/'


I use a lot of whole lemons in cooking and not sure whether waxed or unwaxed lemons are best.  I have used both but concerned about both coatings on lemons. I stopped using waxed lemons when I found unwaxed ones but they are treated with chemical fungicides and pesticides (Imazalil and propiconazol) for a longer shelf life.  These are toxic and carcinogenic! Where can I buy unwaxed and untreated lemons from?

A number of  specify  for zesting. Unwaxed citrus fruit are not widely available here in Sweden, so I have to make do by attempting to remove the wax before zesting. Recently I have had , and now I wonder whether it is even worth the trouble.  Citrus fruit have a natural wax coating that is washed off along with orchard grime at the packing house. A new protective coating is applied before packing, and it is this that I am concerned about.  I have two concerns. First there is a food safety issue. Reading the  and  food additive regulations, I see that some substances are permitted for citrus and fruit such as apples and pears where the peel is normally eaten. Other substances are only to be used on citrus or other fruit where the peel is not normally ingested. On the face of it this seems to suggest that the consumption of citrus peel has not been taken into account. I understand that this may not be the case, but since neither regulatory body clarify the issue (at least not in the linked documents), I feel my concern is warranted.  My second concern is regarding whether the taste of the peel is compromised by the coating. This is a tricky question for me to answer since I have no access to untreated citrus. There is the additional difficulty that there are so many substances permitted, and the supermarkets here give no indication of what is used. Presumably some types of coating taste better and others worse. I include this part of question with the faint hope that there may be someone reading who is not subject to the same limitations.  Is it worth bothering even trying to wash the wax of citrus?


I am trying to call the event from button through css. It not working. When i click the delete button the listed file need to be removed from list.   i couldn't able to place the input type also. I am trying to get multiple fileupload similar like gmail add and delete. Anyone help on this

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


I'm a little confused when I run the code below:  int Maxi(int A[]) {     return sizeof(A)/sizeof(A[0]); }  int main() {     int A[5] = {1,2,3,4,5};     print("%d \n", Maxi(A));     return 0; }   And I just get the result 2. It seems that sizeof(A) turns out to be 8, which is the size of a pointer. I know this may not be a question worthy asking, but I must miss something and I just cannot figure it out right now.  But if I do this:  int main() {     int A[5] = {1,2,3,4,5};     print("%d \n", sizeof(A)/sizeof(A[0]));     return 0; }   It's all right then, and I thought it is related to the passage of value between functions, but I'm confused.  Thanks!

First off, here is some code:  int main()  {     int days[] = {1,2,3,4,5};     int *ptr = days;     printf("%u\n", sizeof(days));     printf("%u\n", sizeof(ptr));      return 0; }   Is there a way to find out the size of the array that ptr is pointing to (instead of just giving its size, which is four bytes on a 32-bit system)?


I would like to title case every sentence ending with parentheses containing uppercase letters only NB: do not title case certain words such as "for, and, the" for instance. So the original sentence is:  foundation for economic education (FEE)  And it should be like that:  Foundation for Economic Education (FEE)  Any help is much appreciated! Here is my "faulty" code, it capitalizes everything before the parenthesis... (^[\p{L}\W]+)([(][\p{Lu}]{3,}[)]$)  \U\1\2

What is the easiest way to capitalize the first letter in each word of a string?


This is the error message I get in my Ubuntu server 14.04.4LT while installing packages:  could not get lock /var/lib/dpkg/lock - open (11 resources temporary not available) unable to lock the administrative directory (/var/lib/dpkg/) another process using it.

I get this error when trying to use apt-get:  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?     How can I fix this?


I'd like to calculate $\int_{-1}^1(1-x^2)^n\ dx$, but I have no idea how. After searching through this website, I found out that we can transform the integral into Beta function, by using substitution. However, I'm having trouble finding the right substitution. I tried using $x = 1 - 2t$. Then the integral becomes $$-\frac{4^n}{2}\int_{3}^{-1}t^n(1-t)^n\ dt.$$ What's inside the integral is similar to Beta function. But the boundaries are not. It should have been $$\int_0^1t^n(1-t)^n\ dt.$$ Any idea what substitution should I choose?

How to show that :  $I_n = \int_{-1}^{1} (1-x^2)^n dx $ is equal to $\dfrac{2^{2n+1}(n!)^2}{(2n+1)!}$ ?  With integration by parts ? I don't know how to prove this equality. Someone could help me ? Thank you in advance :)


I would like help to show the following:  If $f \in C^\infty$, then $f''(x) = \lim_{t \to 0} \frac{f(x + t) + f(x - t) - 2f(x)}{t^2}$  This is the definition of second order derivative by differential coefficients. The first order case is just the definition of derivative, but I'm having trouble with the second order case. I'm really confused, don't even know where to start. Thanks in advance

Show $$\lim_{h \to \ 0} \frac{f(x + 2h) - 2f(x+h) + f(x)}{h^{2}} = f''(x)$$   Proof:  By definition:    $$f'(x) = \lim_{h \to \ 0} \frac{f(x + h) - f(x)}{h}$$  Using this idea it would imply:   $$1)\ \ f''(x) = \lim_{h \to \ 0} \frac{f'(x + h) - f'(x)}{h}$$  As such it is required that I find an expression for $f'(x+h)$. This is where I'm not sure if the step I took is legitimate.  An expression for $f'(x + h)$ is:  $$f'(x+h) =  \lim_{h \to \ 0} \frac{f(x + 2h) - f(x + h)}{h}$$  Combining this with the definition of $f'(x)$ and inserting it into 1) you arrive at: $$\lim_{h \to \ 0} \frac{f(x + 2h) - 2f(x+h) + f(x)}{h^{2}} = f''(x)$$   As required.    Concern: I feel a discomfort with this solution. Even though "mechanically" it worked out, if I am taking the limit as $h \rightarrow 0$ that would mean $x + 2h$ and $x + h$ both go to $x$. But I am attempting to use the idea that $x +2h$ goes to $x + h$. Perhaps it is a notation idea that I need to communicate better, but I feel it is larger than just that.


My professor gave us an example application to compare with our own work.  When I try to run on the console I get the following errors.      Exception in thread "main" java.lang.ExceptionInInitializerError Caused by: java.lang.NullPointerException         at java.desktop/javax.swing.ImageIcon.<init>(Unknown Source)         at Craps.CrapsGameFrame.<init>(CrapsGameFrame.java:150)         at Craps.CrapsGameFrame.<clinit>(CrapsGameFrame.java:74)   I've had similar errors in previous assignments involving javafx and I was able to fix them by making changes to resource pathways or the controller, however I do not have access to the src files for this application.  Is it a bad application or am I doing something wrong?  Any help is appreciated, thanks

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?


While debugging some errors, I accidentally deleted sources.list.d and sources.list at "/etc/apt". Now, I cannot install or do anything just because those files do not exist. How can I get those files back? Is there any way to recover them? I have a copy of the context of the sources.list. I would greatly appreciate your help.

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


I was trying to make the progress work in time with the program, while it's time goes on.  In the below code the progress is working but just inside the for loop. How to let the progress grow with the task of the program ?  private void readFromFile(File cf2) throws IOException, Exception {     //System.out.println("okay");     FileReader fr = new FileReader(cf2);     try (BufferedReader bw = new BufferedReader(fr)) {         System.out.println("Wait while reading !");         for (int i = 0 ; i <= 100 ; i++) {             Thread.sleep(10);             System.out.print(String.format("[%s]%d%%\r", progress(i), i));         }         while(bw.readLine() != null)         s1 += bw.readLine();     } }  private static final StringBuilder res = new StringBuilder();  static String progress(int pct) {     res.delete(0, res.length());     int numPounds = (pct + 9) / 10;     for (int i = 0 ; i != numPounds ; i++) {         res.append('#');     }     while (res.length() != 10) {         res.append(' ');     }     return res.toString(); }

I'd like something like a generic, re-usable getPosition() method that will tell me the number of bytes read from the starting point of the stream.  Ideally, I would prefer this to work with all InputStreams, so that I don't have to wrap each and every one of them as I get them from disparate sources.  Does such a beast exist?  If not, can anyone recommend an existing implementation of a counting InputStream?


I want to connect to my database and get some values of a specific table, that table has a prefix, and that prefix is stored in an array.  $statement = $db->prepare('SELECT * FROM ' . $conf['database']['tableprefix'] . 'candy');   Now I wanted to know, if there is any way, I can replace this $conf['database']['tableprefix'] with a placeholder, as the prefix and the 'candy' string need to be together without space.

Why can't I pass the table name to a prepared PDO statement?  $stmt = $dbh->prepare('SELECT * FROM :table WHERE 1'); if ($stmt->execute(array(':table' => 'users'))) {     var_dump($stmt->fetchAll()); }   Is there another safe way to insert a table name into a SQL query? With safe, I mean that I don't want to do  $sql = "SELECT * FROM $table WHERE 1"


I have a rule based set of expressions for styling a map according to the contents of the 'Layer' field.  e.g if the Layer starts with a 'C'   "Layer" ILIKE 'C%' colours the line red.  Is it possible for me to colour lines which don't fit into any of my pre defined categories ?  i.e I want to have a feature set called 'Other' into which anything that does not fit my pre-defined rules goes.  I suppose it is theoretically possible to have CASE/ else/ or / but this could run into 100s of lines of code.  Is there a way of saying - 'if a feature in the 'Layer' field equals none of the above, then style it like this....?  That is the best way I can think of explaining it.

This question centers the Symbology tab in QGIS 3.0.  I'm working with categorical data describing event venues in the Chicago area. This is a point dataset which will be overlayed on a street basemap.   Bars Nighclubs Theatres Parks Restaurants Galleries Other   I would like to use the Symbology tool in the Properties window to display "Bars" specifically in red, and "all other values" (nightclubs, theaters, other, etc.) in yellow.  The attribute field I am using is called "Type"  Fundamentally, I have solved this problem using the following process:   Symbology Column Drop Menu -> Select "Categorized" "Formula" button "Type"  =  'Bars' (syntax) Select "Classify" button Outcome: classifcation of "0" represented in Yellow, and "1" in Red.  "1" = "Bars", "0" = "all other values/anything that is not a bar" Change Legend entry for "1" value to read "Bars" Change Legend entry for "0" value to read "All Other Venues"   Indeed, this process solves the problem of isolating the desired value and representing all other values.  I would however like to clarify... is this the only way to isolate one value and represent all others?  Many of the folks I work with are coming from the ArcMap 9 and 10 environments, which make this process super easy using selectable options in the GUI rather than formulas.    Have I missed a GUI method of completing this task while solving this problem or should I start working with formulas?


Find the limit: $\lim_{n \to +\infty}(\frac{1^p + 2^p + ... + n^p}{n^p} - \frac{n}{p + 1})$, where $p \in \mathbb{N}$. I've got an idea to transform this sequence into $lim_{n\to +\infty}(\frac{x_n}{y_n})$ and to use Stolz's theorem. But in 2 days I didn't get ideas for this transformation.

Evaluate  $$\lim_{n\to\infty} \left(\frac{1^p+2^p+3^p + \cdots + n^p}{n^p} - \frac{n}{p+1}\right)$$


I had Dell studio 1536 laptop with windows vista defaults already installed. recently I decided to shift from Microsoft windows to ubuntu.  I installed Ubuntu gnome 3. After installation It's look like that everything is ok. but I found that ubuntu perform much more slowly than Vista!!!  I discovered that ubuntu uses an alternative driver for my Graphic card. Take a look to this:    Then i decided to download & install proper ATI (AMD) driver, from .  My on-board graphic card is: ATI radeon HD 3200  THE QUESTION: IS IT IMPORTANT TO REMOVE PREVIOUS AMD DRIVER WHICH INSTALLED BY DEFAULT?  AND THEN WHAT IS ATICONFIG ? SAVE X WINDOW CONFIGURATION FILE?  TAKE A LOOK TO THIS SCREEN SHOT:    any suggestion would become helpful

After upgrading to 12.10 quantal, the packaged version of fglrx no longer works. I discovered that this is because there is a separate 'legacy' fglrx driver for the HD 2k-4k series cards, but it is incompatible with the xorg server on 12.10.  This is the most current version of the driver for HD 2000 through HD 4000 series cards. You can't use the non-legacy fglrx driver, but you can use the open-source radeon driver if you prefer your WM compositing to be laggy and your YouTube videos to play like they would on a Pentium MMX series:    Usually this driver can be installed in the following way, necessary because apt-get install fglrx would pull in the non-legacy driver:  wget http://www2.ati.com/drivers/legacy/amd-driver-installer-12.6-legacy-x86.x86_64.zip unzip amd-driver-installer-* sudo sh ./amd-driver-installer-*.run --buildpkg Ubuntu/quantal sudo dpkg -i fglrx*.deb sudo aticonfig --initial -f   If you use a different version of fglrx (for example, a newer 12.9 that doesn't support those cards) then the final command will give you an error no supported hardware detected or something similar. However, everything works at this point and you will get a reasonable xorg.conf:  ... other stuff  Section "Device"         Identifier  "aticonfig-Device[0]-0"         Driver      "fglrx"         BusID       "PCI:1:5:0" EndSection  ... other stuff   At this point you're supposed to reboot and everything will be working with the fglrx driver. However, upon rebooting, you'll be treated to the following errors in Xorg.0.log when fglrx attempts to load:  (EE) Failed to load /usr/lib/xorg/modules/drivers/fglrx_drv.so: /usr/lib/xorg/modules/drivers/fglrx_drv.so: undefined symbol: noXFree86DRIExtension   Some searching around will show that this is a problem with the legacy ATI drivers not supporting xserver 1.13 or newer. () ATI has released a fixed driver for its most recent (HD 5000 series or later) cards, but not for the 'legacy' cards yet. The non-legacy ATI drivers can't be used with the old cards.  What should an Ubuntu user, using one of these HD 2000-4000 series cards, do?    Wait for an updated 'legacy' ATI driver that properly works with xserver 1.13?   Downgrade back to 12.04 Precise, which uses xserver 1.11? Try to downgrade xserver on 12.10 Quantal to 1.12, which could possibly break Unity and GNOME? Forced upgrade to HD 5000 series or later card? (Not possible with integrated graphics...) Some other 1337 action that fixes this problem painlessly?


This is from Discrete Mathematics and its Applications   This is the book means when mentions a list of common ways to express conditional statements   After going through the list, I immediately recognized "q is necessary for p". Translating to the "if p, then q" form, I got "If you want to get promoted, you must wash the boss's car.   Another interpretation of this that I got - from what I learned on  is   "You can get promoted only if you wash the boss's car". This means the only path to promotion is washing the boss's car. If you managed to get promoted(get there) without washing the car, the contract is broken.  Does all of that sound right?

Here is what my book says about the different ways implications are worded     I am struggling with how "if p, then q" is logically equivalent to "p only if q"  The example I came up with   With "if p, then q" - If Russell plays in the NFL, he plays football.  With "p only if q" - Russell plays in the NFL only if he plays football.  Say Russell plays in the NFL, plays football and plays soccer.   With regards to that statement, my thought would be that "If Russell plays in the NFL, he plays football" implication would evaluate to true because Russell plays in the NFL and he plays football. However, with regards to "Russell plays in the NFL only if he plays football", wouldn't this evaluate to false because it says that the only way for Russell to play in the NFL is if he plays football. That means that playing football and soccer would not be a path for Russell to play in the NFL because it is not the  defined only way, only playing football.   Can someone clarify this?


I've a responsive navbar, but if i open the nav there will be a drop down menu and i will be hidden under the footer.  So how can i push the footer down, only when the Navbar is open?  I've sticked the footer to the bottom like this:  width: 100%; height: auto; position: absolute; bottom: 0; left: 0;   JSFiddle:

I have a simple 2-column layout with a footer that clears both the right and left div in my markup.  My problem is that I can't get the footer to stay at the bottom of the page in all browsers.  It works if the content pushes the footer down, but that's not always the case.


My understanding of how regular rowstore indexes are stored is in a type of b-tree data structure, but I was wondering because of the different nature of columnstore indexes, what type of underlying data structure is used?

One of the new features in SQL Server 2012 codenamed Denali is the   I know a good bit about regular old row-store indexes, like the b-tree structure, differences in storage between the leaf level and b-tree pages, affects of included fields, optimizing to use them, order of keys, etc.  I'm having difficulty getting any good info on the internals of a columnstore index.     How is it structured? Is there a b-tree?  Some other structure in place? How is data organized? What sorts of specific operators are best suited to use it? Any other anti-patterns to be avoided when using them?   A lot of what I can find out about them are basically the exact opposite of a "normal" index, i.e. no ordering of keys, no included fields, nonclustered ONLY.  Any insights are appreciated.


Hello I came across a math equation and I was wondering what did the "e" stand for?  the equation is : y=47931x-1E+0.8 Can someone please help me by showing what the E stands for and the answer for my equation.  I know that I need to sub in a point for x so the only thing stopping me from answering the question is what to do for the 1E+0.8 part.

I often find this at the bottom of pages.  Page generated in 0.00013899803161621  Sometimes, I come across  Page generated in 9.0122222900391E-5  What does that time mean? I tried searching Wikipedia for E and maths but found the . My guess is E stand for Exponential and -5 is the power it is raised to. And the displayed time is a really small number. But that doesn't make sense when compared to the other time in the question. 0.00013899803161621 is bigger than 9.0122222900391E-5. If it means x times $10^{-5}$, then 9.0122222900391E-5 will be 0.000090122222900391 which is smaller than 0.00013899803161621. What does E stand for?


I was thinking about blue-shifting of light and I couldn't help my self but think about the limits of blue shifting mechanism and since we know energy of a photon is directly proportional to the wavelength of light by the well-known formula: $E = \frac{hc}{\lambda}$   We know this therefore we can say that the maximum energy an single photon can carry must be equal to the energy of the universe so we can say $E = E_{universe}$ now if we assume the energy of universe is $ E_{universe} = \infty$ then we could also say that $\lambda$ must be $0$ which cannot make any sense as it implies all the waves all exists in the same place. Which in my opinion seems unimaginable.   That said, we must assume the $E_{universe}$ is an finite value therefore suggesting $\lambda = \frac{hc}{E_{uniserve}} $. Now we can say as the energy increases the the $\lambda$ must decrease in value, but I concluded there must come a point at which the wavelength gets smaller than the smallest length possible $h$ (planks length) surely that must mean that after a photon reaches that level of blues-shifting it should be impossible for it to blue-shift anymore, as any more blue shifting may push it beyond the limit of $h$ and therefore break laws of physics but I am a mere speculative student therefore can someone answer my questions.  So my question is what is the limit of the most energetic wavelength in electromagnetic-spectrum? If so what if a photon attains such energy levels what will happen if we attempt to blue-shift the light even more, what will or should happen?

As a start I assumed  which is the reciprocal of  as the frequency upper limit, but not so sure. On the other hand, is there a lower limit? Can we consider the reciprocal of our universe as a theoretical limit which is not yet limited, or just assume 0? I am just curious to know if you have any ideas with thanks.


Why is it right?   And why is guilty until proven innocent wrong?  I think I have some kind of basic understanding but hopefully can learn more from your contributions.

What is the philosophical basis for the notion that somebody is "innocent until proven guilty"?  This seems to imply that we can confidently assert that a person is innocent until proof to the contrary emerges.   But that is obviously fallacious. Rather, the statement should be "neither innocent nor guilty, until proven to be either innocent or guilty".  No?


I have managed to use roman page numbering and now want to have arabic numbering starting on the same page as chapter 1. My code so far produce arabic number 2 on the same page as chapter 1. I already use \setcounter but to no effect.  \documentclass[10 pt, a4paper, leqno, oneside] {report} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage{lscape} \usepackage{caption} \usepackage{subfig} \usepackage[section]{placeins} \usepackage{listings} \usepackage{url} \usepackage{longtable} \usepackage{multirow} %\usepackage{geometry} \usepackage{graphicx} %\usepackage[export]{adjustbox} \usepackage[table]{xcolor} \usepackage[swedish, english]{babel} \usepackage[tmargin=1cm]{geometry} %\usepackage{blindtext}  \begin{document}  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  % The title page %%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  \input{titlepage}  \pagenumbering {roman}  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % The Abstract Page %%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \chapter*{Abstract}   } %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % TOC %%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \tableofcontents{}  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Chapters %%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  \setcounter{page}{1} \pagenumbering{arabic} \include{chapter1}  %Background \include{chapter2}  %Theory \include{chapter3}  %Results \include{chapter4}  %Analysis and conclusions \include{chapter5}  %Discussions  \end{document}

In my Master thesis, I would like to have the title page without any page number and an acknowledgments section and the table of contents with roman numbers. The rest of the document should be numbered arabic.  I have tried this, to have roman numbers for the Table of contents and normal numbers for the rest.  \documentclass[12pt,ngerman,openany]{report} \usepackage{titlesec} \usepackage{titletoc} \usepackage{cite} \usepackage[a4paper]{geometry} %\usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage[ngerman]{babel} %\usepackage{ngerman}{babel} \usepackage[T1]{fontenc} \usepackage{graphicx} \usepackage{float} \selectlanguage{ngerman} \usepackage{amssymb} \usepackage{amsmath} \usepackage{url} \usepackage{epstopdf} \usepackage{scrhack} \usepackage{listings} \usepackage{caption} \titleformat{\chapter}{\rmfamily\huge}{\textbf\thechapter.}{25pt}{\huge\textbf} \defcaptionname{ngerman}{\lstlistingname}{Code} \defcaptionname{ngerman}{\lstlistlistingname }{Codeverzeichnis}  \lstloadlanguages{R}  \lstset{% general command to set parameter(s)    basicstyle=\sffamily\footnotesize, % print whole listing small    keywordstyle=\sffamily\footnotesize\bfseries, % ubold black keywords    identifierstyle=, % nothing happens    commentstyle=\sffamily\footnotesize\slshape, % green comments    stringstyle=\sffamily\footnotesize, % typewriter type for strings    showstringspaces=false, % no special string spaces    numbers=left,    numberstyle=\sffamily\footnotesize,    stepnumber=1,    numbersep=10pt,    showspaces=false,    showtabs=false,    frame=lines,    morecomment=[l]{\%},    float=htbp,    numberbychapter=true  }   \begin{document} \let\cleardoublepage\clearpage   \pagenumbering{roman}  \tableofcontents  \clearpage  \vspace*{75mm} \chapter{Einleitung} \section{Motivation} bla bla bla \section{Ziel}  bla bla \chapter{Stand der Technik zur Mustererkennung} \section{Die Zeitreihen} bla bla \subsection{Beschreibung} bla bla \subsection{Erklärung}  bla bla  \subsection{Vorhersage} bla bla \subsection{Kontrolle} bla bla \section{Feature Extraktion} bla bla \subsection{Autokorrelation} \subsection{Was ist Autokorrelation?} bla bla   \subsection{Autokorrelation und Zeitreihen} bla bla  \subsubsection{Zeitreihe-Diagramm}  bla bla \subsubsection{Lagged Streudiagramm} bla bla  \subsubsection{Autocorrelation-Function (Korrelogramm)} bla bla \subsection{Spektralanalyse} \subsection{Was ist Spektral-Analyse} bla bla \end{document}


I am going to make a huge melon/carrot farm, 300 x 100 or something similar. How much water (per block?) do I need to fill my area with as many crops as possible but still grow at the max speed?

What factors affect soil hydration and crop growth time? What is the most efficient layout of dirt and water to grow crops?


Here's example picture below. How to make all the white areas transparent? Triangles, line and text. I have tried Pathfinder but I can't get it work correctly. Thanks in advance :)

In the image below you'll see the white section (highlighted blue). The black section behind it is one path, and the white another. How do I remove the white from the black so it becomes transparent? Hope that makes sense <3


I am learning C++ and studying Chapter 18 of Vandevoorde and Josuttis's C++ Templates. I retyped their code for Expression Templates, but the following is producing the error   sarray1.cpp:36:6: error: ‘T& SArray<T>::operator[](size_t) const’ cannot be overloaded    T& operator[] (size_t idx) const {       ^ sarray1.cpp:32:5: error: with ‘T SArray<T>::operator[](size_t) const’    T operator[] (size_t idx) const {   Here's the code:  template <typename T> class SArray {  public:  ...    T operator[] (size_t idx) const {     return storage[idx];   }    T& operator[] (size_t idx) const {     return storage[idx];   } ... };   I am just learning C++ so I hadn't seen an instance of an overloaded function that differed only be return type, but I see that this is indeed done: . I also see that [] is not on the  in C++. I can't think of what else could be going wrong. What is the reason for the above error?

Why don't more mainstream statically typed languages support function/method overloading by return type?  I can't think of any that do.  It seems no less useful or reasonable than supporting overload by parameter type.  How come it's so much less popular?


Say I have a toy dataset as follows:   Harry Potter and  Harry Potter and the Goblet of  Goblet of Fire  Harry Sorcer's Stone  Harry Potter and the Sorcer of The Rings The Lord of the Rings  The Lord of    Each of the above is part of, or the full title, of a book. In the example above there are Harry Potter Books and Lord of the Rings Books. If I wanted to cluster these by book (say Harry Potter is cluster 0 and Lord of the Rings is cluster 1) would the following approach be appropriate:   Approach: To preprocess the data I would keep only letters, lowercase letters, remove stop words, and tokenize. I would then use a tf-idf feature vector with K-Means clustering. Is there a better or more sound approach for this kind of problem? This is not limited to Harry Potter or Lord of the Rings books, there could be thousands of different books. Thanks!   EDIT: What are some alternative features that are used for clustering short text? It seems that the tf-idf features are very sparse.

I am working on a text clustering problem. The data contains several sentences. Is there a good algorithm which reaches high accuracy on short text?  Can you provide good references?   Algorithms such as KMeans, spectral clustering does not work well for this problem.


I am a beginner at AI and ML. I have been given a dataset, where I have noticed the columns are relative to one another. So is there any CART or ML model that can work with relative data ? For example in Decision Tree, the tree looks like :   if X[0]<192:      if X[1]>24:        if X[2]<12:        ...  I'm looking for a Decision Tree, that works like this :   if X[0]>X[1]:    if X[1]<X[2]:       ...  Is there any such Machine Learning Model ?

Assume the features in the dataframe are columns - A,B,C and my target is Y  Can my decision tree have a decision node which looks for say, if A>B then true else false?


Python subprocess call is supposed to run as command as is, but it is complaining if there is a pipe in it. Here is my code:  #!/usr/bin/python  import sys import subprocess import time service_name= "mysrvc" state ="STOPPED" mycmd ="sc query " + service_name + " " + "|" + " findstr" + " " + state  print(mycmd) if subprocess.call(mycmd)==0:   print("Service stopped successfully")   The Error I get is :   ERROR: Invalid Option; Would you like to see help for the QUERY and QUERYEX commands? [ y | n ]:   If I change the command to just   mycmd = "sc query " + service_name    I am able to run the script successfully. It is just the pipe and the arguments following it which is a problem. If I run sc query mysvrc | findstr STOPPED directly on command line it works fine.  How can I get this to work? Note that I run this python script using jython2.7. I wasn't successful in using win32serviceutil because it couldn't find the module win32serviceutil.

How do I execute the following shell command using the Python  module?  echo "input data" | awk -f script.awk | sort > outfile.txt   The input data will come from a string, so I don't actually need echo.  I've got this far, can anyone explain how I get it to pipe through sort too?  p_awk = subprocess.Popen(["awk","-f","script.awk"],                           stdin=subprocess.PIPE,                           stdout=file("outfile.txt", "w")) p_awk.communicate( "input data" )   UPDATE:  Note that while the accepted answer below doesn't actually answer the question as asked, I believe S.Lott is right and it's better to avoid having to solve that problem in the first place!


I want to create a data frame in R combining the bands wth the shapefile. The final file will have the pixels as rows, the bands as well as the other columns from the attribute table from the shapefile.  I want a csv table where the columns are the Landsat bands (say band 2, 3 and 4) along with other columns that are there in the attribute table of the shapefile (Country, State, Village name, Lat, Long etc)

I have given a Geotiff image and its corresponding Lidar data (x,y,z) in UTM coordinates. I need to merge the Lidar data with the RGB values from the image.   That means, at the end, I need to plot (3D) each point of the LiDAR cloud color coded with its corresponding RGB value from the Geotiff image.  I converted the Lidar data into a shapefile using QGIS. What should I do next?   In R, I tried the plot3D function, but, it did not work. I'm attaching the , shapefile, and   Edit:  I've done the following program as shown below:   require(raster)  require(maptools)  # to take shape files #require(car) # for scatter3D  require(plot3Drgl)  ##setwd("C:\\Users\\Bibin Wilson\\Documents\\R") ##source('Lidar.r')  data = read.csv("C:\\Users\\Bibin Wilson\\Desktop\\Lidar\\lidardata.csv") #nr = nrow(data) nc = ncol(data)  nr = 500  require(rgdal) X = readGDAL("C:\\Users\\Bibin Wilson\\Desktop\\Lidar\\image.tif")  topx = 4.968622208855732e+05; topy = 5.419739403811632e+06;  final = matrix(nrow = nr, ncol = nc+2)  for(i in 1:nr) {  x = data[i,1]  y = data[i,2]  rr = round((topy-y)/0.0833)  cc = abs(round((x-topx)/0.0833))  if(rr == 0) {   rr = 1  }  if(cc == 0) {   cc = 1  }  final[i,1] = x  final[i,2] = y  final[i,3] = data[i,3]  final[i,4] = rr  final[i,5] = cc }  for(i in 1:nr) {  x = final[i,1]  y = final[i,2]  z = final[i,3]       rr = final[i,4]  cc = final[i,5]  if(rr <= 5086 && cc<=3265) {   r = X[rr,cc,1]/255   g = X[rr,cc,2]/255   b = X[rr,cc,3]/255   c = cbind(r,g,b)   scatter3D(x,y,z,2,c)  } }   But while trying to plot the graph, it shows the following error:     Error in [.data.frame(x@data, i, j, ..., drop = FALSE) :      unused argument (1)   Edit:  I got the 3D model without the RGB as shown below:


I have GNOME Shell 3.16.4 installed on my Ubuntu 15.10 machine. However I get the old boring Unity like file manager. Here's a picture of my file Manager. See the top bar is like Ubuntu and button are on the left.     However, I want this my top bar completely like one below. Where you get to type the path. Also, you get the close, maximize and minimize button on the right and only back-forward buttons on the left.

Unfortunately, Gnome's  address bar is not showing the full path in its top bar. How can I change this behavior?  I'm looking for a solution to display a editable text field instead, like in the good old days.


I already did UV editing then shading, donut was normal, like it should have been. But somehow changed to purple. I read that means something is not connected. In shading it is connected like it should be, only here in texture paint in left window you see there is donut texture selected but there is nothing below. Maybe there I acidentally pressed something.

I made a character, and its one of my first times texturing, and I saved my character into a new folder, and when I came back to the model ALL the textures were pink, I used to know what to do, but I stopped texturing, how do I bring my textures back?


Ran into a bizarre problem in QGIS ( 2.18.4). I am trying to load a shapefile with extension *.shp.  When I choose Add Vector Layer -> Browse, I do not see any option to load ESRI Shapefiles.    I must be missing something very elementary.

I recently installed QGIS 2.18.4 after using ArcMap for many years. I want to add several existing ESRI shapefiles (.shp) created in Arc, to a QGIS project. To add a new layer in QGIS, I select the "Add Vector Layer" button and then click "Browse" to go find the layer. Then I navigate to the proper folder. However, the drop down menu at the lower right of the "Open an OGR Supported Vector Layer" window does not include ESRI Shapefile on the list. The first one on the list is GeoJSON. Everything after "G" appears to be okay (all the way down to "X-Plane/Flightgear") but any file formats from A through F have been cut from the list. Since "ESRI" starts with "E" it does not show up on the list. Strange thing is when I first installed QGIS, ESRI Shapefile appeared on this list. So I must have accidently done something to change how that list is populated and I want to know how to change it back.   If I type in the name of the ESRI shapefile that I know is in the folder, it and all other files starting with those letters appears in the prompt window that appears. And QGIS will correctly load the Shapefile. However, I want to be able to see all those ESRI Shapefiles without having to know and type in the first letter so it will appear in the prompt. I want it to appear in the file type drop down (or drop up?) menu.


Every time I see Data interacting with a computer or network he is using a terminal or communicator just like everyone else.  Surely a bluetooth or communicator device could easily be incorporated into his body.  Does he have integrated wireless and just chooses not to use it to appear more human, or is there some other canon reason for not being wireless?  Data at terminal wearing a communicator

In the earlier episodes of The Next Generation is where I noticed it, and I realise he could be inputting commands into the command terminal, but why isn't his positronic brain interfaced with the command console in that case?   I can't remember the exact example but there are episodes where he goes to the computer to look things up despite having encyclopedic knowledge of everything which could be known by the computer. Any explanation?


I am having a problem in understanding what happens when i put negative value to step in case of slicing.  I know [::-1] reverses a string. i want to know what value it assign to start and stop to get a reverse.  i thought it would be 0 to end to string. and tried  f="foobar"  f[0:5:-1]---> it gives me no output. why?  and i have read start should not pass stop. is that true in case of negative step value also?  can anyone help me to clear my doubt.

I need a good explanation (references are a plus) on Python's slice notation.   To me, this notation needs a bit of picking up.   It looks extremely powerful, but I haven't quite got my head around it.


I'm sure we all know its profanities, but is there any word or phrase that can represent "#@$%!"?

Is there a name for the use of symbols in place of curse words, for example #$@&%*!?


$${\sqrt{a+b+c} + \sqrt{a}\over b+c}  + {\sqrt{a+b+c} + \sqrt{b}\over a+c} +{\sqrt{a+b+c} + \sqrt{c}\over b+a} \ge {9+3\sqrt{3}\over2\sqrt{a+b+c}}$$   I tried AM-GM, which only gives large terms without any answer.  $${\sqrt{a+b+c} + \sqrt{a}\over b+c}  + {\sqrt{a+b+c} + \sqrt{b}\over a+c} +{\sqrt{a+b+c} + \sqrt{c}\over b+a} \ge 3\sqrt[3]{\left({\sqrt{a+b+c} + \sqrt{a}\over b+c}\right) \left({\sqrt{a+b+c} + \sqrt{b}\over a+c}\right)\left({\sqrt{a+b+c} + \sqrt{c}\over b+a}\right)}$$  Now this will never simplify to anything.  using a different approach i got,   $${\sqrt{a+b+c} + \sqrt{a}\over b+c}  + {\sqrt{a+b+c} + \sqrt{b}\over a+c} +{\sqrt{a+b+c} + \sqrt{c}\over b+a} \ge \sqrt{\left({\sqrt{a+b+c} + \sqrt{a}\over b+c}\right) \left({\sqrt{a+b+c} + \sqrt{b}\over a+c}\right)}+\sqrt{\left({\sqrt{a+b+c} + \sqrt{c}\over b+a}\right)\left({\sqrt{a+b+c} + \sqrt{b}\over a+c}\right)}+\sqrt{\left({\sqrt{a+b+c} + \sqrt{c}\over b+a}\right)\left({\sqrt{a+b+c} + \sqrt{a}\over b+c}\right)}$$  which also does not simplify further.  breaking the individual terms on the LHS also does not help nor does multiplying each term on LHS by its conjugate. :<  This was a introductory problem, so i guess there must exist a easy solution which i can't find.   Any hints will be helpful.

I was doing the the following problem- Prove that $$\frac { \sqrt { a+b+c } +\sqrt { a }  }{ b+c } +\frac { \sqrt { a+b+c } +\sqrt { b }  }{ c+a } +\frac { \sqrt { a+b+c } +\sqrt { c }  }{ a+b } \ge \frac { 9+3\sqrt { 3 }  }{ 2\sqrt { a+b+c } }. $$ I normalized this to $a+b+c=1$ and simplified to get- $$\frac { 1 }{ 1-\sqrt { a }  } +\frac { 1 }{ 1-\sqrt { b }  } +\frac { 1 }{ 1-\sqrt { c }  } \ge \frac { 9+3\sqrt { 3 }  }{ 2 }.$$ By Titu's lemma, $$\Rightarrow \quad \frac { 1 }{ 1-\sqrt { a }  } +\frac { 1 }{ 1-\sqrt { b }  } +\frac { 1 }{ 1-\sqrt { c }  } \ge \frac { 9 }{ 3-(\sqrt { a } +\sqrt { b } +\sqrt { c } ) } .$$ However the RHS is maximized when  $\sqrt { a } +\sqrt { b } +\sqrt { c } $ is maximized which is at $\sqrt { 3 } $, $$\Rightarrow \quad \frac { 1 }{ 1-\sqrt { a }  } +\frac { 1 }{ 1-\sqrt { b }  } +\frac { 1 }{ 1-\sqrt { c }  } \ge \frac { 9 }{ 3-(\sqrt { a } +\sqrt { b } +\sqrt { c } ) } \le \frac { 9 }{ 3-\sqrt { 3 }  } =\frac { 9+3\sqrt { 3 }  }{ 2 } .$$ What went wrong? You can view the rest of the problems .


At the moment I try to debug the class java.awt.Component. If I try to inspect a computed local variable (by typing Shift+Ctrl+I) I get the following message:    But the variable must be initialised at the moment!  Do you now that issue? Can you help me?  Thanks!!

Sometimes when I am debugging code in Eclipse it happens that although I can see and inspect class member variables without any difficulty I am unable to inspect the values of variables declared locally within functions. As an aside, any parameters to the current function lose their 'real' names and instead one sees their values listed in the Variables window as arg0, arg1, arg2, etc but at least the values are visible.  This is occurring at present in relation to classes defined within the core JDK. I have verified that the installed and current JRE is a JDK.  Is anybody able to shed some light on this behaviour?


Does anyone know how to set Windows Explorer Details View to allow the file modified time to show the number of seconds? This used to work in old Win XP. Since the wizards at MS seemed to have removed that capability is there a GPO or a registry setting that might still allow for this setting?...such that Explorer Details View would show HH:MM:SS in the Modified time column. Thank you for any guidance, history, reason, etc...

This is primarily for Windows 7, but I work in multiple versions and would happy to be able to do it in as many of them as possible.  Currently, when I open Explorer and look at a list of files, the date modified column shows something like:  09/18/2013 10:03  I would like it to display:  09/18/2013 10:03:42  I've tried changing the region and language settings for the short time format from HH:mm to HH:mm:ss, but it says it ignores seconds for that.  Does that mean I'm just out of luck?  And again, I'd like to be able to do this in any other  previous versions of Windows too.  It's useful for me as a developer to be able to see the seconds in a lot of situations.  Minor clarification: I did find , which helped me to improve the file properties display, but I wanted to be able to view the full timestamp for all the files in a folder at once, instead of individually.


VtR reviewers: Using external tools is not a "tar" command, so, this is not a duplicate of those other mentioned questions.  FAT32 supports max 4gb files. To use my 16GB media, I've been battling with tar's -L and -M and -F and -V switches, and managed (with a hackery -F kludge) to get tar to split my archive into multiple smaller files - all good.  However - I can't work out how to get it to read those back in...  Can someone tell me what tar command I need to type to store 10gigs of files into a FAT32 USB drive using tar, and what tar command is later needed to read them back out again?

I need to backup a fairly large directory, but I am limited by the size of individual files. I'd like to essentially create a tar.(gz|bz2) archive which is split into 200MB maximum archives. Clonezilla does something similar to this by splitting image backups named like so:  sda1.backup.tar.gz.aa sda1.backup.tar.gz.ab sda1.backup.tar.gz.ac   Is there a way I can do this in one command? I understand how to use the split command, but I'd like to not have to create one giant archive, then split it into smaller archives, as this would double the disk space I'd need in order to initially create the archive.


While installing Unity tweak, I am getting following error:   sudo add-apt-repository ppa:freyja-dev/unity-tweak-tool-daily sudo apt-get update sudo apt-get install unity-tweak-tool  W: Failed to fetch http://ppa.launchpad.net/freyja-dev/unity-tweak-tool-daily/ubuntu/dists/precise/main/source/Sources  404  Not Found W: Failed to fetch http://ppa.launchpad.net/freyja-dev/unity-tweak-tool-daily/ubuntu/dists/precise/main/binary-i386/Packages  404  Not Found E: Some index files failed to download. They have been ignored, or old ones used instead.

PPA seems to be constantly offline. Whenever I use sudo apt-get update, this error is shown:  W: Failed to fetch http://ppa.launchpad.net/ 404  Not Found   How do I fix these errors?


I have a dual boot ubuntu and windows 8. Ubuntu is default os to start up and countdown select the default os to boot If I don't change that before. When I order between ubuntu and windows 8 countdown automatically hide and then, I have to press enter to boot from any highlighted os without time limit.My question is: How can I disable countdown for always and I select which os starts up with using up/down arrow key myself and until I don't select  and don't pressing enter, that freeze on grub menu. Any ideas would be my pleasure  Note: There is no /etc/default/grub file in my ubuntu.  Edit: I reinstalled grub (sudo apt-get --reinstall install grub2 grub-pc) and now i have a/etc/default/grub file but the countdown did not stop with this changes:  # If you change this file, run 'update-grub' afterwards to update # /boot/grub/grub.cfg. # For full documentation of the options in this file, see: #   info -f grub -n 'Simple configuration'  GRUB_DEFAULT=0 GRUB_HIDDEN_TIMEOUT=0 GRUB_HIDDEN_TIMEOUT_QUIET=true GRUB_TIMEOUT="-1" GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian` GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" GRUB_CMDLINE_LINUX=""  # Uncomment to enable BadRAM filtering, modify to suit your needs # This works with Linux (no patch required) and with any kernel that obtains # the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...) #GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"  # Uncomment to disable graphical terminal (grub-pc only) #GRUB_TERMINAL=console  # The resolution used on graphical terminal # note that you can use only modes which your graphic card supports via VBE # you can see them in real GRUB with the command `vbeinfo' #GRUB_GFXMODE=640x480  # Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux #GRUB_DISABLE_LINUX_UUID=true  # Uncomment to disable generation of recovery mode menu entries #GRUB_DISABLE_RECOVERY="true"  # Uncomment to get a beep at grub start #GRUB_INIT_TUNE="480 440 1"   I delete double quote GRUB_TIMEOUT="-1" around -1 which is automatically added to it and save then running sudo update-grub I get the following warning:  Warning: Setting GRUB_TIMEOUT to a non-zero value when           GRUB_HIDDEN_TIMEOUT is set is no longer supporte

In Ubuntu 12.04 (or above), how do I set the GRUB time and the default OS (that I see at boot time) as I'm dual-booting Windows (7/8) and Ubuntu (12.04 or above)?


I'm trying to keep my footer at the bottom of my web page. Just having it at the bottom of the page works fine, but when I add content via a button, the body exapands but the footer stays on it's current position - meaning the body goes over the footer.  Here's my footer CSS:  .footer { position: absolute; right: 0; bottom: 0; left: 0; }   The website is in React so here's a layout page that I use to structure the page          <div>             <Header>             </Header>             <Body className="body">                 {this.props.children}             </Body>             <Footer className="footer"/>         </div>   Any ideas on how to proceed?  In response to this being a duplicate question: This question is different to other questions as this one is about a footer that is already at the bottom of the page, but doesnt stay that way when new content is added dynamically.

I have a simple 2-column layout with a footer that clears both the right and left div in my markup.  My problem is that I can't get the footer to stay at the bottom of the page in all browsers.  It works if the content pushes the footer down, but that's not always the case.


Is there a way to know which processes are listening to a given key binding?  For example, suppose I want to know which programs will do something when I press Ctrl+g. I guess the X server manages this, but how can I view the listening events?  To be clear, I'm not asking for how to set key bindings on X, but for how to find all processes which will do something when some combination of key presses (or mouse events for that matter) is used, possibly using command line tools.

What command line tools exist to list and manage X server grabs? (That's grab as in key and pointer grabs, i.e. restricting the use of a particular key or mouse button to a particular application, or constricting the mouse pointer to remain in a particular screen area.) I'm looking for a hypothetical xgrab utility that would show things like  Key     0x00f00ba5  0x123   0 Button  0x00f00ba5  2        Pointer 0x00abcdef     meaning that there has been a call to XGrabKey(display, 0x123, 0, 0x00f00ba5, ...) and so on with XGrabButton, XGrabPointer, XGrabKeyboard, XGrabServer (if possible). The display format doesn't matter, what I want is some way to see who's grabbing what, and possibly some way of revoking these grabs (if it's possible, I'm not sure if the X11 API allows that).


I've got a high-traffic (imagine tracking server) node.js server that's going to run on AWS EC2. There is no disk operation involved, but a lot of DynamoDB requests (in same zone), ElastiCache usage and as I said - a lot of network I/O (small packets, < 0.5kB, about 5-10 per second).  What would be best solution for this situation? A few smaller-scale servers like m1.medium or m1.large in a load-balancer, or a single m1.xlarge server? Main problem with xlarge I have is that it offers a lot of storage which I absolutely don't need...

This is a  about  Related:      I have a question regarding capacity planning. Can the Server Fault community please help with the following:   What kind of server do I need to handle some number of users? How many users can a server with some specifications handle? Will some server configuration be fast enough for my use case? I'm building a social networking site: what kind of hardware do I need? How much bandwidth do I need for some project? How much bandwidth will some number of users use in some application?


How do I get started?  If you need 5 points to answer a question why do you need to ask needless questions to get 5 points?

As a new user, I find it impossible to contribute to the community or to even begin contributing. I know why the reputation system is in place and I respect it, but at the same time it is too hard on new users.  It started with me wanting to upvote a question...     "Vote Up requires 15 reputation"   Just to appreciate a good question that helped me I need 15 rep? OK..., so I find out how I can get reputation points. More or less, I need to ask a question for +5 and add an answer for +10. I don't have any questions at the moment and I don't want to spam a random question, but I did happen to have a slightly different answer to the earlier question that I wanted to upvote. So I try to answer...     This question is protected to prevent "thanks!", "me too!", or spam answers by new users. To answer it, you must have earned at least 10 reputation on this site.   Now... I know this doesn't apply to every question, but at the same time, this means I'm forced to answer yet another question, and I don't want to go around looking for random questions and spam irrelevant answers...  Now I'm stuck. So I try to talk to some other users in the chat rooms about how to go about getting reputation points and how they first started. I entered into a "casual chat room".     You must have 20 reputation on Meta Stack Overflow to talk here.   Yes... I can understand why this is enforced, because we don't want new users to spam chat rooms, but all I wanted to do was ask for help. So I can't even talk to anyone about my newbie problems. So okay, I'll just settle for upvoting comments in the question that helped me. I don't see an upvote hover-over button so I can't even do that.    So now I'm stuck at 1 reputation point, unable to cross that 15 rep barrier, and even after posting this question I'll only have 6 rep points and still unable to do anything, and I'll be forced to look for questions to answer. Yes, I should be contributing to the community, but I shouldn't need to begin answering or making questions to upvote questions and answers. This only spurs more spam/irrelevant answers if anything.   Very, very, very new-user unfriendly.


This is a very very basic question, and I am looking at it more from point of view of physics. The small intestine is a highly coiled structure, which means it has horizontal coils as well. I can understand the vertical downward movement of food (when the person is in standing position) due to gravity, but how come the food can move in horizontal direction?  Any insights will be highly appreciated.  Thanks

If a person positions him/herself upside down and swallows food, will it reach the stomach against gravity? If so how?


When closing a question I am presented with this dialog:    Which is nicely laid out and clear what options are available to me (As to why the question should be closed).  However when I choose Off Topic.  I get this dialog which IMO appears cluttered and a bit too full on, making it harder to chose the correct option.    In a future release would it be possible to maybe have a bit more of padding between the options or colour contrast (Black and grey) or a heading, like in the first dialog.  For example:  General Computing Hardware/Software     .... specific content   Does not demonstrate a minimal understanding of the problem being solved     .... specific content   I think this would make it slightly easier on the eye and make the options stand out.

As everyone is becoming aware, the .  When voting to close a question, the first dialog is nicely laid out and easy to look at:    But the dialog containing the off-topic reasons is considerably harder to read and assimilate due to its layout and the fonts/weighting used. It's almost a wall of text:    When you've changed things, you want to make it easy for people to follow the new process. You don't want them to struggle to work out what the appropriate reason should be.    Can we have this re-jiggered to match the style used in the first close dialog?


Someone on Math.StackExchange got the Informed badge several hours ago, but it still shows 1/1 for Informed:    This is weird, because normally, the next badge already says that you got it while you didn't get it already. It is also weird that after several hours, it hasn't been fixed if it was catching.   I've found several cases of this on Math.SE and StackOverflow. It also happens in the Autobiographer badge where the badge was awarded 15h ago.

Noticed the bug on SuperUser profile page, Newest badge is also Supporter and next badge is also Supporter.


Is there any rule as to what is used in the beginning of a sentence, 'I' or 'Me'?  Example: 1) I and x are good friends.          2) Me and x are good friends.  Which is correct? Or are both of these correct?

I've always been taught to put myself last when referring to myself in the same sentence as others but the usage of "me and..." seems to be everywhere these days. The misuse of the word "me" instead of "I" aside, is there some new rule I haven't heard of? Shouldn't we put ourselves last regardless of the "me"/"I" usage?  Examples of "correct" usage:      My friends and I went for some ice   cream. Did you see my friends and me   at the ice cream stand?   Examples of "incorrect" usage:     Me and my friends went for some ice   cream. Did you see me and my friends   at the ice cream stand?   Note: I was also taught that the only person who could put themselves first was the queen.


I have been working on a problem "Find the sum of all the coefficients of the expansion of $P(x)=(x−2)^{100}$." Knowing that the polynomial is far too large to calculate, I tried to find a way to find each coefficient individually, but so far, I have been unsuccessful. Does anyone know what steps I have to take to calculate the sum of the coefficients?

I have this problem: given $N$,  $1 \leq N\leq 100$ integers which are roots from a polynomial, calculate the sum of coefficients from that polynomial  for example: given $3$ integers $2$, $2$ and $3$, I can calculate the polynomial $$x^3 - 7x^2 +16x -12,$$ so the sum of coefficients is $-2$  but if I have $100$ integers, I think calculating the polynomial will be enormous, so is there some way to find this sum of coefficients?


I've got the basics of bash scripting (I think anyways), and i'm trying to move on to more advanced stuff.  I am trying to write a script that will perform input validation (the user must input either yes or no) and i'm trying to do this by combining a function and an if then else statement.  This is what i'm working on so far.  #!/bin/bash func () {      echo "Enter yes or no:"     read var1 }  if [ $var1 != yes ] || [ $var1 != no ] then     func else     echo "I'm glag you said $var1" fi  exit 0   I know that i'm using the wrong if then else operator/syntax, but I can't find the correct syntax threw googling.  I want it to run the function if var1 is either equal to yes or no, so the user can't input something else.

I've programmed in a number of languages for two years now, I mean that I know how to design and implement a decent solution for a given problem.  However, bash is being a major headache to me, just nothing does work as expected—or even without errors.  All of the guides I've found were incredibly informal, not properly summarising its syntax or telling the most common errors you can make.  So what can you recommend me?


I have a Windows 10 virtual machine in VirtualBox on Ubuntu host.  I have accidentally deleted some files on virtual machine, and I need to recover them.   I have used ntfsundelete before but I think I can't use that now because my Windows partition is in .vdi file, not on a device.  So is there a way I recover those files?

My Ubuntu 12.04.1 running on virtualbox ran out of space while I was installing software on it and now it is . I've got files I need to recover from it. I have the ubuntu64.vdi file on my Windows 7 (host) laptop and I was wondering if there is any way of recovering the files from the vdi file. In parallel, I generated a fresh 12.04.1 machine on virtualbox in the same laptop, and I'll use that one instead of the borked one. I can add the borked vdi to the list of disks in the working one. Then I used gnome nautilus to mount the borked disk. I can find the files in there, but they are about 2 months old. I think this coincides with the last time that I did a virtualbox snapshot of the machine, but not the last time I got a working machine, which was yesterday. Is there any way of mounting the vdi as of yesterday, just before it crashed? EDITED: Here is what Virtual Media Manager tells me about my ubuntu64.vdi file:  EDITED2: I copied my ubuntu.vdi to an external USB with plenty of disk space. I tried using Windows to clone it, but got an error:  I tried the same from the working VM via a shared folder of the USB drive, and it started the cloning. Took a good while, but finished successfully: root@precise64:/media/sf_E_DRIVE/copy_of_ubuntu64_vm_folder_20140224/ubuntu64#  VBoxManage clonehd ubuntu64.vdi ubuntu64.raw --format RAW 0%...  10%...20%...30%...40%...50%...60%...70%...80%...90%...100% Clone hard disk created in format 'RAW'. UUID: 90f99198-18e1-40ee-85fe-c083dcbb1ac3  EDITED3: After creating the raw file, I run testdisk with Deeper Search, I get a list like this:  Ater Deeper Search has finished, I get a list like this:  But I don't know which one is which snapshot... Any ideas?


I am trying to search for a match inside a text that contains the words:  [IF (anytext) [OF] (anytext).... endofline   in a given text, I have tried this pattern without luck:  ^(\[IF(.*?)\[OF\]).*$   It works if the text is only one line, but when I feed in a full text with several lines it doesnt works.

For example, this regex  (.*)<FooBar>   will match:  abcde<FooBar>   But how do I get it to match across multiple lines?  abcde fghij<FooBar>


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If $a_n$ → a, $b_n$ → b, then $c_n$ = ($a_1$$b_n$+$a_2$$b_{n−1}$+···+$a_n$$b_1$)\n → ab.   Hint: Write $a_n$ = a + $\epsilon$$_n$, where $\epsilon$ → 0. Then:  $c_n$ = ($a_1$$b_n$+$a_2$$b_{n−1}$+···+$a_n$$b_1$)\n = a [($b_n$ + $b_{n−1}$ + ··· + $b_1$)/n]+[($\epsilon_1$$b_n$ + $\epsilon_2$$b_{n-1}$ + ··· + $\epsilon_n$$b_1$)/n]  The Questions:  The first part tends to ab (why?), and it remains to show that the second part tends to zero

When $\lim_{n\to\infty} x_n = a$, and $\lim_{n\to\infty} y_n = b$, find the limit, $$\lim_{n\to\infty} \frac{x_1 y_n + x_2 y_{n-1} + \cdots + x_n y_1}{n}.$$ Thank you for your help in advance.


I have two disks in my laptop, one is a 1TB HDD and one is a 512GB SSD. I had Windows 10 on the HDD and wanted to install Ubuntu on the SSD. As I did that my HDD drive got formatted and is now called DATA and looks like this.    I want to install Windows back on it but I'm worried that it will end up messing up my Ubuntu installation. How do I handle this properly?

I had Ubuntu 14.04 LTS installed on my Laptop. After a while I had some troubles starting it up. I decided to reinstall Ubuntu.  I had 3 ntfs partitions, 2 ext3 partitions the mount point for the first was / and for the second was ./local and a swap partition. During the reinstallation I chose the option: "erase Ubuntu 14.04 and reinstall".  During the reinstallation the power cut off. After it worked again I turned my laptop on to try to restart the installation process. I couldn't find any options other than:   Erase disk and install Ubuntu Something else   When I chose Something else I couldn't see my partitions. Instead I found this:  Device                         Type     Mount point     Format?     Size      Used     System     /dev/mapper/ubuntu--vg-root  /dev/mapper/ubuntu--vg-root   ext4                                 631381 MB unknown  Linux device-mapper (linear)(631.4 GB) /dev/mapper/ubuntu-vg-swap_1  /dev/mapper/ubuntu-vg-swap_1  swap                                 8493 MB   unknown /dev/sda  /dev/sda1                     ext2                                 254 MB    27 MB  /dev/sda5                                                          639877 MB unknown   At the Testdisk phase I have this:


I'm trying to upgrade my drush install on my local ubuntu machine but when I type in 'composer global require drush/drush:dev-master' I get the following error:  Changed current directory to /home/lupiyardo/.composer ./composer.json has been updated Loading composer repositories with package information Updating dependencies (including require-dev) Your requirements could not be resolved to an installable set of packages.    Problem 1     - Installation request for drush/drush dev-master -> satisfiable  by drush/drush[dev-master].     - drush/drush dev-master requires codegyre/robo ~1.0.0-beta1 ->  satisfiable by codegyre/robo[1.0.0-beta1] but these conflict with your  requirements or minimum-stability. Installation failed, reverting ./composer.json to its original content.   Ok, so I determined it meant I didn't have codegyre/robo. I . I tried running composer require drush/drush:~8 and it seems to install it fine. However, after doing so when I run drush status it still shows drush version 5.10.0 as the current version.  I also tried installing codegyre/robo, :  composer require codegyre/robo:~1   But then I get this error:  ./composer.json has been updated Loading composer repositories with package information Updating dependencies (including require-dev) Your requirements could not be resolved to an installable set of packages.    Problem 1     - The requested package codegyre/robo ~1 is satisfiable by  codegyre/robo[1.0.0-beta1, 1.x-dev] but these conflict with your  requirements or minimum-stability.   Installation failed, reverting ./composer.json to its original  content.   So I'm still stuck. Perhaps I need to fix my composer.json file but I'm not sure how to do that...  So I edited my composer.json file and removed everything in there under 'require' and then ran: sudo composer global require drush/drush:8.1.2  That gave me even more errors:  Your requirements could not be resolved to an installable set of packages.    Problem 1     - Can only install one of: pear/console_table[v1.3.0, 1.2.1].     - Can only install one of: pear/console_table[v1.3.0, v1.2.1].     - Can only install one of: pear/console_table[v1.3.0, 1.2.1].     - drush/drush 8.1.2 requires pear/console_table ~1.3.0 -> satisfiable      by pear/console_table[v1.3.0].     - Installation request for drush/drush 8.1.2 -> satisfiable by      drush/drush[8.1.2].     - Installation request for pear/console_table (locked at 1.2.1) ->     satisfiable by pear/console_table[1.2.1].   Installation failed, reverting ./composer.json to its original content.

I'm transitioning a Drupal 6 site to Drupal 8.1 so following the official instructions, I set up a new install in its own directory. Since this is only one site, I followed the instructions to put my database credentials in sites/default/default.settings.php after the declaration of the $databases array.  Running drush --status returns the following.  Drush version          :  8.1-dev                                           Drush temp directory   :  /tmp                                              Drush configuration    :                                                    Drush alias files      :                                                    Drupal root            :  /media/psf/Home/apps/newp                         Drupal Settings File   :  MISSING   Since this Drupal is 8.1-dev that must mean I need to upgrade it. Since this is a global install using Composer, I run composer global update.     Your requirements could not be resolved to an installable set of   packages drush/drush dev-master requires codegyre/robo ~1.0.0-beta1   Checking the drush-ops page on github doesn't show any anomalies like this nor my Google search.   What am I overlooking?


I am currently strugelling with the following problem:  I would like to create a TikZ graph in which I can click on the node text (hyperref) to jump and zoom in to another part of the graph:    I thought about  \begingroup \hypersetup{pdfview={XYZ ?? ?? ??}} \hyperlink{hello}{Reference} \endgroup     what kicks in the problem of knowing the exact PDF coordinats and zoom factor for the node. (Can TikZ provide that?)  Do you know any solution for that?

I remember long time ago, seeing PDF documents (such as online PDF versions of newspapers) that had hypertext boxes around paragraphs, such that when you clicked inside those boxes the surrounded paragraph will be zoomed in to exactly that paragraph in the Acrobat Reader window. I am not sure what tool was used to create those PDFs, and unfortunately I can't find one example at the moment.   Is it possible to reproduce such zoom-on-click feature with some pdflatex code? To repeat: the requested feature is to create hypertext boxes around paragraphs or figures that when clicked the PDF viewer would zoom in into that region.  This feature can be useful in PDFs with lots of structure in a given page, such as small paragraphs or figures or figure captions scattered around the page.  (Beamer has a "zoom in" feature (\framezoom) but it is not the same thing because that creates a new page with the zoomed region, and I just want to force the PDF reader to enclose the area in the same page by only zooming. I am also aware of marquee zoom in Acrobat but it is not what I am looking for because it is not aware of the content.)