When I ssh between different pcs I can omit my username (tom) and just type   ssh pc_name   instead of   ssh tom@pc_name   I like this feature, and have got into the habit of using it.  Unfortunately, on one of my computers I went for the user name tommy.  Everytime I connect to this computer I forget to write tommy@creative_pc and wonder why my password doesn't work.  Is there a way to tell ssh what user name to use when the username is omitted?  Edit: Just found the following question that is similar:   It didn't come up on my initial search.

I use ssh on a variety of machines, mainly linux. Accounts on these machines vary in naming scheme: if my name is First Last, then I have accounts: first, flast, last_f, lastf, and sometimes I need to log in as root. For each machine I use, I would like the openssh client to know which account to use when I don't specify on the command line.  So the question is: How do I make ssh server Do The Right Thing when a username is not specified?


I'm searching for an example proof of the above formula as distribution over and in basic proportional modal logic, I.e. in some of the standard systems K, S4 or S5.

Is it possible to prove the distribution axiom of modal logic? I have proven all the conclusions of propositional modal logic using this axiom, the definitions of the four standard modal operators, and the postulate that some contingent proposition is true. I wanted to know if it was possible to prove this distribution proposition (also called Kripke property):   $$ \square (p \rightarrow q) \rightarrow  (\square p \rightarrow \square q)$$ It basically distributes the necessity operator over the components of every necessary conditional proposition. Most modal logic books accept this as an axiom in addition to others, but I want the fewest axioms possible as I have already reduced them to the distribution axiom, modal semantics and definitions, and (some contingent proposition is true). Is there any further reduction possible by proving the distribution axiom. And if so please provide a natural deduction proof of this distribution statement from previous principles in modal logic.


When you use the explorer in Windows and start typing some letters, the explorer automatically focuses files that starts with the same letters you typed. When I try to do this in Ubuntu's file manager (Nautilus), it starts searching overall for files instead of focusing them directly.  How can I change this to behave like Windows' explorer?

Until now I was using a "traditional" version of Nautilus: that that comes with Ubuntu 10.10. Now I'm using 3.6.3, included with Ubuntu 13.04 (most likely any recent version is equivalent for the scope of my question, anyway).  One major difference between the two is the search-as-you-type behavior: in classic versions of Nautilus, when you typed an input, the file with the closest alphabetical match would become the selected one, the eligible files/folders being restricted to the current directory.  The new behavior is to perform an optionally-global search instead.  Can one configure Nautilus to provide the previous functionality ?


Suppose we have two objects:  var a = { foo: { bar: 1 } } var b = { foo: { bar: 2 } }   If I set the object b to a (a = b), I expect that a takes the value of b, not the reference. So, in this case:  a = b a.foo.bar = 3 console.log(b.foo.bar);   I expect that the last console.log shows 2, not 3. Why? Just because I changed a property related to a, not to b.   I can't understand why JavaScript also changes the b property and how to avoid this unexpected behaviour.  How to avoid this behaviour? Should I assign object to variables in a different way?

The primitive types (number, string, etc.) are passed by value, but objects are unknown, because they can be both passed-by-value (in case we consider that a variable holding an object is in fact a reference to the object) and passed-by-reference (when we consider that the variable to the object holds the object itself).  Although it doesn't really matter at the end, I want to know what is the correct way to present the arguments passing conventions. Is there an excerpt from JavaScript specification, which defines what should be the semantics regarding this?


I came across with the lemma below on Isaac's Algebra:  Lemma. Let $F \subseteq R$, where F is a field and R is a domain. If $|R:F|<\infty$ then R is a field.  As far as I know, $|E:F|$ denotes the degree of a field extension so here, $E$ is a field. In the book it is said that when "an integral domain $R$ contains a field $F$, this forces $R$ to be a unitary overring of $F$".  I would like to know how should I think $|R:F|$ as and what does it mean to be a unitary overring of some field?

This is an exercise in some textbooks.     Let $E$ be an algebraic extension of $F$. Suppose $R$ is ring that contains $F$ and is contained in $E$. Prove that $R$ is a field.   The trouble is really with the inverse of $r$, where $r\in R$. How to prove that $r^{-1}\in R$, in apparent lack of a characterization of $R$.  It occurred to me to use the smallest field containing $R$ ($R$ is easily shown to be an integral domain), that's the field of quotients, and proving that it's $R$ itself, but I don't really know how to proceed.  A not-too-weak, not-too-strong hint will be much appreciated.   Beware $ $ Readers seeking only hints should  beware that there is now a complete answer.


I want to publish my app as free app on Salesforce AppExchange. I have already joined ISV partner portal through  and selected "AppExchange Partner Program". And I have read in salesforce packaging guide that for releasing the app I only need to register on partner portal which I had already done.   I also created a case through it but I got replied "Have you looked at our partnerships yet? You need to sign up for one in order to list on the AppExchange." and they provided  link.  Now do I have to register for AppExchange Partner Program Model separately, if yes then please guide me where can I do so because I didn't find any register link on there AppExchange Partner Program Models page.  Thanks in advance.


I know this is not a new question, and I know it depends on the context and what I would like to do with the data, but I am still finding it difficult to solve this problem in practice. And I haven't found any good answer online (this question was marked as possible duplicate, but I do not think this is the case, so I have modified my question, I hope it is clearer now).  For example: I have a  of modeled atmospheric N deposition for the whole world, with a resolution of 5 by 3.75 degrees. Now I would like to resample it to a finer resolution, say with cubic resampling from GDAL warp.     EDIT:  The reason I want to do this is that I would like to estimate N deposition per country. I understand I am introducing an error when I do any resampling, however as you can see in the image, the pixels are really quite large compared to the size of an average country.  Now I could run a zonal statistics on a world countries vector layer, using this raster image as it is. However, I suspect that my results would be of better quality if I resample the raster image first, to a higher resolution. If I am wrong, than please let me know and I will close this question myself.  Question: Can you please explain what logical steps and reasoning I should follow to decide the new resolution of the raster image? The aim here is to then run a Zonal Statistics on the higher resolution raster image, with a vector layer containing country boundaries.  I would like this to be an example of how to make such a decision, I don't care so much about the answer to this specific case.

I'm looking for recommendations on best practices for dealing with raster data layers with different resolutions and projections. The advice I've been given is to always resample to the layer with the lowest resolution before performing any analysis, but this seems like huge waste of precision to me and I've never been given a solid explanation for why it should be done.  When is it reasonable to resample to match a higher resolution grid and what are the implications compared to resampling to a lower resolution?  I realize that this is likely highly situation dependent. I'm mostly looking for general guidelines, but here's my specific scenario for reference:  Scenario: I'm looking to construct a spatial regression model predicting land use based on a variety of environmental and socio-economic layers. My land use map is Landsat derived and hence 30m resolution. Examples of explanatory layers include the  (3 arc-seconds, ~90m) and  climate layers (30 arc-seconds, ~1km).


I know how to redirect stdout into a file:  import sys sys.stdout = open('log.txt', 'w') print 'test'   This will create a log.txt where test will be written in it. However, test will not be print in stdout.  How can i print and redirect test in both terminal and file without changing every print statement in the program.  PS: I know that redirecting sys.stdout is bad (but i still need to do it)

Edit: Since it appears that there's either no solution, or I'm doing something so non-standard that nobody knows - I'll revise my question to also ask: What is the best way to accomplish logging when a python app is making a lot of system calls?  My app has two modes.  In interactive mode, I want all output to go to the screen as well as to a log file, including output from any system calls.  In daemon mode, all output goes to the log.  Daemon mode works great using os.dup2().  I can't find a way to "tee" all output to a log in interactive mode, without modifying each and every system call.    In other words, I want the functionality of the command line 'tee' for any output generated by a python app, including system call output.  To clarify:   To redirect all output I do something like this, and it works great:  # open our log file so = se = open("%s.log" % self.name, 'w', 0)  # re-open stdout without buffering sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)  # redirect stdout and stderr to the log file opened above os.dup2(so.fileno(), sys.stdout.fileno()) os.dup2(se.fileno(), sys.stderr.fileno())   The nice thing about this is that it requires no special print calls from the rest of the code.  The code also runs some shell commands, so it's nice not having to deal with each of their output individually as well.  Simply, I want to do the same, except duplicating instead of redirecting.  At first thought, I thought that simply reversing the dup2's should work.  Why doesn't it?  Here's my test:   import os, sys  ### my broken solution: so = se = open("a.log", 'w', 0) sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)  os.dup2(sys.stdout.fileno(), so.fileno()) os.dup2(sys.stderr.fileno(), se.fileno()) ###  print("foo bar")  os.spawnve("P_WAIT", "/bin/ls", ["/bin/ls"], {}) os.execve("/bin/ls", ["/bin/ls"], os.environ)   The file "a.log" should be identical to what was displayed on the screen.


I have a hard disk which is in NTFS. I want to make it writable without formatting.  I have gone through some solution for it but its working in previous version not in el captian.  I tried this  but when doing this step   sudo mv /sbin/mount_ntfs /sbin/mount_ntfs.original  sudo ln -s /usr/local/sbin/mount_ntfs /sbin/mount_ntfs   its says its not permitted.

What is the best, easiest, preferably cheapest way to make OS X write to NTFS-formatted drives in Mac OS X?


I realise the title is somewhat ironic.  I have started playing a new game, it is exciting, well-paced, suspenseful; everything an rpg-er like me could ask for.  The issue is the description of, well, everything, is lacking. The GM is feeling a bit inferior in that respect. Some examples might be:   You are in the town square, with a large group of people in it, not too packed, but movement will be somewhat restricted A short, gruff man answers the door. He only stands about waist-height and appears to be drunk. You enter the clearing, The forest surrounds on all sides, save a gap in the trees opposite you. A web covers the ground with a hole in the middle that looks like a tunnel entrance   It's not that he's withholding information, he just doesn't have anything else to say.  He approached me about it, saying he wanted to improve on his story telling, and I gave him some advice, but I don't really have much experience in that area myself. What practices can he implement to try and boost him along to improving?

Whenever I'm running or playing a game, I consistently run into an issue of setting atmosphere. I've realized the best way to do this is through more effective, engaging descriptions of settings, actions, and objects that the characters see and feel.  As a player, I feel that my actions are generally "I attack the goblin," or some variation thereof, but I'm afraid that I'll stumble over my words and further confuse the other players and I'll resort to "I attack the goblin" as to not drag the game out longer.  As a DM, my issue tends to be more with setting atmosphere with settings, locations, and objects. Effectively, the flavor texts that comes with walking into some amazing location that the characters (not necessarily the players) should be suitably impressed by. My goal here is to engage the players with some degree of spectacle, and be more inquisitive in their environment and whatever lies within it.  How can I create more descriptive, concise flavor text for the games I play in?


In Java 7 with the new I/O APIs, is there an easy way to list a directory's content by last modified date? Basically I only need to get the file the wasn't modified for the longest time (sort by last modified ascending, take first filename).

I want to get a list of files in a directory, but I want to sort it such that the oldest files are first.  My solution was to call File.listFiles and just resort the list based on File.lastModified, but I was wondering if there was a better way.  Edit: My current solution, as suggested, is to use an anonymous Comparator:  File[] files = directory.listFiles();  Arrays.sort(files, new Comparator<File>(){     public int compare(File f1, File f2)     {         return Long.valueOf(f1.lastModified()).compareTo(f2.lastModified());     } });


I have a problem in C in Keil which is below this is sample C code.  struct A {     uint8_t header;     uint16_t volume;     uint16_t temp;     uint8_t footer; };   union {     struct A Packet;     uint8_t buff[6]; } A_union;   The problem is I want to fill struct with a header,footer and data and serialize it with buff but union changes byte offset (I cant even see footer in buff)as you can see in the picture. how can I solve it?  Update: as Sander suggested in  I solved the problem by modifying struct as below      struct __attribute__((__packed__)) A{ ...}

Why does the sizeof operator return a size larger for a structure than the total sizes of the structure's members?


could you help me with this problem, please?   If $U$ is a principal ultrafilter on $I$ such that $\{a\}\in U$. Show that $Ult(\mathfrak{A}_x:x\in I)$ is isomorphic to $\mathfrak{A}_a$ and $[f]=f(a)$ for each $f$ and $j$, the embedding is the identity.

Show that:  If $U$ is a principal ultrafilter, then the canonical inmersion $j$ is an isomorphism between $\mathcal A$ and $Ult_{U}\mathcal A$


For a point $x$ and a non-empty subset $A$ of a metric space $(X, d)$, define \begin{align}\inf\left\{ d(x,a):a\in A\right\}\end{align} Prove that if $y$ is another point in $X$ then $$d(x,A)\leqslant d(x,y)+d(y,A)$$

Following a reference from "Elementos de Topología general" by Angel Tamariz and Fidel Casarrubias.     Since the sum and the product of real continous functions, defined in any topological space, are continuous we can easily prove that every metric space is a Tychonoff spaces. So we suppose that $(X,d)$ is a metric space and we consider a closed set $F$ a point $p\notin F$ and so we define a function $f:X\rightarrow[0,1]$ by the condiction    $$ f(x)=\frac{d(x,p)}{d(x,p)+d(x,F)} $$   where $d(x,F):=\mathscr{inf}\{d(x,a):a\in F\}$. So we observe that $f(p)=0$ and $f(x)=1$ for any $x\in F$; then $f$ is continuous, since any function $g:X\rightarrow\mathbb{R}$ defined as    $$ g(x)=d(x,A) $$       for any $x\in X$ and for any fixed $A\subseteq X$, is a countinuous function and so $f$ is continuous  function, since the sum and the ratio of continuous function is a continuous function.       Well by definition of Tychonoff space we can claim that the metric space $(X,d)$ is a Tychonoff space.   Well unfortunately I don't be able to prove that the function $g$ is continuous: could someone help me, please?


From the title of the question You may presume what I am asking. Is there a way to get around that.For example photons from hubble deep field have travelled 13 billion light years and we still see a picture as it was 1m from us. Can something very dense vibrate and transmit the vibrations at the speed of light and photons are just these vibrations. Do conclusions from Michelson-Morley experiment predict with certainty there is no any possibility for a conductor of waves (EM and gravitational)?

If we look at light as a collection of little particles, we can say that dimmer light has its photons more spread out.  But if we look at light as a wave, then there no gaps unless specifically placed there on purpose.  So how can one interpret the formation of gaps between the photons?


Do you say I´ll arrive in the first week of July? or on the first week of July?

I have found the following usage of "on", "at" and "in" on the internet. Is there any other exception and/or rule for that?  Prepositions of Time Use in for  Months: in April / in September / in that month Seasons: in (the) summer / in (the) winter Years: in 1332 / in 1984 / in that year / in the next year Long Period(s) of Time: in former century / in 90's / in the Ice Age / in the past / in the future  Exceptions: in the morning / in the evening Use at for  Time: at 8 o'clock / at 9:30 / at bedtime / at sunset / at dinnertime / at 5:33:10 AM  Exceptions: at Christmas (= during the Christmas holidays but not necessarily on December 25th) / at Easter  / at noon / at night / at the weekend / at the present time / at the moment Use on for  Days: on Monday / on Friday / on Christmas Day (= on December 25th) / on Easter Sunday / on Independence Day Dates: on February 18th / on her birthday / on 21 March 2015 / on  Notice:  We have in the morning and on Monday but we say on Monday morning, not in Monday morning, and so on. When we say last, next, every, this we do not also use at, in, on: She runs next Tuesday. (not on next Tuesday) / He leaves us every Easter. (not at every Easter) / I See you this evening. (not in this evening) Look at these examples for the combination of times in a sentence: We will meet next week at six o’clock on Monday. / I heard a funny noise at about eleven o’clock last night. / It happened last week at seven o’clock on Monday night.   Look at  as well which says:  This all hints at a coherent metaphor: hours and other short periods of time are places; days are surfaces; months and longer time periods are containers.


How many of you {know/knows} English?   Without knowing the outcome of the above question are we supposed to use a singular verb or a plural verb?  This question is different from the one already asked as this question is used with a main verb 'know' where as the previous one with 'be' verbs.

We had an argument in our collage if it's possible to have such structure:     "How many -singular noun- is there?"   For example:      How many chair is there?   The claim of the supporters: This structure should be used in case that t is not known whether there is one one or more chairs there. While just in case that it is known certainty that there are more than one chair, it should be "how many chairs are there".    The claim of the opponents: This structure cannot be since using the phrase "how many" always should be with a plural noun.  Both sides are not native English speakers, then I would like to know what is the truth.


I am trying to prove that a matrix A is diagonaizable. The matrix is 4x4, with a diagonal of a and the rest b, where b is not zero. I have found the determinant, and am going to find the eigenvectors, however, is it true that if $A=A^T$ then A is diagonalizable? If so, how can I prove this?   Thanks!

A matrix is diagonalizable iff it has a basis of eigenvectors. Now, why is this satisfied in case of a real symmetric matrix ?


I am creating the ssh tunnel using ssh -D 1080 hasinet from hasnoinet host, when from another session on hasnoinet do: curl google.com:1080. It doesn't work.

The machine via which I'm SSHing to the remote/host machine (same network/LAN) has access to the Internet but the host doesn't.  Running updates and installing packages on the host gets quite inconvenient because then I have to start a proxy locally and then configure the remote machine to use it.  So I was wondering if there is a easier way of doing this via, maybe, SSH or something else?  I have a realization of the complexities that lie within, but was curious to know.  Using plink through Emacs (if it matters).


In my settings for Google Analytics I need to add a javascript snippet in the "after" section, to track a second account (the main account works fine).  I added this:     ga("create", "UA-xxxxxxxx-x",  {"cookieDomain":"auto"}); ga("set",   "anonymizeIp", true); ga("send", "pageview");   It does not work at all though. How shall I change this to make it work? The Google Analytics module version is 7.x-2.3.  Note: I don't think this question is a duplicate of "": the other question is about two different domains, I have only one domain, which is tracked by 2 accounts. Also under the text box where I am supposed to paste my javascript snippet in the GA module UI, you can find this text: '     This is useful if you'd like to track a site in two accounts   ... which suggests that you really can track 2 accounts for 1 site. My problem is that the snippet I entered does not work. The second account does not recieve any data.

I am working on a Drupal mulsite project (using single database) and using Google Analytics module for this.  I have follow the below steps for GA configuration:   Created a domain name example1.com and a sub-domain name example2.com. Create an account on GA and create property for both of this domain name in GA account. Both property give me two different Tracking ID (same as below screenshot).      Into the configuration setting of GA from drupal admin section I have added Web Property ID of example1.com and into domain setting added both the domain name example1.com and example2.com into the section of List of top-level domains (a same as attached screenshot).      Now this configuration is only working for emample1.com, not for example2.com. So can anyone please tell me how can I use Web Property ID of domain exmaple2.php to get the result?


I have the following .   I am trying to use constraints to make the camera follow the cube(named "logic bricks player"). I tried copy location with offset to keep the camera at its height, but it did not work. Also just parenting the camera does not work cause it loses the rotation. Even when I tried to bypass it by pressing "Keep transform" the camera disappeared!?! (I know this cause I used plane to track it).   The thing is though, that the constraints worked in the 3d viewport but failed to work during gameplay.   I have no idea what I am doing wrong and I am new to the use of constraints in bge. So how do I fix my problem?  (credits for the hand rig go to eGlyde from blendswap,it was his model)

In the game engine, my object needs to point at a target. How can I get it to aim at something that is constantly moving in unpredictable patterns? The constraints actuator does not have a "track to" that I can see however the 'track to' is exactly the effect I want. I'm using v. 2.71.


I'm trying to find the easy but a somewhat stable way to create a split power rails Vcc Vee for the opAmp applications. Any specific known IC for this purpose?

For the circuit of opamp 741. we have to supply the dual power for it. How can I make a dual power supply from single. For example, make a (+9V)-GND-(-9V) from single 9V battery ?


I seem to have lost the overview about my bibliographystyle and citation in footnotes. I am in dire need of your help. What I would like to achieve, is to have the bibliography in APA-Style, exactly like , and inside the text, to cite with footnotes that show the following: Author. (year), p. 375  Here is my the relevant code that I use so far. As you can see, I already use footnote citations, but unfortunately, without the desired bibliographystyle apacite yet. How can I combine the two?  \documentclass[12pt]{report}  \usepackage[style=authoryear,autocite=footnote, backend=bibtex]{biblatex} \bibliography{biblio}   And here an example of a citation command I use, where [23] is the page number:  \autocite[23]{corpore21}   Thsi gives me the following citation in a footnote: Pieth 1997, p. 23.  In advance, many many thanks for helping me out.

So for a report my teacher gave us exact prerequisite for the layout. He wants in text footnote citations in the author-year style and the bibliography in  the APA (5th) style. EDIT: The reference list should be numberd and sorted according to the appearence and I think corresponding to the footnote number.  Because I do not want to merge 5 .doc (MS Word) files from my group members and format everything in MS Word I need to get this to work in LaTeX.  Currently I am trying to get this to work with biblatex and Biber, but the combination of the two styles turns out to be very difficult to me. I am not set on biblatex. So, if it can be done with BibTeX or whatever, that is fine.


I want some users to have access to certain items under the 'edit' tab but hide others...  I know you can allow a role to 'edit' or not 'edit' a published node content type but that enables and disables the whole of the edit tab!

I'm working on a site in which I'd like anon users to be able to create nodes of a certain type, but I only want them to be able to see/edit some of the fields on that content type.   I can't go into details just yet, but the goal of the site is to crowd-source the collection of information and then have a few administrators who will approve and groom the data. That's why I want anon users to be able to create nodes and only access a few fields. Then admins will be able to supplement that data by adding values into the other fields and then publish that node.  How do I restrict access to fields basing on the roles the users have?


The question is if modern particle accelerators (or cosmic rays for that matter) can create black holes. Has those events been detected? If not, how far are we in terms of orders of magnitude energy? Bonus question: is creating black holes scientifically interesting? I've read , but the accepted answer is about string theory and politics. My question is about energies and devices required.

A black hole is so powerful to suck everything into itself. So is it possible that mini black holes can be created? If not then we could have actively disproved the rumors spread during LHC experiment.


1) Could someone provide a definitive answer please on how to install wine with 32 bit architecture and how to successfully launch ADE on my version of linux please? Previous tutorials say install wine 1.4 but the repositories are either outdated packages or can't be located... 2) Also, if terminal throws the error that it's an unsecure repository, I try --allow authenticated but the update still gets refused by default. How can this be solved? I've tried previous answers to questions on here and video tutorials, nothing seems to be relevant to what I'm attempting and on my fresh install of the newest Ubuntu Linux 5.8.0-43-generic. I have an account on ebooks.com to read books on the computer, it only has Adobe Digital Editions in windows and mac. So after installing wine and winetricks but didn't know it needed 32 bit architecture exclusively so ADE would not launch. Wine executed the set up file but not the installed ADE.


I wrote a java application, want to register it as a service, so wrote a bash script in /etc/init.d/. Here is the script:    #!/bin/sh # # chkconfig: 345 50 83 # ### BEGIN INIT INFO # Short description: Trigger Beamer on system startup # Description: Trigger blupay beamer on system start up ### END INIT INFO  #Source function library . /etc/rc.d/init.d/functions  #targets beamer config file if [ -f /etc/sysconfig/beamer ]; then     /etc/sysconfig/beamer fi   #start httpd in the C locale by default. BEAMER_LANG=${BEAMER_LANG-"java"}  # Path to beamer. beamer=/home/blupayss/Desktop/BeamerApp prog=beamer pidfile=${PIDFILE-/var/run/httpd/beamer.pid} lockfile=${LOCKFILE-/var/lock/subsys/beamer} RETVAL=0  start() {      echo -n "starting $prog"     LANG=${BEAMER_LANG}     RETVAL=$?     java -jar ${beamer}/Beamer.jar     echo         [ $RETVAL = 0 ] && touch ${lockfile}         return $RETVAL } stop() {     echo -n $"Stopping $prog: "         killproc -p ${pidfile} -d  $beamer         RETVAL=$?         echo         [ $RETVAL = 0 ] && rm -f ${lockfile} ${pidfile} } reload() {     echo -n $"Reloading $prog: "     if ! LANG=$BEAMER_LANG $beamer $OPTIONS -t >&/dev/null; then         RETVAL=6         echo $"not reloading due to configuration syntax error"         failure $"not reloading $beamer due to configuration syntax error"     else         # Force LSB behaviour from killproc         LSB=1 killproc -p ${pidfile} $beamer -HUP         RETVAL=$?         if [ $RETVAL -eq 7 ]; then             failure $"beamer shutdown"         fi     fi     echo }  # See how we were called. case "$1" in   start)         start         ;;   stop)         stop         ;;   status)         status -p ${pidfile} $beamer         RETVAL=$?         ;;   restart)         stop         start         ;;   force-reload|reload)         reload         ;;   *)         echo $"Usage: $prog {start|stop|restart||force-reload|reload|status}"         RETVAL=2 esac  exit $RETVAL   When I execute it as sudo service beamer start, then java applicaition gets launched successfully. However it returns an error: /etc/sysconfig/beamer: Permission denied How can I make my script access /etc/sysconfig/beamer?

I want to turn my system on automatically every day. So I use the below code in my Python script, but sudo asks me for a password every time:  os.system('sudo sh -c "echo date \'+%s\' -d \'+ \        24 hours\' > /sys/class/rtc/rtc0/wakealarm"')   How can I run this script without sudo asking for the password every time?


On , although the OP still has an active account (and the profile link in the question's flair renders normally), if you look at  you'll see that the OP's name (and that of some others) is being rendered as plain text, as it would if the user had been deleted.        What's going on here? Is it related to the fact that the question was migrated? Is it a bug?  At the very least I'd expect the OP's linkification to be consistent, across both pre-migration and post-migration content.

Background: when question is migrated from site A to site B and the author doesn't have account in site B, their name will appear "gray" until they log in to site B and associate the accounts, then the avatar show and all is good. No problems here, same for answers and their authors. Problem: if user from site A posted comments while the question was still in site A, their name will stay gray and unclickable even after they logs in and have account in site B:  , but most likely it's global problem, not specific to that one occurrence.


I have many folders with many images in each one. I want to open a new file explorer window with all the images from all folders. Here is a screenshot :    In each folder there are many images I want to open a new window of file explorer that will contain all the images from all folders so I can browse them easy instead entering and exit each folder.

Let me give you an example of the rather odd functionality I'm after. Imagine you have your local HDD, an external HDD, and a usb stick, all containing a folder called "MediumMedley". When all these storage mediums are connected, you want to query all these locations and display a merger of the results within one location, to have a proper overview.  Can anyone think of any ways to achieve something akin to this? Bonus points if the end result is a windows explorer window (I want full explorer functionality, ie thumbnails, context menus etc).  One approach I tried was to do a custom search (looking at this SU question:  ), which works, but as far as I can tell (doing an empty * search) you can only get windows search to show a flattened hierarchy of the queried folders - not very helpful.  I could easily write a .net app myself to do exactly this, but I won't be able to easily build a pretty client with context menus, thumbnails etc...  --  PS: I need these folders each in their own storage medium, as exemplified, for reasons. Don't tell me that I should just use dropbox. Unless you know a trick that solves what I ask.


What I need is easy to explain but couldn't do it :-(  I want to grep a command output not showing the matching lines and x lines after that. Eg.  # fdisk -l Disk /dev/ram0: 64 MiB, 67108864 bytes, 131072 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes   Disk /dev/ram1: 64 MiB, 67108864 bytes, 131072 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes   Disk /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes   I want to skip lines with 'ram' string and 6 lines after that, so the output would be just:  Disk /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes   Something like sudo fdisk -l | grep -v "ram" -A 6

Consider a text file with the following entries:  aaa bbb ccc ddd eee fff ggg hhh iii   Given a pattern (e.g. fff), I would like to grep the file above to get in the output:  all_lines except (pattern_matching_lines  U (B lines_before) U (A lines_after))   For example, if B = 2 and A = 1, the output with pattern = fff should be:  aaa bbb ccc hhh iii   How can I do this with grep or other command line tools?    Note, when I try:  grep -v 'fff'  -A1 -B2 file.txt   I don't get what I want. I instead get:  aaa bbb ccc ddd eee fff -- -- fff ggg hhh iii


After installing OS, When opening "MY Computer" it shows first hard disk as "C", why so?   Why Hard disk labeling starts with C rather than A?

Why is it that I see an A: drive and a C: drive but not a B: drive?  Is there a reason why the disk partitions start at C? And is it possible to change that letter designation?


When adding a bug report via Android app, list of specification items added to message body automatically. And for the last one (OS) extra space character is added.

In the Stack Exchange Android app ➡ About ➡ Submit a bug report, when trying to report a bug, by default the configuration details are showing in the body section.      The content in the screenshot is as below (for reference of future search):    - App Version: 1.0.85 - Device Manufacturer: Motorola - Device Model: XT1033  - OS Version: 5.1 (2)   The four items are to be shown in the same bulleted list order, but there is one extra space before the - OS Version:, so it is causing the first three items to be in the same bulleted list order and the last one in the sub bulleted list.   The rendered output is below:   App Version: 1.0.85 Device Manufacturer: Motorola Device Model: XT1033   OS Version: 5.1 (2)    The issue is in the recent questions with the  +  .


We need to transfer coal from point $A$ to point $B$ using a train. There is $9000$ tonne at point $A$. The distance between point $A$ and $B$ is $3000$ km. Train can carry only $3000$ tonne included its fuel. Also train consumes $1$ tonne coal per $1$ km. How much coal can be transferred from point $A$ to $B$?  I can do only $1500$. But can't prove it is optimal.

I'm dealing with the following variant of the well-known :     A 1000 mile wide desert needs to be crossed in a Jeep. The mileage is one mile / gallon and the Jeep can transport up to 1000 gallons of gas at any time. Fuel may be dropped off at any location in the desert and picked up later. There are 3000 gallons of gas in the base camp. How much fuel can the Jeep transport to the camp on the other side of desert?   So instead of "exploring" the desert or trying to drive as far as possible, the problem here is to transport as much fuel as possible for a given distance.  I've thought about reducing this problem to the well-studied ones, but I can't come up with anything that makes sense. I don't even know how to approach this.  Any pointers?


I am new at Ubuntu and by mistake, I ran a command to install Xubuntu OS while I was trying to install sound drivers by taking help from . As a result, I lost my root account on Ubuntu, and Xubuntu is started on my laptop. Is there any way to get back to Ubuntu and get access to my user account which I have lost and in which I have all of my data? Commands that I ran: sudo apt-get --purge remove linux-sound-base alsa-base alsa-utils sudo apt-get install linux-sound-base alsa-base alsa-utils sudo apt-get install gdm ubuntu-desktop sudo apt-get install gdm xubuntu-desktop sudo reboot

With regards to Plymouth --  Are there alternative boot screens available?  What's the easiest way to change the boot screen?


This could be a classic problem or my wording might be totally off, but I can't seem to find an answer to this problem:  Given $n\in\mathbb{Z}$ with prime factorization $n=p_1^{q_1}\dots p_m^{q_m}$, how many integers divide $n$?  For the sake of this problem, let's ignore $1$ and $n$ until the end.  First off, we have that there are at least $q_1\dots q_n$ divisors, since there are $q_1$ divisors made up of $p_1$ (namely $p_1,p_1^2,\dots,p_1^{q_1}$), thus the same holds for $p_2,\dots,p_n$  I've never done much with combinatorics, so I'm not quite sure how to begin counting unique divisors by mixing and matching distinct primes.  Any thoughts?

I know that one way to find the number of divisors is to find the prime factors of that number and add one to all of the powers and then multiply them together so for example  $$555 = 3^1 \cdot 5^1 \cdot 37^1$$  therefore the number of divisors = $(1+1)(1+1)(1+1) = 2 \cdot 2 \cdot 2 = 8$  What I do not know (and can't seem to find when I look) is WHY this relationship exists or a formula which shows its proof.  Has anyone seen such a formula?


In Ubuntu 20.04 executing a command from terminal, for example sudo apt-get install libsdl2-2.0-0  displays a screen, in this case referring to a font, but this happens with any screen with text. For example, one which describes a EULA, when a <ok> appears at the bottom, clicking on the <ok>; pressing Return; pressing Esc - anything - nothing gets beyond the screen. Finally, kill terminal restarts it. Retrying gives the following output: jim@HP-Nbook-Linux:~$  sudo apt-get install libsdl2-2.0-0 [sudo] password for jim:  E: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 59271 (apt-get) N: Be aware that removing the lock file is not a solution and may break your system. E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), is another process using it?  So now I have a second problem which I do not know how to address.

After a recent update, ttf-mscorefonts-installer prompted me to accept its license agreement.     ┌─────────────────┤ Configuring ttf-mscorefonts-installer ├─────────────────┐  │                                                                           │   │ TrueType core fonts for the Web EULA                                          │                                                                               │ END-USER LICENSE AGREEMENT FOR MICROSOFT SOFTWARE                             │                                                                               │ IMPORTANT-READ CAREFULLY: This Microsoft End-User License Agreement           │ ("EULA") is a legal agreement between you (either an individual or a          │ single entity) and Microsoft Corporation for the Microsoft software           │ accompanying this EULA, which includes computer software and may include      │ associated media, printed materials, and "on-line" or electronic              │ documentation ("SOFTWARE PRODUCT" or "SOFTWARE"). By exercising your          │ rights to make and use copies of the SOFTWARE PRODUCT, you agree to be        │ bound by the terms of this EULA. If you do not agree to the terms of          │ this EULA, you may not use the SOFTWARE PRODUCT.                              │                                                                               │                                  <Ok>                                         │                                                                           │   └───────────────────────────────────────────────────────────────────────────┘    Screenshot:   For some reason my terminal will not allow me to accept, or for some reason I am pressing the wrong hotkey...  I've tried every letter on the keyboard and Enter among others...  I'm sure there is a very simple and obvious solution to this.  I've also just tried to remove the package completely however the terminal states that due to the package not being correctly installed, I should reinstall the package before removing it.  Very frustrating!  Essentially, because I cannot successfully install this package, I can't really ever upgrade my system because I always have to end up terminating the terminal with the license agreement (thus the upgrade fails).


NOVICE HERE  I want to retrieve the string value in my database and convert it to integer so that I can add integer when I press btnorder.  This is the code:  package jeriel.robie.zairhya.seki.blessie;  import java.sql.*; import java.util.logging.Level; import java.util.logging.Logger; import javax.swing.JOptionPane; import javax.swing.table.DefaultTableModel;  public class Owner extends javax.swing.JFrame {  public String dataBaseName= "feed"; public String dbURL="jdbc:mysql://localhost:3306/"+dataBaseName; public Connection con; public Statement s; public ResultSet rs1;  public Owner() {      initComponents();      try {         Class.forName("com.mysql.jdbc.Driver");     } catch (ClassNotFoundException ex) {         Logger.getLogger(Stock.class.getName()).log(Level.SEVERE, null, ex);     }      try {         con=DriverManager.getConnection(dbURL,"root","");     } catch (SQLException ex) {         Logger.getLogger(Stock.class.getName()).log(Level.SEVERE, null, ex);     } }      I think the error is here in the method. I don't know where it is. This is my first to encounter this error.  public void orderitem() throws SQLException, ClassNotFoundException {     s = con.createStatement();     ResultSet rs = s.getResultSet();     String temp = rs.getString(3);     int x = Integer.parseInt(temp);     int y = x + Integer.parseInt(txtitemquantity.getText());     s.execute("UPDATE stock SET itemquantity=" + y + "WHERE idnumber=" + "'" +      txtstockid.getText() + "'"); }  private void btnorderActionPerformed(java.awt.event.ActionEvent evt) {                                              try {         orderitem();     } catch (SQLException | ClassNotFoundException ex) {         Logger.getLogger(Owner.class.getName()).log(Level.SEVERE, null, ex);     } }    Here is the ERROR  Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at jeriel.robie.zairhya.seki.blessie.Owner.orderitem(Owner.java:92) at jeriel.robie.zairhya.seki.blessie.Owner.btnorderActionPerformed(Owner.java:261) at jeriel.robie.zairhya.seki.blessie.Owner.access$500(Owner.java:17) at jeriel.robie.zairhya.seki.blessie.Owner$6.actionPerformed(Owner.java:168) at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)

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


I stumbled upon  question online:  $$A=\begin{bmatrix}5&6&&\cdots&6 \\6&5&6&\cdots&6 \\&&\ddots&& \\6&\cdots&6&5&6 \\6&\cdots&&6&5 \end{bmatrix}\in \mathbb R^{82\times 82}$$  I also found a way to solve this in Chegg:    Is there a better way to solve this problem maybe by reducing it to upper triangular form?

This question aims to create an ""  of numerous questions that ask about determinants of specific matrices (I may have missed a few):              The general question of this type is  Let $A$ be a square matrix of rank$~1$, let $I$ the identity matrix of the same size, and $\lambda$ a scalar. What is the determinant of $A+\lambda I$?  A clearly very closely related question is  What is the characteristic polynomial of a matrix $A$ of rank$~1$?


I have a simple Win 10 batch script to open a bunch of folders within Explorer at system startup, however there's a problem with the last command's path containing whitespaces, as instead of opening a new Explorer window as expected, it opens a CMD window with the path as a system command: @ECHO OFF start C:\Users\Darek\Fallout2 start C:\Users\Darek\Fallout2\data\scripts start C:\Users\Darek\Pobrane_2 start "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC"  How do I write the last command so it works correctly?

I need to start a program (virtual machine) in the background with a start command on Windows' 7 command line. Normally you would do this like that:  start /b cmd yourprogram   But I need to pass some arguments and when I so it like this (without /b flag to see the debug information):   start C:\Users\USER>start "c:\Program Files\Oracle\VirtualBox\VBoxHeadless.exe" -startvm "debian604 64"   I get this error message:     Windows cannot find '-startvm'. Make sure you typed the name   correctly, and then try again.   On the other hand when I do it in the current command line window without the start in the beginning the virtual machine runs normally - but in the foreground.   Any solutions?


I felt that  question I had was in the grey area between SO and SoftwareEngineering.se and I ended up asking it on SoftwareEngineering.se (clearly), however someone there has said that it would be a better fit for SO. I would like suggestions as to where it should go, either comments, or upvote=leave it on SoftwareEngineering.se, downvote=move it to SO.

There seems to be more than a few computer science/programming Stack Exchange networks (is that the correct term?). Stack Overflow, being the first, has by far the most users, questions, and answers.  What is the reasoning for creating the others, and are there clear guidelines for which kinds of questions should be posted? I can see a large amount of potential overflow, many cases of people not getting a good answer to their question, because the person who has the answer isn't browsing that particular network at the moment.  I understand that they were probably created for organizational purposes, but wouldn't it almost make more sense to just have them as categories under Stack Overflow, keep them separated but still connected, instead of making people have to create multiple 'account's, one for each network?  I am sure there was a very good reason to break them up, but as someone that is new to SE, it can be somewhat intimidating to decide which one to post in to ensure you get a good answer. For example, if I am a computer science student, my first instinct might to be to post in the computer science network, until I see that it literally has 1% of the users as the Stack Overflow network, which still seems to be for programming/computer science related questions.  So my second instinct would then to be to post it into the Stack Overflow site on the basis that I have a significantly higher chance of my question being seen and getting a good answer. Then I notice that there is also a 'programmers' network, and I don't even begin to know where that fits in. I, and I am assuming most people, will probably just post on Stack Overflow to be safe.  My question is, other than the short little description blurb of each one, is there a clear cut set of guidelines which what each network is intended for, what kinds of questions should go to each one, and is anything being done to encourage people to post in these newer, smaller (more specialized?) networks as opposed to just posting in big daddy Stack Overflow?  Now again, this is for computer science/programming/"why isn't this code doing what I want?" related questions, I am not saying that if I had a question about Linux or WordPress or something I would have the same confusion.


For example in Wolfram mathworld, you get these two definitions of covariance.    cov(X,Y)    =   E[ (X - E[X])(Y - E[Y]) ]             =   E[XY] - E[X]E[Y]      I don't see why they are equal.

I know two formulas for variance:   $$\operatorname{variance}(f) = \operatorname{expectation}((f(x) - \operatorname{expectation}(f^2(x)) \\ = \operatorname{expectation}(f(x)^2) - \operatorname{expectation}(f(x))^2$$  How are these two the same?   Also how is $$\operatorname{cov}[x, y] = E((x − E[x])(y − E[y])) = E[xy] − E[x]E[y]$$


Why the poor Wizard Families(like Weaseleys) do not turn to the muggle world to earn some easy money and then change the Muggle money back to Wizard one and get better financially. Things like    Organizing Magic shows, (The magic He/She does looks like real!!!) cheating in Casinos (well not so a good thing...) Setting up a business for any product (as you should only need a duplicating charm to create as many product as you want) and much more.    I believe there is no restriction of usage of Magic in front of Muggles for adult wizards as long as Muggles don't get too suspicious, and I don't think Muggles will start believing in a Wizarding world out of just a Magic show. Also Muggle Money can be changed into Wizarding Money at Gringotts or how else would Muggle Born have bought the Wizard things?     "Oh look Molly, they are changing Muggle Money" said Arthur looking at nervous Hermione's parents who were standing just by the counter.

Why, oh why, don't the Weasleys "conjure" up some diamonds/gold/etc, sell 'em to Muggles, and get rich? They could buy a mansion (like the Malfoys), and live there happily ever after.  I know there's  that prohibits one from conjuring food (which doesn't make much sense to me, either). Even if it applied to gold, what about all the other elements/compounds/materials? Could the law really be 'don't let a wizard conjure something if it'll make them richer'? That's totally nonsensical.  Why does Wizard society still have poor people, especially if they're talented?


Let $r_b$ and $m_b$ respectively be the exradius of the excircle opposite $B$ and the median drawn from the midpoint of side $CA$ of acute triangles $\triangle ABC$. Prove that $$\large r_a + r_b + r_c \ge m_a + m_b + m_c$$   We have that $$[ABC] = \sqrt{\frac{r_a + r_b + r_c}{2} \cdot \prod_{cyc}\frac{r_a - r_b + r_c}{2}} = \frac{4}{3}\sqrt{\frac{m_a + m_b + m_c}{2} \cdot \prod_{cyc}\frac{m_a - m_b + m_c}{2}}$$  Let $r_a - r_b + r_c = r_b'$, $m_a - m_b + m_c = m_b'$ and so on, we have that $$\sum_{cyc}r_b' \cdot \prod_{cyc}r_b' \ge \frac{16}{9} \cdot \sum_{cyc}m_b' \cdot \prod_{cyc}m_b'$$  In order to prove that $r_a + r_b + r_c \ge m_a + m_b + m_c$, which could be rewritten as $$r_a' + r_b' + r_c' \ge m_a' + m_b' + m_c'$$, we need to prove that $r_a' \cdot r_b' \cdot r_c' \le \dfrac{16}{9} \cdot m_a' \cdot m_b' \cdot m_c'$.  You could do that preferentially... or let $p - a = a'$, $p - b = b'$, $p - c = c'$, we need to prove that $$\sqrt{(a' + b' + c') \cdot (a'b'c')} \cdot \left(\frac{1}{a'} + \frac{1}{b'} + \frac{1}{c'}\right)\ge \sum_{cyc}\sqrt{b'(a' + b' + c') + \frac{(c' - a')^2}{4}}$$  $\left(p = \dfrac{a + b + c}{2}\right)$ in which I don't know what to do next.

Let $m_a, m_b, m_c - $ are median of triangle $ABC$.   Prove that:   $$ m_a + m_b + m_c \le 4R + r $$   I used   $$m_a^2=\frac{2b^2+2c^2-a^2}{4}$$ $$R=\frac{abc}{4R}$$ $$r=\frac{2S}{a+b+c}$$ and $R \ge 2r$


Do i need a visa if I arrive on Emirates flight and depart to Kuala Lumpur on KLIA? I am South African.

Do I need a transit visa for a layover via airports in the UAE, such as Dubai International Airport or Abu Dhabi International Airport? If so, what are the requirements for such a visa? Can I get the transit visa on arrival?


I am an international student whose native language is not English. I am planning to apply for a Phd program in math or applied math in US in the future and general GRE test is a requirement.   From most posts , I know I should put more attention in related research experience and GRE test only matters when it's low. But I am wondering what it means exactly. I know most universities have a minimum score for TOEFL speaking session but didn't find any information about GRE general test.  My classmates told me that based on previous record, in order to get admitted by a top program (top10 or 20), both verbal (V) and quantitative (Q) can't be bad. For Q I should aim at 140 but they are not sure about V. I also checked some forums such as mathgre. I found a lot of local applicants got verbal score higher than 135. To achieve that, I must put a lot of effort which will reduce my time about research significantly.  Hence I want to know what kind of gre general score is acceptable for international applicants who plan to apply for top theoretical phd programs? Based on my understanding, most programs usually higher GRE subject score for international students, will you usually have different language requirements for local/international students (except toefl) when you review the application materials?

When applying to a PhD program in the US, how does the admissions process work? If an applicant is weak in a particular area, is it possible to offset that by being strong in a different area?  Note that this question originated from this . Please feel free to edit the question to improve it.


$3$ is clearly an example, but I can't seem to find any other. How do I prove (or disprove) that $3$ is the unique solution?

Find all $n>1$ such that $\dfrac{2^n+1}{n^2}$ is an integer.   I know that $n$ must be odd, then I don't know how to carry on. Please help. Thank you.


The method0~method4 work not well. I add this into validator of jQuery. The wired result shows. How can I fix it.   var conditions = [     {         "regexp": ".{8,}",         "message": ""     },     {         "regexp": "[A-Z]",         "message": ""     },     {         "regexp": "[0-9]",         "message": ""     },     {         "regexp": "(.)\\1{3}",         "message": ""     },     {         "regexp": "[a-z]",         "message": ""     } ];      for (var i in conditions) {         var methodName = "method" + i;         pwdRules[methodName] = true;         pwdMsgs[methodName] = conditions[i].message;          $.validator.addMethod(             methodName,             function(value, element) {                 return value.match(conditions[i].regexp) != null;             },             conditions[i].message         );     }

I am using the  validation plugin. Great stuff! I want to migrate my existing ASP.NET solution to use jQuery instead of the ASP.NET validators. I am missing a replacement for the regular expression validator. I want to be able to do something like this:  $("Textbox").rules("add", { regularExpression: "^[a-zA-Z'.\s]{1,40}$" })   How do I add a custom rule to achieve this?


If capacitors are just two conductive components sandwiching an insulator, then why aren't all PC board, or at least their traces, considered capacitors?

For the magnitude of nF or µF capacitors, I hope I can build them on a PCB board. The capacitor is like a two metal layer and something between them.   Is this possible?   Not buying the capacitor, just design the capacitor on the PCB board. Double metal layers on the PCB board.


I'm running Ubuntu 18.04.1 on a server and trying to install ) but am having trouble as I'm quite new to Ubuntu and the instruction raise errors.  The installation instructions from the project give the commands:  sudo easy_install ebaysdk   or   sudo easy_install https://github.com/timotheus/ebaysdk-python/archive/master.zip   Both of which give the error:  sudo: easy_install: command not found   I haven't been able to pip install it either because it isn't available in Ubuntu packages.  Is there another simple way to install this python package?  Many thanks  Edit: I've not been able to get easy_install to work by following answers in other posts. Is there another way to install from a url?

I am trying to install MYCROFT on Ubuntu 18.04 following this:   cd ~/ git clone https://github.com/MycroftAI/mycroft-core.git cd mycroft-core bash dev_setup.sh   I am getting this error:   sudo: easy_install: command not found   This error is because the script dev_setup.sh line 168 is trying to execute:  easy_install pip==9.0.1 # force version of pip   I have installed:  sudo apt-get install python-setuptools sudo apt-get install python-pip python-dev build-essential   However the      easy_install   command is still not recognised. Any ideas?  Update:  By commenting out that line in the script allows the script to run. However there is a module error, voice recognition module missing, when doing an audio test.


Using \section{\color{red}{text}} sometimes produces an error, and sometimes not, depending on the amount of preceding text. This behaviour is extremely cumbersome, you can add or remove harmless text to switch behaviour without finding the real source of error.  Here is a minimal example (documentclass book is important):  \documentclass{book}  \usepackage{xcolor} \usepackage{lipsum}  \begin{document}  \lipsum %  aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa aaaaaaa a  \section{\color{red}{Color}} \end{document}   I use lualatex (but also pdflatex of latex reproduces the same behaviour) This minimal example produces the following error message:  ! Package xcolor Error: Undefined color `RED'.  See the xcolor package documentation for explanation. Type  H <return>  for immediate help.  ...                                                l.31 \end{document}   If you remove one block of the aaa's, or add one \lipsum more, than the error does not appear!!  I'm not looking for a solution, to work around the problem, see  . And I actually do not care to much about, if \section{\color{red}{text}} produces an error or not, but it should do it always or never, and should not depend on the inoccent context, which actually has nothing to do with the error. I have a lot of \color commands im my text, and it was extremely cumbersome to find the real source (and moreover to find this relatively easy "minimal" example), since I had the line \section{\color{red}{text}} in my text for a long time already without any problems, and suddenly it causes an error, because some innocent text was added somewhere else. This is no fun!! ;-) I hope this can be chanced.  Thanks, Georg

i have written all the text in black color, but i get this error several times in the same page:  ! LaTeX Error: Undefined color `BLACK'.   i tried to solve it by writting this: \definecolor{black}{gray}{0,0,0} but it didn´t work.   what should i do?


The problem is from [ISLR][1] Problem 5.R.R2. The data is .     Consider the linear regression model of $y$ on $X_1$ and $X_2$. Next, plot the data using matplot(Xy,type="l"). Which of the following do you think is most likely given what you see?   The answer is:       Our estimate of $s.e.(\beta^1$) is too low.   The explanation is:     There is very strong autocorrelation between consecutive rows of the data matrix. Roughly speaking, we have about 10-20 repeats of every data point, so the sample size is in effect much smaller than the number of rows (1000 in this case).   But I could not understand it... According to my opinion, , the denominator of this equation (that used to calculate the estimation of standard error for coefficient) indicates no difference whether xi sequence is autocorrelated or not.

It  that OLS residuals autocorrelation is not always an issue, depending on the problem at hand. But why residuals autocorrelation would  the coefficient standard errors? From the :      While it does not bias the OLS coefficient estimates, the standard   errors tend to be underestimated (and the t-scores overestimated) when   the autocorrelations of the errors at low lags are positive.


I'm currently developing a game and hoping to sell it in the future. Right now I'm about to make a facebook page and release a trailer, and I realised my game has a similar name to an already existing game developer, "lucid games", and in their website they call themselves just "lucid" which is what I was expecting to call my videogame (lucid). But also it's a British studio, and I'm from Ecuador. So I was wondering if this could be an issue?

I published my game  the other day. I checked there was no game on Google Play with the same name. But today I searched for "eyeroller" on Google (Yes, I should have done it a long time ago) and realized there is a game named . They are completely different games, as you can see.  What are the legal implications of this? Can things like trademarks and copyrights be a problem? Should I change my game's name?


My friend plays 4e and he enjoys the swordmage class. He was wondering if it's in 3.5 so he can use it in a campaign I'm making. Is it?

What is the best class or classes in 3.5e to build a character that uses both a sword and either arcane magic or psionics which can be fluffed as arcane magic and focuses on fighting powerful individual creatures?    I have a foundness for those that can sling spell along with blade, like Dak'kon from Planescape: Torment.  So, given that, how do I make the best Gishy character I can?  Specifically, the group is looking for a character focused on delivering high damage or other debilitating effects to an individual target.  There is no need to balance sword and magic, though I would prefer to have the melee abilities remain at least relevant through at least mid-levels.  This question:  is related.  But I am specifically looking to optimize for high targeted damage output and have no need to balance between sword and spell if focusing on one is more effective.  I have considered the duskblade and that may be the best answer, but as I have limited experience with 3.5 I want to find out if I should use a pure duskblade, a duskblade which steps into other classes, or some other class I have not considered.  In this particular case, the characters will start at level 7, and equipment rules are liberal as long as the characters can afford it.  I'm not sure how long this will last so I am focused on the next few levels instead of trying to plan all the way out to 20.  It will be a party of 5.  Not all of the rest of the characters have been fully fleshed out, but we will have a cleric and a wizard.  The other two are more up in the air but they one is looking at various rogue classes and the other is looking at some sort of melee class, with this gishy rounding out the team.  The initial encounter is up in the air, but there is a definite fondness for gryphons.  We do know that we will be working up to dragon in relatively short order, which is a factor in wanting to focus on large damage output to individual creatures as opposed to being able to deal with numerous weaker creatures.  The setting is "modified Forgotten Realms".    I personally own absolutely no 3.5 books, but we have access to a fair bit and just about anything from WoTC is permitted.  I am new to 3.5, but I have a fair bit of roleplaying experience including AD&D.    Thematically, I envision the character as a generally honorable, but working as a monster hunter and mercenary.  I definitely favor swords though specifically which sword is flexible.  Dak'kon from Planescape would be an excellent example of what I would like to build, as would The Witcher.  Based on Kryan's excellent answer, it seems to be leading up to using duskblade and a specialist wizard to lead into Abjurant Champion.


Can someone please help me thanks!  this is where I got the image from

How do I put a backdrop behind the model that I am creating so that I can compare the picture to the model while editing?


Problem in book is, If G is a group with center Z(G), and if G/Z(G) is cyclic, then    G must be abelian. I konw how prove this but my question if G is abelian then Z(G)= G then there is no meaning of problem, am I write if not please explain me.

Continuing my work through Dummit & Foote's "Abstract Algebra", 3.1.36 asks the following (which is exactly the same as exercise 5 in ):     Prove that if $G/Z(G)$ is cyclic, then $G$ is abelian. [If $G/Z(G)$ is cyclic with generator $xZ(G)$, show that every element of $G$ can be written in the form $x^az$ for some $a \in \mathbb{Z}$ and some element $z \in Z(G)$]      The hint is actually the hardest part for me, as the quotient groups are somewhat abstract. But once I have the hint, I can write:  $g, h \in G$ implies that $g = x^{a_1}z_1$ and $h = x^{a_2}z_2$, so \begin{align*}gh &= (x^{a_1}z_1)(x^{a_2}z_2)\\\  &= x^{a_1}x^{a_2}z_1z_2\\\ & = x^{a_1 + a_2}z_2z_1\\\ &= \ldots = (x^{a_2}z_2)(x^{a_1}z_1) = hg. \end{align*} Therefore, $G$ is abelian.  1) Is this right so far?  2) How can I prove the "hint"?


So here's my situation: I'm a senior electrical-engineering major student in a decent-ranked university (60-80), and I've been working in a lab in our department and published 2 papers as the second author (conference paper, IEEE) and currently I'm in charge of two projects so I may publish more before I graduate. The thing is: I have a low GPA (2.9), but there is a reason: I've been an athlete of the fencing team in our university, and for two years I've been the vice captain of it. I have to go to practice every night, Monday to Thursday, so I don't have a lot of time to study. My boss, who got her PHD degree from CalTech, trusts me a lot so I will have a kickass recommendation. She refers me as a student who's "not very good at theoretical learning, but always creative and can solve practical problems very well." She also granted me the fellowship.  I want to go to those well-ranked engineering schools, like UIUC or Berkeley, and pursue a master's degree (and even a PHD, if possible). Although I do have a good research background, I'm worrying about my gpa. Most schools do have a gpa threshold, but is it possible for me to get into these schools? Thank you.

I have a master's degree in International Studies, and a double major with Computer Science from undergrad.  My transcripts suck.  There's no other way to dress it up.  I have pretty good teaching experience, and my GRE scores are awesome, and I suspect my recommendations are as bland as everyone else's.  Basically, to an admissions committee, I suspect I'm the model of a student who is probably smart enough but didn't work hard enough.  I want to do a Ph.D. in Political Science, but the response from my applications is looking pretty grim.  Am I permanently out of the running, or is there something I can do for the next few years which will help to counterbalance my unfavorable GPA?


I have Fujitsu Siemens Intel(R) T2080 1.73GHz 1.00 GB (894 MB usable) 32-bit Operating System in my laptop. What is the best Ubuntu for this System ?. thanks

For a given hardware configuration, how do I find out if Ubuntu will run on it? What considerations should I take into account when choosing an Ubuntu version and  such as:    with a lighter desktop than the usual Gnome and Unity  with the even lighter LXDE desktop   Obviously Ubuntu does not run on some processor architectures. So how do I go about choosing the right version and derivate. How can I find out the minmal system requirements?


I have multiple text file around 2000 text file in folder. I want to remove those file which are blank file.

This will notify us if the file is empty:  [[ ! -s $file ]] && echo "hello there I am empty file !!!"   But how to check if a file has blank spaces (spaces or tabs)?   empty file can include empty spaces / TAB


Let $(G, ·)$ be a group, and let $a, x$ ∈ $G$. Show that the orders of $x$ and   $axa^{−1}$ are equal.   My attempt:  In order to show that the orders of $x$ and $axa^{−1}$ are equal, I have to show that $axa^{−1}$ = $x$.   Since $G$ is a group, we have that $axa^{−1}$ = $a.(x.a^{-1}) = (a.x).a^{-1}$ (associativity) = $a^{-1}.(a.x)$ (commutativity) = $(a^{-1}.a).x$ (associativity) = $e.x = x.e = x$ (property of the identity element).  Hence, I've shown that $axa^{−1}$ = $x$, and so their orders are equal.  Is my proof correct? Did I make a mistake somewhere? Do you have other suggestions?

I am trying to prove that any conjugate of $a$ has the same order as $a$.  Let $G$ be a group and let $a \in G$.  An element $b \in G$ is called a conjugate of $a$ if $b=xax^{-1}$.  My professor gave us a hint.  Prove $a^k=e$ iff $b^k=e$ for all $k \in \mathbb{Z}$ implies $o(a) = o(b)$.  My first move is to $b^k = (xax^{-1})^k = (x^{-1})^ka^kx^k = (x^{-1})^kex^k = (x^{-1})^kx^k=x^{-k+k}=x^0$  I am not sure that I am doing this correctly?  I am trying to get $b^k=e$.  However when I raise $(xax^{-1})^k$, I am not sure if I what I have done is correct?  I am kind of confused here.


I create digest of articles, and I need to use package \usepackage{nimbussans} on the title page. But when I included and use it, I have a lot of troubles with all the rest document -- there is not working textbf{} and \bf for example. How I can disable this package? Or include it only on one page. MacOS, MacTeX, write in VS Code with LaTeX add-on.

The standard font packages make global changes to the fonts in my document. What if I want to use a particular font for just a portion of my text?   How do I find the right name of the font? How do I select the font? How do I restrict the scope of the font change?     There are separate answers for different flavors of TeX (quick links):


I am an Indonesian passport holder living in France, married with a French citizen and have a Residence Card. Do I need DATV (Transit visa) in Heathrow, London for my 6 hours transit for my flight to Qatar? I will not have immigration clearing, just airside transit basically. Thank you for any answer and help.

Is there a website or some other way to find out if I need a transit visa for a short stop in the UK on my way somewhere else? Ideally this should give me the answer for all nationalities, and take into account any other visas I may have.


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


I would like to extend polylines (roads) to existing points (addresses points). Mostly driveways that are very close to the points. Extend Line does not do it since it requires a specified distance and that varies from case to case.

Is there an efficient way to extend lines to points in ArcMap? I have a utilities dataset, where I do not want to change the original geometry, but instead add to it in order for end vertices of lines tor each to the nearby junction points.   I would not want to do this manually thousands of times. Is there a way to extend lines to points? I have tried extending the lines to themselves then snapping all within a certain tolerance, but this alters the original geometry. I have also tried integrating the lines, but again, it alters the original geometry.  After thinking a bit more, I am going to try and create points at the end vertices, then create lines from points using selected end vertices and the junctions, then I will merge the lines with the original polylines. My only concern is ensuring the attributes are appropriately merged and how to obtain an appropriate selection.  I do not want to extend all lines, only certain ones.  The rule is hard to put logically, but some lines used to intersect a cad feature, and others just ended near them...


I'm used to rendering heavier files but cycles isn't rendering the one I'm currently working on for some reason, it renders just fine in the viewport even with the sampling increased exponentially and it still only takes around 60mb of memory but when I render the scene it says out of memory and doesn't render. plus the model isn't visible through the camera with viewport render.

Essentially, my problem is that i am trying to render a scene, however, blender crashes on me early during the render. I only have about 14 total objects in the scene. (It's not that complex) I tried to render a different blender file which was bigger than the one that i am having problems with, and the scene renders just fine. There is no difference in the render presets for both of these files. However, i still cannot render the other scene. It gets to preparing scene data, but then it crashes.  Thank you.


I need help in this question please I have tried several times. Create a file, /home/jack/secretf7b079, containing the string secret5cd51b. Make sure the file is owned by jack. Use a group to enable cedric to also read the file, but not write to it. Make sure pedri can't access the file. The code I have used by jack user: cat > /home/jack/secret7b079 and include the string secret5cd51b. sudo adduser cedric jack, to add the user cedric to jack group. chmod 640 /home/jack/secret7b079 Thanks!

I'd appreciate help with a couple questions regarding standard file permissions. Assume that I'm not using access control lists.     If a file is associated with multiple groups, must all groups have the same permissions?   If the group permission includes write access, can any member of any group the file is associated with change the file permissions? Can such a person change the file owner?   Say now the file permission is rwxr----- (owner can do everything, but group members can only read). I am in the group associated with the file. I am also the file owner. Which permission am I granted? Read-only, or rwx?


Every day my computer says it has updates that I have to click and install. Now, the updates have settings in which I can supposedly control what is being checked and how often, and what to do when updates are being found.   Yesterday I only left the Important security updates checked (and I unchecked Recommended and all that other stuff), and under Automatic updates section I set to check Every fortnight (which is the rarest possible option).  Then I selected the option to Install security updates without confirmation. It asked me for password to make the changes, and then saved. Today I got on my PC, and again, I get the notification that updates are available, and it's waiting for me to click to install them.   For what difference it might make, I have the "regular" Ubuntu 18.04. installed with KDE desktop manually installed afterwards.   Can I get it to not ask me about updates, ideally ever?  If this is not possible, how can I have it at least respect the Every fortnight option so I don't have to click it every day?

I read  how to enable silent automatic updates for Google Chrome. However, I have other repositories like spotify, docky and others for which I would like to enable silent updates.   I am trying to do this in my Ubuntu 10.04 system. But this question applies to all Ubuntu versions. I have the unattended-upgrades package installed.  How can I do this?


Is logistic regression a linear model which separates the two classes with linear decision boundary?   Can we use logistic regression for non linear problems as well?   I looked at python sklearn and I don't see how to make a non linear logistic regression, so wondering if logistic regression cab be applicable for non linear problems as well.  Considering the hypothesis function h(theta) = 1/1+exp(z)  where z is theraT * X. I hope we can make z as a non linear function by increasing the degree. Does it affect the linear decision boundary to be a non linear?

Since we are using the logistic function to transform a linear combination of the input into a non-linear output, how can logistic regression be considered a linear classifier?  Linear regression is just like a neural network without the hidden layer, so why are neural networks considered non-linear classifiers and logistic regression is linear?


If I use \begin{align*}...\end{align*} and out of it I write a text then there is a big vertical space between the text and the mentioned environment. Why is there that space? And how can I erase it? Also in this case I think that the vertical space is too much. For example in tabular environment or other environments there is much less vertical space. Why is align environment different?  \documentclass[12pt]{article} \usepackage[top=0.3in, bottom=1.2in, left=0.8in, right=0.8in]{geometry}  \usepackage{multicol}  \usepackage[utf8]{inputenc}  \setlength{\parindent}{0cm}  \usepackage{setspace}  \usepackage{xltxtra} \usepackage{xgreek} \setmainfont[Mapping=tex-text]{GFSDidot.otf} \setsansfont[Mapping=tex-text]{GFSDidot.otf}  \usepackage[fleqn]{amsmath} \usepackage{unicode-math}  \setlength{\mathindent}{0cm}  \newcommand{\3}{\vspace{0.3cm}}  \title{} \author{} \date{}  \begin{document}  \begin{multicols*}{2}   70 \begin{align*} &e^{jz}=\cos z+j\sin z\\ &\cos z=(1/2)(2\cos z)=\\ &=(1/2)(2\cos z+j\sin z-j\sin z)=\\ &=(1/2)(\cos z+j\sin z+\cos z-j\sin z)=\\ &=(1/2)(e^{jz}+e^{-jz}) \end{align*}   \end{multicols*} \end{document}     70  \begin{align*} &e^{jz}=\cos z+j\sin z\\ &\cos z=(1/2)(2\cos z)=\\ &=(1/2)(2\cos z+j\sin z-j\sin z)=\\ &=(1/2)(\cos z+j\sin z+\cos z-j\sin z)=\\ &=(1/2)(e^{jz}+e^{-jz}) \end{align*}

I need to display math in my report, but is it possible to remove the vertical space around align*?  A little example is the following (where I just want the align* to have the same vertical space as a \\  \documentclass[10pt,danish,a4paper,oneside,fleqn]{report}  \usepackage[english]{babel} \usepackage{amsmath}  \begin{document}  ssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss \begin{align*}   A{\cap}B\ & =\ {\left\{{b,d,e}\right\}}{\;}{\cap}{\;}{\left\{{a,b,f,g}\right\}}   \\   \nonumber\ & =\ {\left\{{b}\right\}} \end{align*} ssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss \\ ssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss  \end{document}


My bicycle tire specification is 40-622 (700x38C-28x1 5/8 x 1 1/2), would you please tell me the right size of the proper inner tube?

If you had 35mm tires (Schwalbe marathon supremes to be specific) would you get innertubes speced as 28-35mm or 35-42mm? Or whichever is cheaper?


I have always been told and understood that rainbows occur from water droplets and the light gets dispersed into its colors. I also understand that light travels in straight lines. This might sound like a stupid question but it most likely has a simple answer: Even though light travels in straight lines, why do rainbows appear to be bending?

From the article that I read on physics classroom website on rainbow, rainbow is formed with red on the top and violet on the bottom because violet refracts more, and has a smaller angle of deviation and red refracts less and has a bigger angle of deviation. So the red light rays come out of the water droplet steeper than do the blue rays. This steepness requires you to look higher up in order to see the  red part of the rim.  Here is also an  I saw of my question on PhysicsSE.  But the answer to that question doesn't really answer my particular question about the concepts of the formation of rainbow.  Two questions:   Water droplets being so small, and the width of rainbow so big, how then is the whole rainbow still shown in ROYGBIV, but not composed of rainbows of smaller width, the colors of each too shown in the order of ROYGBIV?  What is described in the PhysicsClassroom seems to only work for the very top portion of the entire rainbow that is horizontal. I don't see how it would work for the vertical portion, the part where the rainbow starts from the ground. At this portion, the observer does not have to change his/her angle of viewing in relative to the ground in order to see the two (violet and red) extremes of the color band.    please attach a picture of a single droplet and how rays from the Sun comes in and out of the droplet and into the observer's eye.


This may seem like a stupid question.  I'm using Ubuntu 15.10 with GNOME Terminal 3.16.2. When I was new to the system, I often typed 'l' or 'la' instead of 'ls' to list files, and would then be told that these were not valid commands. I obviously then typed 'ls' properly. Now I notice that typing 'l' and 'la' do the same thing as 'ls'.  What's going on here? Has the terminal learnt the common mistakes that I make, and made aliases to account for them, or is this a new feature that I've installed without realising?

I just mistyped ls as la. Without noticing, I ran it:  tim@Hairy:~$ la detection.sh   output-2.jpg  output-4.jpg  output-6.jpg  output-8.jpg Test1.pdf output-1.jpg   output-3.jpg  output-5.jpg  output-7.jpg  output-9.jpg          tim@Hairy:~$ ls detection.sh   output-2.jpg  output-4.jpg  output-6.jpg  output-8.jpg Test1.pdf output-1.jpg   output-3.jpg  output-5.jpg  output-7.jpg  output-9.jpg    What's the difference between ls and la?


Once I start Ubuntu, it blinks between a black screen with the cursor in the bottom right and a terminal-ish window.  After a bit, it gets stuck on the screen shown in the image. All I can do is go through tty 1-6. Any suggestions?  (Sorry if it’s a dumb question)

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


I want remove all <audio> shortcode in my post with preg_replace, but that dosnt work for me:  $content = preg_replace('#<audio>(.*?)</audio>#', '', $content);

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


After being marked as duplicate:  Ok I see that now this is a duplicate, and I apologize for a seemingly silly question. It's just from my perspective it was difficult to realise what to "search" online to solve this problem because I didn't know using == with strings in this manner was a problem to begin with! Even so, I'm still wondering why is using the test array still work in the for loop at the bottom of the code despite it checking with == and not .equals() but it doesn't work for the array created with stored Scanner input? It's because one of these methods still worked in finding p with == and not .equals() that made me think it was the method of storing the array that caused the problem and look in the wrong places for answers.  Problem:  I'm trying to make a simple AI for a problem I'm working on in Java, and part of it requires storing user input with the Java Scanner library in order to make an array of strings that represents a game board or "grid". I decided to store the input of this array "grid" one by one, asking the user to enter element for the current array position. The array is a 2-dimensional array and the input is stored one by one via two for loops one nested in the other as you can see near the start of the code I have provided below. I made a method called displayGrid that prints out the contents of 2-dimensional array in the form of a grid and it seems to take in the input correctly and the board displays correctly.  However when I try to search this "grid" after storing it with input (by using for loops as you can see near the end of the code snippet) the if statement there can't seem to verify as true even when I have stored the letter "p" in the first part of running the program when the Scanner is storing input into the array, and the displayGrid method actually prints out the array correctly showing there is in fact a "p" in the array. In any case, this part of the code is supposed to check if there is a "p" in the array and if there is return it's column position which I tried doing but it always returns 0 since it cannot verify that if statement as true.   The strangest thing though is that if I make a test array that is composed of strings as you can see at the very start of the code, and try the loop at the bottom of the code on this test array it does find "p" and print it's column value.   So are there any ideas why the loops at the bottom cannot find the "p" value of an array created from the scanner inputs near the start of the code - even when my displayGrid method shows that this array does contain a "p"? Thanks in advance!  Note: I haven't included rest of the code because it was largely irrelevant, but I can post it if it's really needed.   public static void main(String[] args) {     // tests     String[][] test = {{"-", "p", "-"},{"-", "-", "-"},{"-", "-", "-"}};      // running main program     Scanner in = new Scanner(System.in);      int n = 0, boardSize;     boardSize = n*n;     do {         System.out.print("Enter n dimension of your game grid (for an nxn sized board): ");         n = in.nextInt();     } while(n < 3 || n > 100 || n % 2 == 0);      String grid[][] = new String[n][n];      System.out.println("Please enter the contents of your array now.");      for (int row = 0; row < n; row++) {         for (int col = 0; col < n; col++) {             System.out.print("Enter element at grid location: [" + row + "] [" + col + "]: ");             String temp;             temp = in.next();             grid[row][col] = temp;         }     }      // display grid for testing     displayGrid(grid, n);      // test     for(int row=0; row<grid.length; row++) {          for(int col=0; col<grid.length; col++) {              if (grid[row][col] == "p") {                 System.out.println(col);             }         }     }

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I'm using this template style found here: .  I used Bibdesk to create my .bib file. The citekeys weren't working, I was simply getting [ ?] for every citation, so I replaced them all with hand done references, and am trying to create the bibliography using  \cite{*}. However, it's not creating a bibliography and I'm getting no error messages explaining why.   This is the excerpt from the main.tex file that references bibliographical stuff. I've been reading through similar problems but haven't found anything that worked for me. Thanks for any help!  \lhead{\emph{Bibliography}} % Change the page header to say "Bibliography"  \bibliographystyle{unsrtnat} % Use the "unsrtnat" BibTeX style for formatting the Bibliography  \bibliography{Bibliography} % The references (bibliography) information are stored in the file named "Bibliography.bib" \nocite{*} % pulls everything in the bibliography file.

I've browsed the forums and found a number of posts that have addressed this issue, but none of the solutions seem to work for me. I have the following script that I just copied from the bibtex home page to get familiar with it. Instead of the citation number I get a question mark. I compile using Latex+Bibtex+Latex+Latex+PDFLatex+ViewPDF just as has been previously suggested and the problem persists.   \documentclass[11pt]{article} \usepackage{cite}  \begin{document}  \title{My Article} \author{Nobody Jr.} \date{Today} \maketitle  Blablabla said Nobody ~\cite{Nobody06}.  \bibliography{mybib} \bibliographystyle{plain} \end{document}   My bibliography (Bib.bbl)  @misc{ Nobody06, author = "Nobody Jr", title = "My Article", year = "2006" }    Looking at previous posts one thing that is concerning is that my .bbl looks empty as shown below. Further, I don't have a .blg  \begin{thebibliography}{}  \end{thebibliography}


First of all I'm reposting this question as at the previous one I haven't got the   satisfactory answer. The problem is : If $G$ be a group and $H, K\le G$.  $\mid G:H\mid$ and $\mid G:K\mid$ are co-prime.Show that $G=HK$.  My attempt to to prove this : First considering a map $\phi :L_1\rightarrow L_2×L_3$ where $L_1, L_2$ and $L_3$ are left cosets of $H\cap K, H$ and $K$ respectively. Now ,just proving that this map is injective and will be surjective iff $G=HK$shows that $\mid G:H\cap K\mid=\mid G:H\mid \mid G:K\mid$. Now the result $lcm(\mid G:H\mid,\mid G:K\mid)\le \mid G:H\cap K\mid \le \mid G:H\mid \mid G:K\mid$ implies the required result.But my question is how to prove the required result without going through the mapping part.I have posted the result previously, but haven't got the satisfactory answer.Please help me to prove this.

I'm struggling to proof that if $H$ and $K$ are subgroups of  finite index of a group $G$ such that $[G:H]$ and $[G:K]$ are relatively prime, then $G=HK$. I don't know why I can't answer it, because this question seems easy. I'm stuck maybe because I've studied so far just Lagrange's theorem and some of its consequences. But I think we don't need much more, because this is the material covered so far by the Hungerford's book.  I need help.  Thanks.


Let $(\Omega, F,P) $ be probability space.  If $X\in L^1(\Omega)$ , show that: $\forall \epsilon >0, \exists \sigma >0$ such that: $$ [\forall A\in F : P(A)<\sigma ]\Rightarrow   [\int_A |x| dP $$

Hello all mathematicians!! Again, I am struggling with solving the exercises in Lebesgue Integral for preparing the quiz. At this moment, I and my friend are handling this problem, but both of us agreed this problem is a bit tricky. The problem is following.   Let ($X,\mathcal{A},\mu$) be a measure space and suppose $\mu$ is $\sigma$-finite. Suppose $f$ is integrable. Prove that given $\epsilon$ there exist $\delta$ such that   $$ \int_A |f(x)|\mu(dx) \;\;<\;\;\epsilon $$  whenever $\mu(A) < \delta$.  Could anybody give some good idea for us? Think you very much for your suggestion in advance.


So, I've got Skyrim downloaded and everything, my computer more than meets the requirements and when I go to press the play button on the startup window nothing happens.   I've updated my video card drivers, updated my firewall setting, and searched google for any related problems people are having with the game. The only thing that I can find is that people are having the game crash due to some sound problem.   Well, I would try some of the solutions to that problem but my game won't even start at all.  Any ideas?

Whenever I boot up Skyrim, it crashes as soon as it reaches the main menu with no dialog or anything. I thought this was related to my using dual monitors somehow, but I disconnected the other monitor and the game still crashed. I tried running the game in different resolutions, both full-screen and windowed, at various quality settings; no dice. My computer does meet the minimum requirements to play Skyrim.  How do I fix this problem?


Let's suppose I am making a library in C, that contains functions api1(), api2(), and api3(). However, those functions are very complicated, so I need other functions to make them. Let's call those functions subfunc1(), subfunc2(), and subfunc3(). What I want is that the users of this library can only use api1,2,3() and not subfunc1,2,3(). I can't just declare them static, because I want to place api1,2,3() into api.c file, and subfunc1,2,3() into subfunc.c file. So my questions are:  Is there any way to achieve this, besides including subfunc.c file into api.c file and declare subfunc1,2,3() as static? If including subfunc.c file into api.c file is the only way to achieve this, is it recommended? Is it widely used in practice? If not, why?

Some platforms mandate that you provide a list of a shared library's external symbols to the linker. However, on most unixish systems that's not necessary: all non-static symbols will be available by default.  My understanding is that the GNU toolchain can optionally restrict visibility just to symbols explicitly declared. How can that be achieved using GNU ld?


We are searching for an API that lets you create your own deals for your own mobile app. Seems stackoverflow might be aware of it but still is not a software question. Which stack exchange site is the most appropriate? Thank you

I have a list of requirements for a program, but I don't know what program meets these criteria. That's about general-purpose software, for example, not a programming IDE or statistical workbench, questions about which would certainly go to respective sites.  Is this question appropriate on Stack Overflow? Where should I ask about it? On Super User or elsewhere?


How is it possible to calculate modulo of the following equation:  $3^{P^5} \mod P$  If $P$ is a really big prime number 174449211009120179071170527.  Thanks

I've read about Fermat's little theorem and generally how congruence works. But I can't figure out how to work out these two:   $13^{100} \bmod 7$ $7^{100} \bmod 13$   I've also heard of this formula:  $$a \equiv b\pmod n \Rightarrow a^k \equiv b^k \pmod n $$  But I don't see how exactly to use that here, because from $13^1 \bmod 7$ I get 6, and $13^2 \bmod 7$ is 1. I'm unclear as to which one to raise to the kth power here (I'm assuming k = 100?)  Any hints or pointers in the right direction would be great.