Just upgraded to Mac OS X.9 Maverick and XeTeX (at least us used from TexWorks, which is all I've tried) now seems to be broken though it was working before. Error message when I try to typeset with ConTeXt/XeTeX:     /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in   'require':   /usr/local/texlive/2013/texmf-dist/scripts/context/ruby/base/switch.rb:501:   invalid multibyte escape: /\xFF/ (SyntaxError)    from   /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in   'require'     from   /usr/local/texlive/2013/texmf-dist/scripts/context/ruby/texexec.rb:11:in   `'   Anyone else having this? Any ideas?  (I'm relatively new to both TeX and Macs, as well as this site, so apologies if this is inappropriate, poorly asked or a stupid question. :) )  Edit: The problem occurs even on minimal files with both ConTeXt/XeTeX and ConTeXt/pdfTeX but not with ConTeXt/LuaTeX. Complete reinstallation of MacTeX has not helped.

I recently upgraded to Mac OS X 10.9 (Mavericks) and tried to run a old ConTeXt document using  TeXWorks. I got the following error:  /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/universal-darwin13/rbconfig.rb:212: warning: Insecure world writable dir /usr/local in PATH, mode 040777 /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require': /usr/local/texlive/2013/texmf-dist/scripts/context/ruby/base/switch.rb:501: invalid multibyte escape: /\xFF/ (SyntaxError)     from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require'     from /usr/local/texlive/2013/texmf-dist/scripts/context/ruby/texexec.rb:11:in `<main>'   I had earlier loaded MacTeX 2012. I got the same error as above. So I thought may be it has to do with my TeX installation. I removed MacTeX 2012 and installed MacTeX 2013. But ended up with the same problem (error message as above).  I am kind of lost. I am new to Mac and was enjoying the TeX/LaTeX/ConTeXt experience.  Would appreciate help.


I am trying to install Ubuntu 15.04 on my Windows 7 HP pavilion g6. Since it already has 4 partitions even if a create a new unallocated partition the Ubuntu installer shows it as "unusable". The 4 partitions are as follows   1 system  2 (c:) 3 recovery  4 hp_tools   How can I add and use an extra partition?

I first noticed an issue when trying to install Linux Mint 14 as a third OS alongside Ubuntu 12.10 and Windows 7 - I was unable to create another partition to install Mint to.  Poking around, I realised that I had reached the limit of primary partitions: (from left to right of the table) 1) a ~100 MB primary partition that I meant to use for storing Grub files but never got down to, 2) a 25 GB extended partition, with the entire partition containing an ext4 Ubuntu partition, 3) a ~513 GB partition containing Windows 7, 4) some ~50 GB of unallocated space, and finally 5) a 4 GB swap partition.   I decided to wipe off the first ~100 MB partition, which I didn't need anyway. This brought me to a dilemma, however: as Ubuntu, during initial installation, had created an extended partition for itself, which meant that I could not create any more. Having an extended partition for Ubuntu is virtually useless as there is only enough space to contain Ubuntu itself, and the benefits of extended are worthless here. And if I go ahead and install Mint now, I would face the same issue of too many primary partitions in the future should I want to create any more.  What I'd really like to do is this: convert the current extended partition into a normal primary partition, and create a new extended partition in the unallocated space for all future partitions. Is this possible, and if so how? Thanks in advance!


I don't have an android phone.please help me to acess whatsapp on ubuntu.

How can I install WhatsApp in Ubuntu? Related:


I'm currently working on a project where the user is required to register, and we are considering only providing social logins, and not providing a site only registration.  The reason behind this is that the data we will be storing for the user is trivial, and the only sensitive thing would be email and password. However if we use social logins this data is handled for us by the 3rd parties.  This means that we would not need to purchase a SSL Certificate for the website and save money on something that is a hobby/passion project.  We believe if we provide a decent spread of social logins that 99% of the audience will be covered anyway. We are also mindful not to overload the user with too many choices, so were thinking of providing: Facebook, Google+, Twitter, Microsoft  Would this cause a negative effect on sign up rate? Are these sites the optimum 4 to reduce overload, but cover the audience?

There are obvious advantages to limiting sign-ups to a service like Facebook connect - getting a name, age, avatar, etc. without the annoyance to your customers of asking them to fill it all in.  We are currently considering this, but there are some good arguments for using other services as well - such as Twitter, LinkedIn, Google, etc.  I can even think of some very good reasons (privacy being chief amongst them) to still keep our own sign-in.  The issue then is that giving people too many options is not a good UX.  Our target audience is subject specific (architecture, language learning, etc.) so we can't predict our customer audience very well yet.  What would you use for sign-ups and why?  Edit: I need to add that our application is targeted at mobile use, so screen real estate is also a consideration in showing many options.


I Have applied for Poland exhibition  central European dental exhibition and UK health GB which I am refused how should I apply for Poland under these circumstances My show is on 22 September I have paid the exhibition fees.

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


Let   $X=(X_n)_{n\in\mathbb N_0}$ be a Markov chain with values in a at most countable Polish space $E$ and $\mathcal E$ be the Borel $\sigma$-algebra on $E$ $(\operatorname P_x)_{x\in E}$ be the distributions of $X$ $N(y)=\sum_{n\in\mathbb N_0}1_{\left\{X_n=y\right\}}$ be the number of visits of $X$ in $y\in E$    Clearly, $$\operatorname E_x[N(y)]=\sum_{n\in\mathbb N_0}\operatorname P_x[X_n=y]\;.$$  I've read that it holds $$\operatorname E_x[N(y)]=\sum_{k\in\mathbb N}\operatorname P_x[N(y)\ge k]\;,$$ but I don't understand why this is true. Is it a typo and what's really meant is "=" instead of "\ge"?

Let $X$ be a non-negative random variable and $F_{X}$ the corresponding CDF. Show,   $$E(X) = \int_0^\infty (1-F_X (t)) \, dt$$   when $X$ has : a) a discrete distribution, b) a continuous distribution.   I assumed that for the case of a continuous distribution, since $F_X (t) = \mathbb{P}(X\leq t)$, then $1-F_X (t) = 1- \mathbb{P}(X\leq t) = \mathbb{P}(X>  t)$. Although how useful integrating that is, I really have no idea.


I am new with android development. I am using TABLayout and I am having a problem getting information from the JSON data set inside a fragment.  Inside the fragment, I implement an AsyncTask that is evoked inside the fragment’s method onCreate.  In doInBackground I save the JSON data in an object (eventsDetail) that is public for the fragment class.  Inside of onCreateView I use eventsDetail to populate various string widgets. Also, I populate longitude and latitude data to a map (SupportMapFragment).   When I first enter at onCreateView I have no issues. Then I leave the fragment. When I go back into the fragment again, I receive the error (java.lang.NullPointerException) on the eventsDetail object.  Has anyone encountered this problem? I think the problem is that I am accessing the JSON incorrectly.

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


I have a Beamer presentation with note pages, in which everything renders just fine with pdflatex.   However, when the file is compiled using xelatex (I need to use fontspec), texts in frames after a note page are not visible -- they are rendered in white colour. This problem is reproducible when using Beamer v3.33.  %% Compile with xelatex \documentclass[handout]{beamer}  \mode<handout> { \setbeameroption{show notes} \RequirePackage{pgfpages} \pgfpagesuselayout{2 on 1}[a4paper,border shrink=5mm] }  \begin{document} \begin{frame} A test, A test! \note{ } \end{frame}      \begin{frame} This text does not appear! \note{ } \end{frame} \end{document}   While this problem can be solved by compiling with lualatex, I'm wondering if there's any thing one can do to make it work for xelatex?

I'm using beamer with xelatex to prepare a talk.  If I switch on notes on right I'm experiencing strange behaviour:  When using csqoutes in the title, all normal text afterwards becomes invisible (or white). The text selectable in the output pdf. Note that the text is also visible in the small preview on the note page.  This does not happen when using pdflatex or lualatex.  MWE:  \documentclass{beamer} \usepackage[autostyle=true,german=quotes]{csquotes}  \usepackage{pgfpages} \setbeameroption{show notes} \setbeameroption{show notes on second screen=right}  \begin{document}    \begin{frame}         \frametitle{\enquote{Enqouted Title}}     \end{frame}      \begin{frame}         \frametitle{This is the second slide}         Lorem ipsum dolor sit amet, consectetuer adipiscing elit.     \end{frame} \end{document}   Update:  csqoutes is not the culprit. Seems to be a general problem when using xelatex and beamer with notes enabled.  New MWE:  \documentclass{beamer}  \usepackage{pgfpages} \setbeameroption{show notes} \setbeameroption{show notes on second screen=right}  \begin{document}     \begin{frame}         \frametitle{First Slide Title}         Here be text     \end{frame}      \begin{frame}         \frametitle{This is the second slide}         Lorem ipsum dolor sit amet, consectetuer adipiscing elit.     \end{frame} \end{document}


Now if some hardware device does not work I have to Google out what kernel options I should turn on to compile a kernel module for this hardware. I hope there is a better way to do it.  Somehow when I boot from live-cd my hardware magically works "of of the box". I guess live-cd contains lot's of modules for various hardware and the kernel somehow knows which module to load and use. Can I do something similar without using live-cd? Say I run lspci, find out all the available information about the hardware and using this information find out what module to compile?

As far as I know, the kernel detects hardware, adds information to sysfs creates a device in /dev and then generates a udev event. My question is, do device drivers do all of this or it is the kernel itself? If drivers do it, then they would know the device major and minor number to create the file in devtmps.   I also understand (maybe wrongly) that it is udev who calls modprobe to load the drivers that handle a device.   I was told that they do so with the contents of the MODALIAS uevent environment variable, thus loading all modules whose aliases match this string (the correct driver). In short: what are the steps of hardware detection in linux and WHO performs each step: the kernel itself, the driver inside the kernel or udev in userspace. Thanks.


I just got got by a gotcha. This code acts as you would expect:   keys = range(8)  DICT={} for k in keys:     DICT[k] = [] print DICT #returns #{0: [], 1: [], 2: [], 3: [], 4: [], 5: [], 6: [], 7: []}  DICT[1].append('mkay') print DICT #returns #{0: [], 1: ['mkay'], 2: [], 3: [], 4: [], 5: [], 6: [], 7: []}   But if I initialize the dictionary differently, the appending behavior is totally different:   DICT = dict(zip(keys,[[]]*len(keys))) print DICT #returns #{0: [], 1: [], 2: [], 3: [], 4: [], 5: [], 6: [], 7: []}   So it looks the same. But it's not:  DICT[1].append('mkay') print DICT #returns #{0: ['mkay'], 1: ['mkay'], 2: ['mkay'], 3: ['mkay'], 4: ['mkay'], 5: ['mkay'], 6: ['mkay'], 7: ['mkay']}   Does anyone know what's going on here? Thought I'd post this as well for anyone else who might get got by it.

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


I am reading .   In Page 14, Section 1.6.2 Accesibility, for "internal" access modifier it says "Access limited to this program".  What is a surprise for me is that we can read this as "it is possible to access some stuff in a program from another program".  How is that possible? Can you give an example where one program accesses part of the other program? E.g. an access to another program that we can prevent using the access modifier "internal".

Could you please explain what the practical usage is for the internal keyword in C#?  I know that the internal modifier limits access to the current assembly, but when and in which circumstance should I use it?


I have $25$ people who will be split into groups of $5$ people each day over $5$ days in $5$ different locations. Can I rotate them so that they all meet each other only once and visit each location only once over the $5$ days?

I have 25 people who will be split in to groups of 5 people each day over 5 days. Can I rotate them so they all meet each other only once? Help! Sorry forgot to mention they all meet in 5 different locations


I'm writing a paper about Data Augmentation and I'm looking for some way of increasing the size of a dataset. I'm already aware of the techniques used for images (transformations, PCA, blurs, etc.) but I'm having trouble finding augmentation techniques for classic numeric datasets such as Iris for example.  I already explored some obvious methods which are the following :   Uniform Random Generation : This really naive method consists of creating a new instance based on the min an max of the existing ones, the value of each feature is generated randomly with a uniform probability. (The mins and maxs are calculated from the values of the concerned feature of the concerned class each time) Normal Random Generation : Same as Uniform but the probability function is now a gaussian curve. Which is of course less naive since generated value fit the initial data distribution. Adding Noise : This method is a little different since it consist of cloning initial values, but each time adding some noise to it. This methods aims to strengthen the models and prevent overfitting.   I'm kinda new to ML and data augmentation and these 3 methods can look pretty obvious, i was wondering if anyone had an idea of different methods/algorithms to do such a task.  Thanks for your advices.  DP  NB: Text Augmentation is out of my project scope but if you have any info on that, please share !

In many machine learning applications, the so called data augmentation methods have allowed building better models. For example, assume a training set of $100$ images of cats and dogs. By rotating, mirroring, adjusting contrast, etc. it is possible to generate additional images from the original ones.  In the case of images, the data augmentation is relatively straightforward. However, suppose (for example) that one has a training set of $100$ samples and few hundred continuous variables that represent different things. The data augmentation does not anymore seem so intuitive. What could be done in such case?


I have a mantaflow liquid simulation in the 2.92 version of Blender. This simulation starts at the beginning of the animation but stops before the animation ends. When the animation plays past the last frame of the fluid sim, the domain becomes rendered as a giant cuboid because there is no more fluid data. I would like the fluid simulation to stay frozen on its last frame, rather than be a cuboid for the rest of the animation.  I know that it is possible to make a duplicate of the simulation with the fluid modifier applied on the last frame of the sim, but this causes shading inconsistencies and I would rather not do that.  Instead, is there a way to freeze the fluid simulation on the last frame without making duplicate objects? Possibly manipulating data, or a setting that I am not aware of?

So  i have a scene with a few objects, and a water simulation in the scene. However I want to animate the camera turning around in the scene, while the water simulation is frozen in time. So something like a time freeze effect. But when ever I try to render an animation it renders the water simulation too. I just need one frame of the water simulation. Is there a way to do this?


Does Ubuntu 16.04 know how to automatically switch between gpus (if present) with the default open source drivers?  For example running a game on the dedicated card but only using the integrated one for processes that don't require much graphics power.

I have installed Ubuntu GNOME 15.10. I installed the nvidia tested proprietary driver and then I restarted. Afterr that I selected as primary GPU the Intel driver for normal use. However, when I enter a steam game(Portal) the graphics is bad so In order to play normal I have to switch manually to the nvidia driver again and reboot again. After the game I have to manually select as primary driver the Intel one and reboot again. It is so boring. QUESTION: How to automatically switch gpu graphics driver when I enter a game or something that needs more GPU?


Let $k \geq1$. How can i show that $$\sum_{n \leq k} \frac{\mu(n)}{n} = O(1).$$where $\mu(n)$ is the mobius function. I already tried the Euler Summation Formula but i can't show it. Is there any simple way to show this or does anyone have a link regarding this statement. Thank you very much!!!

So I am trying to prove the above stated formula. I am completely new to number theory so I thank you in advance for baring with me. I start off by using the definition:  $\frac{\phi(n)}{n} = \sum_{d|n} \frac{\mu(d)}{d}$  Where $\phi$ is Eulers function, and $\mu$ is the Mobius mu function. From here, I use the Mobius inversion formula to give:  $\frac{\mu(n)}{n} = \sum_{d|n}d\frac{\phi(\frac{n}{d})}{n}\mu(d)$  Now summing $n$ up to $x$:  $\sum_{n \leq x}\frac{\mu(n)}{n} = \sum_{n \leq x}\sum_{d|n}d\frac{\phi(\frac{n}{d})}{n}\mu(d)$  Now I'm not fully sure on how I can rearrange things inside the two summations on the right hand side, so leaving things as they are; using that $\sum_{d|n} \mu(d) = 1$, if and only if $n =1$. Hence:  $\sum_{n \leq x}\frac{\mu(n)}{n} = \sum_{d|1}d\phi(\frac{1}{d})\mu(d)$  Thus $d=1$. Subbing this in:  $\sum_{n \leq x}\frac{\mu(n)}{n} = \phi(1) = 1$  I am not sure what I have missed (or done wrong) as to have an equality and not a triangle relation. Any suggestions or ideas would be greatly appreciated


Benjamin Franklin thought of electricity as a fluid, and said when there is abundance of fluid it is positive, stating positively charged fluid flows in electricity. Further, Thomson found that negatively charged particles flow and not positive ones, as the cathode rays exhibited characteristics of negatively charged particles. But how we first clarified what is what? How we distinguished between two types of charges and established their properties? Positive charges repel positive charges and attract negative ones. But from there we can't say whether the particle we are trying to understand is positive or negative. So how Thomson said electricity is flow of negative charges?

Nobody has yet defined the actual meaning of a charge, or why a negative charge is different from a positive charge.   Everybody knows that positive charge is due to protons and negative charge is due to electrons, but what does the charge mean?  Why were negative and positive charges so designated?  Was it also a possibility to call the charge of an electron positive and the charge of a proton negative?


Do you need other results to prove this? Could you use proof by induction? I don't know where to begin regarding how to prove this.

I was wondering if someone could help me clarify something regarding the effect of swapping two rows on the sign of the determinant. I know that if $A$ is an $n\times n$ matrix and $B$ is an $n\times n$ matrix obtained from $A$ by swapping two rows, then $$\det(B)=-\det(A)$$ but I don't know how to prove this. I have been looking for proofs at internet, and read in both in textbooks and lectures notes that are available that this result is very hard to prove and most approaches rely on induction and so was wondering if there is something wrong with using that $\det(AB)=\det(A)\det(B)$ and then writing $B=EA$ where $E$ is an elementary matrix swapping two rows and using this result to get $\det(B)=\det(E)\det(A)=-\det(A)$ (since showing that $\det(E)=-1$ in this case is not that hard).


In the past, there's been an issue with Microsoft not allowing you to deactivate an Expression Studio key. Basically, you get two licenses. If you assign them both (say one to a desktop and one to a laptop), then you upgrade to a new machine (say you replace your laptop), you have to buy a new copy of Expression Studio ($600 for Ultimate). This seems ludicrous to me, and I'm wondering if anyone knows if this policy is still in place. I can't seem to find a EULA online anywhere, so I don't know where to find this information. I know my laptop is due for replacement soon, and I want to know if I'm going to have to sink $600 into a software product I already purchased.   Is there an appropriate StackExchange forum for the above question?

Is it appropriate to ask questions about software licenses/licensing on ? Or is the appropriate place  ? Or is there no appropriate site currently and we should suggest such a site on ?


Hello guys I got a question if an example I have downloaded the free game plus of august can I play them at anytime if my subscription is on like in 3 month would they be available

I bought a three months membership for PlayStation Plus some time ago. This membership has already expired. While it was active, I got the classic PSOne Resident Evil titles for free. Will I be able to re-download them now without having to purchase a new PSPlus membership?


What is the sum of $1 \cdot 2x + 2 \cdot 3x^{2} + 3 \cdot 4x^{3} + \dots$ ?  I have been stuck on this problem with no direction. I have tried multiplying the sequence with $x$ and trying out $S-Sx$ but have gotten nowhere. Any help?  Thanks.

$\sum_{n=1}^\infty n*(n+1)*x^n$  Hello everyone,  I need help in solving the question above.  I started with $\frac{1}{1-x} = \sum_{n=0}^\infty x^n$, if differentiated it once so it became $\frac{1}{(1-x)^2} =\sum_{n=1}^\infty nx^{n-1} $ but from here I don't know how to continue. Thanks.


Every distribution of Linux has its own set of built-in command line programs. For example: cat, grep etc. Now, my question is: How are these built-in programs implemented and where can I find the source files? For example, I want to use the time command. I know that I can find the compiled binary file in /usr/bin/time but that does not provide me with the source of it. I assume this is a program that was compiled from C. Is this the way all built-in programs are implemented in the Linux environment and what is the way to go when I want to create my own custom command line programs? Should I write those in C and compile these with C or is it also advisable to write it in Bash and just add the script to PATH?

I often come across interesting Linux commands that make me wonder; what are these commands actually doing?  Yes, they might be 'force-removing dependencies', 'installing programs' and doing lots of other stuff, but I'd like to know how they're doing it.  Looking into the source code seems the right thing to do then, but where am I supposed to get it from?  I suppose they'll be written in C?  EDIT: I'm not talking about packages installed using apt-get. I'm looking for the source code of linux/unix commands.


This person acts strong when really he is going through a hard time. What's an original word for this?

I'm looking for a word (a noun) to describe a person who faces the challenges of life (small and large) courageously despite the risk of failure.   It would be nice if this noun does not necessarily imply that the person has experienced setbacks himself, rather that this wisdom of having courage could also have sprung out of reflection about possible risks. But that's just a bonus.  I'll be using the word as the name for a character type in a game (other characters include saint and criminal), so it needs to be a single noun.


I think a graphical approach is the best way, but can algebra be used? With IVT, from x:[0,1] a solution must exist.

There is an unique solution with $x$ being approximately $0.739085$. But is there also a closed form solution?


Let a belong to the set of (Rationals - Integers)  How would you prove the following:     a squared belongs to the set of (Rationals - Integers)

Is my proof that the square root of a positive integer is either an integer or an irrational number correct?  The proof goes like this:  Suppose an arbitrary number n, where n is non-negative. If $\sqrt{n}$ is an integer, then $\sqrt{n}$ must be rational. Since $\sqrt{n}$ is an integer, we can conclude that n is a square number, that is  for some integer a.  Therefore, if n is a square number, then $\sqrt{n}$ is rational.  Suppose now that n is not a square number, we want to show that the square root of any non-square number is irrational.  We prove by contradiction. That is, we suppose that the square root of any non-square number is rational. So $\sqrt{n} = \frac{a}{b}$, where $a,b \in Z^+, b \neq 0$. We also suppose that $a \neq 0$, otherwise $\frac ab = 0$ , and n will be a square number, which is rational.   Hence $n = \frac {a^2}{b^2}$, so $nb^2 = a^2$.    Suppose $b=1$. Then $\sqrt n = a$ , which shows that n is a square number. So $b \neq 1$. Since $\sqrt n > 1$, then $a>b>1$.  By the unique factorization of integers theorem, every positive integer greater than $1$ can be expressed as the product of its primes.  Therefore, we can write $a$ as a product of primes and for every prime number that exists in $a$, there will be an even number of primes in $a^2$. Similarly, we can express $b$ as a product of primes and for every prime number that exists in $b$, there will be an even number of primes in $b^2$.  However, we can also express $n$ as a product of primes. Since $n$ is not a square number, then there exist at least one prime number that has an odd number of primes.  Therefore, there exists at least one prime in the product of $nb^2$  that has an odd number of primes. Since $nb^2=a^2$ , then this contradicts the fact that there is an even number of primes in $a^2$ since a number can neither be even and odd.  Therefore, this contradicts the fact that $\sqrt n$ is rational. Therefore, $\sqrt n$ must be irrational.  Is this sufficient? Or is there any parts I did not explain well?


I wrote a code which read multiples ligand files and one receptor file and calculates the distance between XYZ coordinates of receptor and ligand files one by one. then want to write the output file for every specific ligand files separately. but my code just writing one output file and writing results for all the ligand files in one file. Below is my code:    import re   import math   import glob       class Atom:          def __init__(self, resname='', resnum='', atomid=0, chainId='',    x=0.0, y=0.0, z=0.0, atomname = '',  element = ''):     self.x=x     self.y = y     self.z = z     self.resname = resname     self.resnum = resnum     self.atomid = atomid     self.chainid = chainId     self.atomname = atomname     self.element = element     self.resnum = resnum  def __init__(self, line):     self.x = line[28: 38].strip()     self.y = line[39: 46].strip()     self.z = line[47: 56].strip()     self.resname = line[17: 21].strip()     self.resnum = line[22: 28].strip()     self.atomid = line[7: 12].strip()     self.chainid = line[22]     self.atomname = line[13: 16].strip()     self.element = line[77:78]  def caluDistence(proteinatom, ligandatoms, cutoff = 4.0):    matchedAtom = []    for atom in proteinatom:     atomX = float(atom.x)     atomY = float(atom.y)     atomZ = float(atom.z)     for hetatom in ligandatoms:         hetatomX = float(hetatom.x)         hetatomY = float(hetatom.y)         hetatomZ = float(hetatom.z)         d = math.sqrt((atomX - hetatomX)**2  + (atomY - hetatomY)**2  +   (atomZ - hetatomZ)**2 )         #print (str(d))         if d <= cutoff:             if atom in matchedAtom :                 continue             matchedAtom.append(atom) return matchedAtom return d  pdb = "receptor.pdb" lig = "D:\\python\\workspace\\practise\\exhau15\\frag1\\out_ligand_*.pdbqt" files=glob.glob(lig) proteinatom=[] for line in open(pdb, 'r').readlines():    if line[0:6] == 'ATOM  ':     atom = Atom(line)     proteinatom.append(atom) ligandatoms = [] for file in files:     print("current file :" +file)     with open(file) as f:             for line in f:                 if line[0:6] == 'ATOM  ':                     atom = Atom(line)                     ligandatoms.append(atom) matchedAtomList = caluDistence(proteinatom, ligandatoms) outfile = "out2.pdb" output = open(outfile, 'w') for atom in matchedAtomList:   output.write("current file name:    " + file + "     "  + atom.resname + "     "   + atom.resnum + "        " + atom.element + '\n' )     output.flush()    output.close()

I want to write a program for this: In a folder I have n number of files; first read one file and perform some operation then store result in a separate file. Then read 2nd file, perform operation again and save result in new 2nd file. Do the same procedure for n number of files. The program reads all files one by one and stores results of each file separately. Please give examples how I can do it.


I've been struggling with the following problem. I don't really know how to tackle this, but I suspect that it is not hard at all.  Let $G$ be a group and $f\colon G\to G$ an isomorphism such that $f$ is an involution ($f^2=1_G$) and $e$ is the only fixed point of $f$ (that is, $f(x)=x\implies x=e$)  I must prove that $G$ is abelian.  How should I proceed here ?  The problem gives a hint: show that every element of $G$ can be written as $x f(x)^{-1}$. I suspect that then one can use some result like "$G$ is abelian $\iff x\mapsto x^{-1}$ is a group morphism  ", but I haven't tried yet because I don't see why the hint holds.  Any help is appreciated, thanks in advance!

Let $G$ be a finite group and $f:G\to G$ an isomorphism. If $f$ has no fixed points (i.e., $f(x)=x$ implies $x=e$) and if $f\circ f$ is the identity, then $G$ is abelian. (Hint: Prove that every element in $G$ has the form $x^{-1}\cdot f(x)$.)   With the hint, I can see that for all $t\in G$, $f(t)=t^{-1}$, and since $f$ is an isomorphism, $G$ is abelian. But I can't see how to prove the hint or why it's evident.  Source : Rotman J.J. Introduction to the theory of groups, exercise 1.50


Proxy tunneling failed: Proxy Authentication Required Unable to establish SSL connection.   this is what shown while trying to download using wget..what is it??how to get my downloads right??

$ wget https://raw.github.com/mseknibilel/OpenStack-Grizzly-Install-Guide/master/KeystoneScripts/keystone_basic.sh  --2014-03-05 12:55:27--  https://raw.github.com/mseknibilel/OpenStack-Grizzly-Install-Guide/master/KeystoneScripts/keystone_basic.sh Resolving proxy4.xxxxx.com (proxy4.xxxxx.com)... 10.201.51.54   Connecting to proxy4.xxxxx.com (proxy4.xxxxx.com)|10.201.51.54|:8080... connected. Proxy tunneling failed: Proxy Authentication RequiredUnable to establish SSL connection.  Could someone let me know, where and in which file I need to set proxy password and user to get wget working?.


When working with a general matrix $A=$ \begin{bmatrix}a & b\\c & d\end{bmatrix},  I find that the eigenvalues are:  $\lambda = \frac{d+a \pm \sqrt{(d-a)^2+4bc}}{2}$  I then find that eigenvectors, $e=$ \begin{bmatrix}-b\\a-\lambda\end{bmatrix}.  I also know that under iteration with initial vector $x_n$ = \begin{bmatrix}x_0\\y_0\end{bmatrix},  we have $x_{n+1} = Ax_n$.  The matrix $A$ converges to a line with a slope $m$.   I am told that the slope of this line is in the same direction as the eigenvector associated with the largest eigenvalue.   How do I prove this?

Suppose I am given a $2$x$2$ matrix $A=$ \begin{pmatrix} a & b \\ c & d \end{pmatrix}  And an initial vector $x_n$ = \begin{pmatrix} x_0 \\ y_0\end{pmatrix}.  Under repeated iteration $x_{n+1} = Ax_n$, we find that $x_{n+1}$ converges to a line in the direction of the $eigenvector$  of $A$ of the form $X$= $[u,mu]$ where $m$ is the slope of the line.  I know that this process somehow also involves the largest $eigenvalue, \lambda,$ of $A$, though I am unsure how it connects.  My question is: How does the largest eigenvalue connect to this repeated iteration, how do I find the slope of the line of convergence $m$, and what is meant by the "direction of the eigenvector"?


The observable universe is 90 billion light years across. But the age of universe is 13.8 billion years. Light would take 90 billion years to cross this distance, how could matter move that far in only 13.8 billion years? Was it moving faster than light at the time of big bang?

The observable universe is approximately 13.7 billion years old. But yet it is 80 billion light years across. Isn't this a contradiction?


I hate narrator. I realize it can be helpful for people that can't see well but I don't have that problem. I keep accidentally pressing whatever keys open it (I still haven't found out what it is) and losing focus on whatever program I had open. Is it possible to remove narrator from my computer forever?

I've install Windows 8 on a BootCamp macbook air The problem is that the command key located differently from the winkey in a normal keyboard, therefor, I keep clicking Winkey+Enter which starts the narrator (which is really annoying!)  Is there a way to disable this shortcut?


I have a class which has public Assembly LoadedAssembly { set; get; }  var assemblyName = AssemblyName.GetAssemblyName(fullPathToDLLFile); myClass.LoadedAssembly = Assembly.Load(assemblyName);   This class I keep under Application.Current.Properties["MyClass"].  I try to null it like Application.Current.Properties["MyClass"] = null; but it doesn't help.  I see that the loaded assembly works (It has a timer inside and it is working).  How do I can clean it?  (I don't use something like   AppDomain d = AppDomain.CreateDomain("NewDomain", null, domaininfo); to load assembly.)

I would like to know how to unload an assembly that is loaded into the main AppDomain.  I have the following code:  var assembly = Assembly.LoadFrom( FilePathHere );   I need/want to be able to unload this assembly when I am done.  Thanks for your help.


How would I interpret a transformed dependent variable (4th root) with some of its predictor variables transformed as well? In our study, we transformed our dependent variable to 4th root, $Y^\frac{1}{4}$, and one of our predictor variables to $\ln(X)$. How would I interpret that?

I'm using fourth root (1/4) power transformation on my response variable, as a result of heteroscedasticity. But now I'm not sure how to interpret my regression coefficients.   I assume that I would need to take the coefficients to the fourth power when I back-transform (see below regression output). All of the variables are in units of dollar in millions, but I would like to know the change in dollar in billions.    While holding the other independent variable constant, a billion dollar change in fees, on average, leads to a change of 32 (or 32,000 dollars) in collections. I take 0.000075223 * 1000 (to get to billions) ^ 4 = 0.000032. Now do I multiply this number by 1 million or 1 billion (the original unit of the dependent variable is in millions)?  lm(formula = (Collections^(1/4)) ~ Fees + DIR)                   Estimate      Std. Error  t value            Pr(>|t|) (Intercept)   2.094573355     0.112292375   18.653  0.0000000000000151 Fees        **0.000075223   **0.000008411    8.943  0.0000000131878713 DIR           0.000022279     0.000004107    5.425  0.0000221138881913


In other words how can we say that for coprime numbers $a$ and $m$, the Diophantine equation $ax-my=1$ is always solvable?   I would like to have some intuitive understanding too in addition to proof. Eg- if $a$ is one of the factors of $m$ then we are sure that the solution doesn't exists because for some $x=t$, $at$ becomes equal to $m$. So, it always lie in the residual class in which 0 is contained and hence can never belong to the one in which 1 is contained.

I want to find a set of integer solutions of Diophantine equation: $ax + by = c$, and apparently $\gcd(a,b)|c$. Then by what formula can I use to find $x$ and $y$ ?   I tried to play around with it: $x = (c - by)/a$, hence $a|(c - by)$.     $a$, $c$ and $b$ are known. So to obtain integer solution for $a$, then $c - by = ak$, and I lost from here, because $y = (c - ak)/b$. I kept repeating this routine and could not find a way to get rid of it? Any hint?  Thanks, Chan


Why in KNN Euclidean distance is preferred over Manhattan for low dimension dataset whereas for high dimension, manhattan is preferred?

I read that 'Euclidean distance is not a good distance in high dimensions'. I guess this statement has something to do with the curse of dimensionality, but what exactly? Besides, what is 'high dimensions'? I have been applying hierarchical clustering using Euclidean distance with 100 features. Up to how many features is it 'safe' to use this metric?


I am trying to solve the following problem.   Assume that we are given 26 distinct positive integers. Show that either there exist 6 of them $x_1<x_2<x_3<x_4<x_5<x_6$, with $x_1$ dividing $x_2$, $x_2$ dividing $x_3$, $x_3$ dividing $x_4$, $x_4$ dividing $x_5$ and $x_5$ dividing $x_6$ or there exist six of them, such that none of them divides another one of these six.  A possibly good start is to assume that, in every six of these numbers, there exists at least one dividing another one of the same six.  Update. I have found a solution of the problem (for 17 numbers though) in a Russian site. As unbelievable as it may sound, this problem was a question in a 1983 Soviet Mathematics contest (Турниры Городов) for student of 7-8 grades!  I am presenting the solution I found in that site below as an answer,  and it is generalised for $n^2+1$ distinct integers, where we show that either there exist $n+1$ of them dividing each other or none diving none else.

Today my friend asked me following question:  Consider the set $ A= \{1,2,3,4,5\}$ By using the elements of this set, can you find a permutation that neither has an increasing sequence of length 3, nor has a decreasing sequence of length 3?  for example:   $3,4,2,1,5$ has an increasing sequence of length $3$, namely $3,4,5$   $5,3,1,2,4$ has a decreasing sequence of length $3$, namely $5,3,2$  I feel like I cannot find such a sequence. I guess problem is that this set has 5 elements and therefore I cannot create such a sequence. If it had 4 elements, I would find lots of sequences with that property. (With the same number of elements, length 4 would be OK too.) But how can I prove it to him? Could you please explain to me?  Best Regards


Judy wanted to know if the flight ticket to Shanghai was valid.  Can I replace "if" with "whether" in the sentence above?

Could someone please help me with these sentences? I need to know  Which one doesn’t sound natural? Which one is formal and which one is not?   A - I don’t know whether this word fits in the sentence. B - I don’t know if this word fits in the sentence.   C - I don’t know whether or not this word fits in the sentence. D - I don’t know if or not this word fits in the sentence.   E - I don’t know whether this word fits in the sentence or not. F - I don’t know if this word fits in the sentence or not.  For me only D doesn't work and sounds not idiomatic. Meanwhile for me all of these sentences can be used in both written and spoken languages. Do you confirm me?


Bizarrely came up with this while asleep ...  $$ \tag{1} \frac{1}{-1} = \frac{-1}{1} $$ and $$ \tag{2} \sqrt{\frac{a}{b}} = \frac{\sqrt{a}}{\sqrt{b}} $$ Thus combining (1) and (2): $$ \tag{3} \sqrt{\frac{1}{-1}} = \sqrt{\frac{-1}{1}} $$ which using $\sqrt{-1}=i$ gives, $$ \tag{4} \frac{1}{i} = \frac{i}{1} $$ contrary to the property, $i^{-1} = -i$  Would it be correct to suggest that you cannot move the negative from top to bottom without crossing a branch-point in the square root?  If I have not made a mistake, I am incredibly surprised that I wasn't taught this as a rule at high-school!

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}


Is possible to install the Intel Graphics Driver manually on 18.04? I've an HP tablet with Z8500 CPU and the main problem is: it's impossible to play a simple video because the GPU offload lacks. On 16.04 with the Intel Graphics Update tool it went very well but it's not supported now.

Can someone help me out and explain or point me in the right direction on how to check video drivers and see if my video card running okay?  I had 10.04 installed on my Thinkpad r61 with Compiz Manager and life was great, until the machine took water damage. I bought an ASUS (X54H) since and am trying out 12.04, but the desktop just doesn't look right.  I always struggled with video driver installation. There are no proprietary drivers available in the hardware manager.  When I run lspci | grep VGA:  00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)   I will greatly appreciate your help. I want to use Linux more, but like I said video drivers appear to be my biggest concern. I have also tried 12.04 on my desktop PC, but again failed to configure video card, so switched back to Windows 7.


I am passing NSDictionary to my function as a parameter. I want it's key and values to be in order as I inserted. for eg. expected output is:   mutable dict:{             zKey1 = Value1;             fKey2 = Value2;             aKey3 = Value3;         }    I have tried following ways to create and set value for keys.      NSMutableDictionary *mutableDict = [[NSMutableDictionary alloc]init];         [mutableDict setObject:@"Value1" forKey:@"zKey1"];         [mutableDict setObject:@"Value2" forKey:@"fKey2"];         [mutableDict setObject:@"Value3" forKey:@"aKey3"];      NSMutableDictionary *dic2=[[NSMutableDictionary alloc]initWithObjectsAndKeys:@"1004",@"userId",@"cucumber",@"domain",@"168d5c02f ",@"token",@"1004",@"userId1",@"cucumber",@"domain1",@"168d5c02f ",@"token1", nil];       NSDictionary * dict = [NSDictionary                                dictionaryWithObjects:@[@"Ravi",@"33",@"India",@"India"]                                forKeys:@[@"name",@"age",@"location",@"country"]];         NSArray *sortedKeys = [[dict allKeys] sortedArrayUsingSelector: @selector(compare:)];          NSMutableArray *sortedValues = [NSMutableArray array];         for (NSString *key in sortedKeys) {             [sortedValues addObject: [dict objectForKey: key]];         }      NSString *obj1=@"1004";         NSString *obj2=@"cucumber";         NSString *obj3=@"168d5c02f";          NSString *key1=@" userId";         NSString *key2=@"domain";         NSString *key3=@"token";         NSLog(@"dict %@",dict);          NSDictionary *dict8 =[NSDictionary                               dictionaryWithObjects:@[obj1,obj2,obj3]                               forKeys:@[key1,key2,key3]];   But nothing has worked I am always getting output as       mutable dict:{         aKey3 = Value3;         fKey2 = Value2;         zKey1 = Value1;     }        dict8 {         domain = cucumber;         token = 168d5c02f;         userId = 1004;     }       dict {         age = 33;         country = India;         location = India;         name = Ravi;     }      dic= {         domain = cucumber;         domain1 = cucumber;         token = "168d5c02f ";         token1 = "168d5c02f ";         userId = 1004;         userId1 = 1004;     }   It is always sorting values according to alphabetical order of keys. Many people say that NSDictionary is an unsorted container. But it does gets sorted. Need help desperately. Thank you in advance.

I have an NSDictionary (stored in a plist) that I'm basically using as an associative array (strings as keys and values).  I want to use the array of keys as part of my application, but I'd like them to be in a specific order (not really an order that I can write an algorithm to sort them into).  I could always store a separate array of the keys, but that seems kind of kludgey because I'd always have to update the keys of the dictionary as well as the values of the array, and make sure they always correspond.  Currently I just use [myDictionary allKeys], but obviously this returns them in an arbitrary, non-guaranteed order.  Is there a data structure in Objective-C that I'm missing?  Does anyone have any suggestions on how to more elegantly do this?


There are questions which have accepted answers but the answers are either irrelevant to the present day context (though the question is still relevant) or link to web pages that no longer exist.  Here is an example of a question answered with a dead link:    Here is an example of a question answered with a solution that is no more applicable today (the answer targets an obsolete version of the subject application while the question does not specify the version):    I am interested in getting up-to-date answer to both the questions. Can they be reopened?

I'm looking around for answers to my questions on several Stack Exchange sites and the good boy that I am I don't want to ask duplicate questions.  Often I find that there are other people who asked the same questions, sometimes years earlier, but still don't have an answer. I'd figure I could bump these back to top, but if I don't have enough rep for a edit (or comment), how would I do that?  Or, in that case, I should just post a 'newer' version of the same question?


I'm trying to add boxes around my links like in   but I don't get the boxes only the number. \documentclass[a4paper,UKenglish]{article} \usepackage{graphicx}  % \usepackage[utf8]{inputenc}  \usepackage{amsmath,amssymb,amsthm} \newtheorem{theorem}{theorem} \usepackage{comment}        \usepackage{caption}  \usepackage{subcaption}   \renewcommand{\thesubfigure}{\roman{subfigure}}   \usepackage[ruled,vlined,algo2e]{algorithm2e}  \usepackage[utf8]{inputenc} \usepackage{xcolor}  \usepackage{hyperref} \hypersetup{backref=true,            pagebackref=true,                    hyperindex=true,                     colorlinks=false,                     breaklinks=true,                     urlcolor= black,                     linkcolor= blue,                     bookmarks=true,                      bookmarksopen=false,     filecolor=black,     citecolor=blue,     linkbordercolor={1 0 0} }  \AtBeginDocument{\hypersetup{pdfborder={0 0 1}}}% <-----------   \begin{document}     \begin{theorem}\label{lemma1} adfsdfadf \end{theorem}  \ref{lemma1}     \end{document}

MacTEX-2014, TeXShop 3.36.1 on Mac OS 10.9.5 -- when using hyperref I do not see the colored border that should appear around the hyperlinks in the pdf.  for example, when compiled with pdflatex, the code below should produce a pdf with a green border around the link on the right of "abc", but it does not. Any idea how to check where the problem is?  \documentclass{article} \usepackage{hyperref} \hypersetup{colorlinks=false,pdfborder=0 0 1,citebordercolor={0 1 0}} \begin{document}  abc \cite{123}  \begin{thebibliography}{99} \bibitem{123} efg \end{thebibliography} \end{document}    this is the list of files from the generated .log     File List   article.cls    2007/10/19 v1.4h Standard LaTeX document class   size10.clo    2007/10/19 v1.4h Standard LaTeX file (size option)   hyperref.sty    2012/11/06 v6.83m Hypertext links for LaTeX   hobsub-hyperref.sty    2012/05/28 v1.13 Bundle oberdiek, subset hyperref (HO)   hobsub-generic.sty    2012/05/28 v1.13 Bundle oberdiek, subset generic (HO)     hobsub.sty    2012/05/28 v1.13 Construct package bundles (HO)   infwarerr.sty    2010/04/08 v1.3 Providing info/warning/error messages (HO)    ltxcmds.sty    2011/11/09 v1.22 LaTeX kernel commands for general use (HO)   ifluatex.sty    2010/03/01 v1.3 Provides the ifluatex switch (HO)     ifvtex.sty    2010/03/01 v1.5 Detect VTeX and its facilities (HO)    intcalc.sty    2007/09/27 v1.1 Expandable calculations with integers (HO)      ifpdf.sty    2011/01/30 v2.3 Provides the ifpdf switch (HO)   etexcmds.sty    2011/02/16 v1.5 Avoid name clashes with e-TeX commands (HO)   kvsetkeys.sty    2012/04/25 v1.16 Key value parser (HO)   kvdefinekeys.sty    2011/04/07 v1.3 Define keys (HO)   pdftexcmds.sty    2011/11/29 v0.20 Utility functions of pdfTeX for LuaTeX (HO)   pdfescape.sty    2011/11/25 v1.13 Implements pdfTeX's escape features (HO)   bigintcalc.sty    2012/04/08 v1.3 Expandable calculations on big integers (HO)     bitset.sty    2011/01/30 v1.1 Handle bit-vector datatype (HO)   uniquecounter.sty    2011/01/30 v1.2 Provide unlimited unique counter (HO)   letltxmacro.sty    2010/09/02 v1.4 Let assignment for LaTeX macros (HO)    hopatch.sty    2012/05/28 v1.2 Wrapper for package hooks (HO)   xcolor-patch.sty    2011/01/30 xcolor patch   atveryend.sty    2011/06/30 v1.8 Hooks at the very end of document (HO)   atbegshi.sty    2011/10/05 v1.16 At begin shipout hook (HO)   refcount.sty    2011/10/16 v3.4 Data extraction from label references (HO)    hycolor.sty    2011/01/30 v1.7 Color options for hyperref/bookmark (HO)     keyval.sty    2014/05/08 v1.15 key=value parser (DPC)    ifxetex.sty    2010/09/12 v0.6 Provides ifxetex conditional    auxhook.sty    2011/03/04 v1.3 Hooks for auxiliary files (HO)   kvoptions.sty    2011/06/30 v3.11 Key value format for package options (HO)     pd1enc.def    2012/11/06 v6.83m Hyperref: PDFDocEncoding definition (HO)   hyperref.cfg    2002/06/06 v1.2 hyperref configuration of TeXLive        url.sty    2013/09/16  ver 3.4  Verb mode for urls, etc.    hpdftex.def    2012/11/06 v6.83m Hyperref driver for pdfTeX   rerunfilecheck.sty    2011/04/15 v1.7 Rerun checks for auxiliary files (HO)    nameref.sty    2012/10/27 v2.43 Cross-referencing by name of section   gettitlestring.sty    2010/12/03 v1.4 Cleanup title references (HO)


I would like to run sudo commands yet every time I try it askes me to login and I can't type in the terminal window and I can't enter my password using alt+f2, same for ctrl+alt+f2. could you please help me?

When I'm about to install a program in the terminal it wants the password:  [sudo] password for xxx:   But when I start to type my password nothing happens. What should I do?


When viewing questions in android app, I've tried to see how many upvotes and downvotes the question has. Normally it is done by clicking on the score, but it didn't work in app. I have the privilege on the site.  Is that option hidden somewhere or simply not implemented?

This feature is missing in Android App and this  is same but in general (Mobile web).  Additionally, once this feature is implemented, we might accidentally hit the 'Up' or 'Down' vote (In smaller devices). The author might wonder why their post got downvoted.


So I have the value of N. I have to use this value of N to find the value of D. N = 265291078722948385089717069136983657793 Now I read about RSA algos and found out that N=PQ | where P and Q are prime factors   I found - P - 14716976826788780483 Q - 18026193955816294571   The following is an example of what I've approached Choose p = 3 and q = 11 Compute n = p * q = 3 * 11 = 33 Compute φ(n) = (p - 1) * (q - 1) = 2 * 10 = 20 Choose e such that 1 < e < φ(n) and e and n are coprime. Let e = 7 Compute a value for d such that (d * e) % φ(n) = 1. One solution is d = 3 [(3 * 7) % 20 = 1]  We have P = 14716976826788780483 Q = 18026193955816294571 N = 265291078722948385089717069136983657793 E = 65537 (given) φ(n) = 265291078722948385056973898354378582740    [using (p-1)(q-1)]   I'm unable to solve the equation  (d * e) % φ(n) = 1 for the above values. We need to find/derive D. I tried using this online calculator  But it doesn't accept large values Any help is appreciated

When given $p = 5, q = 11, N = 55$ and $e = 17$, I'm trying to compute the RSA private key $d$.  I can calculate $\varphi(N) = 40$, but my lecturer then says to use the extended Euclidean algorithm to compute $d$. That's where I get stuck.    Here's my work so far:  First I use the Euclid algorithm to calculate:  40 = 2(17) + 6  17 = 2(6) + 5 6 = 1(5) + 1 = gcd   So I know the GCD is 1. Applying the 'extended' section of the algorithm:  6 = 40-2(17) 5 = 17-2(6) 1 = 6-1(5) 1 = 6-1(17-2(6)) 3(6) = 1 (17) 3(40 - 2(17)) - 1(17) 3(40) - 3(17)   I know the answer is $33$, but I have no idea how to get there using the extended Euclidean algorithm. I can't figure out why I'm getting $3(40) - 3(17)$ when I know the answer should contain $33$.


Assuming this structure:

title1

5

title2

1

title3

3

   How can I sort the elements with the class .sortable to show in ascending/descending order based on the class .price inside of the divs? It should happen when clicking a button.  I know that with arrays I could use the .sort method, but as this is not an array, I don't really know how to approach this.

is there a quick way to sort the items of a select element? Or I have to resort to writing javascript?  Please any ideas.  <select size="4" name="lstALL" multiple="multiple" id="lstALL" tabindex="12" style="font-size:XX-Small;height:95%;width:100%;"> <option value="0"> XXX</option> <option value="1203">ABC</option> <option value="1013">MMM</option> </select>


I have an XML file, and i want to get the text from one tag, but if that text contain another tag to ignore it. For example :  <?xml version="1.0"?> <entries>   <entry accente="B" diacritice="B">     <sense class="0" value="B">       <definition>         <RegDef>Hello  <i>world.</i> Today is Saturday.</RegDef>       </definition>     </sense>   </entry>  </entries>   the output should be : "Hello world. Today is Saturday.  What is the best method to do this?

Is there a good way to remove HTML from a Java string? A simple regex like replaceAll("\\<.*?>", "")   will work, but things like &amp; wont be converted correctly and non-HTML between the two angle brackets will be removed (i.e. the .*? in the regex will disappear).


These are my partitions. I have dual boot with windows 10 and Ubuntu 16.04 LTS. I installed Ubuntu without creating a swap partition. I have only root (/) and /home partitions. I want a swap partition for Ubuntu to run smooth. How do I do it?.

I did not create a swap partition during Ubuntu installation.  Later, I freed up some space and made a swap partition.  Now after each boot up, I am manually opening gparted to right-click the swap partition to turn on the 'swapon' option.  How can I automatically enable the swap partition at boot?  Also, if I had not created the swap partition, what are my other options?


is the a tool for Ubuntu, either bootable from an external USB or in-OS, that would allow creating full-partition backup of the system, and restore it if needed to bring the system and all the files in exact same state.  Ideally I'd like it to be in-OS, or if bootable it should back up to the same USB as itself (the install in question is very small). For reference, I am using Paragon Backup and Recovery on Windows for smth similar, it supports both bootable and in OS (using shadow copy) mode.

This question is asked many times but I haven't got the right answer.  What I want is to create a partition where I backup my current Ubuntu partition that appears in the GRUB menu. If one day my Ubuntu won't to start I lunch the backup partition and voila my system is restored.   Currently I use CloneZilla but the problem is I must have always on me a usb key that contains CloneZilla.    EDIT:  df -h /dev/sda5           55G     39G   14G  74% / none               4,0K       0  4,0K   0% /sys/fs/cgroup udev               997M    4,0K  997M   1% /dev tmpfs              202M    1,2M  200M   1% /run none               5,0M       0  5,0M   0% /run/lock none              1006M    8,0K 1006M   1% /run/shm none               100M     36K  100M   1% /run/user parted -l nothing


Hi I have read the questions that written before about this subject but I did not found the answer that related to my question. when I have run my code in android studio it was appeared this error of  "Caused by: java.lang.NullPointerException: Attempt to get length of null array"  Here is the line that cause of the error in my code for the main activity :     Blockquote   File[] files= root.listFiles();

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?


On my Ubuntu machine, if I don't have a particular application installed, the message often points me to the correct package.  Example:  $ rz The program 'rz' is currently not installed. You can install it by typing: sudo apt-get install lrzsz   Is there any way to automate the invocation to install, so that my shell will execute sudo apt-get install .... on its own if such a situation arises?  Alternatively, is there a shortcut so that the entire sudo a ... sz command doesn't have to be typed/copied in?  To clarify:  does not meet the requirements because:   This fails for the example above. lrzsz is the package but rz is the application. apt tells me the right package to install; I don't want to use $1. This would apply for java etc. too.... It can get quite irritating in practice as it offers to install my typos; e.g., if I type ptyhon instead of python:  $ ptyhon Do you want to install ptyhon? [N/y] y Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package ptyhon

When I type a command not found in a PATH in ubuntu, I get something like this:  $ rdesktop The program 'rdesktop' is currently not installed.  You can install it by typing: sudo apt-get install rdesktop   I believe it's a script that looks up the APT archives and suggest an installation package. I'd like to change it so that it offers me to download it at the press of a 'y'. Two questions:  1) Where is the file located?  2) If I just add the install line in the trivial way, it's going to complain that I'm not a root and will fail (because the rdesktop was ran as a mundane user). How do I make it ask for a password and use it to get root access?


Blender was working fine for me a few weeks ago, recently had to replace my ssd, reinstalled blender2.91, and i cant get any materials to display, not in shading, not in uv edit, not in layout/edit mode. If i open up the default starter scene, select the cube, go to material menu select base colour change it, got to material preview/rendered view, i get a weird grey void where the object should be, if i render it renders as a transparent object amid a black background, same thing if i change the base colour to be an image texture. Tried 2.90, a few of the 2.8 builds, same issue, checked for updates to my graphics card, there were none. if i go in to texture paint mode, the image texture is visible, but only in solid viewport rendering short video of issue here

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


Whenever you enter the US, you are required to fill out , which asks for your personal details and whether or not you're bringing in any restricted goods. Whenever you are entering the UK, you are required to fill out a  and passengers entering Canada fill out an . As far as I can tell the immigration officers usually completely ignore whatever details you wrote in those forms and simply scan your passport to enter your details into their computer. It therefore looks like a complete waste of time, as the majority of passengers have no goods to declare anyway and therefore the immigration forms get thrown away right after you get your passport stamp.  So what's the point of these forms/declarations? Why require absolutely everyone to fill them out? As a bonus question explain why car passengers are spared from this obligation and are instead asked verbally if they have something to declare.   Update: no more landing cards in the UK! Now just waiting for US and Canada to remove their outdated practices.

When I clear passport control in every country I've visited so far, one of the first things the officer does is scan my passport and pull up my info on his computer.  He then collects an arrival card from me that contains exactly the same info as what's in my passport, plus some info about my trip (duration of stay, address, etc.).  When I go to leave the country, I am (usually) required to then submit a departure card, which – unlike the arrival card – is 100% redundant with what's in my passport.  These pieces of paper are considered so important that travelers are not permitted to enter/leave the country without them.  What is their purpose, if most (all?) of the information on them can be collected from the passport?


In The Fellowship of the Ring (movie), Gandalf arrives at the Shire to much fanfare.  In particular, young children chase his wagon hoping to see some magic.  This would logically imply that Gandalf was well known in the Shire, since the children would be too young to remember him if he was not a regular visitor. However, the movie and the book differ somewhat. Is there canonical evidence in the books that Gandalf was indeed a regular enough visitor, or at least had been to the Shire very recently before the party?

It has been a while since I read the Lord of the Rings novels (don't have a copy at the moment) but I seem to recall he went to Hobbiton at least once, as the young hobbits were always excited to see him.   Did he travel there often?


Any help with this: construct a sequence of continuous functions defined on $ [0,1] $ which converges pointwise but not uniformly to a continuous limit ?  Thank you.

Please help me out with this problem:  Let $f_n(x) : [0,1] \to \mathbb R$ be a sequence of continuous functions convergent at every $x \in [0,1]$ to a continuous function $f: [0,1]  \to \mathbb R$ . Does $f_n$ converge uniformly to $f$?  My first solution: I read this example in  posted earlier and I think it works: Take a sequence $f_n:[0,1] \to \mathbb R$ such that $f_n$ increases linearly from $0$ to $1$ on the interval $\left[ 0,\frac{1}{n} \right]$, decreases linearly from $1$ to $0$ on the intreval $\left[ \frac{1}{n}, \frac{2}{n} \right]$, and is $0$ on $\left[ \frac{2}{n},1 \right]$. Then $f_{n} \to 0$ nonuniformly.  Is this answer true? Also, if anyone can give some examples of such function with detailed proof, I will very appreciative?


Like I'm trying to develop an application that already has data(paragraphs) . So the user will basically press a button to open up the specific texts.   From the tutorials I've done, I can only add them from the app, while I would want them to already come with the app. how would I go about this with sqlite or should I use something else?

If your application requires a database and it comes with built in data, what is the best way to ship that application? Should I:   Precreate the SQLite database and include it in the .apk? Include the SQL commands with the application and have it create the database and insert the data on first use?   The drawbacks I see are:   Possible SQLite version mismatches might cause problems and I currently don't know where the database should go and how to access it. It may take a really long time to create and populate the database on the device.   Any suggestions? Pointers to the documentation regarding any issues would be greatly appreciated.


Andromeda is moving towards the Milky Way Galaxy at around 250,000 mph, but I wonder what is the direction of our Milky Way Galaxy? Are these two galaxies heading towards each other or Andromeda will catch up Milky Way? The Milky Way is moving at approximately 1,400,000 mph.

As the title says. If everything is moving outward, thrown by the Big Bang, how could two Galaxies end up with velocity vectors that run them into each other?


So this comment in this question  states :     We play a strict RAW game except for discrete, specified exceptions. The AoO's I'm making are not based on threatened area (e.g. Greater Trip, Greater Reposition) but rather are the result of targets provoking attacks of opportunity from everyone. Threatening an area is only important for certain kinds of AoOs. – the dark wanderer    combined with this statement in the post :     occasionally she's shooting into melee from ~1800 ft   leads me to believe that RAW you can take Attack of Opportunities from 1800 ft away. We're going to be starting up a new game of pathfinder soon and I want to know how to do this. So I can do this in my game it sounds awesome.  So any race class extra ability or item you can find from official pathfinder sources is fair game (no consumable items). You can even have a friend to help set up the AoO's. If you can do it with the classes and feats mentioned in the question that spawned this bonus points to you. I'm expecting the answer to be no, but I haven't played pathfinder in a while maybe some new rules came out.

Spawned from the comments in , does the Snap Shot feat allow AoOs outside of Threatened range against the target of Greater Trip?  Snap Shot:     While wielding a ranged weapon with which you have Weapon Focus, you threaten squares within 5 feet of you. You can make attacks of opportunity with that ranged weapon. You do not provoke attacks of opportunity when making a ranged attack as an attack of opportunity.   Greater Trip:     You receive a +2 bonus on checks made to trip a foe. This bonus stacks with the bonus granted by Improved Trip. Whenever you successfully trip an opponent, that opponent provokes attacks of opportunity.   The specific case cited has the ranger character making AoOs against enemies tripped by a partner with Greater Trip up to 1000ft away, but the question holds for much shorter distances. If a character has Snap Shot, and no other feats which increase their Threatened area, could that character make AoOs against a creature tripped with Greater Trip 30' away?


I can't find the "GNOME Tweaks" app/tool using Ubuntu 20.04 Software app. I wan't to use it to customise my Desktop Icons. Any help is greatly appreciated. Sincerely DB

How do I get to the Universe Repository in supported versions of Ubuntu?


Here's my attempt to prove this. I'm not sure about it, but i hope i'm correct.  Let $a=λ, λ\in \mathbb{Z}$. Then $a^2=λ^2=3\frac{λ^2}{3}$. When $λ^2$ is divided by 3 there are three possible remainders $0,1,2$. So  $$ λ^2=3k \lor λ^2=3k+1 \lor λ^2=3k+2   $$   $ λ^2=3k \rightarrow a^2=3\frac{3k}{3}=3k $ $ λ^2=3k+1 \rightarrow a^2=3\frac{3k+1}{3}=3k+1 $ $ λ^2=3k+2 \rightarrow a^2=3\frac{3k+2}{3}=3k+2=3μ, μ\in \mathbb{Z} $   Therefore $$a^2=  \begin{cases}        3k \\       3k+1    \end{cases} $$ where $k$ is an integer.  Can someone verify this? Any help will be appreciated. Thanks in advance!

Prove or disprove: For every integer a, if a is not congruent to 0 (mod 3), the a^2 is congruent to 1 (mod 3)  SO this is for abstract algebra and I am really struggling with this. Here are some of the definitions and theorems I think would apply.  -an integer a divides and integer b if there is an integer q such that b=aq -Let a and b be integers, with a>0. Then there exist unique integers q and r such that b= aq+r and 0<=r  The question says hint: use 2 cases but I'm not really sure what that means. I'm guessing it wants me to look at it when a is congruent to 0 and when it's not? so i tried to do that but just ended up stuck. below is as far as i got with that attempt  Proof: Case 1 There should be some information about letting variables exist in certain number sets here  assume a is not congruent to 0 mod 3, then 3 does not divide a-0, therefore a-0 does not equal 3q for some q in the integers  I was trying to get this to wind down to thus 3 divides a^2-1 but even tho it seems true (I couldn't find a counter example) I couldn't figure out how to prove it with what I have.  Next i tried reversing it thinking I could contradict it or something.  I think this would be case 2? assume a is congruent to 0 mod 3, then 3 divides a-0 and a-0=3q for some q in the integers, then 3q=a since 0 is the additive identity, therefore 3 divides a,  and again stuck and my brain hurts a little..  Can anyone help me figure out how to work this.


In my statistics class, it was proven that the sum of independent and identically distributed random variables distributed according to an exponential distribution follows a gamma distribution using moment-generating functions. However, one thing that confuses me is how the formula for the Gamma distribution seems to come out of nowhere; i.e. the proof confirms that it is correct, but it does not seem to derive it from the exponential distribution definition.

Let $X_1$ and $X_2$ be independent and identically distributed exponential random variables with rate $\lambda$. Let $S_2 = X_1 + X_2$.  Q: Show that $S_2$ has PDF $f_{S_2}(x) = \lambda^2 x \text{e}^{-\lambda x},\, x\ge 0$.  Note that if events occurred according to a Poisson Process (PP) with rate $\lambda$, $S_2$ would represent the time of the 2nd event.   Alternate approaches are appreciated. The approaches provided are commonly used when learning queueing theory & stochastic processes.     Recall the Exponential distribution is a special case of the Gamma distribution (with shape parameter $1$). I've learned there is a more general version of this  that can be applied.


For instance, take the gamma function. Somehow there is a way to use the identity $f(z+1)= z f(z)$ and  the condition $f(1)=1$ to derive the Euler/Laplace integral representation of the gamma function $\Gamma(z)$ using complex analysis as a solution to the functional equation, but how is that done? From what I have seen it is some kind of complicated analytical process involving contour integrals, can you apply a similar process to other functional identities?

Usually, when someone says something like $\left(\frac12\right)!$, they are probably referring to the Gamma function, which extends the factorial to any value of $x$.  The usual definition of the factorial is $x!=1\times2\times3\times\dots x$, but for $x\notin\mathbb{N}$, the Gamma function results in $x!=\int_0^\infty t^xe^{-t}dt$.  However, back a while ago, someone mentioned that there may be more than one way to define the factorial for non-integer arguments, and so, I wished to disprove that statement with some assumptions about the factorial function.    the factorial   is a  for $x\in\mathbb{C}$ except at $\mathbb{Z}_{<0}$ because of singularities, which we will see later. is a monotone increasing function that is concave up for $x>1$. satisfies the relation $x!=x(x-1)!$ and lastly $1!=1$     From $3$ and $4$, one can define $x!$ for $x\in\mathbb{N}$, and we can see that for negative integer arguments, the factorial is undefined.  We can also see that $0!=1$.  Since we assumed $2$, we should be able to sketch the factorial for $x>1$, using our points found from $3,4$ as guidelines.  At the same time, when sketching the graph, we remember $1$, so there can be no jumps or gaps from one value of $x$ to the next.  Then we reapply $3$, correcting values for $x\in\mathbb{R}$, since all values of $x$ must satisfy this relationship.  Again, because of $1$, we must re-correct our graph, since having $3$ makes the derivative of $x!$ for $x\in\mathbb N$ undefined.  So, because of $1$ and $3$, I realized that there can only be one way to define the factorial for $x\in\mathbb R$.  Is my reasoning correct?  And can there be only one extension to the factorial?    Oh, and here is a  to how I almost differentiated the factorial only with a few assumptions, like that it is even possible to differentiate.  Putting that in mind, it could be possible to define the factorial with Taylor's theorem?


I'm trying to install the most up-to-date NVIDIA driver in Debian Stretch. I've downloaded NVIDIA-Linux-x86_64-390.48.run from here, but when I try to do.  sudo sh ./NVIDIA-Linux-x86_64-390.48.run   as suggested, an error message appears.  ERROR: An NVIDIA kernel module 'nvidia-modeset' appears to already be loaded in your kernel. This may be because it is in use (for example, by an X server, a CUDA program, or the NVIDIA Persistence Daemon), but this may also happen if your kernel was configured without support for module unloading. Please be sure to exit any programs that may be using the GPU(s) before attempting to upgrade your driver. If no GPU-based programs are running, you know that your kernel supports module unloading, and you still receive this message, then an error may have occured that has corrupted an NVIDIA kernel module's usage count, for which the simplest remedy is to reboot your computer.   Any help to finish the installation nvidia drivers?

I'm trying to install the most up-to-date NVIDIA driver in Debian Stretch. I've downloaded NVIDIA-Linux-x86_64-390.48.run from , but when I try to do  sudo sh ./NVIDIA-Linux-x86_64-390.48.run   as suggested, an error message appears.  ERROR: An NVIDIA kernel module 'nvidia-drm' appears to already be loaded in your kernel.  This may be because it is in use (for example, by an X server, a CUDA program, or           the NVIDIA Persistence Daemon), but this may also happen if your kernel was configured without support for module unloading.  Please be sure to exit any programs              that may be using the GPU(s) before attempting to upgrade your driver.  If no GPU-based programs are running, you know that your kernel supports module unloading,             and you still receive this message, then an error may have occured that has corrupted an NVIDIA kernel module's usage count, for which the simplest remedy is to               reboot your computer.   When I try to find out who is using nvidia-drm (or nvidia_drm), I see nothing.  ~$ sudo lsof | grep nvidia-drm lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1000/gvfs       Output information may be incomplete. ~$ sudo lsof -e /run/user/1000/gvfs | grep nvidia-drm ~$   And when I try to remove it, it says it's being used.  ~$ sudo modprobe -r nvidia-drm modprobe: FATAL: Module nvidia_drm is in use. ~$    I have rebooted and started in text-only mode (by pressing Ctrl+Alt+F2 before giving username/password), but I got the same error.  Besides it, how do I "know that my kernel supports module unloading"?  I'm getting a few warnings on boot up related to nvidia, no idea if they're related, though:  Apr 30 00:46:15 debian-9 kernel: nvidia: loading out-of-tree module taints kernel. Apr 30 00:46:15 debian-9 kernel: nvidia: module license 'NVIDIA' taints kernel. Apr 30 00:46:15 debian-9 kernel: Disabling lock debugging due to kernel taint Apr 30 00:46:15 debian-9 kernel: NVRM: loading NVIDIA UNIX x86_64 Kernel Module  375.82  Wed Jul 19 21:16:49 PDT 2017 (using threaded interrupts)


Is there any way to import raw MATLAB output into .tex documents?  I have already seen verbatim package as a solution, but it does not meet my demands for 2 reasons:   Matrix elements are not aligned, especially when some elements have decimal digits and others don't. It is not quite convenient, in case MATLAB generates a large output.   Also, I have tested matrix2latex.m but it seems useful only for matrices.  As I said before, it would be convenient to me if I could just import the raw MATLAB output into my .tex file, keeping the format as the one in MATLAB command window.  Thank you!  Edit: Added output generated by an .m script.

This question led to a new package:      Does anybody have a quick and easy way to typeset some relatively long MATLAB code in the appendix? I looked up a few methods, and the mcode package emerged as a possibility, but it seems to be unmaintained...  I have a ton of equations in my code, so I'd prefer a solution that avoids having to use $ to denote equations.  Also, if possible, if there's a way to keep all of MATLAB's "natural" coding colors (e.g. green for comments), that would be great...  Any idea?


My PC (Windows 8.1, dual booting with Windows 10 Dev Preview) won't boot, every time I try it just goes to Automatic Repair which always fails. Things I tried:   Safe mode doesn't work (goes to Automatic Repair). sfc /scannow doesn't work (message: There is a system repair pending ...) sfc /scannow /offbootdir=d: /offwindir=c:\windows didn't work either. (message: Windows Resource Protection could not perform the requested operation.) I did chkdsk /r c: twice didn't find any errors. Tried Startup repair with installation USB a couple of times, most recent one said "root cause found: registry is corrupt" When I first tried System Restore I was able to see restore points (the latest restore point was a windows update of the 13th but it didn't let me restore saying that I need to enable the system protection, my PC stopped working on the 14th) but I can't see any restore points. Refresh doesn't work. (message: There was a problem refreshing your PC. No changes were made) bootrec /fixmbr, bootrec /fixboot, bootrec /rebuildbcd none of them worked.   I do have registry back ups, but I'm not sure how to do a restore if I can't go to safe mode. Is there anything else I should try before giving up and reinstalling?

I just tried to install some updates for my laptop, and now it is stuck in an automatic repair loop. From what I've been able to find so far in the logs, I believe it is some problem with the registry.  The system restore tells me that there are multiple restore points available, including one it created just before attempting to install the updates. However, it tells me that I can't restore my C: drive because "You must enable system protection on this drive".  Is there a way that I can enable system protection on my drive through the command prompt? Failing that, is there a way to restore just the registry (either manually or automatically)? I've been able to open up regedit, though I have no clue what part of the registry is corrupted.  Update:  Here's the only relevant thing the SrtTrail.txt log has to say about the issue:  Root cause fount: --------------------------- Registry is corrupt.  Repair action: System Restore Result: Failed. Error code = 0x1f Time taken = 588875 ms  Repair action: Registry roll back Result: Failed. Error code = 0x3 Time taken = 0 ms   Update 2:  I booted using the legacy boot and managed to surface a new error:  Realtek PCle FE Family Controller Series v1.27 (10/31/11) PXE-E61: Media test failure, check cable    Looks like this is a red herring. This just means that I can't boot from the network.


as a noun originally comes  from French “doctour” from Latin “docere”, to teach; all terms with a positive connotation:         c. 1300, "Church father," from Old French doctour, from Medieval Latin doctor "religious teacher, adviser, scholar," in classical Latin "teacher," agent noun from docere "to show, teach, cause to know,"      The meaning of doctor as a verb is related to the original noun. But from the late 18th century it develops a negative connotation:        1590s, "to confer a degree on," from doctor (n.). Meaning "to treat medically" is from 1712; sense of "alter, disguise, falsify" is from 1774.       (Etymonline)   :        To alter or tamper with something dishonestly; cook: We doctored the receipts/ He doctored the booze (1774+).      (The Dictionary of American Slang)  This later meaning appears to be English specific, as the negative connotation does not appear to present in other European languages such as French, Spanish or Italian.   How did the term doctor develop the decidedly negative meaning  of alter, falsify?

This is a phrase I’m particularly confused about, because it’s used often when something is manipulated or changed.  For example, sometimes images surface online that are clearly Photoshopped, but people refer to them as “doctored” images. Why use the word “doctored” here?


Having an alphabet of letters A-Z and numbers 0-9, how to get  like:  ['AA', 'AB', ..., 'AZ', 'A0', 'A1', ..., 'Z9', '0A', '0B', ..., '98', '99']   As a side question, what is this type of number system called?

How can I get the Cartesian product (every possible combination of values) from a group of lists?  Input:   somelists = [    [1, 2, 3],    ['a', 'b'],    [4, 5] ]   Desired output:  [(1, 'a', 4), (1, 'a', 5), (1, 'b', 4), (1, 'b', 5), (2, 'a', 4), (2, 'a', 5) ...]


I usually clean my soldering iron's tip before turning it off. Yesterday I read an article where someone suggested to tin the tip before turning off the iron. Is this a good idea? And how would it help? My station is a Weller WSM-1 if it makes any difference.

I recently purchased a new soldering station (Aoyue 936). This is my first relatively good quality soldering tool, so I want to ensure I maintain it properly.  My question relates to tinning the tip once I am done using it. The manual which came with my product says:  "When you are not using your iron, make sure you leave a large lump of solder on the tip. This maintains the tinning of the tip, and the tip will last much longer."  However, after substantial reading around the internet, I can't find any such suggestion for tip maintenance. So my question is, when I'm done soldering and am putting it away for storage, do I simply melt a big glob of solder on the tip and put it away, or melt solder on the tip, wipe it off on the sponge, and then store it.  Note: When I try the latter method, the tip initially looks shiny, but after a minute, it gains a slight copper colored tint.


I'm having trouble articulating what it is I'm looking for, so I'll start with an example.      Candy is delicious.       Candies are delicious.      Vegetables are delicious.      Fruit is delicious.   So, I guess, when referring to a general category or group of things, are there any rules for which ones become plural, which remain singular, and which can be expressed either way?  I was trying to explain to a student why you'd say "prepositions are challenging to learn", and not, "preposition is challenging to learn", and I've come up short.  Any insight would be welcome!

I have a question about uncountable nouns that are used as countable in certain situations. When it comes to some uncountable nouns such as fruit, cake, coffee etc., I have found out that they can be countable if they indicate specific items. Here's an example.   I love chocolate cake. → The term cake is treated as a singular noun because here, cake is a general term.  I need a cake please. → Here, a cake means one of the cakes displayed in the bakery where I am visiting. Here, cake means the ‘whole’ cake.  I need a piece of cake. (at a coffee shop) → Here, a piece of cake means a part of the whole cake.    Usually, if we say,  "I'd like some cakes"  it means I would like some pieces of cake, not the whole ones. In fact, my grammar book, Grammar In Use by Raymond Murphy, explains this.  It says: “When people say ‘some cakes’, it usually means ‘some pieces of cake’, not the whole ones.” If this rule is correct, can I apply this rule to other uncountable nouns listed above? Here are some other examples:  I love fruit as a dessert. (compared with sweets). I sell fruit in the market. (compared with vegetables) I am now eating some fruits. (some apples and bananas)  I like to drink coffee in the morning. (compared with tea) May I have one coffee please? I need one Americano. (at Starbucks)  I like fish. (compared with meat) Look at those fishes in the fish bowl. There are several gold fishes! I need one salmon and two tunas.   However, some uncountable nouns are always uncountable as far as I can see. For example,  I love to eat cheese when drinking wine. I came here to buy some cheese. → in this case, even though I indicate some specific kinds of cheese or one kind of cheese, I still say ‘cheese’, right? I shouldn't say a cheese, or a few cheeses. Am I correct?  I love meat. May I have some beef and pork? Some pounds of beef, a pack of pork... → Here, I can't say “I need those beefs and porks”, can I?  I usually put milk in my coffee. I need two cartons of milk. → I can't say “I need two milks” unlike “two coffees", can I? I need one vanilla-flavored milk and one strawberry milk.--> In this case, though, I kind of feel that I can count them because it states a more specific kind of milk.


Evaluate $$D=\begin{vmatrix} -2a &a+b  &a+c \\   b+a& -2b &b+c \\   c+a&c+b  & -2c \end{vmatrix}$$  My try:  Applying $R_1 \to R_1+R_2$ we get  $$D=\begin{vmatrix} b-a&a-b  &a+b+2c \\   b+a& -2b &b+c \\   c+a&c+b  & -2c \end{vmatrix}$$  Now apply $$C_1 \to C_1+C_2$$  $$D=\begin{vmatrix} 0&a-b  &a+b+2c \\   a-b& -2b &b+c \\   2c+a+b&c+b  & -2c \end{vmatrix}$$  Now apply $C_2 \to C_2 +C_3$  $$D= \begin{vmatrix} 0&2a+2c  &a+b+2c \\   a-b& c-b &b+c \\   2c+a+b&b-c  & -2c \end{vmatrix}$$  Now use $R_3 \to R_3+R_2$  $$D= \begin{vmatrix} 0&2a+2c  &a+b+2c \\   a-b& c-b &b+c \\   2c+2a&0  & b-c \end{vmatrix}$$  any way to proceed here using elementary operations?

i have to prove:   $$\begin{vmatrix} -2a &a+b  &a+c \\   b+a&-2b  &b+c \\   c+a&c+b  &-2c  \end{vmatrix} = 4(a+b)(b+c)(c+a)$$   I have tried many calculations between the rows and columns of the determinant to get to the answer i want to solve the exercise however none of them gave me something right. Can someone help?


I am using Ubuntu 16.04  When I run the command sudo apt-get update, I get a 404 Error on two packages from PPAs (fossfreedom and nesthib).   How might I correct these problems?

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 would like to know what would you say what is the benefit of an LME model over a GEE model in the following context: Variable eyes is a variable with 2 factors: right and left Variable visit is a factor with the visit number (can be 1, 2, 3, depending on the patient) An analysis of longitudinal data (or cross-sectional, really) where I analyse the eyes of a person. So I am including the same person twice in the study. In the context of a crossectional, I would include eyes as random effects. And in the context of a longitudinal, I would include a nested Visit/Eye. Which ones would you think are the benefits of LME over GEE? Thanks

I have been quite happily using mixed effects models for a while now with longitudinal data. I wish I could fit AR relationships in lmer (I think I'm right that I can't do this?) but I don't think it's desperately important so I don't worry too much.  I've just come across generalized estimating equations (GEE), and they seem to offer a lot more flexibility than ME models.  At the risk of asking an over-general question, is there any advice as to which is better for different tasks? I've seen some papers comparing them, and they tend to be of the form:  "In this highly specialised area, don't use GEEs for X, don't use ME models for Y".  I haven't found any more general advice. Can anyone enlighten me?  Thank you!


After I typed and executed the following command line, two errors occrued, can anyone tell me the reason and solutions? I'm using ubuntu 20.04. Thanks ! sudo add-apt-repository 'deb  focal main' errors: E: Malformed entry 58 in list file /etc/apt/sources.list (Component) E: The list of sources could not be read.

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


Hello I want to change text in my textView , but dont know how.  I tryed to change it like this   TextView textView3 = (TextView) findViewById(R.id.textView3); textView3.append("hi");   But this textView is in another xml-file.   the compiler outputs FATAL EXCEPTION: main java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.nividimka.shopapplication/com.example.nividimka.shopapplication.ShopActivity}: java.lang.NullPointerException at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2351) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2403) at android.app.ActivityThread.access$600(ActivityThread.java:165) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1373) at android.os.Handler.dispatchMessage(Handler.java:107) at android.os.Looper.loop(Looper.java:194) at android.app.ActivityThread.main(ActivityThread.java:5391) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:525) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600) at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.NullPointerException at com.example.nividimka.shopapplication.ShopActivity.onCreate(ShopActivity.java:62) at android.app.Activity.performCreate(Activity.java:5122) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1150) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2315) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2403)  at android.app.ActivityThread.access$600(ActivityThread.java:165)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1373)  at android.os.Handler.dispatchMessage(Handler.java:107)  at android.os.Looper.loop(Looper.java:194)  at android.app.ActivityThread.main(ActivityThread.java:5391)  at java.lang.reflect.Method.invokeNative(Native Method)  at java.lang.reflect.Method.invoke(Method.java:525)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)  at dalvik.system.NativeStart.main(Native Method)

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?


We're doing a Motion Tracking project in class and we had to use Project From View for the UV on the building we intend to create the VFX meteor explosion, but when I went back into the Blender v2.83 file to continue my work, the picture is only a pink rectangle? (See below) Since it's a school project, I can't move into any higher versions of Blender, but need to work within this v2.83 only. Also, we're in Spring Break, so I'm unable to ask my teacher how to fix this, but I need to complete it this week. If anyone can help, please do, this is really the only part hanging me up as I do understand the rest of the assignment.  Thank you.

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?


In the list of , when I'm trying to upvote a comment, receiving the following error message as a popup.     This comment is not eligible for voting or flagging   But I am able to flag the comment. That is not matched with the error message. Can the error message be corrected?

When trying to upvote a comment made on a locked post (ordinary lock, not historical lock which remove the vote arrows and flag altoghether) we are greeted with such error message:        Or in words:     This comment is not eligible for voting or flagging   Being the curious type, I went straight away and tried to flag, fully expecting the same message... just to see the flag dialog open up just fine:        I was able to flag as well.  Can the error message please be changed to just "This comment is not eligible for voting"? Or of course, if it's not the intended behavior really disable the option to flag?  The original post on which I experimented is now deleted, but  you can play with.


This is a simplified example, but the goal is to have a function that returns a function given a set of arguments, and the returned function should have those arguments expanded into numbers/strings.  The example here returns a function that checks whether a set of coordinates are within a rectangle:  function createFunction(startX, startY, width, height) {     return function(x, y) {         if (x >= startX && x <= startX+width && y >= startY && y <= startY+height) {             return true;         }         return false;     }; }  var myFunction = createFunction(5, 10, 200, 100);  console.log(myFunction); //startX and the other arguments aren't expanded   The problem described in the comment above is that the arguments from the "createFunction"  function aren't expanded into values, and if one used the returned function it would create an error because startX and the other arguments aren't globally defined.  How do I return a function with the variables expanded?

How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, variables and the like), but does not understand closures themselves?  I have seen  given on Wikipedia, but unfortunately it did not help.