If we have a periodic motion happening in frame A and if a moving frame B was to observe the event, B would see the time period reduced to $\frac{T_A}{1+v/c}$. This happens because of the finite amount of time light takes to deliver the message to B that change occurred in A Apart from this, there is time dilation from SR that affects the mechanism of periodic motion itself. That is if the period of motion is $T_A$, (time between ticks of any clock), the period as observed by B would be $T_B = T_A\sqrt{1-\frac{v^2}{c^2}}$ So if two frames are in relative motion, shouldn't we consider both effects? I mean in common physics questions like : If I were to look at the clock in a moving spacecraft, And if my clock ticks once every second, then at what rate would his clock tick? I believe it should be : $\frac{1}{1+v/c} \times\text{dilated time between ticks} $ $=\frac{1}{1+v/c} \times \ \sqrt{1-v^2/c^2}={\sqrt{\frac{1-v/c}{1+v/c}}}$ but textbooks just mention the dilation factor only.

I've been pondering the precise mechanism of time dilation for the example of a simple pendulum in two different situations:   The observer and ground are at rest in one frame of reference;  the pendulum is moving at high speed with respect to that frame. The observer is at rest in one frame of reference; the pendulum and the ground together move at high speed with respect to that frame.   user8260 has pointed out that in situation 1, in the pendulum's frame $g$ is greater by $\gamma^2$ compared to $g$ in the observer's frame. Thus in the pendulum's frame the period is less than it is in the observer's frame by a factor of $1/\gamma$, just as one would expect from time dilation.  But what about situation 2? Here, compared to the pendulum frame, the observer sees the pendulum with the same length in a stronger gravitational field, yet observes a longer period. Does the inertial mass of the pendulum change differently than its gravitational mass? Also, does the analysis depend on whether the plane of swing is perpendicular or parallel the direction of motion?


I'm trying to insert a string into the database , but when it contains single quote('), the query becomes invalid.    $set_content=$_POST['content'];   $result = pg_query($db,"INSERT INTO programmes(title,picture,content) VALUES('$set_title','$pic_path','$set_content');");

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


I haven't been working with javascript before, so I am still learning the basics.   I have included two javascript files in my main file called index.html. The reason for this is to let users select which javascript file to show (diagram 1 or diagram 2) by clicking on the navigation tool bar. The problem is that both of these javascript files have a equal method called window.onload, so they replace each other. How can I prevent these two javasript files to replace each other?  First javascript file:  window.onload = function {// Preview diagram 1}   Second javascript file:   window.onload = function {// Preview diagram 2}   Here is a snip of what I have in my index.html  <script type="text/javascript" src="js/diagram1.js"></script> <script type="text/javascript" src="js/diagram2.js"></script>

I develop Joomla websites/components/modules and plugins and every so often I require the ability to use JavaScript that triggers an event when the page is loaded.  Most of the time this is done using the window.onload function.  My question is:    Is this the best way to trigger JavaScript events on the page loading or is there a better/newer way? If this is the only way to trigger an event on the page loading, what is the best way to make sure that multiple events can be run by different scripts?


I have two open programs, but I want to view both of them at the same time. Dragging and adjusting them manually takes time, and I might have to do this every day. Is there any shortcut for doing this in Ubuntu?  I'm thinking something like this:

In Unity, are there any pre-defined shortcuts, e.g. to open the dash or unhide the launcher?


Show that it doesn't exist any of natural number  $ n = 4m + 3$ that $  n= x^2+y^2 $ for any natural x and y  Show that every prime number in form $ p=4m+1 $ could be showed as $ p = x^2+y^2$ (x and y are natural)  I checked it and it

Primes of the form $p=4k+1\;$  have a unique decomposition as sum of squares $p=a^2+b^2$ with $0<a<b\;$, due to .  Is it correct to say that, primes of the form $p=4n+3$, never have a decomposition into $2$ squares, because sum of the quadratic residues $a^2+b^2$ with $a,b\in \Bbb{N}$ $$ a^2 \bmod 4 +b^2 \bmod 4 \le 2? $$  If so, are there alternate ways to prove it?


when I run my Interface created with  java swing netbeans the Jbuttons move from their original location and many errors appear. I didn't find what those errors mean.  while running the interface, it always stops working and it stuck.  Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException     at com.sun.java.swing.plaf.windows.WindowsTabbedPaneUI.paintContentBorder(WindowsTabbedPaneUI.java:145)     at javax.swing.plaf.basic.BasicTabbedPaneUI.paint(BasicTabbedPaneUI.java:791)     at javax.swing.plaf.ComponentUI.update(ComponentUI.java:161)     at javax.swing.JComponent.paintComponent(JComponent.java:779)     at javax.swing.JComponent.paint(JComponent.java:1055)     at javax.swing.JComponent.paintChildren(JComponent.java:888)     at javax.swing.JComponent.paint(JComponent.java:1064)     at javax.swing.JViewport.paint(JViewport.java:731)     at javax.swing.JComponent.paintChildren(JComponent.java:888)     at javax.swing.JComponent.paint(JComponent.java:1064)     at javax.swing.JComponent.paintToOffscreen(JComponent.java:5232)     at javax.swing.BufferStrategyPaintManager.paint(BufferStrategyPaintManager.java:295)     at javax.swing.RepaintManager.paint(RepaintManager.java:1249)     at javax.swing.JComponent._paintImmediately(JComponent.java:5180)     at javax.swing.JComponent.paintImmediately(JComponent.java:4991)     at javax.swing.RepaintManager$3.run(RepaintManager.java:808)     at javax.swing.RepaintManager$3.run(RepaintManager.java:796)     at java.security.AccessController.doPrivileged(Native Method)     at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)     at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:796)     at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:769)     at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:718)     at javax.swing.RepaintManager.access$1100(RepaintManager.java:62)     at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1677)     at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:312)     at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:745)     at java.awt.EventQueue.access$300(EventQueue.java:103)     at java.awt.EventQueue$3.run(EventQueue.java:706)     at java.awt.EventQueue$3.run(EventQueue.java:704)     at java.security.AccessController.doPrivileged(Native Method)     at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)     at java.awt.EventQueue.dispatchEvent(EventQueue.java:715)     at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)     at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)     at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

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


I am a bit lost how to factor $a^{k} - b^{k}$. I know it links to the binomial theorem but I can't remember how to do it. Could anyone explain?

but I don't understand how:  $$a^n - b^n = (a-b)(a^{n-1} + ba^{n-2} +\cdots + b^{n-1})$$  follows from  $$x^{n-1} + x^{n-2} +\cdots + x + 1 = \frac{x^n - 1}{x-1}$$  Could someone explain to me how the summation of the the geometric series explains the factorization?


I am a seaman working on a cruise ship and my company arranges flights for our return home on completion of our contracts.  I am a New Zealand National and they have booked me a flight from Santiago to Sydney (Australia) which has a stop at Auckland (NZ).  I am then required to wait in Sydney before I can then catch the flight they have booked for me from there back to Wellington.  I have informed my company but they won't change my flight. What I wanted to know is if I could just disembark the plane at Auckland and arrange my own flight back to Wellington?  Could I inform the checkin in Santiago that I would want my bags off in Auckland?  Would there be any problems?

Say I want to book a flight from Fort Lauderdale to Chicago.  Say the airline also flies to St. Louis from Fort Launderdale but has a connecting flight through Chicago.  If I book that flights from FLL->ORD->STL and just get off in Chicago, what possible problems can I run into, assuming I didn't check any bags and only have carry on?  This scenario exist for Southwest, but I wanted this be more of a general question that would apply to all airlines.


Throughout the Harry Potter series, Professor Trelawney makes many different prophecies and predictions. Although most of them are implied to be nonsense, often enough they still get fulfilled. Which ones have come true? Which ones have been proven false? Which ones are still possible?  How many of Trelawney's prophecies have come true?  I'm not asking if Divination in Harry Potter is real, or what it is. I am asking for a finite list of which of Trelawney's prophecies came true, and which ones didn't.

What is Divination really like when it is not just a school subject, but is practically applied by a competent Wizard?  Is there a definition of what counts as Divination in the Harry Potter universe?  Most of what we know about Divination in the Harry Potter universe is through the school courses of Professor Trelawney and Firenze, plus a few remarks by Professor Dumbledore and Professor McGonagall.  I don't believe these give a fair representation of Divination in the real world, just like how the school curriculum of the first three years of Harry's Defense Against the Dark Arts class wouldn't tell much about how Defense Against the Dark Arts is used by adults.  To give some specifics, which of the following (if any) are Divination?   Professor Snape's task of finding out about the Dark Lord's plan. Professor Dumbledore finding out lots of details about the past of the Dark Lord. Professor Dumbledore coercing Kreacher to tell him what's happened to Sirius.   Professor Dumbledore detecting magic in the cave. The visions Harry had, showing what the Dark Lord or his Snake were doing. The spell used to reveal the last spell cast by a wand, as seen in Goblet of Fire. The Sorting Hat determining the personality traits of a young wizard. The Specialis Revelio spell cast by Hermione on the Riddle diary. The examination the Ministry of Magic has done on the objects Professor Dumbledore has left in his will to the trio. The tests done on the Firebolt that Harry got as a gift, ensuring that it is not jinxed. The Homenium Revelio spell cast by Hermione to find humans in the Black manor. What the Marauder's Map does. The two real prophecies of Professor Trelawney.   I have guesses about how some of the above are Divination and some aren't, but they are all based on what I've heared of divination outside the Harry Potter universe.  There is, however, probably some material in the books, interviews, Pottermore, or other resources that I don't know about.  To address a particular argument you might give about the prophecies of Professor Trelawney, recall that Professor Dumbledore wanted to keep Trelawney in Hogwarts to protect her, after the first prophecy and the immediately following events.  The way he insisted that she stay after she was sacked from her teaching position (in the Order of the Phoenix) clearly shows this, together with what he says about the matter in Half-Blood Prince chapter 20:     I cannot ask Firenze to return to the forest, where he is now an outcast, nor can I ask Sybill Trelawney to leave. Between ourselves, she has no idea of the danger she would be in outside the castle. She does not know – and I think it would be unwise to enlighten her — that she made the prophecy about you and Voldemort, you see.   This means that Professor Dumbledore may have applied Trelawney regardless of how good Divination teacher he thought she was, and regardless of whether the prophecy is Divination or not.  Can you give other examples of Divination used by Wizards, other than the ones related to school courses?  This is a speciesist question, I'm specifically asking only about human Wizards, not about divination practiced by Centaurs or House Elves or Goblins or other creatures.  Remark.  The original reason why this question came up is a disagreement in the thread


I am still seeing deck recipes with cards from Kaladesh block like  and . I thought that Kaladesh block was rotating, are the cards still legal?

I have a list of cards for a deck I want to build or buy. What should I do to check whether that deck is legal in a particular format (Standard, for example)?


I have been trying to work this problem out for a bit and am stuck.  Does anybody have any ideas how to proceed or solve this?  I think this has something to do with rings and fields but I can't seem to find the connection.    EDIT: I know the other proof listed as a duplicate here, but it uses Cauchy's Theorem and  we are not allowed to use that because we skipped that chapter.

Let $n$ be a positive integer. Show that any group of order $4n + 2$ has a subgroup of index 2. (Hint: Use left regular representation and Cauchy's Theorem to get an odd permutation.)  I can easily observe that $\vert G \vert = 2(2n + 1)$ so $2 \mid \vert G \vert$ and 2 is prime. We have satisfied the hypothesis of Cauchy's Theorem so we can say $G$ contains an element of order 2.  This is where I am stuck  I am confused about how the left regular representation relates to the group. So my understanding at this point is that every group is isomorphic to a subgroup of some symmetric group. My question: is the left regular representation $\varphi : G \to S_G$ an isomorphism? where $G \cong S_G$ or is $S_G$ the same thing as $S_{\vert G \vert}$ and $\varphi$ is only an injection? I'm using Dummit and Foote for definitions.  I saw an argument online that said that since we have an element of order 2, there is a $\sigma \in S_G$ of order 2, but it is a product of $2n + 1$ disjoint 2-cycles. I don't understand how they could claim this and tried working it out on my own but didn't get there. -- They then went on to use the parity mapping $\varepsilon : S_G \to \{\pm1\}$ and since we have an odd permutation $\sigma$, we have $[S_G:\text{ker }\varepsilon] = 2$. I understood their computation but not how that directly shows that $G$ has a subgroup of order 2? unless $G \cong S_G$ because of how left regular representation is defined. (but again, I'm not understanding that concept very well yet.)  So, to be clear about my questions:   What is meant by left regular representation, is it an isomorphism or just an injection? and how would it be used here. If it is an isomorphism, the argument online starts to make more sense, but how can they say that since $\sigma$ is even, it is made up of $2n + 1$ disjoint transpositions? If you have a full, proof, I'd appreciate it, but good hints are just as good!   Thanks you!


I'm looking for "Experience Stack Exchange" or probably "Personal Experience Stack Exchange" site (I can't recall the exact name) but can't find it.  I used to visit it few years ago or so.  On that site people used to ask questions about all type of personal experiences including but not limited to: love, relationship, marriage etc, and I'm not talking about "User Experience Stack Exchange".   Any idea what happened to it?

I was wondering if there are any sites where I can ask questions about social life and public relationships - like how to confront insults and deal with them, how to build someone up,  etc.?


I watched this show when I sass a kid (80-90s) about a boy that has some kind of powers. It’s set in the UK I think, in a cabin/lodge. It has a spooky theme where you see a prism slowly making taking position as the center piece. I think it has the ray of light hitting it and it goes through the prism and out comes more rays. And I think you can see the boys face as the prism becomes hes third eye at his forehead. And the main color is greenish I think. The episodes is about the boy, maybe 10 years old. He is been taking care of by a woman I believe. And not every episode was something sci fi in it. I think the series was about the boy trying to figure out his powers.

I'm trying to remember this show, 80's or early 90's, about a boy who receives telepathic messages from an alien, and his family thinks he's going crazy. All very serious and dark. The only thing I remember are the credits and cuts to commercials: they show the protagonist's head over an eerie landscape, spinning very slowly and fading into an alien's egg or something.   The name of the show was the name of the boy, very simple, one word... Ben, or Max, or anything like that.


I am a newbie with Blender (Version 2.83) on Windows 10. I want to do one simple job: import a SVG file and scale it in Blender. I downloaded a football image in SVG file format, its name is like: C:\Temp\Brzauca01.svg Now, I open Blender 2.83 and delete the default image, then I import the football SVG file, but I can't see it from Blender. So I tried the following to scale the SVG image. I typed S, then 5 trying to make it as 5 times as its original size, but I can't see any visual effect. You can see the Blender IDE after I imported SVG file and after I typed S, 5 By the way, another picture you can see that I can use InkScape 1.0 to show the Brzauca01.svg, it is a football image in SVG format. Please advice what I should do to show the visual effect for scaling a SVG file.

I've tried multiple times to  import a SVG file from illustrator CS5.5 to Blender 2.71 and 2.73. However, I do not see a mesh, curve, or anything pop up in my "Outliner" window. So I know its not so small I can't see it. I even made sure under user preferences that the "import and export of SVG 1.1 format" is "checked." I've tried even just importing text from illustrator and I'm still getting no where. What can I do to resolve this problem? If this is common error with this version of Blender, then what can I do to transform an image into a 3D object in Blender?


Window failed to start. A recent hardware or software change might be the cause. To fix the problem: 1. Insert your window installation disc and restart your computer. 2.choose your language,and then click next. 3.click repair your computer. If you don't have this docs , contact your system administrator or computer manufacturer for assistance. Status: 0xc000000f Info : the boot selection failed because a required device is inaccessible.

I am getting the following message whenever I start my laptop:  Windows Boot Manager   Windows failed to start. A recent hardware or software change might be the cause.   To fix the problem:    1. Insert your Windows installation disc and restart your computer.    2. Choose your language settings, and then click "Next."   3. Click "repair your computer."  If you don't have this disc, contact your system administrator or computer manufacturer for assistance.     File: \Boot\BCD    Status: 0xc000000f  I have googled about the error, and from the message it looks like I need to boot my laptop from the Windows installation disc.  My laptop has Windows 7 Professional SP1 x86 installed, but when I try to insert Windows 7 Professional x86 I get the same error. Do I require an SP1 disc? I did setup CD/DVD drive as first in the boot order, but I still got the same error.  Also what other options should I try to get to the Windows 7 System Repair Screen, so that I can repair/rebuild the BCD file?


While there are several similar questions they all seem to deal with 3.5 or Pathfinder.  may contain the key to the answer for this, but focuses on Wildshape, doesn't have an accepted answer despite being 4 years old, and only establishes that natural weapons aren't automatically unarmed strikes (not whether they can be used for said strikes) - a semantic detail that seems important here. I've been struggling to find an official position on this for 5e.  An  asserts that only some examples of natural weapons can be used for unarmed strikes, giving this example from the  (VGtM, p. 115), which says:     [...] your claws are natural weapons, which you can use to make unarmed strikes...   This, however, seems ambiguous to me - is it saying that this specific example creates an exception where these natural weapons can be used for unarmed strikes? If so, the comma seems unnecessary and potentially misleading. A clearer way of putting it might be 'your claws are natural weapons and can be used to make unarmed strikes.' If it was intended the other way, though, it could be clearer to say 'your claws are natural weapons, and can therefore be used to make unarmed strikes.'  Of course, neither of these wordings are used, hence the confusion. Is there an official position on whether natural weapons (which I understand as being a part of the attacking creature's body) can be used for unarmed attacks (which I recall reading are somewhat defined as being made with body parts, certainly that's how it sounds in ) by default1, or whether a specific exception must be made?  1. Also implied by the  descriptive text, not that that's 5e specific though.

So, I got intrigued by grappling after reading  for 5e. It didn't mention if wild shape attacks were considered unarmed strikes, especially in regards to the Tavern Brawler feat's last bullet, which enables a grapple attempt after hitting with an unarmed strike.  It doesn't say in the PHB under the Druid section. In the MM, it says that a beast's attacks are Melee Weapon Attacks. However, the Alter Self spell says that the claws, fangs, etc are unarmed strikes. So, are they or are they not considered unarmed strikes?


I am trying to install ubuntu 18.04 server on a segregated network not connected to the internet, I will connect to a public network later to download packages. When installing, Ubuntu forces me to pick a mirror and download archive components. Which will never work as I am offline. I just need to install the OS right now and download other components later. When installing RHEL or CentOS, I don't have to download components during install. How can I disable this? or is there a different image I need to use? I am using this image located here:  EDIT: I should have mentioned this is a PXE install via UEFI (Not BIOS). The path of install should be  Boot VM to PXE network to get DHCP from PXE server Install OS with PXE DHCP address (Which will never have public internet access) Change port network / vlan to production network post install Configure an IP address post install  Do I need to adjust my PXE append statement? Is there a way to bypass the installer forcing me to perform an install from the ubuntu archive? Workaround: Well, I needed to add a secondary network interface onto the production network for internet access. Now the system has two network interfaces, one of which I would need to remove post install. This works for a virtual network, but defiantly does not work for our bare metal systems. Why must I be connected to the internet?! Is there anyway around this? I have seen guides that you can create a custom image with packages already installed. But those guides are not very clear on how to create an image, also not clear on if those images will work for PXE install. Note: I appreciate people linking me to this post  but like I said in the comment, this did not work. I tried downloading the image, and still, the installer forces me to provide an archive address. This is after trying to give a bogus ip address. There is no way around this.

The latest version of Ubuntu server (18.04) seems to demand network configuration and refuse to boot without it. I have no desire to connect the server in question to the internet for anything, and have installed previous versions of Ubuntu server without network no questions asked.  Is a network connection an absolute requirement for the latest version of Ubuntu server? Or is there something I'm missing?  The installation cannot proceed past the network configuration page unless an ethernet connection is active, by my current estimates. I have no ethernet network within range of the machine so can't test it on an internet-less network. I only have WiFi within immediate range (which does have internet access) but it won't recognise the device and it should be simpler to get the installation to happen without any updates than to go to the effort of finding the drivers to support the WiFi adapter.  Note that this is NOT a duplicate of  since the new installer seems to be the real problem here.


Having a BibTeT file with full journal titles in it, I'm looking for a tool to construct a list of abbreviations following  (it specifies how to abbreviate individual words, which should make it straightforward to generate abbreviations for any title).  I'm ware of JabRef, but it requires a list of title-abbreviation pairs and I don't want to do one by hand if I don't have to.  (I should add that the lists available from JabRef website do not cover the titles I have).

I have a BibTeX file containing many references, where the journal titles are (for the most part) written out in full. I would like to replace these in my reference list with the standard abbreviated titles.  Searching the web I can find many suggested solutions to this problem. These all seem to involve maintaining either maintaining your own database of search-and-replace strings, using a GUI reference manager (Jabref), or editing the whole .bib file so that every journal name is a macro call.  My .bib file has 171 entries (it was originally the references for my thesis and I've kept adding to it since then, using the same file for every paper), so creating and maintaining my own database of journal abbreviations would be a huge undertaking. While I will just start using Jabref if I have to, it doesn't seem right that I should have to use a GUI package to solve such an inherently text-based problem.  What I really want is a script (or even better, a LaTeX package) that will just go through my .bib file and replace every full journal name with an abbreviation looked up in one of the many standard databases that exist for this purpose. (Of course there will probably be some that get missed, but I don't mind fixing one or two by hand.)  I'm guessing that such a painless, transparent solution doesn't exist, but it can't hurt to ask here. It seems to me that this must be a very common thing to want to do, and I'm kind of surprised that the functionality isn't just built into BibTeX in the first place.


Let $A$ be a $3\times 3$ matrix with integer entries such that $\det(A)=1$. At most how many entries of $A$ can be even?  I get a possible solution as $6$ by considering the $3 \times 3$ identity matrix. But I am not sure about that is it possible to have more than $6$ even entries. Please help me enumerate this problem to prove my answer.

Let $A \in M_3(\mathbb Z)$ be such that $\det(A)=1$ ; then what is the maximum possible number of entries of $A$ that are even ?


Is there a reason why the verb is ABSORB but in the noun form the B becomes a P---ABSORPTION?

The question pretty much says it all.  Why is "absorbtion" an incorrect spelling?


In Quantum Mechanics, a state vector $|\psi\rangle$ will evolve in time according to $$|\psi(t)\rangle=e^{-\frac{i}{\hbar}\hat H t}|\psi(0)\rangle$$ Imagine we have a system such that, for a short period of time $T$, the Hamiltonian increases by a constant and then returns to normal, such that $$\hat H=\hat H_0+ \begin{cases} 0 & \text{($t\lt0,\,  t\gt T$)}\\ A & \text{($0\leq t\leq T$)}\\ \end{cases} $$ At $t=T$  we will have $$|\psi(T)\rangle=e^{-\frac{i}{\hbar}AT}e^{-\frac{i}{\hbar}\hat H_0T}|\psi(0)\rangle$$ Now, following the first equation, since after $t=T$ there is no $A$, it should just become $$|\psi(t)\rangle=e^{-\frac{i}{\hbar}\hat H_0 t}|\psi(0)\rangle$$ But this seems strange, it's as if that period of interaction with whatever caused the extra energy had no effect on the particle whatsoever. I think it makes more sense to apply the time evolution operator separately and obtain $$|\psi(t)\rangle=\hat U(t-T)|\psi(T)\rangle=e^{-\frac{i}{\hbar}\hat H_0(t-T)}e^{-\frac{i}{\hbar}AT}e^{-\frac{i}{\hbar}\hat H_0T}|\psi(0)\rangle=e^{-\frac{i}{\hbar}\hat H_0t}e^{-\frac{i}{\hbar}AT}|\psi(0)\rangle$$ Is my idea wrong or is the time evolutikon operator different in this case? If so, the what would be the case for a time-dependent Hamiltonian?

Consider the time-dependent  (or some equation in Schrödinger form) written down as $$ \tag 1 i \partial_{0} \Psi ~=~ \hat{ H}~ \Psi . $$ Usually, one likes to write that it has a formal solution of the form $$ \tag 2 \Psi (t) ~=~ \exp\left[-i \int \limits_{0}^{t} \hat{ H}(t^{\prime}) ~\mathrm dt^{\prime}\right]\Psi (0). $$ However, this form for the solution of $(1)$ is actually built by the method of successive approximations which actually returns a solution of the form $$ \tag 3 \Psi (t) ~=~ \hat{\mathrm T} \exp\left[-i \int \limits_{0}^{t} \hat{H}(t^{\prime})~\mathrm  dt^{\prime}\right]\Psi (0), \qquad t>0, $$ where $\hat{\mathrm T}$ is the time-ordering operator.  It seems that $(3)$ doesn't coincide with $(2)$, but formally $(2)$ seems to be perfectly fine: it satisfies $(1)$ and the initial conditions. So where is the mistake?


I just typed food into the search box at  and this gives me search results containing the word food. The search query is https://opendata.stackexchange.com/search?q=food. [food] .  Same when searching for sleep at : the query is https://productivity.stackexchange.com/search?q=sleep.  But I recently noticed* at other SE sites that if you enter a word that is also a tag name, this initiates a search for the tags:  Search for 'delphi' at  performs https://stackoverflow.com/questions/tagged/delphi Search for 'professionalism' at  performs https://workplace.stackexchange.com/questions/tagged/professionalism  Why this inconsistent behavior? Or is this 'consistent' one way for beta sites and the other way for non-beta?  * At the time I considered this unwanted behaviour—if I want a tag, I'll search for [tag]—but that is another issue, partially adressed .

Asume the following search queries: osx, cocoa, iphone, xcode, applescript, mac, carbon    Searching for osx, cocoa, iphone or xcode like:   http://stackoverflow.com/search?q=osx   Results into searching by tag:   http://stackoverflow.com/questions/tagged/osx   While searching for applescript, mac and carbon like:   http://stackoverflow.com/search?q=applescript   Results into searching by string.  Yes, I know how to search by tags using brackets: [applescript] But why are the queries above interpreted differently? All queries are valid Stack Overflow tags! Why not convert all queries into search by string or search by tag? What is the logic behind? Tag popularity? It seems rather inconsistent to me.


How can we extract the decimal part of a floating point number and store the decimal part and the integer part into two separate integer variables?


I wanted to ask whether they're any difference between Kernel Ridge Regression and normal Ridge Regression. I've fitted a dataset with both models and obtained approximately the same root mean squared errors for both methods. I know Kernel allows us to calculate the design matrix using a closed form and can be computationally quicker but wanted to ask whether in practice there's any difference between the two?

Ridge Regression can be expressed as $$\hat{y} = (\mathbf{X'X} + a\mathbf{I}_d)^{-1}\mathbf{X}x$$ where $\hat{y}$ is the predicted label, $\mathbf{I}_d$ the $d \times d$ identify matrix, $\mathbf{x}$ the object we're trying to find a label for, and $\mathbf{X}$ the $n \times d$ matrix of $n$ objects $\mathbf{x}_i = (x_{i,1}, ..., x_{i,d})\in \mathbb{R}^d$ such that:  $$ \mathbf{X} =  \begin{pmatrix} x_{1,1} &  x_{1,2} & \ldots & x_{1,d}\\ x_{2,1} &  x_{2,2} & \ldots & x_{2,d}\\ \vdots & \vdots & \ddots & \vdots\\ x_{n,1}  & x_{1,2} &\ldots & x_{n,d} \end{pmatrix} $$  We can kernelise this as follows: $$\hat{y} = (\mathbf{\mathcal{K}} + a\mathbf{I}_d)^{-1} \mathbf{k}$$     where $\mathbf{\mathcal{K}}$ is the $n \times n$ matrix of kernel functions $K$  $$\mathcal{K} =  \begin{pmatrix} K(\mathbf{x}_1,\mathbf{x}_1) &  K(\mathbf{x}_1,\mathbf{x}_2) & \ldots & K(\mathbf{x}_1,\mathbf{x}_n)\\ K(\mathbf{x}_2,\mathbf{x}_1) & K(\mathbf{x}_2,\mathbf{x}_2) & \ldots & K(\mathbf{x}_2,\mathbf{x}_n)\\ \vdots & \vdots & \ddots & \vdots\\ K(\mathbf{x}_n,\mathbf{x}_1) & K(\mathbf{x}_n,\mathbf{x}_2) &\ldots & K(\mathbf{x}_n,\mathbf{x}_n) \end{pmatrix} $$  and $\mathbf{k}$ the $n \times 1$ column vector of kernel functions $K$  $$\mathbf{k} =  \begin{pmatrix} K(\mathbf{x}_1,\mathbf{x})\\ K(\mathbf{x}_2,\mathbf{x}) \\ \vdots \\ K(\mathbf{x}_n,\mathbf{x})  \end{pmatrix}$$  Questions:  (a) if there are more objects $\mathbf{x}_i$ than dimensions does it make sense to not use kernels? E.g. let $\mathbf{X}$ be a $50 \times 3$ matrix then $\mathbf{X}'\mathbf{X}$ will be a $3 \times 3$ and we will end up inverting a $3 \times 3$ matrix instead of the $50 \times 50$ matrix we would have to invert were we to use kernels. Does this mean that if $d \leq n$ we shouldn't use kernels?  (b) should the simplest possible kernel be used? It seems that kernels in ridge regression are used to negate the influences of dimensionality and not to utilise certain properties of the feature space (unlike support vector machines). Although, kernels can change the distances between objects so are there any popular kernels oft used in ridge regression?   (c) what is the $O$ time complexity of ridge regression and/or kernel ridge regression?


I am trying to build  with Java 11.  I installed the OpenJDK 11.  The build process fails when it attempts to link against javafx.  I think I have the javafx packages installed:  > libopenjfx-java/bionic,bionic,now 8u161-b12-1ubuntu2 all > [installed,automatic] libopenjfx-java-doc/bionic,bionic > 8u161-b12-1ubuntu2 all libopenjfx-jni/bionic,now 8u161-b12-1ubuntu2 > amd64 [installed,automatic] openjfx/bionic,now 8u161-b12-1ubuntu2 > amd64 [installed] openjfx-source/bionic,bionic 8u161-b12-1ubuntu2 all   How do I install JavaFX such that it is connected to Java 11? I understand that Java 11 decoupled JavaFX, but I believe it can still be used together.

I have Java 8 and Ubuntu 18.04. I'm using NetBeans and when tried to make some program, it couldn't be done because JavaFX is missing.  I installed Java JDK with NetBeans from Oracle's site and thought everything is included but obviously I didn't check it well.   What should I do, what should I install? I'm not so good at this and don't know if problem is with Ubuntu or Java. :(


Let's say I have the following 7 strings  Seven Swans a Swimming Six Geese a Laying Five Golden Rings Four Calling Birds Three French Hens Two Turtle Doves and a Partridge in a Pear Tree   I want to write a regex to capture only the last 5 strings by using negation, negating "Geese" and "Swans". Is there a straightforward way to do it? My best solution is .  The equivalent solution I would like to get is:  .*(Golden|Birds|Hens|Doves|Partridge in a Pear Tree).*

I know it's possible to match a word and then reverse the matches using other tools (e.g. grep -v). However, is it possible to match lines that do not contain a specific word, e.g. hede, using a regular expression?   Input:  hoho hihi haha hede   Code:  grep "<Regex for 'doesn't contain hede'>" input   Desired output:  hoho hihi haha


This is just for fun.   Based on the cost of non-magical items, one could presumably deduce a conversion rate between Pathfinder and the real world. Of course, worlds and nations differ, so some goods or services will be more or less than they will be in other worlds and nations, so several indices would be needed.   Economic indices could include:    Cost of food (meat, bread, eggs, etc.) Cost of a basic meal at a restaurant Cost of lodging Cost of clothing Cost of alcohol Cost of personal transport  etc.

I have been wondering what a gold piece is worth, due to the fact there are many things that cost the same, but in reality, are probably worth radically different prices, such as a Goat and a Whip, which both cost 1 gp.  What is a gold piece really supposed to be worth? Like, how would things be priced if they were in familiar modern monetary units instead of "gp"? That would give me something to base my adjustments to abnormal prices on, such as items not listed in the PHB.


We know int main() returns 0 to OS when it terminates  without error  and non-zero in case of failure. But how will the OS identify normal(without error) or abnormal(error) termination in case of void main().

What is the correct (most efficient) way to define the main() function in C and C++ — int main() or void main() — and why? And how about the arguments? If int main() then return 1 or return 0?  There are numerous duplicates of this question, including:       — For C++, with a very good answer indeed.     Related:


It started after I updated my BIOS settings (virtualization and fast boot). I think I returned them back in place, although I might have changed something and forgot. But my system can't boot normally now for some reason and I don't know what's wrong and what should I check to fix it.  I only see GDM loading bar and then blinking of blank screen with occasional terminal on the startup. I managed to switch to another terminal before but it seems that now I can't even do that -- the login prompt is replaced with black screen again after 2 seconds.  I had a lot of pain setting up the system already, mainly because of the new nvidia card. But now I'm not sure what to check for.  The Secure Boot option is disabled, so that is not the problem.

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


I was looking at some code my co-worker checked in, it looked like this:  return list.OrderBy(item => item.Order).ToDictionary(item => item.Id);   I immediately told my co-worker that his code is wrong, because the Dictionary is a hash table, a non-sorted collection. He should either use an order-preserving collection, or sort the items later as he reads them from the dictionary with foreach, I said.  But he replied "No, no, my code is correct! Look: now that I have added the OrderBy, the items appear in correct order."  Turns out, on the test case, he was right. I tried on some other data, but it still was perfectly sorted!  I told him that he should not rely on this behaviour, but he disagrees, and I'm having trouble explaining why. Besides, I'm interested in why the order so often seem to be preserved.  So my question is... Why does the Dictionary, a fundamentally unsorted collection, looks so much like it is sorted?

I just saw this behaviour and I'm a bit surprised by it...  If I add 3 or 4 elements to a Dictionary, and then do a "For Each" to get all the keys, they appear in the same order I added them.  The reason this surprises me is that a Dictionary is supposed to be a HashTable internally, so I expected things to come out in ANY order (ordered by the hash of the key, right?)  What am I missing here? Is this a behaviour I can count on?  EDIT: OK, I thought already of many of the reasons why this might happen (like the separate list to entries, whether this is a coincidence, etc). My question is, does anyone know how this really works?


I've been running a Postfix/Dovecot mailserver for some time now (Ubuntu server 16.04), without any major issues. I also have a Let's Encrypt certificate issued to my hostname, which I setup in /etc/dovecot/conf.d/10-ssl.conf. That was running fine but as you may know those are only valid for 90 days. I have certbot setup to renew these automatically, which is also working fine.  Suddenly, today, both my Thunderbird, a clients Thunderbird and his iPhone started to complain about invalid certificates. I checked the certificates through certbot certificates to find out that the certificate I use was totally valid, not expired. Inspecting the certificate through Thunderbird told me the certificate had expired the day before, showing me a hash that did not match the current certificate.  So basically, it seems like Dovecot is issuing an expired certificate from some kind of 'cache'. Restarting dovecot just 'magically' fixed it but I'd like to understand what happened here since my DDG searches on certificate caches or alike in Dovecot didn't get me any results. Am I missing something obvious here? It seems like I've overlooked something obvious but can't figure out what.  EDIT This is basically answered  but since my certbot renews on a systemctl timer in stead of a cronjob I will try to provide the answer for that situation here for future reference and anyone in the same boat as I am.

This is a follow up to another question I had, but its quite different so I thought I'd start a new post.    I'm trying to work out why I still get this error message when adding an email account (in this case, in Thunderbird - but I also get the problem on phones as well);    The weird thing is that if I check it on SSL-Tools.net, it looks fine:    I really don't get it - as Thunderbird shows me my certificate is expired here:    Am I missing something? Please let me know if you need any more information to help me debug. I'm not sure what would be helpful.


Blender 2.67 Windows 7 Geforce gtx460  Head model with subsurface scattering and one texture Cpu render - fine, but slow. gpu render - face comes out black! (it was working at first it changed for some reason)  any suggestions? why should this happen.  Here is an image of the problem

As my fedora repos are way behind and still on blender 2.69, I've gone and compiled the latest myself. Everything seems to work and is quite recent. I can even bake CPU SSS, which is great. However I still get the error "Volumes/SSS not supported on GPU". Have I missed a flag or library (eg OSL support) in CMAKE or is this still on the todo list? If its just not finished yet, I don't mean to rush the devs but definitely looking forward to its release.


I don't understand following behavior of lists assignment with tuple. I'm probably missing something evident...  Following code:  a, b = 1, 2 print(a, b)   produces that output:  1 2   as expected. However, following code:  list0, list1 = ([None] * 1, ) * 2 list0[0], list1[0] = 0, 1 print(list0) print(list1)   has following output:  [1] [1]   while I would expect  [0] [1]   What am I missing? I'm using Python 3.7.

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


In my scene I have a circle (curve) and a camera, attached to it via CTRL+P > follow path.  How can I make the camera continue moving along the circle, after the first loop ends?

I'm trying to make one object orbit another. But I want it to repeat, rather than stop at 100 frames. It seems there is no option for this. Is there a way to make this happen?


I have files in the following format: x1 x2 ... x10 x11 ... x101 ...  I want to rename these files, so they all have the same name length: x001 x002 ... x010 ...  I can do this with files, that don't have the non-numeric prefix (just using sort -n followed by a while read x;), but sort doesn't recognize the numeric value, when it's not on the beginning of the file-name.

This is the data what I want to sort. But sort treats the numeric to string, the data it no sorted as I expected.     /home/files/profile1   /home/files/profile10   /home/files/profile11   /home/files/profile12   /home/files/profile14   /home/files/profile15   /home/files/profile16   /home/files/profile2   /home/files/profile3   /home/files/profile4   /home/files/profile5   /home/files/profile6   /home/files/profile7   /home/files/profile8   /home/files/profile9       I want to sort this to,     /home/files/profile1   /home/files/profile2   /home/files/profile3   /home/files/profile4   /home/files/profile5   /home/files/profile6   /home/files/profile7   /home/files/profile8   /home/files/profile9   /home/files/profile10   /home/files/profile11   /home/files/profile12   /home/files/profile14   /home/files/profile15   /home/files/profile16     Is there a good way by bash script? I can't use ruby or python script in here.


I just installed Chromium today and removed Google Chrome via sudo apt-get purge Google-Chrome-stable  The application is gone, but the shortcut in my menu is still there. Does anyone have any ideas on how to remove it?  Here's a screenshot of what I see when I type in "Chr(om)", which is how I typically search for Chromium.

I have installed Chromium and Tweet Deck on it (trough Chrome Store), now I uninstalled Tweet Deck and after that Chromium, the problem is, when I installed Tweet Deck it asked me if I want to create a shortcut to it and I chose YES. Now that both are uninstalled the Tweet Deck icon still appears on Unity Menu over Internet.    I tried to remove the icon from the menu but I can't figure out how to do this. It should be a simple thing to do, but is giving me headaches :P  What I have to do to remove the shortcut and possible junk files from Chromium?  Also my Ubuntu version is 11.10 x64.  (Sorry if I write something wrong)


I managed to get the user's latitude and longitude using HTML-based geolocation.   //Check if browser supports W3C Geolocation API if (navigator.geolocation) {     navigator.geolocation.getCurrentPosition(successFunction, errorFunction); }  //Get latitude and longitude; function successFunction(position) {     var lat = position.coords.latitude;     var long = position.coords.longitude; }   I want to display the city name, it seems the only way to get it is to use a reverse geolocation API. I read Google's documentation for reverse geolocation but I don't know how to get the output on my site.  I don't know how to go use this: "http://maps.googleapis.com/maps/api/geocode/json?latlng='+lat+','+long+'&sensor=true" to display the city name on the page.  How can I achieve this?

I want to retrieve information like the city, state, and country of a visitor from their IP address, so that I can customize my web page according to their location. Is there a good and reliable way to do this in PHP? I am using JavaScript for client-side scripting, PHP for server-side scripting, and MySQL for the database.


I have a jquery ajax call that load a form inside a div and I want to prevent submit of this form but if I use jquery submit function with   $("form").submit(function(e){   e.preventDefault(e);   alert('submit intercept'); });   It does not work if I place in a external js file but works if I put in a script tag after the form that loaded via ajax call.

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


I have two different scripts. I want to get one variable from the script to use another script. I try that method but its give me this answer shown below.   scrip1.py  a=7 print(a) c =10 print(c) b=5   script2.py  from script1 import b print(b)   result is :  7 10 5   How can i get just value of b and the output will be ? :   5

Given the following code, what does the if __name__ == "__main__": do?  # Threading example import time, thread  def myfunction(string, sleeptime, lock, *args):     while True:         lock.acquire()         time.sleep(sleeptime)         lock.release()         time.sleep(sleeptime)  if __name__ == "__main__":     lock = thread.allocate_lock()     thread.start_new_thread(myfunction, ("Thread #: 1", 2, lock))     thread.start_new_thread(myfunction, ("Thread #: 2", 2, lock))


Prove that for any positive integer $n>1$ $$ \frac{1}{n+1} + \frac{1}{n+2} + \frac{1}{n+3} \ldots  + \frac{1}{2n} > \frac{13}{24} $$ I can prove that the series is greater than $\frac{12}{24}$ however i can't prove that it is greater than $\frac{13}{24}$.

Proving $\frac{1}{n+1} + \frac{1}{n+2}+\cdots+\frac{1}{2n} > \frac{13}{24}$ for $n>1,n\in\Bbb N$  To solve it I used induction but it is leading me nowhere my attempt was as follows:  Lets assume the inequality is true for $n = k$ then we need to prove that it is true for $k+1$  so we need to prove $\frac1{k+2} + \frac1{k+3}+\cdots+\frac1{2(k+1)} > 13/24$  I don't know where to go from here please help.


How to make your iPhone beep every 5 minutes

Is it possible to have my iPhone making a sound every hour ? And preferably during day time, like 12 hours a day, and moreover only during weekdays only ?


Let $\phi$ be a homomorphism from group $G$ to group $\overline G$. It is to be proven that if $\overline K$ is a normal subgroup of $\overline G$, then $\phi^{-1}(\overline K)=\{k\in G: \phi(k)\in\overline K\}$ is a normal subgroup of $G$. I tried to prove it as follows:  Suppose on the contrary that $\phi^{-1}(\overline K)$ is not normal to $G$. This means that $\exists x\in G$ such that $xk\ne k'x \;\;\forall  k, k'\in \phi^{-1}(\overline K)$. This implies that $xkx^{-1}\notin \phi^{-1}(\overline K)$ for any $k$ in $\phi^{-1}(\overline K) $.$\tag{1}$ But $\phi(xkx^{-1})=\phi(x)\phi(k)(\phi(x))^{-1}\in\overline K$ as $\overline K\trianglelefteq \overline G$, which contradicts $(1)$ Is my proof correct? Thanks for your time.

Let $\phi:G\to G'$ be a group homomorphism, and let $N'$ be a normal subgroup of $G'$. Show that $\phi^{-1}[N']$ is a normal subset of $G'$.  My attempt: $\phi^{-1}[N']=\{g\in G:\phi(n)\in N'\}$ $$g' n' (g')^{-1}\in N'$$ $$\Rightarrow\phi^{-1}(g' n' (g')^{-1})=\phi^{-1}(g')\phi^{-1}(n')\phi^{-1}(g'^{-1})$$ Thus $\phi^{-1}[N']$ is normal. Is this thinking correct? I feel like I am missing something.


I have some code the uses the following lines: document.execCommand('selectAll', false, null); document.execCommand('copy', false, null);  And it works great. However, Mozilla has marked this command as obsolete. What is a better way of doing this, possibly with React or plain Javascript?

What is the best way to copy text to the clipboard (multi-browser)? I have tried: function copyToClipboard(text) {     if (window.clipboardData) { // Internet Explorer         window.clipboardData.setData("Text", text);     } else {         unsafeWindow.netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");         const clipboardHelper = Components.classes["@mozilla.org/widget/clipboardhelper;1"].getService(Components.interfaces.nsIClipboardHelper);         clipboardHelper.copyString(text);     } }  But in Internet Explorer it gives a syntax error. In Firefox, it says unsafeWindow is not defined. A nice trick without using :


I use texstudio in Ubuntu and I would like to use svg package:  \usepackage{svg}      File `svg.sty' not found. ^^M   The only thing I found is a .  My attempt for installation of this package has failed:  $ tlmgr install svg (running on Debian, switching to user mode!) cannot setup TLPDB in /home/ar2015/texmf at /usr/bin/tlmgr line 5336.   Where am I wrong?  Update  This is my code:  \begin{figure}[ht!] \centering \includesvg[width=140mm]{images/pos_before.svg} \caption{Previous output \label{overflow}} \end{figure}     Please avoid linking to posts which do not solve the problem straight forward.

I just installed texlive-latex-base package from official Ubuntu repo, now I have to add some modules (ucs and utf8x) for compiling .pdf files with Cyrillic encoding, so, how to install it? I found tlmgr - the TeX Live manager, but I have no such command, it seems that I could install tlmgr using : "You may end up in a situation where tlmgr itself does not run due to Perl errors, failed updates, or some other reason. If this happens, the simplest way forward is to download and run " Am I right?  Update:  argon@vprime:~/Documents/diplom$ sudo bash update-tlmgr-latest.sh  [sudo] password for argon:  Verifying archive integrity... All good. Uncompressing TeX Live Manager Updater.......................................................................................................................................................................... ./runme.sh: Cannot find TeX Live root using kpsewhich --var-value=SELFAUTOPARENT. ./runme.sh: Please call update-tlmgr-latest.sh --noexec --keep ./runme.sh: and then call the runme.sh script in the unpacked directory ./runme.sh: with the directory root as the first argument, something like: ./runme.sh: sh runme.sh /path/to/your/texlive/installation/2010 argon@vprime:~/Documents/diplom$ dpkg -L tex tex-common          texlive-binaries    texlive-doc-base texlive-base        texlive-common      texlive-latex-base   So, path to which package should i use?


I need to use some integer values as a part of some file names I create as outputs in a c++ program. For this I use the code above. The thing is my int values ( named n_irrad in the code) goes from 1 to 20000 for example, so I need the file names to be MC_Interface00001.txt, MC_Interface00002.txt, ..., MC_Interface20000.txt. So, ¿how can I set the number of digits in the file name? With the code I'm using I obviously get MC_Interface1.txt, MC_Interface2.txt, ..., MC_Interface20000.txt.  Thanks in advance.  ofstream MC_Interface; string Irrad = static_cast<ostringstream*>( &(ostringstream() << n_irrad) )->str(); string MC_Interface_FileName = "MC_Interface" + Irrad + ".txt"; MC_Interface.open(MC_Interface_FileName.c_str());

How can I format my output in C++? In other words, what is the C++ equivalent to the use of printf like this:  printf("%05d", zipCode);   I know I could just use printf in C++, but I would prefer the output operator <<.  Would you just use the following?  std::cout << "ZIP code: " << sprintf("%05d", zipCode) << std::endl;


Are "everyone", "everybody", "everything", and "everywhere" singular or plural.   I have found people who are say they are singular but also people who say they are plural.  I can anyone give me an explanation?   Thank you

Which is correct?     Everyone were convinced that he would go to the game.   Everyone was convinced that he would go to the game.   I think it's "was", because "everyone" is singular, but I just wanted to check.


I read that every prime number is of the form $6k\pm1$, is this a correct approach to find out if a number is prime?  auto isPrime = [&](int num) {       if (num == 0 || num == 1)         return false;       if (num == 2 || num == 3)         return true;       if ((num - 1) % 6 == 0 || (num + 1) % 6 == 0)         return true;       else         return false;     };

I was reading Wikipedia, and it was given that "all primes are of the form 6k ± 1"  (other than 2 and 3), where k = 1,2,3,4,...  Is this statement correct? If yes, can we use this to test if a given number is a prime number? For instance, we can say that 41 is a prime number, since there exists an integer K (K >= 1), such that 6k - 1 = 41 ==> k = 7.  I am confused why this test cannot be used to test if a number is prime?  Thanks, Sekhar


I read a book as a teenager in the '70s, which had a short one-word title as I remember it, in which the hero is rendered blind at some point, but achieves his mission by 'hitch-hiking' into other heads and using their eyes, shifting from one to another as he nears his goal. This is all very vague, but it was a long time ago! Any clues as to what I'm talking about?

I read a story once about a man who escapes from his pursuers by doing an uncontrolled jump into hyperspace. If I'm not mixing my stories up he was blind but could see through the eyes of other sighted people/animals nearby. He was able to see through his pet but it dies and he thinks he's finished - he's blind and lost in hyperspace but there's a rat on board which he eventually catches by turning off gravity and then he can see through the rat's eyes. He works out how hyperspace operates and can hop back to where he came from.   Can anyone remember the name of the story and the author? I enjoyed it when I was a kid and would like to read it again.


I came across a situation I haven't encountered before this week. I requested access to a PhD thesis from a group this week and was informed that it was not available as it was sealed for 5 years. The group explained that every student had the right to request that their thesis be sealed for 5 years.  The group is located in Austria.  Is requesting that your thesis be sealed from all access really an option? Is this specific to Austria?

I just heard about "dissertation embargoes".  My institution recommends that every graduating student place an embargo on their dissertation.  What is a dissertation embargo, and what is its purpose?


I started to render an animation (of 200 frames), using 1000 samples, at 1920x1080 pixels, of a scene including a fog object and mesh files  (from Alias). It took almost 10 hours for 1 frame, so I think that something is wrong. Is this a usual amount of render time? I want to keep the quality as high as possible. I'm using Cycles rendering with CPU, because when I try to use GPU, Blender shuts down. Specs: AMD Ryzen 5 3600- 6 core processor 16 Gb RAM GTX 1660 SUPER

I have a scene of an office. It has chairs, tables, computers, and so on. I would like to know how I can render this scene faster as I am planning to make animation inside the office and don't want the render to take forever. I know of sampling, resolution and most things in render settings. I have also heard of render passes or rendering using layers.


I am trying to use the & symbol in LaTeX.  I have looked at many LaTeX resourses and all of them suggest using \& to solve the problem.  However, when I try to use this, I still get the error "Misplaced alignment tab character &."  Are there any other suggestions?

Possible Duplicate:             In the itemize environment, how do I use the ampersand symbol & without LaTeX trying to use it as a command?


I've made a graphical interface and I want to use it. When my Ubuntu starts, I want my own graphical interface to load instead of the default one. How can I do that?

How can I create a new Ubuntu desktop environment/window manager?   lists a lot of available environments, but how can I create a new one?  What are the steps to create an Ubuntu desktop environment/window manager?


I want to construct an environment which prints enclosed text and add a predifined box flushright after the text. Here is MWE:  \documentclass{minimal} \newenvironment{problem}{%     \bigskip      \textbf{Problem}     \begin{trivlist}     \item[] }{     \mbox{}\hfil     \linebreak[2]\mbox{}\hfill\fbox{$>>$~Solution}     \end{trivlist} } \begin{document}  \begin{problem}   Shorttext. Shorttext. Shorttext. Shorttext. \end{problem}  \begin{problem}   Shorttext. Shorttext. Shorttext. Shorttext.   Shorttext. Shorttext. Shorttext. Shorttext. \end{problem}  \begin{problem}   Shorttext. Shorttext. Shorttext. Shorttext.   Shorttext. Shorttext. Shorttext. Shorttext.   Short.  \end{problem} \end{document}    Unfortunately, the box is not always positioned as I want. Sometimes it extends beyond the right boundary of the text column instead of being pulled out to the next line. And the box is not flushed right when it is pulled out alone to the last line as the above MWE shows (see 3rd occurence of the problem environment):  UPDATE: I found a solution in The TeXBook, on page 106.    Please advice how to achived desired positioneng of the end box.

I a chat discussion it was suggested that \hspace*{\fill} (with a space before it to allow for a line break) was sufficient to always get the text following aligned to the right. And indeed, it is aligned to the right.    However, in one case it is inserting an additional line  break where one should not be required as illustrated by the last example here.  I want the text bumped to the next line if and only if (iff ) there is no room:    If I remove the space before the \hspace*{\fill}, there are cases (second and third) where a new line should have been inserted but is not:    Related Question:      I have tried the suggestions at the related question and:   Martin Scharrer's suggestion of using \hbox{}\hfill results in the text being on the left for the last case. Herbert's \When macro exhibits a similar problem for the last case. Thorsten Donig's \signed macro does yield the correct number of lines, but portions of the file name for the middle two cases show up on the second line when they easily fit in the first line.     Notes:  I believe that this is unrelated to the problem, as I was able to reproduce the problem without it.  But, am mentioning it here in case it causes an issue with the proposed solution.  I am using \texttt for the file name. This resulted in an additional complication which I initially thought was the cause of the problem.  So, my actual use case is commented out below and it incorporates a solution from        Code:  \documentclass{article} \usepackage[paperwidth=7.0cm,showframe]{geometry} \usepackage{xcolor} \usepackage{xparse}   \newcommand*{\FillLine}[2]{% \noindent\parbox{\linewidth}{%     \raggedright     File:~#2 % <-- Need space here     %Space before \hspace* allows for a break before it     \hspace*{\fill}\texttt{\small CONFIDENTIAL}%  }% }  %\newcommand*{\EnableHyphenationInTexttt}{\hyphenchar\font=45\relax} % %\newcommand*{\FillLine}[2]{% %    \noindent\parbox{\linewidth}{% %       \raggedright %       File:~\texttt{\EnableHyphenationInTexttt#2} % <-- Need space here %       %Space before \hspace* allows for a break before it %       \hspace*{\fill}\texttt{\small CONFIDENTIAL}%  %    }% %}  \begin{document} \FillLine{Name}{Value}  \bigskip \FillLine{Name}{A-Long-Value}  \bigskip \FillLine{Name}{iiiiiii-iiiii-iiiiiii}  \bigskip \FillLine{Name}{Some-Really-Really-Long-Value} \end{document}


Correct me if I'm wrong. Before Tony created a new element, or maybe before Iron Man 3, from what I understand, the Iron man suits are powered via the Arc Reactor in his chest. How was Rhodes able to use the Mark II?  Or to further my question: When did Tony build Arc Reactors in his suits? Because from what I remember they still use the one in his chest from Iron Man movie.

In the Iron Man movie, Tony Stark mentions that he won't sell the Iron Man technology, because he only trusts himself to use it. Because he has an arc reactor built into his chest, his suit can interface with it for power. Unable to produce an arc reactor, Obadiah Stane steals the reactor from Stark's chest to power his Iron Monger suit.  In Iron Man 2, we see Tony's room of older Iron Man models, among them the Mark II and III armors. Both of these armored suits are shown with an arc reactor built into them. This enables James Rhodes to steal the Mark II suit during Tony's birthday party, equipping it as the War Machine suit.  Why would Tony store his extra Iron Man armored suits with power sources built in, when that would enable just anyone to walk in, put on a suit, and leave? He already had an arc reactor at all times. What would storing suits with built in power accomplish? Why would he make extra arc reactors anyway when he should've learned from Stane stealing his reactor tech? Is there a valid, in-universe reason for this, or is it just to enable Rhodey to easily steal a suit?


I am in Netherlands on tourist visa and wanted to buy a iPhone and go back to India. I would claiming the VAT return at Amsterdam Airport but do I need to declare in India and do I need to pay the duty??  I will be using this phone so this phone wont be sealed packed.

I am planning to travel to India (COK airport, Kerala) from United States. I want to take my laptop as well as my tablet (iPad). Am I allowed to take both in my backpack with my documents related my work. I think I am allowed to take only one computer as per the rule. Will the customs consider my iPad as a computer?  What all I can take?   One of my friends took 2 laptops (1 work and 1 personal) and had trouble at the airport.  Also I am planning to take some wristwatches (7 of them, each avg price is 45 $). I read in a website that I can take stuff up to max 35000 INR. Is that true? In that case, how will I manage my stuff?


I would like to reorder a whole file.  file.txt looks like this:   1 10 1 10 2 10 1 11 2 11 2 10   I would like it to look like this:   1 10 1 10 1 11 2 10 2 11 2 10

I have potentially large files that need to be sorted by 1-n keys.  Some of these keys might be numeric and some of them might not be.  This is a fixed-width columnar file so there are no delimiters.  Is there a good way to do this with Unix sort?  With one key it is as simple as using '-n'.  I have read the man page and searched Google briefly, but didn't find a good example.  How would I go about accomplishing this?  Note:  I have ruled out Perl because of the file size potential.  It would be a last resort.


I've read plenty that you need to check and sanitize form data before inserting into database or using in an sql query and I agree with that. But I couldn't find an answer to this, if I only have a number field in my form:   <input type="number" class="form-control" name="max-persons" required>   Do I need to sanitize this? The user can only enters numbers as far as I know.  $maxPersons = $_POST['max-persons']; // or $maxPersons = mysqli_real_escape_string($connect, $_POST['max-persons']);   I'm here concerned about SQL injections here primarily.  Edit: I do not believe this is an exact duplicate of linked question. I'm not asking how to prevent SQL injection. I'm asking SHOULD I take steps to prevent SQL injection in case of number fields.

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


I am struggling to center images in divs.  This is what I have so far:

     How do I get the two images on the right hand side to be centered vertically and horizontally in their respective divs?

I have a div 200 x 200 px. I want to place a 50 x 50 px image right in the middle of the div.   How can it be done?  I am able to get it centered horizontally by using text-align: center for the div. But vertical alignment is the issue..


Is it possible to write a function which inserts an object into the global namespace and binds it to a variable? E.g.:  >>> 'var' in dir() False >>> def insert_into_global_namespace(): ...        var = "an object" ...        inject var >>> insert_into_global_namespace() >>> var "an object"

How can I create or use a global variable in a function?  If I create a global variable in one function, how can I use that global variable in another function? Do I need to store the global variable in a local variable of the function which needs its access?


Actually I used Micromax charger instead of Xolo  charger. I have xolo era x phone. My phone gets switched off if I keep it idle for 4 min.  Why it is happening?

My Nexus 5 D821 (2014)'s original charger started failing to charge the phone since last week. There are 1.8A & 1.2A LG OEM chargers available in ebay.com. Is it okay to use the 1.8A charger? or Should I go for 1.2A charger?


Apologies for any bad formatting. This is number 35 from chapter 3.F of Axler's Linear Algebra Done Right, if you have the text to view. I've been stuck on this one for quite some time: obviously because the vector spaces are infinite dimensional, we cannot create the isomorphism using bases of the spaces. Also, because $\Bbb{R}^\infty$ contains infinite sequences, it is not clear to me how to create an injective function... I also thought that maybe I could develop the isomorphism using finite dimensional subspaces of the respective spaces, which is relatively easy, but being able to abstract that iso for the infinite dimensional spaces is beyond me. Any assistance/explanation would be greatly appreciated.

May I please ask how to show the dual space of the vector space of all polynomials is isomorphic to the infinite-dimensional Euclidean vector space over the reals?  (i.e. Show that $(\Bbb{R}[X])^*$ and $\Bbb{R}^{∞}$ are isomorphic where $\Bbb{R}$ means the set of all reals)


I really want to find out, please answer! I have mii outfit a, too. But i want to earn mii outfit b. By the way, is mii outfit C real or fake or perhaps a mistake in the game?

In Mario Kart Wii I have unlocked everything except the Sprinter Medium Kart and the Mii Outfit B.  How do I unlock these?


As you can try yourself, sometimes searching for a number redirects you directly to a question with that id:  or . But sometimes not: . (I will add that there is a .)  What decides whether you are redirected directly to the question or whether you see search results?  In the cases when from search you are redirected, is there also a possibility do display search results (instead of going directly to the question with that id)?

Just searched for '1955211' in the SO search field.  Expected output: include the question/answer with ID '1955211' in the search results. If the search result set is a single question/answer, redirect to that (I seem to remember, that is already the case).  Actual output: the 'no results' page showed up.  How to fix: If the search term is /^[0-9]+$/ (or whatever a valid question/answer ID is), look up the ID database and include results with the queried ID.  Complicacies: May provide results that are not (at first sight) correlated to the search query, e.g., when searching for 127001 or 123456.  Problems steming from complicacies: If someone can't distinguish between the different result types, he should perhaps re-consider giving answers on SO.


Here is how I see it in the back of the camera and also in photoshop preview:    But when I double click on it to open it in Camera RAW, here is how it is:    What is going on? What has happened?

So I shot photos for my robotics team at an event this weekend and ~95% of them are corrupt. The JPG previews from the camera are fine, but when Adobe Bridge generates its own preview, the corruption becomes visible. It is also visible in Camera RAW, and Finder (Mac OS file manager)  Is this fixable? If not, how do I prevent this in the future? I'm thinking that maybe this is just bad header info (I don't know how NEFs work but it looks like they store color in different channels, and the channel information is mismatched.)  I used a Nikon D5100, shot in NEF (RAW), and no error messages ever appeared on the camera. The camera appeared to be working perfectly normally, so I didn't even notice the problem until after the event was over.  I don't think this is a duplicate of , because that case did not produce a similar looking aberration so I think it was corrupt in a different manner. Also I do not have images with large chunks missing, just channel issues. Also that question does not have any answers detailing how to fix the images for my situation (since I don't have multiple images of the same thing to stitch together)  Take a look:


I posted  then click "Flag" then click "It doesn't belong here" and I get a 404 error        What's the deal?

I attempted to flag ...        ...as "off topic". Although the initial flag dialog loads correctly, every time I selected the "it doesn't belong here, or is a duplicate" option, the next pane would fail to load:        Request URL:https://christianity.stackexchange.com/flags/questions/18136/close/popup?_=1375739403107 Request Method:GET Status Code:404 Not Found   The account had 46 reputation. I tested this on other sites, but found that it only occurred on Christianity.SE. This was my only account that has the for the  but not enough for the .     I have now earned the commenting privilege on Christianity and am no longer able to reproduce this error, confirming its cause.


As the title suggests, i am stuck at the login screen. My system (ubuntu 14.04) was working fine and the problem appeared after i installed all updates and the following restart.  Basically i can log in, but unity won't load. I only see the standard wallpaper (not my personal) and i can use the mouse.  I tried several things...like  -install lightdm-gtk-greeter  -sudo apt-get install compizconfig-settings-manager export DISPLAY=:0 ccsm  -unity --reset  -sudo dconf reset -f /org/compiz/ (shows always wrong command...)  -enabling the unity plugin (the plugin was already enabled,so...)  -rm -rf ~/.compiz-1 ~/.config/compiz-1   If i "startx" (via ALT-CTRL-F1) i get this output  . . . Loading extension GLX modprobe: FATAL: Module fglrx not found. (WW) fglrx: No matching Device section for instance (BusID PCI:081:0:1) found modprobe: FATAL: Module fglrx not found. Loading extension FGLRXEXTENSION Loading extension GLX [glesx] __glESXExtensionInit: No GL ES2.0 capable screen found! The XKEYBOARD keymap compiler (xkbcomp) reports: > Warning:           Type "ONE_LEVEL" has 1 levels, but <RALT> has 2 symbols >                    Ignoring extra symbols Errors from xkbcomp are not fatal to X server The XKEYBOARD keymap compiler (xkbcomp) reports: > Warning:           Type "ONE_LEVEL" has 1 levels, but <RALT> has 2 symbols >                    Ignoring extra symbols Errors from xkbcomp are not fatal to X server   My System: Ubuntu 14.04 64bit I5-3570k ATI Radeon HD 7970 Ghz  Edit: With the old Kernel 3.13-0-24 it works...the newer 3.13.0-27 is the problem

I just upgraded my System to 14.04.  After restarting when the update was finished I did not see any menu bars or panels.   Right clicking and opening a terminal via ctrl+alt+t is not possible. However I can access the terminal via alt+F1. I already tried out installing the unity-desktop again but it didn't change anything .  Do you have any suggestions?


In  which explains types of t-tests for “Independent Two-Sample t-test” example:  We can confirm that the t-statistic is again less than the t-critical value so we fail to reject the null hypothesis. Hence, we can conclude that there is no difference between the mean screen size of both samples.  Null hypothesis was that the average screen size of the sample does not differ from 10 cm. Alternate hypothesis was that the average screen size differs. And also the data is only about sizes of screens. Why can't null hypothesis be that the average screen size differs. and alternate hypothesis, that the average screen size doesn't differ. Not just this example, in every article I have read, every author only told what was chosen for null and alternate hypothesis. But, no one talked about why they chose what they chose. I always think that, why can’t the statement chosen for alternate hypothesis be chosen for null hypothesis and vice versa. And the data won’t have much information too. It’s always up to the article writer to what to choose for null and alternate hypothesis. So, my question is, are there some set of rules, that have to be followed to choose a statement/condition for hypothesis. Or what actually causes a particular statement to be chosen for hypothesis. Or am I missing something.

After taking a statistics course and then trying to help fellow students, I noticed one subject that inspires much head-desk banging is interpreting the results of statistical hypothesis tests.  It seems that students easily learn how to perform the calculations required by a given test but get hung up on interpreting the results.  Many computerized tools report test results in terms of "p values" or "t values".  How would you explain the following points to college students taking their first course in statistics:   What does a "p-value" mean in relation to the hypothesis being tested?  Are there cases when one should be looking for a high p-value or a low p-value? What is the relationship between a p-value and a t-value?


I would like the name and year in my bibliography to be bold. For this I used the following LaTeX code:  \usepackage[backend=bibtex, natbib=true, citestyle=numeric, style=numeric, sorting=nty]{biblatex}  \AtBeginBibliography{% \renewcommand*\mkbibnamefirst[1]{\mkbibbold{#1}} \renewcommand*\mkbibnamelast[1]{\mkbibbold{#1}} \renewcommand*\mkbibnameprefix[1]{\mkbibbold{#1}} \renewcommand*\mkbibnameaffix[1]{\mkbibbold{#1}} \DeclareFieldFormat{parens}{\mkbibbold{\mkbibparens{#1}}} \DeclareFieldFormat{date}{\mkbibbold{#1}} \DeclareFieldFormat{author}{\mkbibbold{#1}} } \DeclareNameAlias{sortname}{last-first} \DeclareNameAlias{default}{last-first}   I write my text on two computers and in both cases I use TeXstudio (with MikTeX). The problem is that on machines (A) the names and years are as desired bold and not on computer (B).  Why? How can I fix this?

I would like to create a custom format for citing authors' names in the text, let's call it "newformat". One option I can think of is creating a new bibmacro for names where the parameters are changed to my liking, such as   \documentclass{article}    \usepackage{filecontents}   \usepackage[backend=biber]{biblatex}[2016/01/01] %the latest version of biblatex?   % biber is version 2.4; the latest?  \begin{filecontents}{\jobname.bib} @misc{Doe12,   author = {Doe, John},   year = {2012},   title = {A macro for formatting names}, } \end{filecontents}  \addbibresource{\jobname.bib} \nocite{*}  \newbibmacro{name:newformat}{\printnames{authors}} \DeclareNameFormat{newformat}{%   \usebibmacro{name:newformat}{\textbf{#1}}{\textbf{#3}}{#5}{#7}%   \usebibmacro{name:andothers}% }  \begin{document}    \section*{Testing the format here}    I am citing   \citename{Doe12}[newformat]{author}    \printbibliography % to make sure that the .bib file is properly formated.  \end{document}   Here, I just used \textbf for the sake of the example, but I ultimately want to use other functions, say upper case or palindrome!  However, I get this weird error message:  ! Illegal parameter number in definition of \blx@defformat@d. <to be read again>                     3 l.20   \usebibmacro{name:last}{#1}{#3                                      }{#5}{#7}%   which seems to indicate that the second option {#3} is not expected. I am a bit at a lost here; I checked the biblatex package and \usebibmacro{name:last} must be given 4 parameters, isn't it? Please advise.


"Only by playing fair, and also without fear, will you ever win."  What is its meaning?    I don't understand the last part "will you ever win". Is it a question?

I have seen this construction quite often:      Online ads have been around since the dawn of the Web, but only in   recent years have they become the rapturous life dream of Silicon   Valley.   What is the rule there?. When your sentence doesn't start with pronoun + verb, invert them as verb + pronoun?. I know it sounds awkward but is it possible (grammatically correct) to use something similar to:      Online ads have been around since the dawn of the Web, but only in   recent years they have become...   And in any case, does this only work with have (or has)? Maybe it works fine with 'had' but I can't think of an example right now.


Why does the integral of the surface area of a sphere equal it's volume?   $$\int{4\pi r^2 \ \mathrm{d}r =\frac{4}{3}\pi r^3}$$  I don't quite understand why the relationship between surface area and volume is this way. Is this true for any other shapes?

When differentiated with respect to $r$, the derivative of $\pi r^2$ is $2 \pi r$, which is the circumference of a circle.  Similarly, when the formula for a sphere's volume $\frac{4}{3} \pi r^3$ is differentiated with respect to $r$, we get $4 \pi r^2$.  Is this just a coincidence, or is there some deep explanation for why we should expect this?


What I would really like is to not have to hit the caps lock button as often as I do for a few key words. I know that many just use lower case only but all of the queries we write at the company I work for do this so it would be nice to not have to worry about it as much.   There are probably other issues that would arise from doing this but I kind of just want to give it a shot for a little while if I can. Thank you.

Is there any FREE "build-in" way to capitalize the "keywords" in the SQL 2005/2008 management studio when you write a sql query?  i.e  truncate table x   should be automatically changed to:  TRUNCATE TABLE x


I tried to install MySQL for my localhost and I managed to break my dependencies, and I can NOT install anything  I have tried:   Purging MySQL commons, client, server, ect. Removing MySQL commons, client, server, ect. apt-get update apt-get clean apt-get autoclean apt-get -f install   When I do apt-get -f install I get this:  Reading package lists... Done Building dependency tree        Reading state information... Done Correcting dependencies... Done The following extra packages will be installed:   libmysqlclient18 The following NEW packages will be installed:   libmysqlclient18 0 upgraded, 1 newly installed, 0 to remove and 10 not upgraded. 4 not fully installed or removed. Need to get 0 B/603 kB of archives. After this operation, 3,503 kB of additional disk space will be used. Do you want to continue? [Y/n] y (Reading database ... 364284 files and directories currently installed.) Preparing to unpack .../libmysqlclient18_5.5.40-0ubuntu1_amd64.deb ... Unpacking libmysqlclient18:amd64 (5.5.40-0ubuntu1) ... dpkg: error processing archive /var/cache/apt/archives/libmysqlclient18_5.5.40-                                                      0ubuntu1_amd64.deb (--unpack):  trying to overwrite shared '/usr/share/doc/libmysqlclient18/changelog.Debian.gz',                   which is different from other instances of package libmysqlclient18:amd64 dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Errors were encountered while processing:  /var/cache/apt/archives/libmysqlclient18_5.5.40-0ubuntu1_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)    If you need more information tell me what to do  Thanks!

For example:  $ sudo apt-get install curl Reading package lists... Done Building dependency tree Reading state information... Done You might want to run 'apt-get -f install' to correct these: The following packages have unmet dependencies: bsh : Depends: libjline-java but it is not going to be installed groovy : Depends: libjline-java but it is not going to be installed rhino : Depends: libjline-java but it is not going to be installed E: Unmet dependencies.   Try 'apt-get -f install' with no packages (or specify a solution).   I get the same or similar errors when I attempt to install clojure1.3, leiningen, and several other packages.   When I try the suggestion made in the error message, this is what happens:  $ sudo apt-get -f install  Reading package lists... Done Building dependency tree        Reading state information... Done Correcting dependencies... Done The following packages were automatically installed and are no longer required:   diffstat linux-headers-3.2.0-26-generic linux-headers-3.2.0-26 dh-apparmor dkms html2text libmail-sendmail-perl libsys-hostname-long-perl Use 'apt-get autoremove' to remove them. The following extra packages will be installed:   libjline-java Suggested packages:   libjline-java-doc The following NEW packages will be installed:   libjline-java 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. 23 not fully installed or removed. Need to get 0 B/72.0 kB of archives. After this operation, 129 kB of additional disk space will be used. Do you want to continue [Y/n]? Y (Reading database ... 226243 files and directories currently installed.) Unpacking libjline-java (from .../libjline-java_1.0-1_all.deb) ... dpkg: error processing /var/cache/apt/archives/libjline-java_1.0-1_all.deb (--unpack):  trying to overwrite '/usr/share/java/jline.jar', which is also in package scala 2.9.2-400 Errors were encountered while processing:  /var/cache/apt/archives/libjline-java_1.0-1_all.deb E: Sub-process /usr/bin/dpkg returned an error code (1)  $ sudo apt-get upgrade Reading package lists... Done Building dependency tree        Reading state information... Done You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies:  bsh : Depends: libjline-java but it is not installed  groovy : Depends: libjline-java but it is not installed  rhino : Depends: libjline-java but it is not installed E: Unmet dependencies. Try using -f.


I have seen that in some countries Skype for Linux is not available. They get redirected to old Skype or they get a message that they don't have access.  When I try to search it using:  apt-cache search skype   It doesn't return skypeforlinux, but it returns skype (the older version). When I search on my pc, it shows skypeforlinux and not skype. These two versions are not compatible for calling each other. So, I want to know how can I install Skype for Linux on my friend's computer who is in another country?  I sent the deb file for new skype but when he launches the skypeforlinux, it doesn't work.

I want to install Skype, but I can't locate it in Software Center or by using Synaptic Package Manager. Can anyone help me?


Show that if $(a,n)=d>1$ and $k$ is any positive integer, then $a^{k} \not\equiv 1 \pmod n$.   I know that the order divisibility property states the following.  If $(a,n)=1$ and $k$ is the order of $a \pmod n$, then for any positive integer $j$, we know that $a^{j} \equiv 1 \pmod n$ if and only if $k \mid j$.  It seems like I could somehow use the "if an only if" part to prove that $k$ does not divide $j$, which would imply the conclusion. But how can I show it formally?

So I know that if $(a,n)=1$, then $a^{\phi(n)}≡1\pmod{n}$ by Euler's Theorem. I also know that $d \mid a^k$ and obviously $d \mid n$. I know I probably need to use this in the proof, but I just don't know how to get started.


Prove that any two medians of a triangle intersect in the ratio 2 : 1. I actually tried with median property but I don't know which theorem I should employ

Prove using similar triangle properties that "any two medians of a triangle divide each other in the ratio $2:1$. I do not know which criteria of similar triangle must be used


In this book the stars went black and the people on Earth took a while to figure out why. The solar system had been surrounded with a 'sheet' to stop human observation. It turns out human observation was causing collapses of quantum wave forms/relativistic possibilities in the universe, and the aliens didn't like that very much.

Basically our thoughts are ruining everything. Like when humans are taught stars are giant balls of gas. To the rest of the universe they aren't but humans think it and destroy alien planets. I think they come to seal us off from the rest of the universe.


I have an Acer Aspire One ZG5 netbook that came with Windows XP. It was loaned to someone, who then put Ubuntu on it. I know nothing about Ubuntu, so I looked for information on this site for help. It walked me through the steps to uninstall Ubuntu using the Terminal. Now the netbook boots to:  Error: unknown filesystem, Grub rescue>   I've tried changing the BIOS and then booting with an XP CD but I keep getting a "Stop Error".  I don't have an Ubuntu Live CD.  When I type ls, it shows the following:  hd0 hd0,msdos5 hd0,msdos1   Is the Ubuntu system gone now?

I have absolutely no experience with Linux, and I desperately need to get my computer back up and running again with Windows.  How do I remove Ubuntu and reinstall Windows?    Editor's note: many of the answers are about removing Ubuntu from dual-boot but keeping Windows (which is a bit complicated), while other answers are about removing Ubuntu from single-boot (which is easy: basically just format the disk while installing Windows). The question as written is ambiguous between dual-boot or single-boot.


I'm running Ubuntu 12.04.2 LTS (Precise Pangolin) and noticed a 30 second delay whenever i log into my server via ssh or perform any kind of login via sudo on that machine. I can provoke immediate execution by killing the defunct dbus-daemon showing up during the delay:  output of ps fax |grep dbus  19222 ?        Ss     0:00 dbus-daemon --system --fork --activation=upstart 19752 ?        Z      0:00  \_ [dbus-daemon] <defunct>   taping into the dbus using dbus-monitor --system i'm getting:  signal sender=org.freedesktop.DBus -> dest=(null destination) serial=7 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=NameOwnerChanged    string ":1.4"    string ""    string ":1.4"   each login. Stopping the dbus service eliminates this problem but probably causes many other... I'm not running xorg on the machine but the packages are present for X11 forwarding capabilities. I've ruled out the common motd script delay and ssh "UseDNS no" fixes one finds when looking up login delay issues. Many thanks in advance for any help with this, it's been driving me crazy ;-)

When I log in on my server I get this:  No mail. Last login: Fri Nov  5 14:22:45 2010...   then I must wait for 5 sec and then is ready...  wolfy@ubuntu-server:~$   Is this wait time normal or should I do something to "repair" this?


I have a folder with around 300 Shapefiles I want to use as masks in the tool Extract by Mask on the same Raster image. I'm using the following model :  But I get the following error :  ERROR 999999: Error executing function. The table name is invalid. Failed to  execute (Extract by Mask)   I'm pretty sure it's because the new raster image loses the original image's spatial reference :  The original image is in GCS WGS 1984. How can I solve this error?

My code will not project and store the feature layer in the scratch.gdb. "ERROR 999999 ... The table name is invalid. The table was not found. [17_5330_51961Lake]"  The interpreter doesn't like "-" characters or beginning or ending in a number. Does anyone know of a work around?  import arcpy import os  mxd = arcpy.mapping.MapDocument("Current") mxdpath = mxd.filePath (filepath, filename) = os.path.split(mxdpath) MCP_Path = str(filepath)  srl = os.path.join(MCP_Path, r"CoordinateSystems\NAD 1983 UTM Zone 17N.prj")  WBYLID = "17-5330-51961"  WBYLIDlabel = WBYLID.replace("-","_")  LakeOut = os.path.join(MCP_Path + "\OutputData\Scratch.gdb", WBYLIDlabel + "Lake") arcpy.Project_management(fl, LakeOut, srl)


So I'm making this adventure map, and kinda got tired of placing NBT command blocks one by one.  Is there a way to fill an area with command blocks that already have a command in them?  The closest i got was just filling an area with command blocks, then manually putting the command on each one of them. But honestly that was too tiresome.  /fill ~ ~-1 ~ ~15 ~-1 ~15 minecraft:command_block    Am i missing anything?

Does someone know how to set a command block with a command inside using the setblock command?  I have created this code /setblock <x> <y> <z> command_block {TileEntityData:{Command:"testfor @p[_=1]"}} but it doesn't works.  Do someone know how to do that?


I just purchased a Trek multitrack 750 1996 in black. I found it in almost perfect condition and want to upgrade the tires. What is the max tire size you can run on the 750 without any clearance issues?

We often get questions on bicycles.stackexchange about fitting wider or narrower tires to bicycles. We have a large number of these with answers suiting the specific bike or style of bicycle in question, but I have been unable to find one that provides a generic answer covering off all things that need to be considered. For most bicycles, the answer is the same regardless of the specific style and sizes of tires in question.   This is intended as a canonical question that we can point closed questions to.


I configured new-mobile-broadband connection. I know that I can connect by clicking as following:    But I want to connect manually to that mobile broadband by using terminal.  How to do with terminal command?

I run Ubuntu 12.04 on an old iMac G3. Since the GUI is too resource heavy I have disabled the display manager (lightdm) and am currently running the computer in console mode. How do I establish a mobile broadband connection from the command line?  When I connect the modem it shows up as ttyUSB0 in the Network Manager device list:  $ nmcli dev DEVICE     TYPE              STATE         ttyUSB0    gsm               disconnected     eth0       802-3-ethernet    unavailable   I have also copied a working connection configuration file from another computer to /etc/NetworkManager/system-connections/Com\ Hem\ Default\ 1. Still, when I try to connect I get an "unknown connection" error:  $ nmcli con up id "Com Hem Default 1" Error: Unknown connection: Com Hem Default 1.   Any clues?


I wanted to prove this by mathematical induction. I have proved that it is less than two and that the sum is greater than 0 but I am stuck on how to prove it to be greater than 1. Please help!!!  I would like a conclusive proof for this. Thank you so much!  I do believe there was an answer to a question similar to this, but the answers provided there did not use mathematical induction to provide the answer.


From $ a, n \in \mathbb {N} $ with $ a> 1 $, show that $ n | \phi (a ^ n-1) $ where $\phi $ is Euler's phi function  Attemp: The way I was going about answering this question was considering $n-x$, where $n - x$ (mod $n$) $\equiv - x$ (mod $n$), and as gcd($-x,n$) = 1

$a$ and $m$ are natural numbers and $a>1$. Prove that $m | \phi(a^m -  1)$.   Any hints how can I prove this statement?


Does increasing number of hidden layers improve accuracy or after adding some layers improvement won't happen? Does increasing number if hidden layers much more than the sufficient number of layers cause accuracy to decrease? Do we need more epoch to train network?

In recent years, convolutional neural networks (or perhaps deep neural networks in general) have become deeper and deeper, with state-of-the-art networks going from 7 layers () to 1000 layers ( in the space of 4 years. The reason behind the boost in performance from a deeper network, is that a more complex, non-linear function can be learned. Given sufficient training data, this enables the networks to more easily discriminate between different classes.  However, the trend seems to not have followed with the number of parameters in each layer. For example, the number of feature maps in the convolutional layers, or the number of nodes in the fully-connected layers, has remained roughly the same and is still relatively small in magnitude, despite the large increase in the number of layers. From my intuition though, it would seem that increasing the number of parameters per layer would give each layer a richer source of data from which to learn its non-linear function; but this idea seems to have been overlooked in favour of simply adding more layers, each with a small number of parameters.  So whilst networks have become "deeper", they have not become "wider". Why is this?


I'm re-creating Space Invaders for a project of mine, and have used a List for all my invaders and other things, but I need to use an array instead. How can I change this list into an array, I'm not familiar with them. See code below.  List<PictureBox> listInvaders;  public Form1()     {         InitializeComponent();         InvaderAnim.Start();          listInvaders = new List<PictureBox> {invader1, invader2, invader3, invader4, etc};   Thanks very much!

Is there a short way of converting a strongly typed List<T> to an Array of the same type, e.g.: List<MyClass> to MyClass[]?  By short i mean one method call, or at least shorter than:  MyClass[] myArray = new MyClass[list.Count]; int i = 0; foreach (MyClass myClass in list) {     myArray[i++] = myClass; }


I want to generate all possible combinations of numbers from a given set of integers. For example: if 1,2 and 3 are the given integers, then all the possible combinations are 123,312,213,231,321 and 132...

How do you generate all the permutations of a list in Python, independently of the type of elements in that list?  For example:  permutations([]) []  permutations([1]) [1]  permutations([1, 2]) [1, 2] [2, 1]  permutations([1, 2, 3]) [1, 2, 3] [1, 3, 2] [2, 1, 3] [2, 3, 1] [3, 1, 2] [3, 2, 1]


When I type on iOS keyboard, I don't find the backtick (`) character. Where is it located? If there isn't, why?

I’ve started using my iPad more and more (especially here on Ask Different) and I’ve found that I can’t find the grave accent character (also known as the "back tick" or "opening single quote"; it's the un-shifted ~ key on the standard US keyboard.  Where can I find this character on the iOS keyboard?