Network account problems with mac server OSX 10.6 Snow Leopard

Okay the situation is this.   Yesterday my company changed our dns server, because our former one, was too unstable to work with. anyway today i went to one of our mac server, because it needed to be configured because of the new dns server. So i tried logging in to the local admin, because it couldn't find the network account server, because of the domain shift, but it just froze when trying to log in.  Okay so I went down to our server room to get a look at it locally. I tried logging in to the local admin, but i froze again. So i tried pulled the network cable out, and suddenly i could login just fine.  I tried logging in via vnc once again and it just hanged. better than it freezing, but still a problem. so i logged in locally. went to system preferences to edit the path to the network account server, so the mac server could find it once more, but then it just froze the system preferences when i went to login options.   So i restarted back and forth some time and finally got to edit the path to the network account server, but when i typed it in, the mac server just say that the network account server is not responding although all other computers, both linux and mac, are using it just fine. I tried updating, rebooting without the network. tried FQDN for the network account server, it's ip, it's hostname nothing work.  Does anyone have any clue to what is going on? cause I really have no idea what to do, other than maybe reinstall the system, which i would like to avoid if possible.


What should be done with questions that have been resolved as a comment instead of an answer?

I'm trying to go through and provide answers to every unanswered question (search "closed:0 answers:0"), somewhat following the spirit that was blogged about at  .  However, I'm finding this much more difficult than it needs to be, as many of the questions have already been answered without the use of an "answer" - but instead, in the form of a comment by either the OP or another poster. I wouldn't mind reading through and skipping these, as long as there was some appropriate action I could take to at least assist with preventing these questions from being seen again from the same query - either by myself or another SO member.  Is there such an appropriate action?  Should we vote to close?  If so, using what reason? Even if I vote to close, what are the chances that 4 other users will also view the question and also vote to close?  (i.e., will my individual vote even do any good?  Is there any report to show recent close votes, so that others may also review and contribute supporting close votes?) Should we post some sort of an answer - even just something to the effect of "this was already answered by the OP's own comment to his answer (above)"? Would something like this be appropriate to flag for moderator attention, and let the moderators deal with it?  (Or would this be considered too trivial?) Should we rename the question title to something standard that can be used in a search exclusion?  (Maybe "SOLVED:"?)  Basically, how can I help to denote questions as "This question is no longer in active search of an answer - though better answers may still be appreciated."? I've already reviewed , which was closed as a duplicate of  - but this requires effort on part of a user who may very likely no longer be active. Otherwise, is there something I should be doing to improve my search to filter out these types of questions? I've run across this many times, so I don't consider it to be a rare issue.  However, the last question like this I just ran across, prompting this question, was .  In this case, the question was self-answered by the OP in the form of a comment, this question is the OP's only question, the OP has no other visible activity on SO, and the OP hasn't been seen on SO since he registered and posted the question 5 months ago. Another one I just ran across is .  However, here the "answer" comment was posted by a reputable and recently active SO member.  Should I leave a comment directed at him, asking him to re-post his comment as an answer, or should I post my own answer echoing his comment?  (Or something else?) Yet another is .  Interestingly, the OP actually self-edited the question to include the "SOLVED:" prefix on to the question, instead of posting his resolving comment as an answer (and ideally accepting it) as he was asked to do by another comment.  This brings up another good idea - is there a "standard" we should use to rename the titles on these "resolved but unanswered" posts that could be used as a search exclusion?  (Also added to the above list.)


Does it mean the molecules of all matter above absolute zero temperature are moving?

According to my knowledge, heat is the energy that is stored in form of kinetic energy of molecules in Brownian motion. However, in a macroscopic view, a rigid body seem to be "stable" but still store heat. I am wandering does it mean in a microscopic view, the molecules of solid matter are still moving?


How to configure smartphone/tablet to have no data connection?

Before going on a trip overseas with no data plan, I need to check how well my  works to geolocate me with just GPS + Glonass + GSM towers.  From experience, I know that just relying on GPS with no data connection pretty much doesn't work: Even after being outside in open skies for hours riding a bike, my  had a very hard time geolocating me, and wouldn't follow after it did, while it did work in just a few seconds when connecting to the Net through wifi.  So, I'd like to experiment while I'm still home: Is it possible to configure an Android device to have no data connection and only rely on other means to geolocate the user?  If needed, I don't mind moving to different ROMs such as CyanogenMod.  Thank you.    Edit: I found the reason why GPS wouldn't work even after hours standing outside: In Settings > Location, the option "Download GPS assisted data only over Wi-Fi networks" was disabled; Once enabled, geolocalizing through GPS alone works OK, although it works faster and better with the Nexus 7 tablet that has GPS + Glonass.


More consistent wording for the synonyms creation page

The tag pages - such as  refer to "master" and "synonym."  The "create a tag synonym" page refers to them as "source" and "target."    Could we have them with consistent names?


new to the forum but had a quick question from my lecture yesterday. I understand string.equals() compares the actual content or characters while string == string compares the references. But where I got confused is he said that within the string pool each string literal is created only once, and that any variables that contain that same string literal will point to that one instance of the string within the string pool. So why not use == comparison then? Won't any variables that contain the same string literal point to the same one in the string pool and return true or false?


I have a desktop computer with:   Intel Pentium(R) Dual CPU E2180 @ 2.00GHz × 2  GeForce GT 610/PCIe/SSE2 graphics.   Until recently it was running Ubuntu 16.04 LTS and 16.10 in dual boot.  Both versions would suspend and awaken correctly.  About a month ago I upgraded the 16.10 installation to 17.04.  At about the same time, there was a large update to 16.04.  Since then neither version will suspend and awaken.  On the sleep button or suspend from the menu or suspend from the power settings, the machine shuts down completely and will only restart from cold with the power button.  There are no errors reported in the pm-suspend log.  I have Nvidia driver 381.22 and the update to 17.04 from last Friday installed.  Can anyone help to resolve this.  There have been no hardware or BIOS changes.  I have tried 375 and 378 as well as 381.09, all with the same result.  The problem occurs on suspend, not on wake up.  The power light on the box goes off after suspend.  It used to flash slowly while suspended.  After today's updates, with kernels 4.4.0-78 and 4.10.0-21, neither version will suspend correctly.  16.04 is using driver 375 and 17.04 is using driver 381.


Approaching speed of light: why do objects appear further away in front of me?

is a video game created by the MIT Game Lab which allows users to experience what it would be like if the speed of light was closer to normal walking/running speeds and thus experience relativistic effects in an otherwise familiar environment.  From the site:     A Slower Speed of Light is a first-person game prototype in which players navigate a 3D space while picking up orbs that reduce the speed of light ... [allowing] the speed of light in the game to approach the player’s own maximum walking speed. Visual effects of special relativity gradually become apparent to the player [as more orbs are collected]... These effects, rendered in realtime to vertex accuracy, include the Doppler effect (red- and blue-shifting of visible light, and the shifting of infrared and ultraviolet light into the visible spectrum); the searchlight effect (increased brightness in the direction of travel); time dilation (differences in the perceived passage of time from the player and the outside world); Lorentz transformation (warping of space at near-light speeds); and the runtime effect (the ability to see objects as they were in the past, due to the travel time of light).   When I play the game and collect enough orbs for relativistic effects to really start becoming significant something happens that I didn't expect: as I accelerated towards objects they appeared to move further away from me (despite length contraction definitely being taken into effect, since I was able to get to those objects faster over a given distance than had I not collected any orbs).  Luboš Motl in  says that this is due to:     the shrinking of transverse directions if you're moving forward (or their expansion if you move backwards) which makes object look "further" (optically smaller) if you're moving forward. Because of this shrinking, you may effectively see "behind your head". You also see things how they looked like some time ago.   Based on my understanding of the Lorentz transformations the directions transverse to one's motion aren't effected ($y'=y$ and $z'=z$ if all motion is in the $x$ direction).  So, what exactly causes this effect that I see in the game and Luboš Motl explains?  Am I misunderstanding the Lorentz transformations?


The best free and most up to date phylogenetic tree on the internet?

I found phylogenetic tree in wikipedia is lacks of accuracy. It actually confusing with versions. Some terms was not scientifically accurate with dna analysis anymore  So are there anyone know where is the most updated datasource on the internet?


Add the full time to CreationDate column in Votes table in Data Explorer

I was trying out some queries in Data Explorer and noticed that, column CreationDate in table Votes doesn't contain the full timestamp. Only the date part is present and time part is set to 00:00:00. Have a look at . It would be nice to have the full timestamp. Possible uses of this are determining how many votes are cast immediately after posting, how many are cast within an hour, and so on. I read  where Greg makes the point that:  up/down voting patterns could strongly correlate with other activity on the site (questions, answers, comments).  But, all these details about posts, comments are available with exact timestamp in User's profile as well as in Data Explorer. The exact voting timestamp can be seen in the Reputation tab. So, if I want to guess who voted me, I can do so by looking at this data. Having exact voting timestamp in Data Explorer won't provide any extra information to aid guessing.


How do I /give myself a named pickaxe with unbreakable in Minecraft Bedrock Edition?

I am on Minecraft pocket edition version 1.2.10.1, and am trying to use the following command:   /give @p stone_pickaxe 1 0 {display:{Name:"The Stone Breaker"},Unbreakable:"1"}  When trying to use this command, it returns Line 1 Column 2 Missing '}' or object member name. Could someone point out what is wrong with my command?


Example of a file  line 1 line 2 line 3 line 4   line 4 should be after line 1  line 1 line 4 line 2 line 3   Important: It could be more than 4 lines somehow the script has to understand that it has to read the last line, not line 4.


Copying folder to multiple destinations in parallel

I have to transfer roughly 250gb of data from a Master Drive to lots of USB drives, all of identical size and brand. When I copy using the GUI in Mac OSX, it waits to copy all the files to one drive and then copies the same files to drive 2.  Is there a way to copy the files across so that each file/bit is only read once and then written multiple times? This would presumably be faster than reading the same data over and over again. I have seen this question asked before, but I couldn't understand how the terminal commands worked.  Just so you know, I have very little experience with terminal, so if anyone has any great code, could they please explain how I would adjust it work with for me?  Many thanks  James


Terminal says 'Read-only file system' after trying to force RGB mode for my display

I'm trying to force RGB mode in macOS to fix the picture quality of my external monitor. I had to do this when I got my MacBook 16". Now, after installing Big Sur, the problem reappears. The instructions I've followed are:  Run: csrutil disable  in recovery mode in order to disable rootless mode.  Run the following patch: patch-edid.rb  and then do the following: sudo mkdir /System/Library/Displays/Contents/Resources/Overrides/DisplayVendorID-472 sudo cp DisplayProductID-361 /System/Library/Displays/Contents/Resources/Overrides/DisplayVendorID-472    but Terminal returns this error: 'read-only' file system I tried the following: mount -o remount /  But Terminal fails with this error: mount: / failed with 64


My flag limit is increasing day by day. I haven't noticed before how many flag I can raise. But since I am noticing it is increased a lot. In last week, I have raised above 200 helpful flags.   I have noticed to increase it from 36. Daily it is increasing by 1. Now it is reached to 40.  Is it good/ bad? On what basis, flag limit is getting increasing daily?


Negative values in dat file are not plotted using PGF

It is going to be trivial but I can't figure out what is wrong with the following.  I have dat file containing exactly this:  -6.13     -25.2630334555      -0.14     -21.3855065611      4.97       -16.396737203      9.97       -12.3655278402     14.96     -4.4686133113      19.89     0      24.96     4.5277219529       29.93     1.7377940655       34.8      0   When I am trying to plot these values like  \begin{figure} \centering \begin{tikzpicture} \begin{axis}[ xlabel={$\vartheta\ [^\circ\mathrm{C}]$}, ylabel={$\Delta C/C_{20}\ \mathrm{[\%]}$}, legend pos = south east, legend entries = {vzorek 1}, grid = both, xmin=-7, xmax=40 ] \addplot[smooth,green,mark=+]   table {data_lab1/kapacity_vzorek1.dat}; \end{axis} \end{tikzpicture} \end{figure}   the first line is omitted - value for -6.13 is not plotted. But why?


I'm currently discussing with a client about a design for a navigation bar. I wanted to get 3rd opinions on general consensus regarding the simplicity of the mobile nav bar.  What I recommend:   What the client wants:   I think that what they want has too many links and no clear CTAs to guide the user efficiently, personally I believe it will lead to more browsing but less sign ups.  Any thoughts?


I use lineno packaage for line numbering. How to restart line number for every new paragraph? The only thing it can restart the numbering is for each new page. Is there any way in Latex that I can have the number of the line for each paragraph so that I know how many lines in each paragraph?


What's a verb that is the opposite of "belong [as a part] to"?  e.g.   A belongs to B.  I belong to my group.  then  B __ A?  My group __ me.  I initially thought about "contains". But I'm not sure if "contain" is an accurate word for describing this part-whole relationship. ("My group contains me"??)


Why are gravitons needed to explain gravitational attraction in quantum gravity?

I've read and heard multiple times that gravity can't be explained by the current understandings of quantum physics. Wikipedia's Gravity entry briefly explains the incompatibility between general relativity and quantum mechanics on the subject of gravity as follows:      In the decades after the discovery of general relativity, it was realized that general relativity is incompatible with quantum mechanics. It is possible to describe gravity in the framework of quantum field theory like the other fundamental forces, such that the attractive force of gravity arises due to exchange of virtual gravitons, in the same way as the electromagnetic force arises from exchange of virtual photons. This reproduces general relativity in the classical limit. However, this approach fails at short distances of the order of the Planck length, where a more complete theory of quantum gravity (or a new approach to quantum mechanics) is required.   Photons, as I understand, are the force carriers of the electromagnetic field which 'transfer' quantized 'bulks' of energy and, as far as I know, they are not needed for a negative particle (let's say an electron) and a positive particle (let's say a positron) to attract.   So, if two positively and negatively charged particles can experience attraction without the need of photons in the process, why are gravitons (or another explanation) needed for gravitational attraction to exist between two masses?  Edit: I'll explain why my question is not a duplicate. These other questions have good, related answers which I actually learned a lot from. I understand that just as the other fundamental forces have force carrier particles described by QM, gravity still has to be explained in the quantum level. However this is specifically what I don't get (and I could be totally wrong): Photons, as I've understood, do not play a role in the attraction between oppositely charged particles. They have other functions like the transfer of energy. So, why does gravitational attraction between two masses need to be explained by the exchange of gravitons?


I am wondering, is there a way to play old Minecraft versions such as Indev/survival test? For example, there was a mod called MCnostalgia, but I don't know if it's still available. I know, half of you are probably going to say, use the edit profile option in the new launcher, but I want to play some versions that the edit profile option does not contain. Is the mod out there? If so, where? Also, is there is any way to legally get old jar files for minecraft and put them In the versions folder? If so where from?


Why are conditional statements assumed to be true?

for example : If you show up for work monday morning then you get the job, the only cases where we know the truth of this statement is if you show up on monday morning,if you don't you can't possibly know if you would have gotten the job. Why in this case do we just assume it to be true? that seems really arbitrary and "unmathsy". Why can't we assume that they are false by default instead? does it being automatically assumed to be true factor in later? I have to apologise since I haven't read that far yet.


Why my Mac book pro shows status 'Battery is not Charging'?

I have a MacBook Pro early 2015.Recently I am facing an issue with the battery. It's not charging. The MacBook works fine when connected to charger, but it turns off when the charger is removed. I did a SMC reset, tried another charger too no results. I also tested my charger on another Mac which works just fine. I took it to the Apple service centre and they said I need to replace the logic board which costs tons of money. I am confused, do I really need to spend this much money if my laptop just works fine with charger plugged in? Here is my battery status  Also status indicator  Please  suggest me what could be the best solution. Thanks in advance.


Where/how do I report a bug on this site?

I can't search because a Captcha keeps failing. There's no one to tell. Who has responsibility for this? Where can I click to report the problem?


force on a moving charge in magnetic field

Need help in understanding the direction of magnetic force in the magnetic field!Totally confused by directions.  Why is it that magnetic force is perpendicular to the direction of magnetic field and velocity of charged particle. Why is it(force) not in the same direction as the magnetuc field


Follow-up regarding right-continuous $f:\mathbb{R} \to\mathbb{R}$ is Borel measurable

I have a follow-up to another question here on math.stackexchange, .  The thread was a couple of years old, so I hope it's okay if I start a new question.  The person who answered the question claimed that the preimage of an open set under a right-continuous function $f: \mathbb{R} \to \mathbb{R}$ is a Borel measurable set because it is the countable union of half-open intervals.  I was trying to think through the "countable union" part.  If we have an open set $U \subseteq \mathbb{R}$, and let $A = f^{-1}(U)$, then certainly by definition if we take $A \cap \mathbb{Q}$, then for every $a \in A \cap \mathbb{Q}$, there is some $\delta > 0$ such that $[a,a+\delta) \subseteq A$, and thus $\bigcup_{a \in A \cap \mathbb{Q}} [a,a+\delta) \subseteq A$.  But then, why does the reverse containment hold (or does it hold at all)?  I tried to prove that $A \subseteq \bigcup_{a \in A \cap \mathbb{Q}} [a,a+\delta)$ using contradiction, but didn't get anywhere.  The best I could come up with was that if $b \in A$ and $b \notin \bigcup_{a \in A \cap \mathbb{Q}} [a,a+\delta)$, then because of the density of the rationals in the reals, we could write $\{ b \} \cup \bigcup_{n \in \mathbb{N}} [a_n,a_n+\delta_n) \subseteq A$, but this clearly didn't get me anywhere...


I'm trying to create a cep program that is able to detect when a user's salary change.so i wrote this code   Pattern     .<comptedata>begin("First Event").subtype(comptedata.class).where(             new SimpleCondition<comptedata>() {                 @Override                 public boolean filter(comptedata event) throws Exception {                     if (event.getoperation()!="virement"){                         return false ;                     }                     return event.getMontantop() != event.getsalaire();                 }             })     .followedBy("seconf Event").subtype(comptedata.class).where(             new SimpleCondition<comptedata>() {                 @Override                 public boolean filter(comptedata event) throws Exception {                     if (event.getoperation()!="virement"){                         return false ;                     }                     return event.getMontantop() != event.getsalaire();                 }             });   but it gives me this error  Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/flink/api/common/ExecutionConfig$ClosureCleanerLevel     at org.apache.flink.cep.pattern.Pattern.where(Pattern.java:159)     at myflink.cep.changePattern.getEventPattern(changePattern.java:19)     at myflink.app.toWarningStream(app.java:69)     at myflink.app.main(app.java:52) Caused by: java.lang.ClassNotFoundException: org.apache.flink.api.common.ExecutionConfig$ClosureCleanerLevel     at java.net.URLClassLoader.findClass(URLClassLoader.java:382)     at java.lang.ClassLoader.loadClass(ClassLoader.java:424)     at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:349)     at java.lang.ClassLoader.loadClass(ClassLoader.java:357)   I understood from this question () that there is a class file that my code depends on and it is present at compile time but not found at runtime, however flink-core already exists in my project structer i tried to make it at runtime instead of compile but It doesn't solve the problem I don't know what should I do


Did relativity make Newtonian mechanics obsolete?

Did Einstein completely prove Newton wrong? If so, why we apply Newtonian mechanics even today? Because Newton said that time is absolute and Einstein suggested it ?   So, if fundamentals are conflicting, how can both of them be true at a time?


Looking for a SF story regarding women growing things in their wombs

I'm looking for the title and author of a short story or novelette that I read quite some time ago.   The main characters are two young women. One is taking correspondence courses, and is constantly being berated by the other one for hoping to rise above her station. They go out to pick up young men, to sleep with them, to get pregnant.  It's not a normal sort of pregnancy, though. The men have some sort of 'coded semen' which grow something other than a child in the woman's womb. It ends up being a product of some kind, which earns the woman money when it is 'born'. The one woman is very careful about who she chooses, as she can only do this so many times. The other... isn't so careful.   At the end, the careful, studious woman achieves what she has been working for - a letter from a government organisation that permits her to become the mother to a human being.  Thank you for reading my question. I've been looking for this story for years, now.


Google Satellite imagery gone wild with QGIS 2.18

I'm using the OpenLayers plugin (version 1.4.3) for my satellite imagery.  When I'm at 1:565 or less (the number on the right is bigger) everything is fine.  See image below.   When I'm at 1:564 or greater the satellite image is incorrectly aligned / scaled.  In this case, I change the number is the bottom readout (circled in red) to avoid moving the map in any way.   I am using an API key.  And can zoom into 1:282 before the image goes away (what appears to be the plugin's way of letting you know the imagery isn't supported at that scale.  I haven't noticed this behavior with Bing imagery, or Google Hybrid, but can't zoom in as far either either case.


Phone numbers with regex (plus and spaces)


How does Unix keep track of a user's working directory when navigating the file system?

Say I log into a shell on a unix system and begin tapping away commands. I initially begin in my user's home directory ~. I might from there cd down to the directory Documents.   The command to change working directory here is very simple intuitively to understand: the parent node has a list of child nodes that it can access, and presumably it uses an (optimised) variant of a search to locate the existence of a child node with the name the user entered, and the working directory is then "altered" to match this — correct me if I'm wrong there. It may even be simpler that the shell simply "naively" tries to attempt to access the directory exactly as per the user's wishes and when the file system returns some type of error, the shell displays a response accordingly.   What I am interested in however, is how the same process works when I navigate up a directory, i.e. to a parent, or a parent's parent.   Given my unknown, presumably "blind" location of Documents, one of possibly many directories in the entire file system tree with that name, how does Unix determine where I should be placed next? Does it make a reference to pwd and examine that? If yes, how does pwd track the current navigational state?


I want to show that $$  a_n = \frac{3^n}{n!} $$ converges to zero. I tried Stirlings formulae, by it the fraction becomes $$  \frac{3^n}{\sqrt{2\pi n} (n^n/e^n)} $$ which equals $$  \frac{1}{\sqrt{2\pi n}} \left( \frac{3e}{n} \right)^n $$ from this can I conclude that it goes to zero because $\frac{3e}{n}$ and $\frac{1}{\sqrt{2\pi n}}$ approaching zero?


NullPointerException in removeDup() of Node class

I'm writing a method to remove duplicate Node, but it keeps getting NullPointerException at line: while (m.next != null).  public class Node {      public int data;     public Node next;      public Node (int data) {         this.data = data;         this.next = null;     }      public void removeDup () {          Node n = this;         while (n != null) {             Node m = n;              while (m.next != null) {                 if (n.data == m.next.data)                      m.next = m.next.next;                 m = m.next;             }              n = n.next;         }     } }


How are Star Wars blasters properly reloaded/charged/etc.?

I've been looking into the inner workings of blaster weapons primarily using Wookieepedia. While most of it I understand, I still can't figure out how many rounds a gun would fire before needing the ammunition component replaced/reloaded. Is there any solid answer?  I'm someone who likes to design and draw his own weapons and such, but likes to keep to how the technology of an era is in mind. While Star Wars weapons don't really have magazines (and you don't really see them reloading during battle), other people's work still has magazines and treat ammunition consumption as though it's pretty much the same as our modern era.  I guess that I just find it hard to believe, with the technology of the Star Wars Universe, that characters would need to carry lots of ammunition (hence why clones/storm troopers/battle droids don't visually seem to carry very much).  Example: DC-15A     "The weapon's tibanna gas cartridge carried enough gas for up to 500 shots, depending on the power settings of the weapon, while the charge pack lasted about 50 shots"   Source:   I've read in several places that this can be seen in two different ways.  1. Which ever ran out first, had to be replaced before the weapon could fire again. 2. The weapon contained two different sources of ammunition (so I guess you could switch between the two)


Why aren't my PIR security lights working through my window?

Can any one help? I purchased a solar powered PIR security light, with the intention of putting it inside my kitchen window. The PIR would be inside the window, but this does not work.  When I go outside to activate the light, it does not work. When I go inside to run my hand across the sensor, it works.  Will a PIR unit penetrate glass, or am I barking up the wrong tree?


Solving linear congruence (modular inverse or fraction) via gcd Bezout equation

Isn't finding the inverse of $a$, that is, $a'$ in $aa'\equiv1\pmod{m}$ equivalent to solving the diophantine equation $aa'-mb=1$, where the unknowns are $a'$ and $b$? I have seem some answers on this site (where the extended Euclidean Algorithm is mentioned mainly) as well as looked up some books but there is no mention of this. Am I going wrong somewhere or is this a correct method of finding modular inverses? Also can't we find the Bézout's coefficients by solving the corresponding diophantine equation instead of using the extended Euclidean Algorithm?


How do I find $(1+i)^{100}$ without expanding $(1+i)$ 100 times?  Is there a quicker way to do this?  The hint was to find the modulus and argument of $1+i$ which I've got as $\sqrt{2}$ and $\pi/4$ but I'm not sure what to do from here.


Finding matrix $B$ is not zero matrix where $AB= 0$

$A$ is defined as an $m\times m$ matrix which is not invertible. How can i show that there is an $m\times m$ matrix $B$ where $AB = 0$ but $B$ is not equal to $0$?   For the solution of this question I think giving an example is not enough because it is too easy to solve this by giving an example, so how can I show that $B$ is not the $0$ matrix?


I am  making a class for graph, maybe i am not doing it the best way but the idea was to start for somewhere.  I have this class graph.h  template <class T> struct node {     int index;     T name;     vector<int> neighbours; };  struct lengths{     int node_1;     int node_2;     int length; };  template <class T> class graph : public vector<node<T>> {      public:         graph();       ... }   and graph.cpp  template <class T> graph<T>::graph(){     directed = false;     //flag for dir graph, default false     nodes = 0;               //number of nodes in the graph  }   and in main i have   graph<int> g;   but when i try to build it i get error  main.cpp undefined reference to `graph<char>::graph()'   I use GNU GCC Compiler [-std=c++14]


Why can't I see my tweets? My profile says I sent 46 (and I did), but when I click on Tweets, I cannot see them and Twitter says:     Send your first Tweet!   Why is that?  (one of my tweets is from yesterday, so not the issue you refer to about old tweets)


Switching between python versions for Arcpy

I’m developing a multi-module project in Python. I’m new to GIS and my boss doesn’t have a strong technical background. I’ve been instructed to use the Arcpy module to do functions such as intersect. The project requirements state I need to use Python 3.3. Is there a contradiction between using the Arcpy module and Python 3.3? I’m using Liclipse (Eclipse styled for Python) and in one module use the  and in another use Arcpy. In properties, if I put the python C:\Python33\python.exe on top then lxml works but Arcpy doesn’t and if I put pythonArcGis C:\Python27\...  on top then Arcpy works and lxml doesn’t. I don’t really understand what’s going on…  Questions: Can Arcpy work with Python 3.3? If yes, how do you get both Arcpy and lxml to work at the same time? If no, then is it possible to launch only the module that uses Arcpy as Python 2.7?


Can a Minecraft PE client connect to a Minecraft server?

I setup a Minecraft server, but Minecraft PE will not connect. Are Minecraft PE and Minecraft incompatible?


How can I mathematically prove that the function $f(x) = x^3$ is not convex?  Graphically it's clear. I computed the Hessian to be $6x$, but not sure how I can conclude the positive definiteness of $6x$.


How to call a parent class function from derived class function?

How do I call the parent function from a derived class using C++? For example, I have a class called parent, and a class called child which is derived from parent. Within  each class there is a print function.  In the definition of the child's print function I would like to make a call to the parents print function.  How would I go about doing this?


Show that $\left|\varphi\right|^{2}+\left|\eta\right |^{2}=\frac{1}{2}\left (\left|\varphi+\eta\right|^{2}+\left|\varphi -\eta\right|^{2}\right ) $

I want to show that  $$\forall_{\varphi, \eta \in \mathbb{C}} \ \left | \varphi  \right |^{2} + \left | \eta  \right |^{2} = \frac{1}{2}\left (  \left | \varphi + \eta \right |^{2} + \left | \varphi -\eta  \right |^{2} \right ) $$  How can I generally prove this? Any help for a starting point of the proof would be greatly appreciated.


Why aren't I being asked to upgrade to 20.04.1

We're well into 20.04.1 but my laptop (18.0.5) isn't offering to upgrade to 20.04.1 when doing regular updates.  All my usual updates are working correctly.  The following may help: ~$ date Fri 14 Aug 07:50:07 AEST 2020  ~$ sudo apt update && sudo apt upgrade ... Reading state information... Done Calculating upgrade... Done 0 to upgrade, 0 to newly install, 0 to remove and 0 not to upgrade.  ~$ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description:    Ubuntu 18.04.5 LTS Release:    18.04 Codename:   bionic  ~$ cat /etc/update-manager/release-upgrades # Default behavior for the release upgrader. [DEFAULT] # ... Prompt=lts  ~$ sudo do-release-upgrade -c Checking for a new Ubuntu release There is no development version of an LTS available. To upgrade to the latest non-LTS develoment release  set Prompt=normal in /etc/update-manager/release-upgrades.  I know I could force the upgrade but I'm in no serious hurry and would prefer the most seamless upgrade - I don't understand why it hasn't prompted me to do so.


If $\alpha_{1},\ldots,\alpha_{m}$ are vectors different from zero vector, then there is a linear functional $f$ such that $f(\alpha_{i})\neq 0$

I am self-studying Hoffman and Kunze's book Linear Algebra. This is exercise 14 from page 106.     Let $\mathbb{F}$ be a field of characteristic zero and let $V$ be a   finite-dimensional vector space over $\mathbb{F}$. If   $\alpha_{1},\ldots,\alpha_{m}$ are finitely many vectors vectors in   $V$, each different from zero vector, prove that there is a linear   functional $f$ such that $f(\alpha_{i})\neq 0, i=0,\ldots,m.$   I thought that prove by induction on $m$ would work. I showed the base case, but I got stuck on inductive step.  I would appreciate your help.


Differences between symmetric, Hermitian, self-adjoint, and essentially self-adjoint operators

I am a physicist. I always heard physicists used the terminology "", "Hermitian", "", and "essentially self-adjoint" operators interchangeably.  Actually what is the difference between all those operators? Presumably understandable by a physicist.


Creating a first C++ project in Visual Studio

My IDE is Visual Studio 2017. I am pretty new in C++ programming so I need a help about understanding principles of creating a new C++ project in Visual Studio. So, in my first solo attempt i just chose a empty project option and afther that i chose to add new item and i write this sample code:  #include <iostream> using namespace std;  int main() {      return 0; }   Afther this step and afther steps with compiling, building and a starting without debugging i did not get any message or consol window with time of code execution or option for entering any key for ending. What is needed for getting this kind of information at the end of code?


combination and permutation words problem

Taking 4 letters at a time from the word 'EXAMINATION', how many  (i) permutation (ii) combination can be made???


Looking for a very gentle first book on number theory

My gf is the classic math-phobe, totally traumatized by math, etc., which surprises me, since she's whip-smart.  The only explanation I can think of is that she got off to a bad start in elementary school.  My own love for mathematics was kindled by an old book on number theory that I found in my school's library.  Unfortunately, I can't remember that book's title or author, so...  I'm looking for a very gentle first book on number theory.


On , we realised that a few tags would need some modification, namely uniformizing the plural/singular type. Is there a way to modify all occurences of a given tag, or should be manually edit them one by one?  Due to the number of modifications needed, we'd rather avoid setting up synonyms for all of them.


Prove that $\sum_n f_n$ uniformly converges.

My attempt For $n$ is even $f_n(x)\leq 0 \implies -f_n(x)\geq 0.$ let us define $g_n(x)=f_n(x) , n$ odd and $g_n(x)=-f_n(x) , n$ even. $$\sum_n f_n(x)=\sum_n(-1)^n g_n(x)$$ Also, given that $f_n$ converges to $0$ uniformly. so, $g_n(x)$ from (2) it is clear that $g_n(x) $ is a decreasing function. By, Leibniz test for alternating series. $$\sum_n f_n(x)=\sum_n(-1)^n g_n(x)$$ converges. $x \in [a,b]$ was aribitrary, So, $\sum_n f_n(x)=\sum_n(-1)^n g_n(x)$ converges and we can define $f$ in $[a,b]$ as $f(x)=\sum_n f_n(x)=\sum_n(-1)^n g_n(x).$ We need to prove the uniform convergence of $\sum_n f_n$ to $f.$ How do I prove the uniform convergence? I tried with $\epsilon$ definition. I am not able to proceed.


I am doing PhD in IT I have Bsc in Math (there wasn't writing in my study) and my masters was course based not research.  Today I got my paper returned with many comments  some of these comments are (boring, need more focus)  There are papers that I enjoy reading, as they have nice flow, they take me from one sentence to another smoothly.  When I write I put what I want to write in bullet points and then struggle connecting sentenses and have the flow from one sentence to the other.  I wonder if there is right way to do academic writing.  Shall I read many papers about the topic I am writing about then squeeze my brain to put that in a paper format.  or shall I take notes from each sentence in the papers I read and then connect them together.  or is there any other way to do the writing?  There must be a way most people use.  I appreciate any help here.


I'm on Ubuntu 18.04, 64 bit.  I downloaded the .deb from the Steam website. I tried installing with Ubuntu Software. It didn't seem to work. I tried installing via the terminal, using various commands and combinations of commands.  sudo dpkg -i ~/Downloads/steam_latest.deb sudo apt-get update sudo apt --fix-broken install sudo apt-get install -f   In Ubuntu Software, it currently lists both "Steam" and "Steam installer" as installed applications. When I go to Steam and click "launch", nothing happens. When I open the show applications menu from the desktop and type "Steam", a program named Steam, with the Steam logo, appears. I click it; nothing happens.  How do I diagnose what is wrong?  How do I figure out why Steam is not running on my computer?  —  EDIT – in response to Organic Marble, here is the code output to the command steam—  Repairing installation, linking /home/elen/.steam/steam to /home/elen/.local/share/Steam Running Steam on ubuntu 18.04 64-bit STEAM_RUNTIME is enabled automatically Installing breakpad exception handler for appid(steam)/version(0) /home/elen/.local/share/Steam/ubuntu12_32/steam: symbol lookup error: /usr/lib/i386-linux-gnu/libxcb-dri3.so.0: undefined symbol: xcb_send_request_with_fds /home/elen/.local/share/Steam/steam.sh: line 444: no match: ssfn*


Prove that the set of eigenvalues of block matrix with blocks $A$ and $B$ is the union of eigenvalues of $A$ and $B$.

Let $A,B,U,O$ four matrix of real entries. $A$ is a square matrix of size $m$, $B$ is a square matrix of size $n$, while $U$ is a $n\times m$ matrix of all entries $=-1$ and $O$ is a $m\times n$ matrix of all entries $=0$. Let us consider the square (block) matrix of size $n+m$: $$M=\left(   \begin{array}{cc}     A & U \\     O & B \\   \end{array} \right) $$ Prove that the set of eigenvalues of $M$ is the union of eigenvalues of $A$ and $B$. This property of determinants should follow immediately if we can show $\det M=\det A \det B$ but I do not know to prove this statement. Any suggestions please?


Why doesn't pstree command show init in Ubuntu 16.04 LTS?

I am trying to examine the output from pstree command. But for some reason it always starts from something called as systemd as opposed to it being init. I have checked to see the process ID's of both init and systemd using ps aux command and init has a PID of 1, while systemd has some other PID. So why isn't init being shown in my pstree's output? Is there an option that I need to give?  Also I did read about systemd vs init controversy, but ubuntu 16.04 LTS still uses init to start everything right?  Update as to why different PIDs?  It turns out that different PIDs that I thought were part of my ignorance. The init had a PID 1, whereas systemd wasn't the thing that I was talking about. Instead when I ran ps aux|grep systemd, I found PIDs for /lib/systemd/systemd-*, where * means some extra characters. So what I was talking about was not systemd, but some other processes that were extensions(is it the correct word?) of systemd I guess.  Some of the examples for that * are as follows  /lib/systemd/systemd-journald /lib/systemd/systemd-udevd /lib/systemd/systemd-timesyncd


Why is IPv6 ping failing to access google.com?

I have found that ping google.com from my Windows 7 box has stopped working.  Below is the output - note that the IPv4 ping works, and Yahoo works. Is my local router at fault here?  C:\Users\Jeff>ping google.com  Pinging google.com [2001:4860:4007:801::1007] with 32 bytes of data: Destination net unreachable. Destination net unreachable. Destination net unreachable. Destination net unreachable.  Ping statistics for 2001:4860:4007:801::1007:     Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),  C:\Users\Jeff>ping -4 google.com  Pinging google.com [74.125.224.206] with 32 bytes of data: Reply from 74.125.224.206: bytes=32 time=5ms TTL=55 Reply from 74.125.224.206: bytes=32 time=5ms TTL=55  Ping statistics for 74.125.224.206:     Packets: Sent = 2, Received = 2, Lost = 0 (0% loss), Approximate round trip times in milli-seconds:     Minimum = 5ms, Maximum = 5ms, Average = 5ms Control-C ^C C:\Users\Jeff>ping yahoo.com  Pinging yahoo.com [98.139.183.24] with 32 bytes of data: Reply from 98.139.183.24: bytes=32 time=98ms TTL=46 Reply from 98.139.183.24: bytes=32 time=86ms TTL=46  Ping statistics for 98.139.183.24:     Packets: Sent = 2, Received = 2, Lost = 0 (0% loss), Approximate round trip times in milli-seconds:     Minimum = 86ms, Maximum = 98ms, Average = 92ms Control-C  C:\Users\Jeff>ping -6 google.com  Pinging google.com [2001:4860:4007:801::1005] with 32 bytes of data: Destination net unreachable. Destination net unreachable. Destination net unreachable.  C:\Users\Jeff>tracert google.com  Tracing route to google.com [2001:4860:4007:801::1008] over a maximum of 30 hops:    1  Destination net unreachable.  Trace complete.


Value of sum of binomials: $P = \binom{N}{0}-\binom{N}{1}+\binom{N}{2}-\binom{N}{3}+ \dotsb + (-1)^N\binom{N}{N}$

$P = \binom{N}{0}-\binom{N}{1}+\binom{N}{2}-\binom{N}{3}+ \dotsb + (-1)^N\binom{N}{N}$  I can calculate the value of this equation manually, but there any direct formula for calculating the value of this equation? Can anyone please help?


Like charges repel and unlike charges attract. But when do like charges attract and unlike charges repel?Please cite an example to justify it.


Anti-wind up scheme in the implementation of PID controller

I want to implement designed PID controller. But I am facing the problem of how to limit the saturation limit in both positive and negative direction? I tried using zener diode, but I would like to know if are there any design procedures to get anti-wind up scheme in the  implementation of PID controller using zener/diode combination?  EDIT:  this is the designed pid controller and i am using TL084 op-amps which has +15 volts and -15 volts as their supply. when the error is generated, due to integrator the control signal(Vc) output is going to saturation point of nearly 15 volts. I want Vc to be in the range of (0.85-3.8 volts), so that i can give this to SG3524 PWM IC to generate constant duty ratio PWM pulses. I tried by putting zener diode of 3.3 volt rating, but now Vc is coming upto 3.5 volts(basically saturation limit has come down to 3.5 volts) . The problem is how to limt the Vc to the specified range. Can any one please suggest modifications for proper design of anti-windup  working scheme of this.  Here VFb=-3 volts and VRef= 3 volts


How to prove $|\sum_{i=1}^n a_i|\le \sqrt{n} \sqrt{\sum_{i=1}^n a_i^2}$

Let $n$ be a natural number and $a_1,a_2,\ldots,a_n$ are real numbers. Then prove that  $|\sum_{i=1}^n a_i|\le  \sqrt{n\cdot \sum_{i=1}^n a_i^2}$.   At first I tried to prove for $n=2$ i.e, $|a_1+a_2|\le \sqrt{2(a_1^2+a_2^2)}$, but unable to proceed. Give me some hint to proceed.


How to setup dual-screen monitors in xorg.conf using Nvidia TwinView?

I have the following xorg.conf file, but TwinView is not working for me when using 2 monitors. Please help me get things sorted out.  # nvidia-settings: X configuration file generated by nvidia-settings # nvidia-settings:  version 295.33  (buildd@allspice)  Fri Mar 30 15:25:24 UTC 2012   Section "ServerLayout"  # Removed Option "Xinerama" "1" # Removed Option "Xinerama" "0" # Removed Option "Xinerama" "1"     Identifier     "Layout0"     Screen      0  "Screen0" 0 0     InputDevice    "Keyboard0" "CoreKeyboard"     InputDevice    "Mouse0" "CorePointer"     Option         "Xinerama" "0" EndSection  Section "Files" EndSection  Section "InputDevice"      # generated from default     Identifier     "Mouse0"     Driver         "mouse"     Option         "Protocol" "auto"     Option         "Device" "/dev/psaux"     Option         "Emulate3Buttons" "no"     Option         "ZAxisMapping" "4 5" EndSection  Section "InputDevice"      # generated from default     Identifier     "Keyboard0"     Driver         "kbd" EndSection  Section "Monitor"      # HorizSync source: edid, VertRefresh source: edid     Identifier     "Monitor1"     VendorName     "Unknown"     ModelName      "Ancor Communications Inc VE247"     HorizSync       30.0 - 83.0     VertRefresh     50.0 - 76.0     Option         "DPMS" EndSection  Section "Monitor"      # HorizSync source: edid, VertRefresh source: edid     Identifier     "Monitor0"     VendorName     "Unknown"     ModelName      "Ancor Communications Inc VE247"     HorizSync       30.0 - 83.0     VertRefresh     50.0 - 76.0     Option         "DPMS" EndSection  Section "Device"     Identifier     "Device1"     Driver         "nvidia"     VendorName     "NVIDIA Corporation"     BoardName      "Quadro FX 1500"     BusID          "PCI:1:0:0"     Screen          1 EndSection  Section "Device"     Identifier     "Device0"     Driver         "nvidia"     VendorName     "NVIDIA Corporation"     BoardName      "Quadro FX 1500" EndSection  Section "Screen"     Identifier     "Screen1"     Device         "Device1"     Monitor        "Monitor1"     DefaultDepth    24     Option         "TwinView" "0"     Option         "TwinViewXineramaInfoOrder" "DFP-1"     Option         "metamodes" "DFP-1: 1280x1024 +0+0"     SubSection     "Display"         Depth       24     EndSubSection EndSection  Section "Screen"  # Removed Option "TwinView" "0" # Removed Option "metamodes" "DFP-0: 1280x1024 +0+0" # Removed Option "TwinView" "1" # Removed Option "metamodes" "DFP-0: 1280x1024 +0+0, DFP-1: 1280x1024 +1280+0" # Removed Option "TwinView" "0" # Removed Option "metamodes" "DFP-0: 1280x1024 +0+0"     Identifier     "Screen0"     Device         "Device0"     Monitor        "Monitor0"     DefaultDepth    24     Option         "TwinView" "1"     Option         "TwinViewXineramaInfoOrder" "DFP-0"     Option         "metamodes" "DFP-0: 1280x1024 +0+0, DFP-1: 1280x1024 +1280+0; DFP-1: 1280x1024_60 +0+0"     SubSection     "Display"         Depth       24     EndSubSection EndSection  Section "Extensions"     Option         "Composite" "Disable" EndSection   Here are my computers specifications:  Computer: Processor           : 2x Intel(R) Pentium(R) 4 CPU 3.00GHz Memory              : 3339MB (2889MB used) Operating System    : Ubuntu 12.04.1 LTS User Name           : chikaru (Mrmagu) Date/Time           : Sat 22 Sep 2012 12:18:13 PM EDT  Display: Resolution          : 2560x1024 pixels OpenGL Renderer     : Quadro FX 1500/PCIe/SSE2 X11 Vendor          : The X.Org Foundation  Multimedia: Audio Adapter       : SB-XFi - Creative X-Fi Audio Adapter       : HDA-Intel - HDA Intel Audio Adapter       : USB-Audio - Producer USB  Input Devices: Sleep Button Power Button Razer Razer Lycosa Razer Razer Lycosa Saitek Cyborg R.A.T.7 Mouse HDA Intel Front Headphone HDA Intel Rear Mic HDA Intel Line HDA Intel Line-Out Front  Printers: No printers found  SCSI Disks: Optiarc DVD RW AD-5200A BENQ DVD LS DW1655 ATA ST380817AS ATA MDT MD1600JS-00S ATA Hitachi HDS72303 ATA ST3320820AS


Alternate grid background color in excel when a value of a single column changes?

I need a formula for conditional formatting to make an Excel 2010 spreadsheet alternate highlighting when a single column changes.  This question, "", is exactly what I want to do, but the suggested solution didn't work for me--it just highlights the first row of each matching value.  I know how to use conditional formatting, but for the life of me I can't figure out or find any pointers on the net so far to make this work.  Ideas?  Here is a link to a picture of how I want my spreadsheet to look when I'm done.  Basically I want every other Disp Number value row to be highlighted.  Seems like it would be a common thing to want to do, and I've seen this asked for in various places, but people struggle with making it work.


Why am I getting an error calling this readFile method?

I'm getting an error using the method readFile which I used in the class RunProgram.  The error I'm getting is:      RunProgram.java uses unchecked or unsafe operations.   The code of my RunProgram class is:   import java.util.ArrayList;   public class RunProgram{           public static void main(String [] args){      String [] namen = Input.geefInputNamen();      ArrayList<Spelers> spelerDatabase = new ArrayList<Spelers>();     spelerDatabase = FileReader.readFile("Player Database");        }  }   The method readFile is defined in the code below:   import java.io.*;  import java.util.ArrayList;   public class FileReader {    public static ArrayList readFile(String naamvdfile) {     ArrayList<Spelers> spelerDatabase = new ArrayList<Spelers>();       try { int LineNr = 4;          File aFile = new File (naamvdfile+ ".xlsx");     BufferedReader aBr = new BufferedReader(new java.io.FileReader(aFile));                      String aLine ="";       while (aLine !=> null) {             aLine = aBr.readLine();             if (aLine != null) {                 String [] lineParts = aLine.split(";", -1);                 if (lineParts.length == 10) {                      int overall = Integer.parseInt(lineParts[1]);                     int shootMid = Integer.parseInt(lineParts[4]);                     int shootDis = Integer.parseInt(lineParts[5]);                     int defence = Integer.parseInt(lineParts[6]);                     int rebounden = Integer.parseInt(lineParts[7]);                     int playmaker = Integer.parseInt(lineParts[8]);                     int atletisch = Integer.parseInt(lineParts[9]);                      Spelers speler = new Spelers(lineParts[0], overall,                         lineParts[2], lineParts[3], shootMid, shootDis,                         defence, rebounden, playmaker, atletisch);                     spelerDatabase.add(speler);                 }                 else System.out.println("Lijn " + LineNr +" is niet volledig                                         ingevuld!");                 LineNr++;             }            }              System.out.println("Aantal spelers dat we inlazen: " + LineNr);     }          catch (Exception e) { }          return spelerDatabase;          }    }   This last code doesn't give an error while compiling.


I have to insert some wires into several electrical connections and have been getting conflicting information on whether or not they should be tinned before inserting.  I'm sure this is a quite simple question to answer with a picture so I have included one below.  To be clear, the screw itself does not make the connection here, but pulls the flat conducting plate on the bottom of the connection toward the flat conducting plate on the top.  Regardless, the connection is still supposed to be a friction fit held together by the force that you apply from tightening the screw.  I suppose the root of what I'm unsure about is whether making an electrical connection under mechanical pressure would suggest you should not tin the wires or if it is specifically the rotation and grinding on a tinned wire that would be caused by the screw that makes tinning these wires a bad idea.  I'm obviously no expert on this topic so any additional explanation on the thought process behind the answer is very welcomed.


How does the new Sangan errata affect Exodia?

Just reading up on the new sangan errata which is;     If this card is sent from the field to the Graveyard: Add 1 monster with 1500 or less ATK from your Deck to your hand, but you cannot activate cards, or the effects of cards, with that name for the rest of this turn. You can only use this effect of "Sangan" once per turn.   So this new Errata states that you cant use the effect of the monster you added until the turn after you use this effect.   To my understanding this means that if you have sangan in an exodia deck and you have both legs and both arms in your hand then if you use the sangan effect to add the head then you wont win until your next turn. Or would the effect of exodia overrule this effect?  And also if you have the head already and three of the other pieces in your hand when you use sangan to add the last one it doesnt have an effect because only the head has the effect and because you havent added the head to your hand then the win condition can still be activated. Or would you still have to wait a turn because the pieces are listed in the effect of the head?


how to freeze/hibernate system apps in non-root android mobilephones

is there any methods to freeze/hibernate bloatwares on android phones? using samsung galaxy note 3


Strange behavior when reading and writing "float" and "double" types in C

When I put 1 for example this return 1.000 (that's fine to me):  #include <stdio.h>  main() {     float num;      printf("Double: ");     scanf("%f", &num);      printf("%f\n", num); }   So, when I put 1 at this it returns 0.000. I don't understand because I used %f to read and write correctly. Can you guys explain me?  #include <stdio.h>  main() {     double num;      printf("Double: ");     scanf("%f", &num);      printf("%f\n", num); }


Error coming during installation veil-evasion

I have already downloaded veil-evasion but i can't install it  $ apt-get install veil-evasion E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission Denied) E: Unable to lock the administration directory (/var/lib/dpkg), are you root? $ sudo -i # cd Veil-Evasion -bash: cd: Veil-Evasion/: no such file or directory # apt-get install Veil-Evasion Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package Veil-Evasion


Black pixels in render when using Cycles material

I already tried adding more subivisions, tweaked the light bouncing parameters, etc, but I cannot get rid of the black pixels when using  Cycles material copied from a YouTube video.    Here is the source if someone wants to check it out:    Thanks!


Why does the light at the bottom of a mug trace a cardiod?

Everytime I go to grab a mug I see a shape in the bottom, which looks oddly like the cardioid. Is there some mathematical/physics answer to this phenomenon?


Finding the radius of incircle of $\triangle ABC$ where each of three other circles is mutually tangent to two sides of the triangle respectively

In acute angled $\triangle ABC$, considering a portion of side $BC$ as diameter, a circle is drawn whose radius is 18 units and it touches two sides $AB$ and $AC$ respectively. Similarly, considering a portion of sides $AC$ and $AB$ as diameters, two other circles are drawn whose radii are $6$ and $9$ units respectively. What is the radius of the incircle of $\triangle ABC$?     Consider the diagram above. Here, $FL = 18, EI = 6$ and $DK = 9$ and yellow marked circle is the incircle.  I couldn't find a way out to determine each side of the triangle $ABC$. I researched with the diagram in Geogebra for a while, connecting or drawing some important segments but nothing seemed to me so much effective or useful.  Is there any formula by which I can get directly the radius of incircle with the given condition? Thanks in advance.  SOURCE: Bangladesh Math Olympiad


I downloaded an .obj-file, and imported it into Blender 2.81, and I get some smooth surfaces - all is good, but I would like to see the flat version, so I go to Object Mode, Object, Shade Flatten - all is still fine.  I then find out I have a lot of duplicates, which I remove from Edit Mode, Mesh, Clean Up, By Distance.  If I then try to smooth it again, I get these weird blobs:   I tried editing the Object Data Property for Normals, Auto Smooth, but that makes no difference from 0 to 180 degrees.  When I click on the individual vertices it looks fine by showing the nearby vertices they are connected to.  What have I done wrong?


Is it possible to launch an application inside a Virtual Machine?

I am currently running Ubuntu 14.04 as my main OS, with a Windows 7 installation inside VirtualBox for things I just can't easily do on Ubuntu (like running Microsoft Office). Now I am wondering if there are ways to send commands from your host to your virtual machine to, for example, launch Microsoft Word.  Does someone know if this is even possible? If it is, I could use it to integrate the Virtual Machine more closely in Ubuntu by making some pretty desktop shortcuts to office for example!


Prove that $x^{2} \equiv -1 \pmod p$ has no solutions if prime $p \equiv 3 \pmod 4$.

Assume: $p$ is a prime that satisfies $p \equiv 3 \pmod 4$  Show: $x^{2} \equiv -1 \pmod p$ has no solutions $\forall x \in \mathbb{Z}$.  I know this problem has something to do with Fermat's Little Theorem, that $a^{p-1} \equiv 1\pmod p$. I tried to do a proof by contradiction, assuming the conclusion and showing some contradiction but just ran into a wall. Any help would be greatly appreciated.


How do I capitalize the first letter of each word in an array of strings? Writing a `for ... of ... loop ` (ES6)

const days = ['sunday', 'monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday'];  for (const day of days) {   console.log(day); }     I need to print the days with the first letters capitalized...


How to colorize an image as in the example?

I have seen such an effect being used in many places however I haven't figured out how to replicate it via Photoshop.  I have tried desaturating the image, placing it under a layer of solid colour and then lowering the opacity of the colour. I have also tried a couple of blend modes, to no avail. The effect is nowhere near the same.  Can someone please tell me the effect used on these images?


Can I add an autoincrement field to a Google Spreadsheet based on a Google Form?

Is it possible in Google Forms to give a unique value to each row it inserts into the spreadsheet as well as the timestamp?


TimeSpan timeSpan = new TimeSpan(124432492); // I am giving ticks here. string duration = timeSpan.ToString("HH:mm:ss:fff");   Conversion gives      Input string was not in a correct format.    Something is not right and i can't see it.  Any ideas?


How did Ramanujan calculate these interesting values for $e$?

While reading a mini-bio about Ramanujan, there was an equation that I found somewhat intriguing:$$e^{\pi\sqrt{58}}=24591257751.99999982\ldots\tag1$$ This is interesting in the way that $e^{\pi\sqrt{58}}$ is very close to $24591257752$, and how Ramanujan managed to calculate such a large number back when computers didn't exist! Others include \begin{equation}35\sqrt{\pi}\ln 2=42.9999986\ldots\tag2\\ 51\ln(36\pi)-2e^\pi+\sqrt[4]{21}=196.99999991695\ldots\\ e^{{\frac \pi 4\sqrt{102}}}=800\sqrt3+196\sqrt{51}\\\vdots\end{equation} And there are much more. So, I'm wondering:  Main Question: Is there some sort of formula, trick or follow-through that you can use that enables you to calculate other fascinating $e$ equations that are very close to an integer? Note: I'm not the best at mathematics. In fact, I haven't even started Calculus yet. I would love it if the answer also had a detailed description of how you solved this.


Let $\omega$ the (n-1) form on $\mathbb{R}^n$ $$\omega=\sum_{j=1}^{n}(-1)^{j-1}x_{j}dx_{1}\wedge\cdots\wedge \hat{dx_{j}}\wedge\cdots dx_{n}$$ Show that the restriction of $\omega$ to $S^{n-1}$ in precisely the volume for this sphere.  What I did was: $\omega$ never vanish on the sphere, because, defining $\sigma\in \Omega^{n-1}(S)$ for $$\sigma_{p}(v_{1},...,v_{n-1})=det(p,v_{1},...,v_{n-1})$$ and $i:S^{n-1}\rightarrow \mathbb{R}^{n}$ the inclusion function, then $\omega=i^{\ast}(\sigma)$ then $\omega\not=0$ and therfore is a volume form.   How proof that $\omega$ is the volume form?   The first thing that comes to mind is show that $\int_{S^{n-1}}\omega=Vol(S^{n-1})$ but I have serious problems with the definition, I think that is to much.   How see that $\omega$ is invariant on $\mathbb{R}^{n}$ under action of $O(n)$


Is it possible to make my players really care about NPCs?

What I'd really like to do, and don't think I have right tools/approach, is to emotionally manipulate my players into making sub-optimal  - even bad - decisions using the NPCs I present them with.  "I can't believe John did that to Jill, let's get him!" "Little Billy is going to die unless we do X" "I know she said she'd destroyed that town but c'mon, it's Claire, she's our friend..."  Making NPCs stand out and memorable isn't the point here, I want the players to really care about them.   Can this be done?  I've read the brilliant answers  and  but want to know if there are any near-guaranteed methods for achieving this, specific examples and the like.  Thanks.


Voltage difference vs number of electrons

When we say a battery has voltage difference, can we deduce the difference in the number of electrons at the two terminals? What does it mean to say there exists a voltage difference?


Search ArrayList with For Loop NullPointerException

I keep receiving this error but I cannot see any logical errors in my code.     Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException   private double getValueOrDefault(String symbol, double defaultValue) {     double value = getValue(symbol);      if (value != -1)         return value;     else         return defaultValue; }  public void createStocks() {     // try get stock realtime values     stocks.add(new TechStock("BB", 30.3));     stocks.add(new TechStock("GOOG", getValueOrDefault("GOOG", 5.8)));     stocks.add(new TechStock("AMZN", getValueOrDefault("AMZN", 6.3)));     stocks.add(new FinanceStock("GLNG", getValueOrDefault("GLNG", 121))); }  public static double getValue(String symbol) {     // read data     try {         URL url = new URL(API_URL.replace("XXX", symbol));         Scanner s = new Scanner(url.openStream());          // find price         while (s.hasNextLine()) {            String line = s.nextLine();             if (line.startsWith("\"price\"")) {                // split shenanigans                String[] f = line.split("\"");                return Double.parseDouble(f[3]);            }         }         // if we reached here: the stock is invalid        return -1;     } catch (Exception ex) {        ex.printStackTrace();     }     return -1; }   public class StockFrame extends Frame  {     private int amount;     private Portfolio portfolio;     private ArrayList <StockMarket> stocks = new ArrayList<StockMarket>();        private TextArea stockDetails;     private TextField purchaseCode;     private boolean found = false;  private int locateStock() {     for(int i = 0; i<stocks.size(); i++) {         if(stocks.get(i).getCode().equals(purchaseCode.getText())) {              return i;         }    }    return -1; }  private void a() {  int position = locateStock(); if(position != -1){     StockMarket bs = stocks.get(position); ..... }   I tried changing I to 1 but I still receive the NullPointerException. The error seems to be located at the int position = locateStock(); but I am unsure.


Failed to create folder while install matlab R2015a on ubuntu 14.04 LTC

error message Failed to create folder (/usr/local/MATLAB/MATLAB_Production_Server/R2015a/).  and also when i creat these folders this msg appear  Unable to create the destination folder /usr/local/MATLAB/MATLAB_Production_Server/R2015a/.  Please choose another destination folder.


A simple graph with $n$ vertices and more than $\frac{3(n-1)}2$ edges is given. Prove that two different vertices $x$, $y$ of $G$ can be found, such that there exist $3$ non-intersecting each other paths connecting $x$ and $y$.   Two paths connecting $x$ and $y$ are non-intersecting if they do not share a vertex different from $x$ and $y$. Simple means no loops or multiple edges between vertices Not sure about how to solve this problem. I tried to use induction.


Improper integral: $\int_1^{+\infty}\frac{\mathrm dx}{x(x+1)(x+2)\cdots(x+n)}$

I've tried many ways, but it seems that it didn't work: $$    \int_1^{+\infty}\frac{\mathrm dx}{x(x+1)(x+2)\cdots(x+n)}      = \int_0^1\frac{x^{n-1}}{(x+1)(2x+1)\cdots(nx+1)}\mathrm dx      = \cdots $$ Any help would be appreciated!


Particles in render not matching preview (Blender 2.8)

I have implemented two identical particle emitters back to back so that i get a looping animation depicting low-poly smoke. I use a blend texture to resize the particles as they go through their life. I baked all dynamics using the button in the cache section of the simulation and everything loops nicely in the viewport.  The problem is that, although everything shows up correctly in the viewport, the particle system behaves weirdly for the last 60 frames or so of the animation when rendered. The smoke particles spawn more quickly and go through the resizing procedure dictated by the texture super fast, leaving the space empty.    As you can see the cursor is at frame 280 in the screenshot and both solid and rendered view show the smoke particles. When I render the image though, the result is this:    I have tried following solutions without success: - Use Cycles instead of Eevee - Have the particles emit only in positive frame ranges as opposed to emitting from -300 to 300 - Following this tutorial for baking particles:  - restarting blender    .blend file with only the particle system:


Ordering by the order of values in a SQL IN() clause

I am wondering if there is away (possibly a better way) to order by the order of the values in an IN() clause.  The problem is that I have 2 queries, one that gets all of the IDs and the second that retrieves all the information. The first creates the order of the IDs which I want the second to order by. The IDs are put in an IN() clause in the correct order.  So it'd be something like (extremely simplified):  SELECT id FROM table1 WHERE ... ORDER BY display_order, name  SELECT name, description, ... WHERE id IN ([id's from first])   The issue is that the second query does not return the results in the same order that the IDs are put into the IN() clause.  One solution I have found is to put all of the IDs into a temp table with an auto incrementing field which is then joined into the second query.  Is there a better option?  Note: As the first query is run "by the user" and the second is run in a background process, there is no way to combine the 2 into 1 query using sub queries.  I am using MySQL, but I'm thinking it might be useful to have it noted what options there are for other DBs as well.


I'm having trouble showing procedural textures (Checker Texture in particular) in 3d View. I can see it in render, but neither Material/Texture/Solid viewport shading helps to see in 3D :(  is a screenshot with my issue. Please help.


Prove that any element of a group can be expressed as a product of elements in a subset.

If X is a subset (not a subgroup)  of a finite group G, and X contains more than half of the elements in G. Show that for each element $g \in G \ ; g=ab \ ; a,b \in X$ My intuition is if you treat X like a coset, $xX$ it will generate G as you vary x. I'm not sure how to show that though. A hint given was that no theory is required.


Examples and Counterexamples of Relations which Satisfy Certain Properties

Definition: Given a set $X$, a relation $R$ on $X$ is any subset of $X\times X$.  A relation $R$ on $X$ is said to be  reflexive if $(x,x) \in R$ for all $x \in X$, irreflexive if $(x,x) \not\in R$ for all $x \in X$, transitive if $(x,y) \in R$ and $(y,z) \in R$ implies that $(x,z)\in R$, intransitive (or antitransitive) if $(x,y) \in R$ and $(y,z) \in R$ implies that $(x,z)\not\in R$, symmetric if $(x,y) \in R$ implies that $(y,x) \in R$, antisymmetric if $(x,y) \in R$ and $(y,x) \in R$ implies that $x=y$.   Given any combination of the properties listed above, is there a nontrivial (i.e. nonempty) relation which satisfies that combination of properties?


How can one check in one's program if it is a service process that was started by systemd?

Is there a documented way to check, from within the code of the program running as the service itself, that it has been started by systemd (as opposed to being started from within an interactive login session, from cron, etc.)?  My current solution is to define an environment variable in the .service unit (Environment=...) and check for its existence in my code.  But there may be something directly available.


What is Stack Exchange's stance on users that move Playground insults elsewhere?

Yesterday, on Stack Overflow, I gave some constructive criticism to a user, when I downvoted (how foolish of me, I know!). Unfortunately as some users do, my point was taking poorly; in this case it was advice that a WHILE loop in T-SQL would perform awfully vs a set-based method and provided a couple of fiddles to do so (which evidenced a huge performance difference).  After a few comments I disengaged as the other user wasn't going to listen and also started to throw play ground insults out; I flagged the comments, moved on.  Unfortunately, they decided to instead start posting comments on my website (which he would have found via my profile). One of these said "Stupid Prostitute" in Turkish, another was the "Right Clicker"  insult they were throwing at me in the answers comments, and also the swear word for "poo".  Now, these don't offend me, this is just a small troll on the internet, but the behaviour is clearly not something that any SE community would want. They clearly aren't going to contribute constructively to any communities.  I realise that I "technically" have no proof, however, the fact that they hurled the same insult is a good indicator.   Does SE have an opinion on such user behaviour, even though they've moved off site?


This is a purely academic question, because this will never happen.  If a PID is stored as type pid_t, and not some arbitrary-precision type, then there is a limit to the number of PIDs that can exist at one time. Is there a defined behavior for when PIDs overflow?  Will the 65536th process kill /sbin/init and create a kernel panic? Or is there some safety measure in place?


Wrapping code (listings, verbatim, or other method) inside a newcommand

For some teaching I've been doing, I'd like to have code from two different languages side-by-side.  To do so, I hacked together a newcommand which uses a tabular environment to arrange two verb environments, but the problems are myriad:   Indentation can only be accomplished by changing spaces to ~'s Any math symbols have to be escaped with \, which requires knowing which ones to escape and which ones not to (can't escape the <'s for instance, otherwise it complains) The <- assignment operator gets changed into an upside down !- when compiled.   The listings environment doesn't work either.  Error message is:  Runaway argument? ! Forbidden control sequence found while scanning use of \lst@next. <inserted text>                  \par  l.23 \codeListing{x <- y}{f(g(x))}   Here's some code to reproduce the problem:  \documentclass[english]{article} \usepackage[latin9]{inputenc} \usepackage{geometry} \begin{document}  \newcommand{\codeListing}[2]{ \begin{tabular}{p{8cm} p{8cm}} \begin{lstlisting} #1 \end{lstlisting} & #2\tabularnewline \end{tabular} }  \section{verbatim test} \begin{verbatim} logLik <- function(x) {    y <<- x^2+2   return(sum(sqrt(y+7))) } \end{verbatim}  \section{codeListing test} \codeListing{}{ logLik <- function(x) \{   ~~y <<- x\^2+2  ~~return(sum(sqrt(y+7)))  \}  }  \end{document}   Is there any way to make a newcommand wrap parameter-passed code?  It doesn't have to be keyword-highlighted or do any of the other tricks that the fancier packages do; it just has to preserve whitespace and no interpret code as latex commands.


two finger scrolling causing a right click (ubuntu 15.04)

When I use two finger scrolling, and then remove my fingers from the touchpad, it is causing a right click at the end.  For example, I'll be scrolling down a wikipedia page.  As soon as I am done scrolling, the right click menu opens up.  It is so frustrating.  Any way to stop this?  EDIT:  I've already set TapButton2=0, but it doesn't solve the problem.  Output of $ xinput --list-props "DLL0665:01 06CB:76AD UNKNOWN":  xinput --list-props "DLL0665:01 06CB:76AD UNKNOWN" Device 'DLL0665:01 06CB:76AD UNKNOWN':     Device Enabled (139):   1     Coordinate Transformation Matrix (141): 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000     Device Accel Profile (270): 1     Device Accel Constant Deceleration (271):   2.500000     Device Accel Adaptive Deceleration (272):   1.000000     Device Accel Velocity Scaling (273):    12.500000     Synaptics Edges (294):  48, 1168, 36, 644     Synaptics Finger (295): 25, 30, 0     Synaptics Tap Time (296):   180     Synaptics Tap Move (297):   61     Synaptics Tap Durations (298):  180, 180, 100     Synaptics ClickPad (299):   1     Synaptics Middle Button Timeout (300):  0     Synaptics Two-Finger Pressure (301):    282     Synaptics Two-Finger Width (302):   7     Synaptics Scrolling Distance (303): -27, -27     Synaptics Edge Scrolling (304): 0, 0, 0     Synaptics Two-Finger Scrolling (305):   1, 1     Synaptics Move Speed (306): 1.000000, 1.750000, 0.143575, 0.000000     Synaptics Off (307):    2     Synaptics Locked Drags (308):   0     Synaptics Locked Drags Timeout (309):   5000     Synaptics Tap Action (310): 2, 3, 0, 0, 1, 3, 0     Synaptics Click Action (311):   1, 3, 0     Synaptics Circular Scrolling (312): 0     Synaptics Circular Scrolling Distance (313):    0.100000     Synaptics Circular Scrolling Trigger (314): 0     Synaptics Circular Pad (315):   0     Synaptics Palm Detection (316): 0     Synaptics Palm Dimensions (317):    10, 200     Synaptics Coasting Speed (318): 20.000000, 50.000000     Synaptics Pressure Motion (319):    30, 160     Synaptics Pressure Motion Factor (320): 1.000000, 1.000000     Synaptics Resolution Detect (321):  1     Synaptics Grab Event Device (322):  0     Synaptics Gestures (323):   1     Synaptics Capabilities (324):   1, 0, 0, 1, 1, 0, 0     Synaptics Pad Resolution (325): 12, 12     Synaptics Area (326):   0, 0, 0, 0     Synaptics Soft Button Areas (327):  608, 0, 557, 0, 0, 0, 0, 0     Synaptics Noise Cancellation (328): 6, 6     Device Product ID (257):    1739, 30381     Device Node (258):  "/dev/input/event7"


Is it possible to tell latexmk to execute mpost paper.mp after each compilation run if paper.mp has changed?  I tried to create a custom latexmkrc rule:  add_cus_dep('mp', '1', 0, 'mpost'); sub mpost {  system "mpost $name" ;  popd();  return 0; }   But this does not seem to work


I just bought new 128GB SSD and I want to install ubuntu on it. Is it possible to instal ubuntu on plain disk with no OS ? I used rufus to put ISO picture to my flash drive.


Upgrading Ubuntu from 12.04 to 12.10 broke my system, completely.

First, I hope that this is not a duplicate, because I found my question quite strange and unique, and I don't have any idea with it.  These days I heard of the new Ubuntu release, version 13.10 and I am quite excited. I have been stuck in 12.04 for such a long time and it's time for a good upgrade. So...I ran update-manager -d and tried to go up to 12.10. (I decided to go up one by one) It took a very long time to download all the required kernel and packages...and soon installing...and some questions asking me if I want to replace the old config files. I did some tweaking with that system before (changing startup applications, TMPFS, zram-enabler, etc) and I thought that it will cause a real crash if I keep these config files. So, I replaced all of them but it goes too slow and it's time I've to go to school. I asked my grandfather if he could help me to click all the 'Replace' buttons for me and shut down the computer after the upgrade finished.  When I was back from school, he told me that he accidentally clicked 'Keep' for the last popup box, and my computer can't function now. The grub menu is still there (made it appear by using the SHIFT key trick), and the splash screen is still visible, and I hope that the login screen is still there, or at least the tty so that I can still do a rescue, but nothing worked. CTRL+ALT+F1 does nothing, and I am sure that the monitor is still functioning.  So what can I do now?


Recursive CTE to get Grandparent, parent, children

I have a data structure that relies on a parent/child model. The top level parent can have multiple children where they can also be parents. Here's an example of how things can look in the tree: 900107     --> 200237             --> 100112             --> 100113     --> 200238             --> 100114             --> 100115                 --> 100120                     --> 100001                     --> 100002 --> 200239 --> 200501 --> 300112 --> 400987 --> 444444  In this example, 900107, 200237, 200238, 100120 are all parents where 900107 is going to be our grandparent. Here's how it looks in the table: ParentPart   Component 900107       200237 900107       200238 900107       200239 900107       200501 900107       300112 900107       400987 900107       444444 200237       100112 200237       100113 200238       100114 200238       100115 100120       100001 100120       100002      I have a recursive CTE that will get me all of the parents and children, but not the "grandkids" or "great grandkids" if they exist. Here's my CTE: CREATE TABLE #Hierarchy ( ParentPart NVARCHAR(6), Component NVARCHAR(6))  INSERT INTO #Hierarchy (ParentPart, Component) VALUES ('900107', '200237'),        ('900107', '200238'),        ('900107', '200239'),        ('900107', '200501'),        ('900107', '300112'),        ('900107', '400987'),        ('900107', '444444'),        ('200237', '100112'),        ('200237', '100113'),        ('200238', '100114'),        ('200238', '100115'),        ('100115', '100120'),        ('100120', '100001'),        ('100120', '100002')   ;WITH hier AS ( SELECT ParentPart AS MainPart, ParentPart, Component   FROM #Hierarchy UNION ALL SELECT hier.MainPart, p.ParentPart, p.Component   FROM hier    JOIN #Hierarchy AS p     ON p.Component = hier.ParentPart )  SELECT ParentPart      , Component   FROM hier     ORDER BY ParentPart, Component  OPTION (MAXRECURSION 0)  This works for the most part....I can get this if I use one ParentPart. We have thousands of ParentParts and we'd need to know who the grandparent is. Ideally we'd want the output to look like this where the parent part is the grandparent and every child and grand child is in the component field ParentPart    Component 900107        200237 900107        200238 900107        200239 900107        200501 900107        300112 900107        400987 900107        444444 900107        100120 900107        100112 900107        100113 900107        100114 900107        100115 900107        100001 900107        100002  What would be the best way to do this?


How can I read my epub books in Google Books for Android?

Has anyone been able to take and place an epub book inside the Google Books app or know how to do it?


What can I do if my allowed duration of stay in the US (based on the passport stamp) is too short?

Completely paranoid about my last experience with US Immigrafion. Leaving the Bahamas(my home) I had a very interesting encounter with an immigration officer. I approached the counter and was asked the usual questions, I was then asked when was the last time I was in the U.S. and I politely told the officer that I didn't remember the exact dates as it was over 6 months ago and that she had my passport so she can verify. I guess that was suspicious to her since it escalated into a bigger ordeal.   Completely unaware of the severity of no phone policy as I've never had a difficult experience when traveling to the U.S. I attempted to call my mother to get the exact dates and the lady completely lost it and told me to put my phone away which I did. She then took my passport and asked me to go into this small white room, obviously some sort of secondary questioning/screening. I waited for almost 30 minutes until she finally arrived and told me "unless you want your visa denied you better have some answers".    I was in complete disbelief that she refused to look in my passport and see the dates. She then asked me to approach the counter which I did and I apologized to her for not being able to remember the exact dates as I had literally just found out my dad has stage 4 cancer and my mind was clustered and that I'd never thought to memorize the dates as I know they are stamped in the passport and the officers usually verify themselves. I then tried to remember the dates and I told her I was in Vegas from August until September and then she brought up the fact that I was in Charlotte and Houston to which I let her know they were simply layovers and I never left the airports.    I made an honest mistake of genuinely forgetting a weekend trip to Atlanta in November which she brought to my attention and I apologized for it. She then proceeds to thoroughly check my bags and upon finding nothing suspicious, takes my passport and returns it with a stamp that says I must return on or before April 29th, extremely puzzled I reminded her that my return flight was for May 5th and she said that means you need to change your ticket and be back by the date stamped in my passport.   I've always had my passport stamped with a maximum of 6 months admittance but this time it was stamped for a little under a month as my departure was April 8th. I'm extremely worried about whether or not this will affect my future travels as my mom, niece and I have already planned to spend the entire summer with my sister in Vegas.   Will this experience affect my future travels and not being admitted for the usual 6 months?


Prove a group of order 12 must have an element of order 2

Question: Prove that a group of order 12 must have an element of order 2.   I believe I've made great stride in my attempt.  By corollary to Lagrange's theorem, the order of any element $g$ in a group $G$ divides the order of a group $G$.  So, $ \left | g \right | \mid \left | G \right |$. Hence, the possible orders of $g$ is $\left | g \right |=\left \{ 1,2,3,4,6,12 \right \}$  Suppose $\left | g \right |=12.$ Then, $g^{12}=\left ( g^{6} \right )^{2}=e.$ So, $\left | g^{6} \right |=2$  Using the above same idea and applying it to $\left | g \right |=\left \{ 6,4,2 \right \}$ and $\left | g \right |=1,$ we see that these elements g have order 2.  However, for $\left | g^{3} \right |$, the group $G$ does not require an element of order 2.  How can I take this attempt further?  Thanks in advance. Useful hints would be helpful.


How did Enrico Fermi calculate the classical Fermi Problem?

From Wikipedia: Fermi was known for his ability to make good approximate calculations with little or no actual data, hence the name. One example is his estimate of the strength of the atomic bomb detonated at the Trinity test, based on the distance travelled by pieces of paper dropped from his hand during the blast. Fermi's estimate of 10 kilotons of TNT was remarkably close to the now-accepted value of around 20 kilotons, a difference of less than one order of magnitude.  I have not been able to find any references explaining how he made this calculation. Please provide a reference or an example calculation.  See also:


Can graphs in GAP be obtained as a visual output

In GAP when we draw a cayley graph of a group using "CayleyGraph" command we get a list. Is there a way to visualize that cayley graph like a figure?  Or else is there any other software that has the ability to visualize?


How to get the curvy node connector lines in the 2.80+ interface?

This is a question about blender’s interface and the way it looks, with no functional difference. I have windows 10, and when switching from blender 2.79 to 2.80 regardless of the machine, the curvy node connector lines for the shader and compositor became straight and boring. However, I keep seeing screenshots on Stack Exchange of users that obviously have 2.80+, but they have the nice curvy connector lines. How is this done?


How is the title of page of a question asked is made? Eg, . The title of page starts with javascript. Does it mean that when asking a question, mandatory at least one tag is required which here is javascript. And therefore, in the list of tags on the question, javascript comes first. And therefore, title of page of this question starts with javascript.    Title of page here refers to <title> in the html code.


What's a word for someone who is constantly asking for same thing?

Hi I'm looking for a word for someone who is constantly asking for something and keeps wanting updates about it. The closest words I can think of is pushy and, to a lesser extent, annoying. But clearly these words don't directly mean what I intend.


What are Unity's keyboard and mouse shortcuts?

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


shutdown now kills everything and then powers down the machine. halt kills everything and then... there is no step 2. It will sit, running but not doing anything, until people stop arguing over whether Emacs or Vim is better.  Why doesn't halt actually power down the machine? Is there a historical reason?


Prime elements in the ring of integers adjoin a complex number.

Let $R=\mathbb Z[e^{i\pi/3}]=\{a+be^{i\pi/3}\mid a,b\in \mathbb Z\}\subseteq \mathbb C$ (a) Show that $R$ is a Euclidean domain using the Euclidean norm $N(u)=|u|^2$. (b) Show that if $p$ is a prime number in $\mathbb Z^+$ and $x,y\in \mathbb Z$ with $x^2+xy+y^2=p$, then $x+ye^{i\pi/3}$ is prime in $R$. (c) Show that if $p$ is a prime number in $\mathbb Z^+$ and $p\neq x^2+xy+y^2$ for any $x,y\in\mathbb Z$, then $p$ is prime in $R$.  I don't know how to show that the division algorithm holds in $R$. For b, I can show that $N(u) = p  = x + xy + y^2$ by simply expanding out the norm of an arbitrary element of $R$. I also remember my professor mentioning that in a Euclidean domain, if the norm of an element is prime in the integers, then the element itself is prime in the ring. But how would I prove this? Also, am I correct in saying that if the norm is a prime number, then the element itself cannot be a unit, as being a unit would imply that there exists $v$ in $R$ such that  $uv = 1$. But $uv = 1$ implies $N(uv) = 1$, which is impossible since $N(uv) = N(u) N(v)$ for all $u,v$ in $R$, and $N(u) = p$, which implies $N(v) = 1/p $, and as $p >=2$, $N(v) < 1$, impossible. Lastly, I would appreciate a hint for part c. Edit : The ring in my question is different from the ring in the other one. Also, the questions themselves are different too. Please unmark it as a duplicate.


Is this an equivalent formulation of "surjective" resp. "epimorphism"?

An $A$-element $x$ of $X$, written $x\in_A X$, is a map $x:A\to X$. If $f$ is a map with domain $X$, and $x\in_A X$ is an element, we write $f(x)$ to denote the composite of $f$ and $x$.  Now say that a map $f:X\to Y$ is cool if $$\forall A\quad \forall x, x'\in_A X\quad:\quad f(x) = f(x')\implies x = x'.$$  In the category of sets, a map is cool if and only if it is injective! In an arbitrary category, a map is cool if and only it is an monomorphism!  Call a map $f : X\to Y$ fresh if for all $A$, and for all $y\in_A Y$, there is an $x\in_A X$ such that $f(x) = y$. It would now be quite nice if, in the category of sets, a map is fresh if and only if it is surjective. 1. Is this true? 2. Also, in an arbitrary category, is a map fresh if and only if it is an ?


Prove that $\int_0^\pi \ln(1+\alpha \cos x)\, dx= \pi \ln\left(\frac{1+\sqrt{1-\alpha^2}}{2}\right)$

Prove that   $$\int_0^\pi \ln(1+\alpha \cos x)\, dx= \pi \ln\left(\frac{1+\sqrt{1-\alpha^2}}{2}\right).$$  This question is under the Leibnitz's Rule section of my book, but I'm not sure if you're supposed to use it here. Using it simply gives the derivative of $\ln(1+\alpha \cos x)$ with respect to $\alpha$, which isn't really useful. Can anyone help?  Edit: So I've taken some suggestions from the comments and worked out the question. I was able to get pretty close to the answer, but I'm unable to get the answer exactly. I've skipped a couple of steps here, but do let me know if I did something wrong.  $$I(a)=\int_0^\pi \ln(1+\alpha \cos x)\, dx$$  $$I'(a)=\int^\pi_0\frac{cosx}{1+acosx}dx$$  $$I'(a)=\frac{1}{a}\int^\pi_0\frac{acosx+1-1}{1+acosx}dx$$  $$I'(a)=\frac{1}{a}[\pi-\int^\pi_0\frac{1}{1+acosx}dx]$$  By the Tangent Half-Angle Substitution,  $$I'(a)=\frac{1}{a}[\pi-\int^\pi_0\frac{1}{1+acosx}dx]$$  $$I'(a)=\pi[\frac{1}{a}-\frac{1}{\sqrt {1-a^2}}]$$  $$I(a)=\int\pi[\frac{1}{a}-\frac{1}{\sqrt {1-a^2}}]da$$  Using normal integrating techniques,  $$I(a)=\pi[ln\sqrt{1-a^2}+1]$$  Note that I can't get the last term, $\pi ln2$. If I can get this last term, I can get the answer. Now, I'm wondering if it is because it is a constant term, and thus when I have differentiated by $a$, in the beginning, the information in that term is lost. Can someone help me continue or point out where I went wrong?


Is there any difference between charming objects (i.e. "adding or changing certain properties of an object") and enchanting them?  Is charming/enchantment used in creation of magical objects?   Do runes play any part in this?   I'd prefer canon answer if possible.


WiFi flush list of available networks (WIN10)

I have a laptop with win 10 I have received a new wireless modem (Zyxel WMG8924-B10A)  While having comp1 connected via wifi, I used comp2 to update settings on the router (update name and pw).  Now comp1 can only see the old name of the network on the list of available networks. And it can no longer connect to the network.  I have tried several things to update the list - including a system restore on the computer... what to do?  It seems that windows keeps a list of available wireless connections that cannot be resat (I'm guessing the name is stored with the mcac-address)  I have tried to:   Delete the connection in control panel Remove it manually with cmd and regedit ()netsh wlan delete profile name=”oldprofile“delete profile from: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Import new wifi profile from other computer Complete system restore


I want to rotate my model and I have X and Y rotations. Here is my code:  D3DXQUATERNION q, qrotation;  D3DXQuaternionRotationAxis(&q, &D3DXVECTOR3(1.0f, 0.0f, 0.0f), m_matrixRotX*0.0174532925f); qrotation = q;  D3DXQuaternionRotationAxis(&q, &D3DXVECTOR3(0.0f, 1.0f, 0.0f), m_matrixRotY*0.0174532925f); qrotation *= q;  D3DXMatrixRotationQuaternion(&worldMatrix, &qrotation);   But I get the same gimbal lock. What is the problem?   EDIT 1: OK, but how can I rotate my object if I have X Y and Z rotations?  EDIT 2: Here is all my code:   m_matrixRotY += (float)m_mouseStateX; m_matrixRotX += (float)m_mouseStateY; if (m_matrixRotY >= 360.0f)m_matrixRotY = 0.0f; if (m_matrixRotX >= 360.0f)m_matrixRotX = 0.0f;  D3DXQuaternionRotationYawPitchRoll(&qrotation, m_matrixRotY*0.0174532925f, m_matrixRotX*0.0174532925f, 0.0f);  D3DXMatrixRotationQuaternion(&worldMatrix, &qrotation);   I want to rotate my object in world static XYZ axis (world orientation not   local orientation). Each frame I get mouse x y states and add them to total rotation. Is it wrong that I am counting total rotation and then creating the quaternion from it?  NOTE: m_mouseStateX = current_mouse_state - previous_mouse_state


Prove language of $0^n1^m$ is irregular for coprime $n,m$.

I need to prove that the language of $0^n1^m$ is irregular if $n$ and $m$ are coprime. (Or to disprove that)  My attempt at this was to use the pumping lemma, and I've gotten $0^{n+(k-1)i}1^m$ after pumping, where $0<i\leq n$. If I'm correct, I only need to prove that $$\forall n,m : gcd(n,m)=1 \ \ \forall i\in\mathbb Z: 0<i\leq n \ \ \exists k\in\mathbb Z : gcd(n+(k-1)i, m)\not=1$$ However, I do not follow how this can be proved.


Formal adoption of Pro-forma comments script into SE engine proper

My  script has now gained quite a following (and it - allegedly - just got bust by upgrading to jQuery 1.7.1). This is a personal request to the team to consider adopting it.   Not that I don't wish to keep on maintaining it, but the next step (allowing users to define one global set of comments to be used across all their sites*) is pretty awkward for me to implement "from the outside", but would be comparatively trivial for the team (I believe).  Goes off to fix script...  * Note: I have a beta half-version of this; it requires   userscripts, and allows you to push/pull between "local" (site-specific) and "global" storage. And even if I get the global sharing 'properly' working, it would still only be for a given machine.


Identifying order of a group from three pieces of information about its' subgroups

Suppose $G$ is a cyclic group that has exactly three different subgroups: The trivial one, a subgroup of order $7$ and $G$ itself. What is the order of $G$?   What is the idea here?


My left knee will only bend 90 degrees. This makes it impossible to ride my bike as the knee needs to bend more than this on the upstroke. Is there a way to shorten the stroke circle so the knee will not have to bend so much? Will this make the motion too unbalanced?


Evaluate definite interval of normal distribution

I know that an easy to handle formula for the CDF of a normal distribution is somewhat missing, due to the complicated error function in it.  However, I wonder if there is a a nice formula for $N(c_{-} \leq x < c_{+}| \mu, \sigma^2)$. Or what the "state of the art" approximation for this problem might be.


How to reset my lost admin password on 14.04

I have read online and I can only find the method where you hold shift just after powering on the system.  I have followed instructions and I have done them. Hut when it tells me to type in a NEW UNIX PASSWORD it doesn't let me type in anything.  Suggestions?


How can I “Delete All” from Inbox mail folder?

Is there a way to mass delete compiled list of emails on iOS devices (like can be done in os x)? I only know two options: select individually & swipe "left" and from bottom select "edit", then selecting each message individually. I tried solution described in similar question without success (described as iOS 7).