I am completely new in Ubuntu. Just installed Ubuntu 14.04. On my other computer running Windows, I am using Avast, free edition.  Do I need anti-virus protection at all?


I've read in a book that I should "use the subjective case if the pronoun is the complement of the linking verb to be".  That is the following sentences are correct:  They believed that the thief was I. /  Hey, it's I. /  Yes, this is she. Who's calling?  OK, a rule is a rule. I don't mind using it, but I have a question for native speakers:  Is this way to say it heard in everyday speech? Will it sound deliberate/unnatural if I use it?


No. I'm not talking about xenophilia.  In both these senses, xenophobia and xenophilia relate to foreigners or strangers.  I am looking for a fear of the same people who live in the same country as you, not foreigners but localers, so to speak.   Essentially I am looking for the opposite of xeno. Ive gone thru the , but I couldnt find any antonyms.  Is there already a term for fear of localers?  If not what appropriate greek/latin prefix would work with the phobe/phile suffixes?


Should I mention my previous Italian Schengen visa refusal in a new UK visa application?

My Schengen visa to Italy was refused in 2013; I had a previous passport back then which I no longer use. I don’t remember if there was any document attached with the reason for refusal, except for a stamp showing date. I assume my visa was refused due to insufficient finances, since I was a student at that time.  I’m now applying for a UK visit visa with a new passport to celebrate new year with my friends. I would like to ask if I should mention about the previous visa rejection in the given section of application. If I mention it on a sincere note, how will it affect the chances of getting my visa to UK? This is my first attempt to secure a UK visit visa; I can’t afford to lose this chance!  Edit  Thank you for guiding me. As I said my passport was stamped and returned without mentioning any reason. How will they verify if I say it was refused due to lack of funds ?


How can I decrease size of my Ubuntu partition?

When I installed Ubuntu on my system my hard formatted entirely and Ubuntu installed on it. Now i want to change partitions of hard disk but it seems is impossible.    How can I resize it?


why this sequence of functions does not uniformly converges?

Show that the sequence: $$h_n(x)=\begin{cases}\frac{x}{n}\left(1+\frac{1}{n}\right) \mbox{ if } x=0\mbox{ or }x\notin\mathbb{Q}\\ x(b+\frac{1}{n})(1+\frac{1}{n})\mbox{ if } x\in\mathbb{Q}. \end{cases}$$  Does not uniformly converges at any bounded interval.  This excercise was taken from the book ``Mathemathical Analysis'' of Tom Apostol.


Card cannot be accessed.Reinsert/change the card or try formatting the card with the camera

I've been using 32 GB SDHC card on my canon EOS 1100D but one day suddenly it showed "card cannot be accessed.Reinsert/change the card or try formatting the card with the camera.". I tried a 16 GB card but it again showed the message. when I used a 4 GB card it worked perfectly with my camera and sorry for my poor english.


Where can I exchange a Faroese crown bank note?

I live in London and would like to sell a 200 kr. Faroe Islands banknote. This should be worth about £20 by the way.  I learn the currency is equivalent to Danish crowns, but none of the UK banks will buy it (hence, I am told by a money changer, that they will not buy it because they cannot sell it onward to a UK bank).  There ought to be an easy solution here that doesn't involve me flying to Copenhagen...


Let $\mathcal G= \{G_\alpha: \alpha < \kappa\}$ be a family of topological groups. My question is this:     Is the topological product $\Pi \{G_\alpha: \alpha < \kappa\} $ a topological group?   Thanks ahead.


Notation in Modular Arithmetic and AKS Algorithm

Section $2$ of  discusses the Idea of the Algorithm.  The paper uses the notation in equation $(2)$: $$(X+a)^n=X^n+a(\text{mod}\enspace X^r-1,n)$$  Does this notation mean $$[((X+a)^n-(X^n+a)\enspace\text{mod}\enspace n)\text{mod}\enspace X^r-1]$$  Also, how does it immediately follows that all primes satisfy the above equation? How can I prove "Mathematically" the two lines comments that succeed equation $(2)$ in the above paper?


$f \in \mathscr{R}[a,b] \implies |f| \in \mathscr{R}[a,b]$

If $f$ is Riemann integrable on $[a,b]$ then so is $|f|$   Here is my attempt:  Since $f \in \mathscr{R}[a,b]$, then $f$ is continuous almost everywhere on $[a,b]$ and is bounded. Let $V$ be a set of points where it is discontinuous so $V$ is of measure zero.  Let $S$ be the set of intervals where $f$ is negative. That is, $S=\{I_1, I_2,...,I_n\}$.  Let $T=\{x_0,x_1,...,x_p\}$ be the set of endpoints of these intervals.  Then $|f|$ is discontinous on $V \cup T$. Since $V \cup T$ is of measure zero, then $|f|$ is continuous almost everywhere on $[a,b]$. It is also bounded since $f$ is bounded.  Hence, $|f| \in \mathscr{R}[a,b]$  $\Box$  Is my proof correct? How can I improve it? What's another way to prove this?


log while hard close the console application C#

I have a Console application Hosted in Task Scheduler. while my job is running, in some scenarios i will store some data in static lists and DataTables. and later i will log those data in single shot.  There is a scenario where technical team will stop the service manually before completion, in this case am missing to log the data that has captured in static list.  Is there any way we can log while the user stops the Console application manually.


Do magic weapons bypass monsters' resistances?

For example, if I use a magic dagger to stab a monster that is resistant or immune to piercing damage, but with no resistance or immunity to magic weapons, does it take full damage or not?


This command  gsettings set org.gnome.shell.extensions.dash-to-dock transparency-mode    can have these values: 'FIXED' 'DEFAULT' 'DYNAMIC' 'ADAPTIVE'.  But none makes the dock bar completely transparent, that is, only the icons are visible.  any ideas?


I want my Qt application to be able to save simple vector graphics to clipboard in a compatible way. On windows I want to be able to paste the graphics into Microsoft Word or Powerpoint. On Linux I want to be compatible with the Open Office.   Which format would you recommend? Can Qt generate EMF in an easy way? Is SVG an option?  Update:  My current plan is to add a piece of native win32 code to render the graphics to emf on windows. This code will not be available on linux.


I'm trying to create an 8.5x11" document, but my system defaults to A4. Being in Canada where US letter is the norm, this is frustrating. I've tried adding   \documentclass[letterpaper]{article}   to the beginning of my document, but I still get A4. I'm on Slackware 14.1, and using pdflatex to generate my document.   Even this small example creates an A4 sized document:  \documentclass[letterpaper]{article}  \title{Title} \author{Your name!} \date{\today}  \begin{document} \maketitle \section*{Fun times with paper sizes} blah blah blah... \end{document}   What am I doing wrong with respect to declaring my paper size, and how can I set US letter to be the default on my system?    Edit:  Here is the command line output:  $ pdflatex swe.tex  This is pdfeTeX, Version 3.141592-1.21a-2.2 (Web2C 7.5.4) entering extended mode (./swe.tex LaTeX2e <2003/12/01> Babel <v3.8d> and hyphenation patterns for american, french, german, ngerman, b ahasa, basque, bulgarian, catalan, croatian, czech, danish, dutch, esperanto, e stonian, finnish, greek, icelandic, irish, italian, latin, magyar, norsk, polis h, portuges, romanian, russian, serbian, slovak, slovene, spanish, swedish, tur kish, ukrainian, nohyphenation, loaded. (/usr/share/texmf/tex/latex/base/article.cls Document Class: article 2004/02/16 v1.4f Standard LaTeX document class (/usr/share/texmf/tex/latex/base/size10.clo)) (./swe.aux) [1{/usr/share/texmf-v ar/fonts/map/pdftex/updmap/pdftex.map}] (./swe.aux) )</usr/share/texmf/fonts/ty pe1/bluesky/cm/cmr10.pfb></usr/share/texmf/fonts/type1/bluesky/cm/cmbx12.pfb></ usr/share/texmf/fonts/type1/bluesky/cm/cmr12.pfb></usr/share/texmf/fonts/type1/ bluesky/cm/cmr17.pfb> Output written on swe.pdf (1 page, 17745 bytes). Transcript written on swe.log.


I'd like to hear from the community on how I should go about implementing GetHashCode (or override it) for my object. I understand I need to do so if I override the equals method. I have implemented it a fair amount of times, sometimes just calling the base method. I understand that my object should equal another instance of the object if it contains the same details (members). What is the best way to get a hash code from the class's members?


Suppose $R$ is a commutative ring with $1$. Further we have an isomorphism $R^m \cong R^n$. Then does that imply $m=n$?  If I consider $R=\mathbb{Z} \times \mathbb{Z} \times \mathbb{Z} \times \mathbb{Z} \times \cdots $, then I think $R^m=R^n$ as both $R^m$ and $R^n$ has countably infinite copies of $\mathbb{Z}$. Hence $R^m \cong R^n$ for any natural numbers $m \neq n$?


I have a friend from Japan who wants a simple explanation.  Which is correct?  "These are their bags."    "This is their bags."


When I log into my friends minecraft server I fall through the world continuously

My friends and I are trying to play the Yogscast Complete pack on a server he has set up on his computer.  When it is just me and him on the server, everything is okay, when I spawn I will fall through the world for about 4 seconds then everything will sync and will be good to go.  However, when someone else tries to join, I start to lag and the friend will just keep falling through the world until I get the message "End of Stream"  He has 10GB of RAM dedicated to the server, has cable internet and any other mod pack works normally when he hosts. Is there some way we can see why this happens, or error codes we can look up?  Any insight would be a great help.


Really struggling with these brakes now. Just installed new pads, but pistons won't separate far enough to put the wheels back in. Tried pushing the piston in using a  plastic tyre remover, but no joy. It seems like one pad (hub side in both cases, front and back) is a lot further out that the other, which suggests sticky pads.  I'm also a bit confused as the pistons move (both pistons on both brakes) as soon as the actuator arm starts moving. I thought they were supposed to have a delay as a valve closed, so I'm wondering if they're actually properly set up at all. I can't see where the bleed valve is though, and if it's opening.  Any advice gratefully received!  Edit; I think there's three problems I'm working on here; i.) The pads are asymmetric; the outside pads are barely showing, the inside ones are protruding by about 2-3mm. ii.) Even with the cable detached and the arms locked out I can't push the protruding pad in. It moves slightly under extreme force, but moves back after the force is removed. iii.) The pads move as soon as the brake lever moves, which I don't think is right.  I'm going to try and clean the edges of the pistons I can get to, as following this you tube video                                and see if that helps at all, will report back.


Answer icons:    Overlap with the popup:    Comment icons and tags too:


Where does half of the work done in charging a capacitor is dissipated?

The energy stored in a charged capacitor of capacitance $C$ with $V$ voltage across it is: $$U= \frac 12 CV^2$$ Whereas the work done in charging the capacitor is: $$W= CV^2$$ This means that $(1/2)CV^2$ amount of energy gets dissipated somewhere else. I learnt somewhere that this is dissipated as heat. But an ideal circuit having just a capacitor with a battery (without internal resistance) provides no resistance. So:  How and where does half of the work done in charging a capacitor gets dissipated?


how does the compiler treat the operator + when the operand is a pointer in C

For example.  int a[]={3,4}; int *p1=a; int *p2=a+1;   In the last line, how can the compiler tell that the +1 in this line is not just a common adding, but a address adding. How can it distinguish from the common adding such as  int i=1+2.   Can someone explain it at the register level?


Why no light travelling inside the window

I have made a simple model with the window with archimesh addon. With the window material i have set to travel the light inside.     But no light travel inside through the window    What is missing the blend file attach below


How to counteract sage (in a pumpkin soup)?

I prepared a pumpkin soup with the secondary ingredients being onions, ginger, garlic, cream, chilli, nutmeg, pumpkin seed oil, and sage. I accidentally added too much of the latter. I wish to neutralise this.  I found and tried the following so far:   General counteracting advice like diluting and adding more of (almost) everything else, both of which I do not wish to do. Physically removing the sage, which are not applicable in my case since the sage was ground.     Adding sugar (or sweet ingredients). I did this to some extent, but perceived no effect. While the sweetness hasn’t spoiled the soup yet, I am afraid that adding more of it might.  recommends to add potatoes, which are claimed to soak up excess spices (in general). I am skeptical about this claim since I cannot find any other source corroborating this. Said source uses a very distancing language in this section. Moreover, if potatoes really suck up flavours in general, they may be of little use for me due to sucking up everything else. By chance, I found that adding salt (or salty ingredients) reduces the effect, but only to a certain extent. Also, this comes with the downside of the soup being overly salty.   Are there any other ways or reasons to assume that my assessment of the above options is too pessimistic?


I am trying to connect my 9 years old Dell XPS M1530 to Wifi. In the  "Additional Drivers" tab, I got the following:   I select the first option under "Broadcom Corporartion" but when I hit "Apply Changes" it instantly goes back to "Do not use the device". This is also happened in "Try Ubuntu" when I tried to test the Wifi connection prior to installation from bootable USB installation drive.  I searched through web but majority of solution assume accessibility to Ethernet connection and I don't have one.  I need a method to solve this issue offline. I need to say I am newcomer to Ubuntu so I would appreciate an answer appropriate to my shallow knowledge. I need also to say I installed Ubuntu alongside Windows 7 and there (in Windows) I don't have any problem whatsoever connecting to Wifi.  Edit  Running the following command: lspci -knn | grep Net -A3; rfkill list  I got the following output:


pass a value to 'this' in a javascript function

This there a way to pass a arbitrary value to "this" in the foo function below;  function foo(a){ var getThis = this; var getA = a;  console.log("getThis:"+getThis); console.log("\n"+a); }  foo(5);   Expected output:   getThis: some value that I can pass 5   Answere to the question:   foo.call('some value that I can pass', 5);   thanks


Thus, axioms are propositions we assume to be true and we use them in an axiomatic theory as premises to infer conclusions, which are called "theorems" of this theory.  For example, we can use the  to prove theorems of arithmetic.  This is one meaning of the word "axiom". But I recognized that the word "axiom" is also used in quite different contexts.  For example, a group is defined to be an algebraic structure consisting of a set $G$, an operation $G\times G\to G: (a, b)\mapsto ab$, an element $1\in G$ and a mapping $G\to G: a\mapsto a^{-1}$ such that the following conditions, the so-called group axioms, are satisfied:   $\forall a, b, c\in G.\ (ab)c=a(bc)$, $\forall a\in G.\ 1a=a=a1$ and $\forall a\in G.\ aa^{-1}=1=a^{-1}a$.      Why are these conditions (that an algebraic structure has to satisfy to be called a group) called axioms? What have these conditions to do with the word "axiom" in the sense specified above? I am really asking about this modern use of the word "axiom" in mathematical jargon. It would be very interesting to see how the modern use of the word "axiom" historically developed from the original meaning.   Now, let me give more details why it appears to me that the word is being used in two different meanings:  As peter.petrov did, one can argue that group theory is about the conclusions one can draw from the group axioms just as arithmetic is about the conclusions one can draw from the Peano axioms. But in my opinion there is a big difference: while arithmetic is really about natural numbers, the successor operation, addition, multiplication and the "less than" relation, group theory is not just about group elements, the group operation, the identity element and the inverse function. Group theory is rather about models of the group axioms. Thus: The axioms of group theory are not the group axioms, the axioms of group theory are the axioms of set theory.  Theorems of arithmetic can be formalized as sentences over the signature (a. k. a. language) $\{0, s, +, \cdot\}$, while theorems of group theory cannot always be formalized as sentences over the signature $\{\cdot, 1, ^{-1}\}$. Let me give an example: A typical theorem of arithmetic is the case $n=4$ of Fermat's last theorem. It can be formalized as follows over the signature $\{0, s, +, \cdot\}$: $$\neg\exists x\exists y\exists z(x\not = 0\land y\not = 0\land z\not = 0\quad\land\quad x\cdot x\cdot x\cdot x + y\cdot y\cdot y\cdot y = z\cdot z\cdot z\cdot z).$$ A typical theorem of group theory is  which states that for any finite group G, the order of every subgroup H of G divides the order of G. I think that one cannot formalize this theorem as a sentence over the "group theoretic" signature $\{\cdot, 1, ^{-1}\}$; or can one?


Out of Universe, was Vader always planned to be Luke's father?

I was watching the original series and got to "I am your father". I thought: is this something the author planned all along or thought of while writing The Empire Strikes Back?


I decided to write my thesis in LyX, got everything working nearly perfectly, but I found a strange problem which google cant help with... I tried to import citation from jabref to lyx, got only error "verify that lyx is running and the lyxpipe is valid" lyx running is, but when i tried to solve lyxpipe problem, I found out that I dont have lyxpipe (lyx and jabref were installed via ubuntu software center and after some searching, I found out that lyxpipe should be there, I tried to remove and reinstall lyx via software center, but still nothing), dont anyone knows whats wrong with my lyx?


Can a line of π lengths be drawn with a compass and straight edge?

I've drawn two random points on a two dimensional plane. If the distance between these two points is one unit, can a line of π units be drawn using a compass and straight edge?  Or, is there a proof that shows this is impossible?


For a given class I would like to have tracing functionality i.e. I would like to log every method call (method signature and actual parameter values) and every method exit (just the method signature).      How do I accomplish this assuming that:     I don't want to use any 3rd party AOP libraries for C#, I don't want to add duplicate code to all the methods that I want to trace,   I don't want to change the public API of the class - users of the class should be able to call all the methods in exactly the same way.     To make the question more concrete let's assume there are 3 classes:     public class Caller   {      public static void Call()       {          Traced traced = new Traced();          traced.Method1();          traced.Method2();       }  }   public class Traced   {      public void Method1(String name, Int32 value) { }       public void Method2(Object object) { }  }   public class Logger  {      public static void LogStart(MethodInfo method, Object[] parameterValues);       public static void LogEnd(MethodInfo method);  }   How do I invoke Logger.LogStart and Logger.LogEnd for every call to Method1 and Method2 without modifying the Caller.Call method and without adding the calls explicitly to Traced.Method1 and Traced.Method2?  Edit:  What would be the solution if I'm allowed to slightly change the Call method?


Is x(t) = ax(t-1) + e stationary or not?

Is $x(t) = ax(t-1) + e$ a stationary process or not? E.g. with $a=0.8$, I would imagine it is not, but if I graph it with random normal error terms it looks stationary.


How can gravity increase $p$ without increase of $\rho$ or $T$?

A point in static fluid has pressure of $\rho$ * g * h, where $\rho$ is the constant density throughout the fluid body, g the gravitational accelaration, and h is the height of the fluid column above that point.  What I can't understand is how this increase in pressure is not accompanied (or caused) by matching increase in density or temperature.  In my understanding, whether it's liquid or gas, pressure basically is the aggregate effect of randomly moving particles exerting force on their surroundings, hence it is connected to the translational kinetic energy of the particles and the frequency of their contact with the surroundings. So it seems any increase in pressure should mean either (1) decrease in volume (or increase in density) or (2) increase in temperature (increased momentum of particles). Apparently this is incorrect as no article on the internet or textbooks I could find suggest this.  What am I getting wrong? How does weight of a fluid column cause pressure rise in microscopic point of view? By making particles faster? Then how come the temperature remains unaffected?


Shutdown and User button missing in panel

I faced with a problem after update,   I missed 2 buttons from above panel, System menu (including shutdown, suspend & …) and User (including log out & …)  how can I restore them !?...


I tried with a few algebraic manipulations with no success. for the system:  $$ \begin{pmatrix} x_1' \\ x_2' \end{pmatrix} = \begin{pmatrix} 4 & -5 \\ -7 & -3 \end{pmatrix}\begin{pmatrix} x_1 \\ x_2 \end{pmatrix} $$  Tried  $x_{1}'=x_{2}$ thus from first equation I get $x_{2}=4x_{1}-5x_{2}$ and then replacing the $x_{2}$ in second equation with $\frac{2}{3}x_{1}$ and the result become $y''=-9y$.  This is not the final answer for some reason, They didn't do any example in class and my logic isn't working here...


I just earned the  badge. I was the 84th to get this one.  Today the URL uses the badge Id to identify a given badge like this:  https://stackoverflow.com/help/badges/891?page=1   Id 891 points to .  Now I'd like to see who has the silver version of this badge. I tried changing the Id part to 890 or 892, but it's not sequentially. I'd have to guess the Id till I find the silver asp.net-mvc-3 badge.  A URL format like this can solve it:  https://stackoverflow.com/help/badges/asp.net-mvc-3?type=silver&page=1   I think it's doable.    Another possibility would be to show the other related versions/types of a badge as links. For example:  In the bronze badge page, offer a link to the silver and gold   versions. In the silver badge page, offer a link to the bronze and gold   versions. In the gold   badge page, offer a link to the bronze and silver versions.


Would you differentiate which are relatives and which are interrogatives? (And I want to know the sub-category (sub-name) of each below, if they are.)        “You can keep it,” said Harry, laughing at how pleased Ron was. (Harry Potter and the Sorcerer's Stone)   Disgusted that the Slytherins had lost, he had tried to get everyone laughing at how a wide-mouthed tree frog would be replacing Harry as Seeker next. (Harry Potter and the Sorcerer's Stone)   His questions showed me how complex and mysterious were certain institutions of the Church which I had always regarded as the simplest acts. (James Joyce, Dubliners)   "I don't give a damn how you lost it as long as you keep it hidden." (Ralph Ellison, Invisible Man)   We revenged ourselves on Leo Dillon by saying what a funk he was and guessing how many he would get at three o'clock from Mr. Ryan. (James Joyce, Dubliners)    The duties of the priest towards the Eucharist and towards the secrecy of the con-fessional seemed so grave to me that I wondered how anybody had ever found in himself the courage to undertake them. (James Joyce, Dubliners)    I noticed how clumsily her skirt was hooked at the back and [8.] how the heels of her cloth boots were trodden down all to one side. (James Joyce, Dubliners)      As Dr. McCawley says:     It is often difficult to distinguish free relatives from interrogative complements, and indeed many examples are ambiguous between the two interpretations. (James D. McCawley, 1988. p.431)   It’s very difficult to distinguish which is relative and which is interrogative. A Korean blogger says, how in “How I spend my free time is a private matter.” is a nominal relative [free relative or fused relative], but in “I want to say how pleased I am to receive this award.” it's an interrogative.   This differentiation is somewhat easy: for the first how functions as CGEL says “combines the function of head of the NP and precuclear element in a modifying relative clause.” And the latter how functions as not referring to something known, something concrete, which can be specified ().


Why is the sum of the digits in a multiple of 9 also a multiple of 9?

The sum of the digits in $9 k$ (where $k$ is an integer) is a multiple of $9$: for example   $$9\cdot 1=9$$ $$9\cdot 7=63 \qquad  \text{and } 6+3=9\cdot 1$$ $$9\cdot 11=99 \qquad \text{and }  9+9=9\cdot 2$$  But why?


Sci-fi book where a human is taken from Earth to help man an alien ship in a fight against other aliens and rises through the ranks to command

The story is about an alien race that comes to Earth and takes a single Earthling to help man a ship to fight an invasion from another people. The human is a psychic as is everyone else on the ship. The main fleet is made up of the alien race, but the ship the human is sent to is crewed by single psychics from different planets. The human has to fight his way up the chain to eventually command the ship. He refuses to retreat when ordered to do so and leads an attack on the invading aliens.


Is an injective ring morphism always a monomorphism?

My question is about rings. I know there exists epimorphisms that are not surjective (e.g. the inclusion of $\mathbb{Z}$ in $\mathbb{Q}$), but I want to know if there is an equivalence (on rings, more exactly, commutative rings with unity) between monomorphisms and injective homomorphisms. If there's that equivalence, would you provide an elementary proof? Or some book where I can find them?


Converting non equidistant point data to raster?

I have a csv file in which first column is longitude, second is latitude and third is temperature. However, the points are not at all equidistant i.e. for each pair of lat-lon I have a value. I want to convert it to 2D raster.   I tried with matlab (triangulation and griddata interpolation), but it was giving me 3D raster (surface).   Also, in ArcGIS I tried using XY data as x-lon, y-lat and z-temp but it was not showing georeferenced points. Is there any way ?


Insufficient storage updating Android app

Every time my Nexus S attempts to update Chrome, It displays an error stating "Insufficient storage available". According to "Manage apps" I have 412MB of internal storage available, which should be more than enough.  Searching Google turns up plenty of people with the same issue, but no definitive answer.  How do I get Chrome to update?


I got this error when using the default settings of the xfce4 panel someone help me :D  icezilla@DESKTOP-9C2LV7B:~/Desktop$ xfce4-panel ** GLib:ERROR:../../../../glib/gtimezone.c:498:init_zone_from_iana_info: assertion failed: (trans.info_index < gtz->t_info->len) Aborted (core dumped)   Ubuntu 18.04 bash on Windows 10 with X410  (xfce4-panel:9123): xfce4-panel-CRITICAL **: 21:37:48.570: panel-application.c:1250 (panel_application_save): expression 'XFCONF_IS_CHANNEL (channel)' failed.


I installed Ubuntu 16.04 and installed dolphin (15.12.3) + FFMpegThumbs so that I can see thumbnails of videos but when I went to the previews the box was just blank.


I dont know if you remember me but you answered my question earlier today in ubuntu help, but i didnt get it. When my computer turns on it loads into a screen looking like this. It's just a grub command line and i have no idea what to do. All my schoolwork is in it. What do I do?


Where do young wizards learn to read, write, do maths and do other basic things?

Harry, Hermione and other wizards with one or more muggle parents learned to read, write, do maths and more at elementary school. Do children from wizard families just learn this at home? And are there tests they have to pass?


What is the most standard way of ignoring output from a python's function?

Let's say that I have function foo that returns a single output. I do not make use of that output in the caller of the function foo.  What is the most elegant way to handle this?  r = foo() # r is not used anywhere later.   Or should I just not do any assignment when calling foo()? The only thing is that I probably get lint warning if I do this.  foo() ....


Locations of Geodetic Survey Benchmarks in Ontario?

Does anyone know where I can find a list of geodetic benchmark locations for Ontario? (If a list even exists that is...)


I installed Ubuntu on my laptop and something happened and my Windows 7 bootloader is missing. I can boot only Ubuntu. So, I tried to do something like suggested here  or , but when I see system recovery option there is no Windows 7 option.


Click event not firing when focus on different form

I have a .NET 3.5 Winforms project. This project has a main form with a toolbar on it with a toolbar button in it. And a simple normal button dropped directly on to the form.  When the main form starts up a smaller sub form is loaded up too in the load event of the main form with the .Show method (so it is not modal which is important).  The focus is on this subform.  When I hover with the mouse over the toolbar button in the main form it responds to the mousehover event but when i click the toolbar button the main form first receives focus, so I have to click again. Only then the click event is fired. When I however do this to the normal button it immediatly responds to the click wether the sub form has focus or not.  So my question is why does this happen? And how can I prevent it so my endusers do not need to click the toolbar button twice?


Why do some powders like flour or matcha green tea causes lumps in hot water while other powders like sugar or cocoa or wheat grass (triticum aestivum) readily dissolve? Wheat grass powder is green and easily dissolves in cold water.  Cocoa:


How to hide an element if I click anywhere but inside in, but also run javascript inside it?

I have a menu button, and if you click it, a menu drops down. Then, if you click anywhere on the HTML except for the menu or the button, the menu disappears. I achieved this by using jquery stopPropogation to prevent the $("html").click event from being triggered if the menu or button are clicked.  However, I added a link to my menu that uses method: :delete, and since jquery is disabled within the menu, the method: :delete is ignored as well, and the link sends a GET request.  Is it possible to achieve a menu that closes if you click anywhere but inside the menu or the menu button, but also have a method: :delete link?
BUTTON

   <%= link_to "LOG OUT", logout_path, method: :delete %>


Can you put disc brakes on road forks originally intended for calipers?

I've decided I want a disc brake, at least on the front, which seems a good enough reason to go bike shopping, but am I overlooking the possibility of fitting a cable pull disc brake to my current bike?  I've been using a ten year old road bike as a commuter.  It has carbon front forks with road caliper/rim brakes and integrated Shimano road brake/gear levers.


Does voltage rating increase on ceramic capacitors have any effect on the performance of the capacitor?

If I have a circuit that is designed for a ceramic, SMD, 0402, 1uF, 10%, 10V rated capacitor, and I swap in a ceramic, SMD, 0402, 1uF, 10%, 25V capacitor would anything change in the circuit?  Would the performance of the capacitor change in any significant or measurable way?


When I import images as planes it shows a random line at the top

So I am making plants for a game and sometimes when I use Import Images as Planes, it has this random line at the top. I've done numerous test to see if my images were the problem, but every time I reimport the file it still has the line. I tried creating a new image, getting rid of other layers, erasing the background numerous times and it still has it. There are some images though that do not have this problem, but it seems to occur most of the time. If anyone could help, that would be more than wonderful.     The top has the random line in it.     The line is not in this image.


Exponential of the differential operator

I am not sure whether this question is even well-posed. But today I learnt that $e^Df(x) = f(x+1)$ where $D$ is differential operator and  $$e^D \triangleq \sum_{i=0}^{\infty} \frac{D^i}{i!}.$$  (ref. )  So I was curious as to whether the differential equation  $$\frac{df(t)}{dt} = e^Df(t) = f(t+1)$$  has any solutions apart from $f = 0$?


find all integers $a,b,c$ such that $a^2=bc+1,$ $b^2=ca+1.$

This was one of the problems in a math contest in India. This is how I tried it: Subtracting the second equation from the first one gives $a^2-b^2=bc-ca$ or $(a-b)(a+b)=c(b-a)$. $a-b=-(b-a)$. Therefore a+b has to be -c. Thus all integers satisfying the condition $a+b=-c$ are such that $a^2=bc+1$ and $b^2=ca+1$. Also if $a-b=b-a,$ it means $a=b.$ Then both $b-a$ and $a-b$ are $0.$ Hence $c$ can thus be any integer. Hence, there are two groups of integers satisfying the required condition $-a=b$ with any $c$ and $a+b=-c.$ Please let me know whether my solution is correct or not.


How find the asymptotic behavior for $x(n)$  if $x^{x^x} = n$?  I supposed that $x = O(\log\log{n})$ and took logarithm two times.  So I get $x = O(\frac{\log\log{n}}{\log\log\log{n}})$  Is it right? How to improve this estimate?


Create recovery disks when Windows 7 will not load

Sony Vaio laptop with Windows 7 Home will not load Windows; automatically goes into startup repair then fails. Unfortunately, there are no restore points and the owner did not create the recovery disks when they purchased the laptop. I have tried the typical things to repair without success; F8 startup options fail (no recovery option available), startup repair fails, repair CD made from a good system fails, booted to another Windows 7 disk fails because its not the same version, CHKDSK, SFC scan, etc.  From a command prompt I can see the recovery partition and it appears to be intact. Is there a way to create the system recovery disks from the recovery partition when Windows will not load?  This unit was purchased at Walmart. The model number is PCG-61611L. Sony's site requires an additional model number to access info. This number is not located on the outside of laptop. Sony indicates there is a text file within Windows which contains this number. Thus far, have not been able to find the file.   F10 and F11 during boot did not work. It appeared F10 tried but all that happened was a row of multi colored pixels across the screen and it froze there.   Saw another post about using gParted to access the drive and change the recovery partition to /boot. Did that and it went farther than before. If successful I will post all the details in case someone else runs into this.   Edit: Found the recovery partition needs to be hidden in order for F10 to work. All that happens when F10 is pressed at startup is it comes to a DOS style boot configuration screen. There are no options for recovery. F11 does nothing. Therefore, I have come to the conclusion the recovery partition may look intact when in actuality it is not functional. The owner will have to purchase recovery disk(s) from Sony since they did not make the recovery disks when prompted.


How can I get the 9 in the following using Regex? /root/.fastai/data/mnist_png/testing/9/8479.png Not 9 in 8479.png. I want to extract the label 9 for the image. Please help


I have problem with sending mail in Crontab #!/bin/sh log_direc="/var/log/snort/alert" email="vodeni1953@heroulo.com" echo "TESST" | sendmail $email < output.txt`  It can run  normal on command and possible to send mail.  But when i put this script to Cron like this MAILTO=vodeni1953@heroulo.com * * * * * /bin/sh /home/weed/Desktop/test.sh  It looks like this  How can I fix it? Thanks


What is the actual meaning of dot product of 2 vectors?

I couldn't get the physical significance of dot product


F test for regressions with a small N with robust standard errors

I have a binary dummy with only a very small number of values for this dummy set to "1" (say 7 out of 120).  When I run the regression the F-test using robust standard errors, the f-test does not show in Stata.  I need to report why this happens. If I remove the robust option, the f-test shows.


Why can't we divide a circumference of a circle with it's diameter perfectly?, In short why is Value of Pi Non Terminating?

Why can't we divide a circumference of a circle with its diameter perfectly?, In short why is Value of Pi Non Terminating? Does that means we can never find exact circumference of any circle?


General question about interfaces in Java

I'm just getting started with interfaces and I cannot grasp the concept.   class Client {     IServer x = new Server();     void m() {         x.p();     } }  interface IServer {     void n();     void p(); }  class Server implements IServer{     public void n() {         System.out.println("Methode n");     }     public void p() {         System.out.println("Methode p");     } }   So client should be able to use the methods provided by server through the interface IServer. Is IServer x = new server(); correct? The examples that I found () all build interfaces and then the main class calls the other class without using the interface. Thank you for your help, I guess I'm just missing something obvious here...


iPhone 5S broken screen root access without iTunes authorization

I have an iPhone 5S with broken screen. I need to save my photos to my PC/Mac; I can't authorize iTunes cause of course the screen is broken and I don't have iCloud, so the only way should be a root access, does anyone knows how to?


I want to prove the following inequality     Let $a$ and $b$ be positive real numbers and $f:\mathbb{R}\rightarrow\mathbb{R}$ a continuous function. Then,   $$\int_{0}^{a}f(x)dx+\int_{0}^{b}f^{-1}(y)dy\ge ab$$   I know that $(a-b)^2 \ge 0$ and so I easily get $2ab\le a^2 + b^2 $ and thus  $ab\le a^2 + b^2 $. I feel like this should guide me to the answer, but I don't know how.


How to Fetch records of Sobject from custom controller in visualforce page?

Like in standard controller we can fetch objects records like: standardcontroller="account"; {!account.name};  how we can fetch from a custom controller?


When I used an exposed filter the filter selection is passed as name/value pair in the url, for example:  members?field_a=valuea&field_b=valueb   How can I set it up to use more of a "pathauto" style url:  members/valuea/valueb


Inconsistent escaping of backslash+backtick characters

When I type the following code:     backtick backslash backslash backtick   In a question or answer, it is interpreted as: \\.  However, in comments, the second backslash escapes the second backtick, which turns the rest of the comment into code-formatted text. See example comment below this question.  I see this question  as a possible duplicate (marked as status-bydesign), but this specific scenario does not seem to be covered.    NOTE: The behavior on MetaSE seems to be different from that on SO. On SO, the rest of the comment turns into pre-formatted text. On MetaSE, one backslash disappear instead.


App Version: 1.0.95 Device Manufacturer: vivo Device Model: vivo 1609   OS Version: 6.0 (1503158401)    When I clicked "open in browser" option in More Options, the app crashed.


I need to build a simple voltage regulator that can drop voltage from 24V(from a DC power supply) to 3.7V and supply at least 2A or more(up to 5A if possibile).  Can I just use a 2 resistor voltage devider? Or should I use a voltage regulator?


Htaccess redirecting 404 URLs to Index page

I am trying to setup my htaccess file such that all 404 pages are permanently redirected to the home/index page using 301. After I configure the htaccess file I try to test that it is working correctly by typing in a bogus URL such as site.com/asdf to see if the 404 will redirect. It does not, it just displays the page not found message from WordPress and fails to redirect to the homepage.  The code I am using (below) seemed to be working over on Stack Overflow (). I have even tried creating a PHP script to use with htaccess to redirect 404's, but still the same result, no redirection.  # BEGIN WordPress <IfModule mod_rewrite.c> RewriteEngine On RewriteBase / RewriteRule ^index\.php$ - [L] RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule . /index.php [L] </IfModule>  RewriteEngine on RewriteCond %{REQUEST_FILENAME} !-f RewriteRule . / [L,R=301] # END WordPress


Could anyone please help me find limit? $$\lim_{n\to\infty} \left(\frac{\left(1 + \frac{1}{n}\right)^n}{e}\right)^n$$ Thank you


Don't revert reputation from suggested edits when reviewer's account is deleted

I noticed something strange in the reputation of one of my accounts today:        Never saw "reverted" event before, so went to  and realized what happened: the user who approved my suggested edit has been removed/deleted their account.  The edit is still there. The post is still there. The effort spent in editing is still there, untouched. I really can't see any reason to take the reputation away in such a case.  Can this please be changed so that the reputation won't be lost? Personally I don't care that much, and got lots of reputation from other sources, but many people have low reputation and each point matters to them.  P.S.  This might be a bug introduced when implementing this recent change about "", so tagging as a bug too.


I need to prove that $\left(1 + \frac 1 {n^2} \right)^n \to 1$.  I tried to use Bernoulli's inequality, but that is not very useful since in the original sequence there is a plus sign. I then tried to use the Sandwich Theorem by finding two sequences which would make bounds for the original one. The lower bound is obvious, the upper bound not so much. I tried using the sequence $\left( \frac 1 {n+1} \right) ^{\frac 1 n}$, but I could not show that this sequence is bigger than the original one for all $n$. Could anyone help me with this?


What is the sum of series in terms of z and N of this expression?

$$\sum_{n=1}^{N}\frac {z^n}{2^n}$$   I attempted to use the method of difference but it didn't work.


How to evaluate these two integrals below $$\int_{0}^{\infty }\frac{\ln\left ( 1+x^{4} \right )}{1+x^{2}}\mathrm{d}x~,~\int_{0}^{1}\frac{\arctan x}{x}\frac{1-x^{4}}{1+x^{4}}\mathrm{d}x$$ For the first one,I tried to use $$\mathcal{I}'(s)=\int_{0}^{\infty }\frac{x^4}{(1+sx^4)(1+x^{2})}\mathrm{d}x$$ but it seems hard to solve.


Can someone explain what's going on between the second equals sign, where things are converted to $r$s?


I have configured a DNS server into a vultr VPS in order to be authoritive for my goddady domain example.com  This is the current configuration of my DNS zone:  ; DNS Servers @               IN      NS      dns.example.com. @               IN      NS      d.ns.buddyns.com. @               IN      NS      e.ns.buddyns.com. @               IN      NS      f.ns.buddyns.com.  dns             IN      A       108.61.xx.xx (my VPS ip)   If I test my domain into   But I get:   *Looks like the A records (the GLUE) got from the parent zone check are     different than the ones got from your nameservers. You have to make sure your parent server has the same NS records for your zone as you do.I detected some problems as follows:*  For d.ns.buddyns.com the parent reported: ['108.61.XXX.XXX'] and your nameservers reported: ['107.191.99.111'] For e.ns.buddyns.com the parent reported: ['108.61.XXX.XXX'] and your nameservers reported: ['213.183.56.98'] For f.ns.buddyns.com the parent reported: ['108.61.XXX.XXX'] and your nameservers reported: ['103.6.87.125'] For dns.example.com the parent reported: ['108.61.XXX.XXX'] and your nameservers reported: ['108.61.XXX.XXX'] For puck.nether.net the parent reported: ['108.61.XXX.XXX'] and your nameservers reported: ['204.42.254.5']   I really don't understand what is happening or if there is any chance to get that test passed.  My domain dns "Glue" record is set into godaddy.com as Hostname like this:     DNS 108.61.XXX.XXX  And all my nameserver are listed as authorative into goddady namserver list for my domain:  DNS.EXAMPLE.COM D.NS.BUDDYNS.COM E.NS.BUDDYNS.COM F.NS.BUDDYNS.COM PUCK.NETHER.NET   I'm really stuck with this  Please, ask for more information if needed


I am doing an error propagation experiment with the CBC mode.I have encrypted a 100 byte text file with openssl. I made the 55th bytes of my encrypted file corrupted.As per theory the corresponding block of 49-64 bytes and the subsequent block of 65-80 bytes should be affected on decryption.But I am only getting the 49-63 bytes impacted in the result.Any help to let me understand this contradiction will be appreciated.


Properties of numbers which are $x^2 + 1$

Why is $x^2 + 1$ not divisible by $11$ where $x$ is an integer.


Problem solving Logical Equivalence Question

I am working with Logical Equivalence problems as practice and im getting stuck on this question. Can somebody help?  Im trying to show that The LHS is equivalent to the RHS  (¬P ∧ ¬R) ∨ (P ∧ ¬Q ∧ ¬R) is equivalent to ¬R ∧ (Q ⇒ ¬(P ∧ ¬R))  I have tried this so far:  (¬(P ∨ R) ∨ (¬Q ∧ P ∧ ¬R))  ¬(¬(P ∨ R) ∨ (¬Q ∧ P ∧ ¬R))  (P ∨ R) ∨ (Q ∧ ¬(P ∨ ¬R))  But im unsure how to carry on from here


Deutsch-Jozsa: why is only one evaluation of $f$ needed?

I might be asking something quite obvious but why is it stated that only one evaluation of $f$ is needed in the Deutsch-Jozsa algorithm? If we have a quantum oracle for $f:\{0,1\}^n\rightarrow\{0,1\}$ and we apply the oracle to the $(n+1)$-qubit state, we get the quantum state $\frac{1}{\sqrt{2^{n+1}}}\sum_{n=0}^{2^n-1}|x\rangle (|f(x)\rangle-|1\oplus f(x)\rangle)$. Why does the algorithm involve only a single evaluation of $f$? In order to apply the quantum oracle, doesn't the application of the quantum oracle involve full knowledge of the function $f$? Don't we have to calculate $f$ for $x=0,1,2,...,2^n-1$?


Why isn't there a truly unified package manager for Linux?

Why isn't there a unified package manager that acts as an interface between the end-user and the underlying low-level package manager (apt, yast, pacman, etc.)?  Is it hard to do and therefore not practical, or is there a genuine obstacle making it impossible to do?


Calculate integral $\int_{-1}^{1} (1-x^2)^n dx $

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


How to break the Y axis in an Excel sheet

I want to break the Y-axis in an Excel sheet. How can I do that?  For example, suppose I have the data in a range from 0-7000 and then range from 22000-28000. I want a break in the Y axis from 8000-20000.


Creating thread of object in different class

I am trying to learn threading here. I have this demo class which prints the nth fibonacci number. No I am trying to create a thread for this demo object in another class threadtest1 and execute it. but I keep getting the following error  Starting thread :Thread[Fibonacci thread,5,main] Exception in thread "main" java.lang.NullPointerException     at threadtest1.startThread(threadtest1.java:21)     at threadtest1.main(threadtest1.java:27)   Can anyone help?  DEMO  class demo implements Runnable { private int limit; public demo(int l) {     limit = l; } public demo() {     limit = 10; } public void startDemo(Thread t) {     t.start(); } public void run() {     int c = 1;     if(limit>2)     {         int i,a = 1,b = 1;         for(i = 3;i<=limit;i++)         {             c = a+b;             a = b;             b = c;         }     }     System.out.println("Fibonacci number["+limit+"] = "+c); } }   THREADTEST1  class threadtest1 { private Thread t; private demo d; private int l; public threadtest1(int l) {     this.l = l;     demo d = new demo(l); } public threadtest1(int l1, int l2) {     this.l = (int)Math.max(l1,l2);     demo d = new demo(l); }  public void startThread() {     t = new Thread(d,"Fibonacci thread");     System.out.println("Starting thread :" +t);     d.startDemo(t); }  public static void main(String args[]) {     threadtest1 t1 = new threadtest1(5);     t1.startThread(); } }


SO is too eager to turn my edited answers into Community Wiki

I like to edit my answers. To clarify, illuminate, add examples, add links, point to new information as it crops up, etc.  It's highly irritating that my effort to improve my answer turns it into a Community Wiki.  Could anything be done to keep me from turning into a collective?


What's the difference between an argument and a parameter in Javascript?

I've found that a lot of developers use arguments and parameters interchangeably and it can sometimes be confusing. I'm hoping to learn the exact difference between the two.


Is it practical to upgrade your Town Hall before you have everything upgraded to the max?

I have heard that it is best to upgrade everything to the max before upgrading your Town Hall. Is this true, or is it impractical?


I want to grant a tech person ssh root access to my Oracle Linux Server 7.7 in the Oracle Cloud Infrastructure to configure something. How can I protocol/log for a ssh user everything he does?  I am aware that he may tamper with protocols (root rights) but I am not expecting him to do so.


Let $R$ be a UFD and $r\in R$ irreducible. If $S=R-(r)$, why is $S^{-1}R$ a PID?   I've finished proving the integral domain part, which was pretty easy.  How to prove it's principal? consider $R \subset S^{-1}R \subset F$, where $F$ is the field of fractions of $R$?  thank you! :p


Can someone point me to a good tutorial explaining the Entity Framework using an XML file instead of a database? I have seen some good tutorials with SQL databases, but I can't make the leap to an XML file.  Thanks!


quoting problem when piping find output into xargs

I have a directory with the following subdirectories, i.e. If I run $ tree -L 1  . ├── 2007-06-20_to_2008-10-01 ├── 2008-07-21_to_2008_08_12-Nokia 2mp ├── 2009-11-01_to_2011-01-10 - All iphone Pics ├── 2011-01-01 palliser-pics ├── 2011-03-10_to_2011-04-12-few iphone pics b4 switch to HTC └── 2011-03-31-to-2013-05-01 ALL HTC pics-backup-prior-to-factory-reset   I would like to see the amount of diskspace those 2 directories and all their contents take up. e.g. desired output, something like  2.7G  2007-06-20_to_2008-10-01 200MB 2008-07-21_to_2008_08_12-Nokia 2mp 1.3G  2009-11-01_to_2011-01-10 - All iphone Pics 667MB 2011-01-01 palliser-pics 2.3G  2011-03-10_to_2011-04-12-few iphone pics b4 switch to HTC 123MB 2011-03-31-to-2013-05-01 ALL HTC pics-backup-prior-to-factory-reset   So I have been trying:  find .  -maxdepth 1 -type d | xargs du -h    but because some of the directory names contain spaces  each line from the find output is producing many WORD's before being passed to xargs, is it possible to fix this?  I know the root cause of the problem is caused by the spaces in the files, and I will use rename to fix if I cant find a way to get disksize with du, find and xargs


Embedding C++ Objects into QML with Context Properties

According to Qt5 documentation:  all public slots of C++ classes that inherit from QObject, are accessible from QML Here what I did:  C++  class MyClass : public QObject {     Q_OBJECT  public slots:     void doStuffFromQmlSlot()     {         qDebug() << Q_FUNC_INFO;     }  public:     MyClass()     {         qDebug() << Q_FUNC_INFO;     } };   my main.cpp contains:  MyClass myClass; QQmlEngine engine; engine.rootContext()->setContextProperty( "myclass", &myClass ); QQmlComponent component( &engine, QUrl::fromLocalFile("qml/qtquick-01/main.qml") ); component.create();   QML  import QtQuick 2.0  Rectangle {     width: 360     height: 360     Text {         text: qsTr("Hello World")         anchors.centerIn: parent     }     MouseArea {         anchors.fill: parent         onClicked: {             myclass.doStuffFromQmlSlot();              Qt.quit();         }     } }   Actually the QtCreator seems to recognixe the exposed myclass object into the QML as it enables auto-completion of both class name (myclass) and the public slot doStuffFromQmlSlot(). When I run the application I unfortunately got the following error:  ReferenceError: myclass is not defined  Any clue on what I'm doing wrong?


How long would it take for the solar core to destroy Earth?

If Earth were at the middle of the solar core, how long would it take to destroy the planet?  Furthermore, how would the planet be destroyed?  To consider the planet to be destroyed, it must be ripped apart in some senses. I'd imagine that the Surface of the Earth would continuously melt and disperse into the sun, until nothing is left.  I've done some research and found that the Sun's energy output is roughly e26, and the gravitational binding energy of earth is e32. So that suggests it would take at least e6 seconds for the Earth to be destroyed.


I have some serious suspition that my boss installed some kind of spy software. Maybe a keylogger, screen capture or something to know what I do when he's not at the office.  I have nothing to hide so I don't know if he doesn't tell me anything because he didn't find anything out of place or because I'm being paranoid and he's not spying me.  Either way I want to be sure if I'm being spied because:   I don't want to work for someone he doesn't trust me me It's illegal and I won't allow anyone to store my passwords (I do access my personal email, homebanking and Facebook account during lunch breaks) and personal information.   So... how can I detect spy software in a iMac running OS X 10.6.8? I have full admin permissions know it.  I tried scanning all folders in my user's and system Library but nothing rang any bell but since I think any of this software would hide the folder (either by location or name)  I don't think I'll find a folder named Employeee Spy Data  I also looked all the processes running at different moments with Activity Monitor but again... it's not like the process would be called SpyAgent Helper  Is there a list of known possible folders / processes to look for?  Any other way to detect?


Suppose $n$ divides $3^n + 4^n$. Show that $7$ divides $n$.

Suppose $n \geq 2$ and $n$ is a divisor of $3^n + 4^n$. Prove that $7$ is a divisor of $n$.  My work so far:  I had a hypothesis that if $n| 3^n + 4^n$, then $n = 7^k$ for some $k\in\mathbb{N}$. But this is not necessarily so. Take $n = 7⋅379$, where $3^7 + 4^7 = 7^2⋅379$. Then, $3^7+4^7$ divides $3^n + 4^n$, and since $n$ divides $3^7+4^7$, we must have $n|3^n+4^n$.


High rep user voted to close as duplicate, but question remained open - wondering why?

I'm a relative high rep user (177k) on Stack Overflow. I am accustomed to being able to unilaterally close a question as a duplicate. But, today when I voted to close as a duplicate , the question did not close. It just registered one close vote.  Did a policy change? Or is there something different about  that keeps it from being subject to the immediate closure as a duplicate?


Cant run any commands - -bash: ls: command not found

I am logged into a remote shell and I had root access to this. I was trying to edit my .bashrc and .bashrc_profiles files when suddenly my connection snapped, leaving the files open. I suspect something went wrong. How can I restore these files from the command line?   I tried copying from /etc/skel, however my cp command is also not working. Neither do nano or vim work.


Let $X$ be a simplicial set. Define the complex $(C^X_\bullet,D)$ by  $$C^X_n=\bigoplus_{X_n} \mathbb{Z}$$ and $$D_n=\sum_{i=0}^n (-1)^i d_i:C_n \to C_{n-1}$$ where the $d_i$'s are the face maps.   I wonder if there is a relation between the homology of $(C^X_\bullet,D)$ and the singular homology of $|X|$, the geometric realization of $X$.   I know that there is a weak equivalence $X \to S|X|$ and that the singular homology of $|X|$ is exactly the homology of $(C^{S|X|},D)$ as defined above. But I cannot conclude yet that there is a homotopy equivalence between the complexes $(C^X,D)$ and $(C^{S|X|},D)$, do I ?


Our United Airlines flight UA6056 from DTW to IAH was delayed on 1/1/2019 scheduled for 8:25am departure and I want to find out when it actually boarded & took off?   They told us at the gate it was delayed 1 hour and to come back to board at 9am. When we returned just before 9am the flight had already left. Without us. For our honeymoon.


Let $\Omega\neq \emptyset$ and let $\{X_\lambda\}_{\lambda \in \Omega}$ be a collection of sets. Define the Cartesian product of the sets $X_\lambda$ to be $\prod_{\lambda \in \Omega}X_\lambda := \{f : \Omega \to \cup_{\lambda \in \Omega}X_\lambda : f(\lambda ) \in X_\lambda \,\forall \lambda \in \Omega\}.$ Prove that the following $3$ statements are equivalent:  If $\Omega\neq \emptyset$ and for each $\lambda \in \Omega, X_{\lambda}\neq \emptyset,$ then $\prod_{\lambda \in \Omega}X_\lambda \neq \emptyset$.  Suppose $\Omega \neq \emptyset$ and that  for all $\lambda \in \Omega, X_\lambda \neq \emptyset$, and $X_\lambda \cap X_\alpha = \emptyset$ if $\lambda \neq \alpha \in \Omega.$  Then $\prod_{\lambda \in \Omega}X_\lambda \neq \emptyset$.  Given a nonempty set $X,$ there exists a function $f : \mathcal{P}(X)\backslash \{\emptyset\}\to X$ so that $f(A)\in A$ for all $A \in \mathcal{P}(X)\backslash \{\emptyset\},$ where $\mathcal{P}(X)$ is the power set of $X$.    The above are all versions of the axiom of choice. I'm thinking of showing that $(1)\Leftrightarrow (3)$ and $(1)\Leftrightarrow (2).$ We first show $(1)\Rightarrow (3).$ Suppose $X$ is a nonempty set. Consider $\Omega := \mathcal{P}(X)\backslash \{\emptyset\}\neq \emptyset$ as $X\neq \emptyset.$ Then for each $\lambda \in \Omega,$ define $X_\lambda := \lambda.$ Then $\prod_{\lambda \in \Omega}X_\lambda \neq \emptyset$ by $(1)$. Let $f \in \prod_{\lambda \in \Omega}X_\lambda.$ Then observe that $f : \Omega \to X.$ Also, $f(A)\in A$ for each $A\in \Omega.$ But how can one show $(3)\Rightarrow (1)$? I'm thinking of constructing some sort of power set, but all I have is a nonempty set $\Omega$ and that for each $\lambda \in \Omega, X_{\lambda}\neq \emptyset.$ $(1)\Rightarrow(2)$ is obvious. But $(2)\Rightarrow (1)$ requires me to explicitly construct disjoint $X_\lambda$'s. If $\Omega$ is uncountable, would this result in problems? How could I work around them?


SharePoint 2013 - Change URL of document library

I created a Document Library called Resource Documents. Would it be possible for us to set a friendly URL on this library so that files may be read with the following URL pattern...  http://site/my-resource-documents/...   rather than  http://site//Resource%20Documents/...


What is the logic that leads to conservation of energy from time invariance?

I have read different accounts of time invariance leading to the conservation of energy, but have not encountered the specific logical explanation for it. Can someone provide it?


Use a single command to call a script that sets environment variables

I have a set of folders with scripts in them.  These are used to setup various environments.  Each folder also has a plain text file that has some settings that are read by the script (so that the settings only need to be updated in one place and can be read by the bash or powershell scripts).  I have another folder that contains scripts that take parameter to determine which folder to execute the script from.  This folder in in the PATH, so that the scripts can be called as you would an executable.  Now, I am have gotten this to work on windows, where I am a bit more familiar, however making this work on Mac has not been kind to me.  I do not want (the users) to have to source the file, I want the script to do that automagically (as is working on Windows).  script root -scripts --env_a --- settings --- bash script for env a --- posh script for env a --env_b --- settings --- bash script for env b --- posh script for env b -path --set_env.sh --set_env.bat  So on Windows, I can > set_env env_a, and the environment variables are available to the current and child processes.  How can I do the same on Mac?


Notation: If $K$ field, $t$ transcendent over $K$, then what is $K[t]$?

I'm a little bit confused by the notation "$K[t]$", what does it denote? I know that $K[X]$ is the polynomial ring over $K$, so the elements $P$ of $K[X]$ look like $P(X) = \sum_{n=0}^\infty k_n X^n$ with $k_n \in K$. Is $K[t]$ then just the image of the homomorphism $P \mapsto P(t)$ with $P \in K[X]$? Wouldn't that just be same as $K(t)$, which is the smallest field that contains both $K$ and $t$? What's the difference?


I have to deal with a lot of numbers in my latex documents. So far, I have been using a rudimentary \newcommand{\VarOne}{1000} to define \VarOne and then use it as it is using \VarOne{} in the document.  Can I use LaTeX to perform basic operations like add/ subtract/ multiply/ divide numbers --- integers/ non-integers?  Also, is there a way to print non-integers with comma separated values? So, \newcommand{\VarOne}{1000.97} produces 1,000.97 when used in the document? I can do this only for integers using \newcommand\mynum[1]{\num[group-separator={,},group-minimum-digits=4]{\the\numexpr(#1)\relax}} macro.


Installing package(s) from local repository

I used following method to install packages by local-repository   mkdir /var/my-lcaol-repo and put all debs inside this folder Create /etc/apt/sources.list.d/my-local.list with deb file:/var/my-local-repo/ ./ and sudo apt-get update Install package(s) by sudo apt-get install [package]   All working fine but there is one problem:   If package which I'm tiring to install from local-repository (i.e /var/my-local-repo) is available from Repository that enabled (example: main or universe) then apt first tries to download packages from online repository and at that time I am not connected to internet , it fails to download archives and stops.  Temporary solution: Disable repository (ex- main or universe) then apt installs package from off-line repository. But I don't want to disable online repository.  Possible solution: Give first priority to off-line repository. How to?  Note: same package version (which is available on main/universe repo) is available in offline-repository


Linux/Bash: Create relative soft links to files in directory tree?

I'd like to make links to all files in a directory tree. Which means, create the same directory structure and make the links in them to the respective subdirectory in the original dir.  That could be done with   cp -R -s ../foo .   But - that needs an absolute path. So rather  cp -R -s `readlink -e ../foo` `readlink -e .`   I would like the resulting links to be relative.  Is there some easy way? E.g. some script or program specialized for that.


Index Out of Bounds exception in simple for loop: index variable is exceeding array length for unknown reason

I'm getting an index out of bounds exception in a toy project I made to follow a tutorial. The loop is supposed to start a bunch of tasks and store the Task objects in an array. After the for loop finishes I await the tasks using Task.WhenAll() and print the result. The loop is supposed to terminate when i < Pages.Length == false, but the out of bounds error is being thrown when i == Pages.Length (after the loop should have terminated).  My main question is: Why is the variable i being allowed to reach Pages.Length?  This seems to be an extremely common loop, so any insight into this would be greatly appreciated.  (The loop in question is the topmost loop on line 6)          private async void AsyncClick(object sender, RoutedEventArgs e)         {             Stopwatch watch = Stopwatch.StartNew();             Task<WebPageData>[] tasks = new Task<WebPageData>[Pages.Length];             ConsoleOutput = $"Starting Download {Environment.NewLine}";             for (int i = 0; i < Pages.Length; i++)             {                 tasks[i] = Task.Run(() => DownloadPage(Pages[i]));             }              WebPageData[] results = await Task.WhenAll(tasks);              for (int i = 0; i < tasks.Length; i++)             {                 ConsoleOutput += $"{results[i].URL} : The length is {results[i].PageContents.Length}{Environment.NewLine}";             }              watch.Stop();             ConsoleOutput += $"Finished downloading in time: {watch.ElapsedMilliseconds} ms";         }           private WebPageData DownloadPage(string websiteUrl)         {             WebClient client = new WebClient();             WebPageData data = new WebPageData() { URL = websiteUrl };              data.PageContents = client.DownloadString(data.URL);             return data;         }    As the code is the debugger throws an error when i == Pages.Length == 3.  I've tried changing i < Pages.Length to i < Pages.Length - 1, which result in the loop being finished, but a null exception later in the code (expected).  I've also tried putting in if(i >= Pages.Length) break into the loop, but it had no effect for some reason.


So i have to prove that: $$\{\neg A\to B,A\to C,B\to D\}\vdash \neg C\to D$$ I can use logical axioms, modus ponens and 'metatheorems'.  Logical axioms:   φ→(ψ→φ) (φ→(ψ→χ))→((φ→ψ)→(φ→χ)) (¬φ→¬ψ)→(ψ→φ)   Also i can use modus ponens(the only rule i can use) and metatheorems   Some thoughts:So i started experimenting with all $3$ tools i have, started asking myself is any of the hypotheses can give as something new using the logic axioms but then  i stalled, and modus ponens can't do much on it's own knowing these hypotheses atleast.My next thought was that i have to use those 2 metatheorems in order to actualy prove one part of $\neg C\to D$ (based on metatheorem 2) meaning i use as a hypothesis $\neg C$ to prove $D$ but i am stuck and i don't undestand even how to start.


This may seem like a dumb question, I've tried many different solutions with setting the charset but nothing helps. I've got a database with different texts for each day, some of them has got the letters åäö and when loading the page, åäö is just visible as question marks in a black rhombus.   It's working perfectly on my other page but I can't figure out what's wrong.  Here's my code.  $conn = mysqli_connect($servername, $username, $password, $dbname);                          if (!$conn) {                             die("Connection failed: " . mysqli_connect_error());                         }                          $sql = "SELECT * FROM xxxx WHERE xxx = 'xxxxx'";                         $result = mysqli_query($conn, $sql);                          if (mysqli_num_rows($result) > 0) {                             // output data of each row                             while($row = mysqli_fetch_assoc($result)) {                         echo '                                                                            <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />                                                                          '.$row["stackinfo"].'
                         '.$row["monday"].'
                         '.$row["tuesday"].'
                        '.$row["wednesday"].'
                       '.$row["thursday"].'
                        '.$row["friday"].'                                                 ';                                 }     } else {                         echo "0 results";                         }                          mysqli_close($conn);   Also, it would be useful if ü, ø, and æ worked as well.  The db uses latin1_swedish_ci.  Thanks in advance!  Update, the full php but without the table name (just for security.)  <?php                       header('Content-Type: text/html; charset=utf-8');                             define('INCLUDE_CHECK',true);                              require 'connection file';                               $conn = mysqli_connect($db_host, $db_user, $db_pass, $db_database);                             if (!$conn) {                                 die("Connection failed: " . mysqli_connect_error());                             }                              $sql = "SELECT * FROM xxx WHERE ClassID = 'xxx'";                             $result = mysqli_query($conn, $sql);                              if (mysqli_num_rows($result) > 0) {                                  while($row = mysqli_fetch_assoc($result)) {                             echo '                                                                                <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
                             '.$row["stackinfo"].'
                             '.$row["monday"].'
                             '.$row["tuesday"].'
                             '.$row["wednesday"].'
                             '.$row["thursday"].'
                             '.$row["friday"].'
                                                         ';                                 }                             } else {                                 echo "0 results";                             }                              mysqli_close($conn); ?>


So i was following a "How to make a fire" tutorial on youtube and i have a render view problem now.   An when i change to render view it looks like this    How can i fix it?


Last year I was curious about some hat stats ().  Unfortunately, this data wasn't collectable at the time I asked.  Please consider collecting the data this year.  You could have an interesting blog post about the data analysis.   Things like:   Out of all the people who earned hats on the site, what percentage of users on Android.SE earned the different mobile app hats (and similarly for the Apple.SE) What is the ratio of "Crabby" people to "Red Shirt" (and "I Voted Today")? What was the long term effect of the Resolution hat? (How many comments were deleted? Did this cause any questions to become eligible for roomba deletion having fallen below the "keep because enough comments"?) What rooms had the most Sumo Judge hat recipients?   You know, that sort of thing.  There's a lot of data analysis possible to pull out of the hats and it would be really nice to either save and distribute this data or do it yourself (it could be fun).


I read this question somewhere  Let a square of length 1 unit and a circle is inscribed in it such that it touches the sides of square.   Now cut small portion(outside the circle) of square from each corner.   As you can se the perimeter of square is still 4 after removing this portion.   Continue this process i.e. cut the square in such a way that shape of cutting square tends to the shape of circle.   Now the main thing is  Perimeter of square =$4$  Perimeter of circle= $2\pi \frac{1}{2}$=$\pi$  Since the the shape of square tends to the shape of circle  Therefore perimter of square $=$ Perimeter of circle ( or may be approximately equal to circle)  That is $\pi =4\ or\  approx \ 4$  If we take side of square of length $a,a>0$ we also reached to the same result.   Can anyone explain whats wrong in this. I am unable to figure out.   Any help appreciated.


Lollipop hide quick settings on Lock screen

I'm sure this would have been asked before. But I couldn't find out yet.  I recently updated to Lollipop in my Sony Xperia Z phone. The notification bar and pull down settings are great.   But on lock screen, I don't want to turn on/off any WiFi, Bluetooth or any  settings. Simply pull down settings should not be allowed on lock screen. How can I do that? Is there any option?  I have pattern lock already.


A fellow on a social site suddenly starts asking me where I am from and what my interests are. I want to tell him that I am not interested in a random conversation and that I'll only answer if he's looking for any certain information. Now, is there a better phrase or word for random conversation? Something that means, sudden useless or pointless talk. I want a more subtle but powerful word.


What is the difference between degree celsius and celsius degree?

It seems similar but can you guys please answer it that what is a specific difference between degree celsius and celsius degree?


Prove that $\lim_{n\rightarrow \infty}nx^n = 0$ for $|x| < 1$.

Prove that $$\lim_{n\rightarrow \infty}nx^n = 0$$ for $|x| < 1$.  I can tell that $\lim_{n\rightarrow \infty}x^n = 0$, and it's going to zero much faster than $n$ goes to $\infty$. But how do I take it from here? And how do I also prove it for negative x's?


Is there a way to track total mission playtime?

Starcraft 2: Wings of Liberty has an achievement to complete the campaign on Normal in under 8 hours. I've already seen this question: , which lists how to earn the achievement, but is there any way to track how much time in total has been spent?  Or do I need to go to the mission screen and add up all the times manually?  I"m just thinking it may be easier to replay a mission for a better time (by reloading a save from before that mission), then it would be to get through the entire campaign to find out I missed by 10 seconds or so.


Is there a way to check whether current user has certain permission via REST API? Preferably without using metadata APIs.


Number of ways to write a natural as a sum of naturals

Problem:  Let $n$ be a natural number, and $S(n)$ be the number of ways $n$ can be written as a sum of naturals.  For instance, $S(3) = 4$ because $3 = 2+1 = 1+2 = 1+1+1$ and these are four different ways.  Note that we count single-term sums, and different permutations.  Find and prove a simple formula for $S(n)$.  My attempts so far has been to try and do this with induction. By testing the first four cases, I have found that the pattern seems to be that $S(n) = 2^{n-1}$ but I'm unable to prove it.  I am open to other ways of doing this besides induction, of course. It just came to mind because of evaluation on naturals only.


Proper way to add a user account via bash script

Here's the script code I'm using now:  getent group $MYGROUP if [ $? -ne 0 ] ; then     sudo su -c "groupadd $MYGROUP" fi sudo su -c "useradd mynewuser -p mypassword -m -g $PRIMARYGRP -G $MYGROUP"   This approach works well on openSuse. But there are several problems with the user account it creates on Ubuntu so I am seeking help here.   the terminal prompt isn't set (echo $PS1 returns nothing) the arrow keys and tab key do not work correctly in the terminal the password doesn't seem to work (although I'm still unclear exactly what this issue is) the /etc/sudoers rights set for this new user are not honored   If instead I manually create the user with adduser (instead of useradd) I don't have these problems on Ubuntu. But I can't use adduser on openSuse (afaik). Therefore, I need a non-Debian-exclusive script or method of adding user accounts via my bash script that works on Ubuntu (and doesn't stop working on other distros).  Finally, I would like to understand  between adduser and useradd. For example, I want to know which skeleton directory is used by adduser as that might be the reason useradd isn't working as expected (because I just accepted the default).   Thanks


I want to change base 10 number to base 16

I'm writing some code(javascript) to change a base 10 number into base 16. I know base 16 have letters if the remainder is between 10 and 15. This is where I am having trouble. I can't change the remainder into the letter.  so far this what I have:    var mynum = 4053,remainder=[];  while (mynum > 0) {    total = mynum % 16;   remainder.push(total);   mynum = Math.floor(mynum / 16);    switch (total > 9 || total < 16) {     case total === 10:       total = "A";       break;     case total === 11:       total = "B";       break;     case total === 12:       total = "C";       break;     case total === 13:       total = "D";       break;     case total === 14:       total = "E";       break;     case total === 15:       total = "F";       break;   }  }  console.log(total,remainder)     Let's say "mynum" = 4053 then I would get 5,13,15. But I want to get 5,D,F.I also tried using a "for" loop but got the same thing. It feels like i'm close but just missing something something, Can someone please help me?  mynum is the actual number, total is the remainder, and "remainder" is where i put the remainder's in a list


Using select by location is a stand alone script

I have script that I run quite regularly in the python window of Arcmap 10.2.2 and am in the process of converting it to a toolbox script so that others can use it more easily.  It uses select layer by location a number of times, for example:  arcpy.SelectLayerByLocation_management(Contours_G_1m, "CONTAINS", peakpoints)   It worked fine in the python window but now that its in a tool it fails with     Parameters are not valid. ERROR 000368: Invalid input data   This is not at all surprising because this tool works on a layer and the script does not add a layer to the map when it creates a new feature class.   Is there any way of selecting the feature in a shapefile rather than a layer by location, or a workaround for using this tool in a script?


How to add a logo to the upper-right or bottom-right of each page in beamer

Friends, I'd like to add a logo to the upper-right or bottom-right of each page in beamer. But I cannot figure it out. I can only add it to the footline. In this case, the title and name are omitted. How can I solve it? Here is a minimal example of my Beamer TeX. Thanks a lot. \documentclass[12pt]{beamer} \mode<presentation> { \usetheme{Madrid} \setbeamertemplate{navigation symbols}{} } \usepackage{indentfirst,amsmath, multicol,amssymb} \usepackage{caption} \usepackage{booktabs,colortbl}   \usepackage{grffile,threeparttable} \usepackage{graphicx,subfig,graphbox}  \usepackage{tikz} \usepackage[absolute,overlay]{textpos} \setbeamertemplate{caption,footline}[numbered]  \def\name{Yan} \hypersetup{     colorlinks = true,     urlcolor = blue,     pdfauthor = {\name}, }     \title[Introduction ]{An Introduction}  \author{     Yan} \institute[CU]   \medskip  \date{\today} % Date   \begin{document}     \tikzstyle{every picture}+=[remember picture]          \everymath{\displaystyle}      \begin{frame}         \titlepage      \end{frame}          \begin{frame}{Outline}          \tableofcontents      \end{frame}      \section{Background}         \begin{frame}{Why}  a integrated   \end{frame}  \end{document}


I have a little problem in service (android).              In my code what i am doing exactly...first i send data through intent to service.  Intent i = new Intent(getApplicationContext(), External.class); i.putExtra("data",data); i.setAction(External.ACTION_PLAY); getApplicationContext().startService(i);   Then in method onStartCommand() i receive that data.  Bundle b=i.getExtras(); data=i.getStringExtra("data");   So in notificationbar with action_play by onPlay() method we get actual data.  Toast.makeText(getApplicationContext(),"I get your message"+ data,Toast.LENGTH_LONG).show();   Then, when i again try to receive that data by with acton_pause by onPause() method i get null, i mean" I get your message null." every time i get that, i initialize every thing make them all static one by one and together but i got null.i am putting my initialization code here ,check that and help me to solve it......  In activity  private static  String data="music is mine";   In External service  private static String data="";   Thanks in advance.


$\mathbb{Z}[G]$ isomorphic to $\mathbb{Z}[H]$ then what can be said about $G$ and $H$?

The question in title has been considered for finite groups $G$ and $H$, but I do not know its situation, how far it is known whether $G$ and $H$ could be isomorphic. I have two simple questions regarding it.  Q.0 If $\mathbb{Z}[G]\cong \mathbb{Z}[H]$ then $|G|$ should be $|H|$; because, $G$ is a free basis for the free additive abelian group $\mathbb{Z}[G]$, am I right?  (I am asking this because in Isaac's character theory, I saw something different argument, not too lengthy, but I was thinking for the above natural arguments.)  Q.1 Are there known examples of finite groups $G\ncong H$ with $\mathbb{Z}[G]\cong \mathbb{Z}[H]$? (In the book of character theory by Isaacs, he stated for metablelian groups $G,H$, $\mathbb{Z}[G]\cong \mathbb{Z}[H]$ implies $G\cong H$; it was proved by Whitcomb, in $1970$; but book has not been further revised, I don't known what is done after $1970$).


So in my "the linux command line" book, it says this  "The PATH variable is often (but not always, depending on the distribution) set by the /etc/profile startup file and with this code:     PATH=$PATH:$HOME/bin"   when i open the etc/profile to see if it's there, it's not....but surely this bit of code has to be in the system? In the environment, there is the path variable, but it's not the same, there are several paths seperated by colons.  Where is this bit of code on my system, if at all?


Saving Animated GIF With Transparency (Photoshop)

I am trying to save an animated GIF, but for some reason areas that are more transparent than others (e.g. the grey shadow) don't come out with opacity, they become fully grey when saved.    When I save it, it turns out like this:    These are my settings when trying to save:


Why is the first letter of a proper noun capitalized

Is it incorrect grammar to make the first letter of a proper noun small letters ?  I found that most of the online grammar checkers will mark it as an error if you don't  capitalize the first letter of a proper noun. What's the logic behind that.


JAVA -- Subtracting doubles returning imprecise value

I am having trouble returning a precise value from a method in which I am subtracting two doubles. I am creating a "bank" software and in this method I am calculating the current interest rate which is set at 30% and is reduced by 2% whenever 5 new accounts are added.   Here is my code:   public class BankAccount {     //static properties     private static double interest = 0.3;     private static ArrayList<BankAccount> accounts = new ArrayList<>();      public static double getInterestRate() {         int y = accounts.size();         double x = interest;         if (y != 0 && y % 5 == 0) {             x-=0.02;         }         return x;     } }   After I add 5 accounts, my method should return an interest rate of 28%(.28) but it is returning a value of 27.999999999999997%(0.27999999999999997). I understand that this is due to floating points but I'm unsure how to resolve this issue. I am unable to pass any of my test cases which are all looking for exactly 28%, 26%, etc...  I'd like to use the BigDecimal class however this is a homework assignment and is graded automatically. To do so we are given a skeleton code template so we use all the correct variables and types.


pgfplots: Multiple (shifted) stacked plots in one diagram

How can I get multiple stacked plots (ybar stacked, stack plots=y) in one diagram, such that there are multiple stacked bars for the same x-coordinate, each slightly shifted? Is there a way to reset pgfplot's zero levels after an \addplot command, such that the next \addplot[xhshift=...] doesn't add something to the current stack, but rather starts a fresh stack?  FWIW, overlaying two plots with scale only axis won't help; I need this to work with groupplot


So nowadays we have this beautiful flagging statistics page http://site.stackexchange.com/users/flag-summary/my-user-id.  It has a nice statistics sidebar, for which I propose to make the specifications clickable:    Clicking one of the entries should filter the list of flags accordingly. This can make it easier to track flags deemed important (e.g. custom ones) among the sea of standard "obsolete comment" flags.    NB. I know that this was , but 2011 predates the current flag summary page, so it seemed valid to file a new request.  As to the reason given there (emotions over declined flags and all that), I contend that it will in most cases be beneficial to have someone note their flag has been declined, possibly with a personal moderator message, as this should improve their future flagging behaviour.


Is there an onto homomorphism $S_4\to S_3$

Prove or disprove that there is an onto homomorphism from $S_4\to S_3$ where $S_n$ is the symetric group of order $n!$.  after long time of searching, I finally success but i just manually tried to associated to element of $S_4$ an element of $S_3$. I wonder if there is an easier technic.


Sql query to select 3rd element from data?

I have written sql query     Select * from Products WHERE Products.Category=="Fruits";   the returned answer is    1-Banana   2-Mango   3-Apple   4-Oranges   5-Grapes   now i want to select fruit at index 3rd only that is Apple using sql indexes  the problem arises every where how should i select the element at 3rd place using its index in sql query?


Why can't Transporter technology be used as a weapon?

Seems like this is the most powerful weapon of all: transport your enemy into a bulkhead, planet, etc. Transport your enemy's ship inside a planet, etc.  Is there some technical reason that it can not be used this way?


Prove that $\frac{2^n-1}n\notin\Bbb N$ for natural $n>1$

Let   $$X(n)=\frac{2^n-1}n;n\in\Bbb N; n>1$$   Prove that $X(n)\notin\Bbb N$.   My try: check this for $n=2$. Then $$X(n+1)=\frac{2^n-1}{n+1}+\frac{2^n}{n+1}$$  So if $n+1$ is odd then $\frac{2^n}{n+1}$ can't be integer, if $n+1$ is even $\frac{2^n-1}{n+1}$ can't be integer.  And then I thought proof is over, however, I realized – this doesn't cover cases where sum of remainders of both fractions is equal to 1.


I am new to ubuntu and linux world. Where can I see the list of all programs installed in ubuntu ?  Ex: If I want to launch "terminal". I need to click the upper left icon and type "terminal". Where is the icon really located ?  I would like to take a look in the programs installed. Are they separeted by category ? I don't know.  Thanks


how to search if user input file exist or not in tkinter python

i have made that when ever someone reg the txt file is created and named on user username. now im trying to check if username txt file is there in dir or not here is the code i tried . im unable to check if username txt file is there . i tried many diff way searched google but no luck some i have mentioned as comment. pls help looking  def db():         a = (E1.get(), E2.get(), E3.get(),E4.get(),E5.get())                  if "./library/"+E1.get() == os.path.isfile("./library/"+E1.get()):         # if E1.get() == os.path.isfile(E1.get()):         # if E1.get()in os.path.isdir("./library/"):              cur.execute("insert into Booking values(?,?,?,?,?)", a)             con.commit()             cur.execute("select * from Booking")             a = cur.fetchall()             ab = int(E4.get())             cost=100             ac = ab * cost             messagebox.showinfo("Congratulation!!", "Your oreder value is %s" % ac)             print(a)              te.destroy()             os.system("library.py")         else:             print("username invalid")


How Does The Debugging Option -g Change the Binary Executable?

When writing C/C++ code, in order to debug the binary executable the debug option must be enabled on the compiler/linker.  In the case of GCC, the option is -g.  When the debug option is enabled, how does the affect the binary executable?  What additional data is stored in the file that allows the debugger function as it does?


A quick example of what I want using bash scripting:  #!/bin/bash echo "Insert the price you want to calculate:" read float echo "This is the price without taxes:" echo "scale=2; $float/1.18" |bc -l read -p "Press any key to continue..." bash scriptname.sh   Assuming that the price is: 48.86 The answer will be:41.406779661 (41.40 actually because I'm using scale=2;)  My Question is: How I round the second decimal to show the answer in this way?: 41.41


Finding the Killing form of $\mathfrak{sp}_{2n}(\mathbb{C})$

How can I find the Killing form of $\mathfrak{sp}_{2n}(\mathbb{C})$? I'm explicitly working with basis vectors in trying to compute $\operatorname{tr}(\operatorname{ad}(a)\operatorname{ad}(b))$ but it's becoming really messy. Is there another way?


Change CTRL-X, -C, and -V hotkeys in Windows to different keys

I use my mouse left-handed, which makes the default Cut/Copy/Paste hotkeys in Windows really akward to use. Is there any way I can change these - say to something like Control-m, comma, and period? That way, I could mouse with my left hand and use my right for the hotkey functions.


Stack Exchange sites need a universal clock that is visible!

Since the Stack Exchange sites run on one clock, and a clock that is not common to most of us (such as those of us in the US), can we display a clock with the site time (UTC) displayed somewhere on every page, such as at the bottom with the other text?  That way we are more aware of when the days turn over, and ecetera...  close votes, delete votes, flags, and normal votes would also benefit from this as well (thanks @Grace Note!)...    What do you guys think? yea or nay? thoughts?


Applying an image with an alpha mask to a plane

I want to place a png file floating over my 3D model's face to create eyes. I've placed the image on a plane that I've UV unwrapped.  The problem I have is that when I render the image, you can see straight through his head.  How can I achieve the desired result?  I'm new to blender so go easy :)


How to add 'title' in references using bibtex?

Its customary not to use title of the research article in Physics Journals refernces. I am currently writing a report where I need to add title of the articles. I do not want to use 'bibitem' to manually write the titles etc. Is there any bibliography style which produces references with titles along with author name, volume, year?


Traveling to Puerto Rico as Student while waiting for OPT

I am an international student. I already finished my program and I am waiting to start my OPT. My I20 already expired and I am waiting for my EAD Card. I have a US valid Driver License. Can I travel to Puerto Rico?


Create a trigger on all the last_modified columns in PostgreSQL

In PostgreSQL 9.5, I have tables with columns in the form   prefix_last_modified timestamp without time zone NOT NULL DEFAULT  (clock_timestamp() AT TIME ZONE 'UTC')   I was looking for a way to set the last modified value automatically updated at each update of the rows, and I found  that defined the function:  CREATE OR REPLACE FUNCTION update_modified_column()  RETURNS TRIGGER AS $$ BEGIN     NEW.modified = now();     RETURN NEW;  END; $$ language 'plpgsql';   Now, I'd like to know if there is any way to pass the column name to the PostgreSQL function and to execute it to the NEW row? E.g.  CREATE OR REPLACE FUNCTION update_modified_column(varchar column)        RETURNS TRIGGER AS $$     BEGIN         NEW.column = now();         RETURN NEW;      END; $$ language 'plpgsql';


I have formatted a partition for Ubuntu. How do I install it on that partition?

I have a formatted 55GB partition as NTFS, the other part of the hard disk has Windows 7.  Is NTFS the right format for Ubuntu? If not how should I format it and with what format?  Once I finish preparing the partition, how do I install Ubuntu on that partition? I'm not sure how to set up dual-boot Ubuntu and Windows.


The new user badge is showing up on meta for users who really aren't new. In this case it was really obvious - turns out they've been on Stack Overflow for 5+ years, but maybe this is their first meta post.  I think it'd be clearer if child metas inherited someone's new user status from the main site.


Metropolis Hastings proposal for one parameter restricted to less than the other

Suppose I have parameters $\theta_0$ and $\theta_1$ with prior  $$ p(\theta_0,\theta_1)=p(\theta_0|\theta_0<\theta_1)p(\theta_1),$$  that is, $\theta_0$ is less than $\theta_1$. The distributions are assumed to be continuous on their support. Apart from the likelihood, there are no other terms involving $\theta_0$ and $\theta_1$. I'm trying to consider potential sampling procedures for these parameters.   My current MCMC procedure is:   Propose a value for $\theta_1$ using a random walk update. Use the independence sampler to sample a value of $\theta_0$ that is restricted to be less than the proposed value of $\theta_1$ using the appropriate truncated density (with the correction). Evaluate Metropolis-Hastings accept/reject.   Does anyone have ideas for other proposals here? The trick is that the support of $\theta_0$ changes, so a random-walk Metropolis step from the previous value of $\theta_0$ isn't guaranteed to fall in the support of $\theta_0$ given an updated value of $\theta_1$, so this set of draws would be rejected in a random-walk Metropolis scheme. This results in very few accepted proposals and increases the number of iterations needed.  My question is similar to a question posited  that was never answered.


What is the difference between a directory name that ends with a slash and one that does not?

Is there any difference between a directory name such as  mydirectory   and  mydirectory/   I noticed this happens when I execute ls in some directories - some of the directory names have a slash and some don't. This is problematic because if I want to access a file contained in a directory, I may need to add a slash at the end:  vi $mydirectory"/"$myfile   or simply do   vi $mydirectory$myfile


I want my pc to hibernate even when I press "shut down".  Either that, or simply remove the "shut down" button from the start menu.  Is there a way to do any of these?


Possible rank of closed orientable manifolds

List all $i$ for which there is a closed orientable $6$-manifold $ M$ with $H_i(M) = \mathbb{Z} \oplus \mathbb{Z} \oplus \mathbb{Z}$.    So, obviously this has to do with Poincare Duality. We can't have $i=0$ or $i=6$ by definition of a manifold. So we are left with the cases $i=1$ through $5$, which reduce to $i=1, 2,$ and $3$, since the rank of $H_1$ is equal to the rank of $H_5$ by Poincare Duality (and thus for $H_2$ and $H_4$, too). I am thinking that setting up the exact sequences here gives me some kind of equation which will lead to a contradiction in some of those cases, but I'm not able to see why yet. Can I get a push in the right direction, and an evaluation of my thoughts so far?


What happens to 5.8 GHz signals when too many transmitters are in a confined space?

I'm helping set up an Airsoft arena in the UK and I plan to have RC-FPV cameras mounted on the weaponry and masks which the players use/wear (similar to wireless drone cameras). As it's an open space we'll be testing the 5.8 GHz bandwidth first using 40 channel transmitters/receivers.  A few people have suggested that using anything over 8 channels in this bandwidth concurrently would cause problems but what would those problems be?   For example:   Would the video become merged or blended with neighboring channels?  Would the receiver swap from transmitter to transmitter depending on the signal strength?  Would it just not work?  Or something else?   It just not working and signal merging would represent a problem for me but just channel hopping is no major issue.  These are the channels available in one of the systems we are considering.   In case it's relevant here are the available specs.  5.8G 600mW 40 Channel Wireless AV Transmitter: Transmitter Frequency /Channel Amount: 5 bands / 8 channel each = 40 frequencies Output Power:600mW Frequency Control: Built-in frequency & phase lock loop AV input: Analog AV signal input ANT connector: SMA (needle inside) Power Supply: DC 7-12 volts Current Consumption: 220mA Size: 54*32*10mm Neat weight: 22g   Some additional specifications as a clarification to answer questions:  I'll be streaming low quality AV (320tvl at 24fps and 22 kHz audio) which should come in at under 18mhz bandwidth per device. The modulation is most likely to be Airwave on one side and Boscam on the other.  To clarify, this is not a duplicate question to . While everyone would like to avoid interference my question relates to what would happen when interference is encountered.


How does TREE(3) grow to get so big? (Laymen explanation)

I am not a mathematician but I am interested in big numbers.  I find them to be really interesting, almost god-like.  I am watching  from David Metzler on YouTube.  I have a basic understanding of some fast growing functions.   David does not cover $\operatorname{TREE}(n)$ which I've read is one of the fastest growing functions.  I've looked at it explained in many places and even asked someone via Quora to help explain it to me, but I still don't get it. I think I need some sort of example of what $\operatorname{TREE}(1)$, $\operatorname{TREE}(2)$ and so on look like.    If anyone could help me understand it I'd be really appreciative.


How to identify hardware performance bottleneck in laptop?

Is there any tool that helps to determine the weakest link of my current laptop hardware specification? Any online guide to help me choose nice balanced configuration for the new laptop?    I need to find the answers:  a) which component should be invested to increase overall performance the most? CPU? GPU? RAM?  b) which component may decrease overall performance and work as a bottleneck for the specific configuration?    The question is general and regards both to validating the current hardware usage (and its possible bottlenecks) and estimating the performance (and avoiding possible issues) of specs I'm going to choose and buy.    P.S. For the specific laptop I need to replace, the following software will be in use:    Windows antivirus, firewall, dropbox service running in the background mail app + web browser with a dozen or so tabs open from time to time: libreoffice apps, movies, games (both online and installed).