I want to customize which app is used to open all unknown plain text files from Quick Look. For example, for extension-less VERSION file, Quick Look shows Open with TextEdit:    I'd like to make VSCode the default editor for unknown file types.  BTW, to even achieve a textual preview of the VERSION file, I had to install .    UPDATE & solution: This question is indeed closely related to , the problem was that neither of the answers mentioned public.data which was necessary for the VERSION file in this example. (Without 'public.data', VSCode was offered for .txt files but not for extension-less files.)  I've updated  to that question to include info about 'public.data', in which case this question is really a duplicate of .

I've seen questions  which don't quite solve my problem.  I'd like to make Sublime Text 3 the default file viewer/editor for all files that currently use textedit.  Most of these files can be command+i'd, but the ones that have no extension cannot. They give all sorts of permissions errors such as the ones in this image   Is there any way to just never use textedit, and instead set sublime as the default editor for all files?


debcargo is a Debian package for packaging rust apps in .deb format. It is  in Debian Buster and above, but I  the package in Ubuntu 20.04 and 20.10. Why is the package not available in Ubuntu? Is it available under some other name?

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


Hi is there any way to have itunes on Ubuntu 14.04? I really need to have this option. I have tried the playon linux option but that seems outdated and does not work. I also tried Vitual box but mu computer has USB 3.0 which is not supported.

I have an iPhone and run Ubuntu on all of my personal computers. Since I did not want to keep a separate partition with Windows on it for the sole purpose of running iTunes, I attempted to install It using Wine.   I installed Wine 1.4 from the Software Center and installed iTunes 10.6.3. When I tried to run it I got a slew of error messages. I hopped over to google where it was suggested that I install it through PlayOnLinux. I did so with the same result. Further googling revealed that iTunes 10.6.x is confirmed to work with Wine 1.5.1 and up.   I installed Wine 1.5.1 following the instructions I found and was unable to get it to open. I did the same with 1.5.9 with the same results. I opened the Package Manager and installed the Wine 1.5.9 packages through it, and it appears to have installed properly.   When trying to install iTunes I got he error "This iTunes installer requires Windows Vista 64 bit or later". Realizing that Wine uses XP as a default I ran winecfg and changed it to Windows 7. This changed nothing and I tried changing it through winetricks to no avail. I even changed it to Vista with the same results.   Does anyone know what is going wrong here and how to fix it? Thanks


I am getting too many query rows 50001 error while running this class method from execute anonymous.  I got same error when annotating execute method in scheduled class with readonly annotation as well. This is where i will be using this in real scenario.  I was expecting i should be able to count upto 1 million rows using readonly. I need to count more than 50000 records.  What am i doing wrong :  public class Test_Aggregate {     @ReadOnly     @RemoteAction     public static void TestAgg() {         List<Custom_Object__c> custList = [SELECT Id  FROM Custom_Object__c];         System.debug('No of records are: '+custList.size());     } }  Test_Aggregate.TestAgg();   why did the below not work as well and threw same SOQL row limit 50000 row error :  AggregateResult logResults = database.query('SELECT COUNT(id) result FROM Custom_Object__c'); integer recCount = Integer.valueOf(logResults.get('result')); System.debug('No of Log records are: '+recCount);   Why does salesforce documentation says : The @ReadOnly annotation allows you to perform unrestricted queries against the Force.com database. It appears misleading. I am not doing any DML etc.  All i am asking is for a simple statistic about my object which stores my data. These statistic seem to be gathered every 24 hours. Why platform does not provide any API so that it can be easily accessed. I have heard of hacks where people scan the html of setup page to get it. Why is platform so limiting that i cant get it without running into limits.

i need to count total number of records in an sObject which can have around one million records. Will the code below work ? If no, how can this be done ? I dont need to use this in a vf page.   I will be using this COUNT() SOQL Query in a batch class which is scheduled to run at specific time.  AggregateResult results = database.query('SELECT COUNT(id) result FROM someSObject');     System.debug('No of ids are: '+results.get('result'));


I updated from Ubuntu 16.04 to Ubuntu 18.04 about 4 months ago and it worked properly for a while, but then I started getting a problem with a login loop. I can drop down into the command line and run commands, but I want to login into the GUI environment.   Emby was put on an old Windows 8 converted to 10 computer that I used.    ASUS M Series M51AC Tower Core i7 4770 3.4 GHz RAM 16 GB HDD 1 TB BIOS Version: 0901 SN:  XXXXXXXXXXXX    Display Hardware:   Results of lspci | grep VGA   01:00.0 VGA compatible controller: NVIDIA Corporation GF119 [GeForce GT 620 OEM] (rev a1)     Kernel Driver:   Results of  find /dev -group video    /dev/dri/card0     /dev/dri/renderD128     /dev/fb0       What x.org is using:  Results of egrep -i " connected|card detect|primary dev|Setting driver" /var/log/Xorg.0.log  [    70.690] (--) NVIDIA(GPU-0): Acer X223W (CRT-1): connected [    71.191] (--) NVIDIA(GPU-0): Acer X223W (CRT-1): connected [    95.213] (--) NVIDIA(GPU-0): Acer X223W (CRT-1): connected   Linux OS:  Results of lsb_release -a    No LSB modules are available. Distributor ID: Ubuntu Description:    Ubuntu 18.04.3 LTS Release:        18.04 Codename:       bionic   IP Address:  Results of dig +short myip.opendns.com @resolver1.opendns.com     xx.xx.xxx.xxx   I have tried fixing this several times, but haven't been able to fix it. I do have the IP address.

My Ubuntu is stuck in a login loop when trying to enter my desktop. When I login, the screen gets black and soon after that the login screen comes back.   I've read that the problem might be caused by an error depending on the graphics, here's my graphics card: ATI Radeon 7670M


I want to make a copy of an object, then after some logic, re-assign the original object the value of the copy.  example:  User userCopy = //make a copy  foreach(...) {   user.Age = 1;   user.ID = -1;    UserDao.Update(user)     user = userCopy;   }   I don't want a copy by reference, it has to be a copy by value.  The above is just a sample, not how I really want to use it but I need to learn how to copy by value.

It's a bit difficult to implement a deep object copy function. What steps you take to ensure the original object and the cloned one share no reference?


Let $a=(a_na_{n-1}…a_o)_b$ and $s=\sum_{i=0}^na_i$ Show that if $b-1 \mid a \iff b-1\mid s $. I’ve found this problem in the number theory book that i read. I think if the Base was $10$, it would be more simple, however i don’t know how to prove this.

I was showing my son how to cast out nines the other day.  He noted that based on the way it worked, we should be able to cast out 7s when we work with octal.  We tested this in several bases and it seems to work.  I am assuming the chance for false positives increases with the decrease in radix (but I don't actually understand the theory well enough to be sure).  But then we got to binary where everything seemed to be a false positive (my son got a huge kick out of the false positive when I showed it to him).  First question:  Are there any articles on check sums (like casting out nines) for other radix and their false positives.  And other methods that avoid the false positives?    Second question:  Is there any check sum for binary that doesn't take longer than the actual calculation (right now we convert to another base and check it, but that takes longer than actually doing the operation)?  Third question: Also, I have seen one book that talked about casting 11s (alternate subtracting and adding the number up starting from the right, and adding 11 if it is negative).  Has anyone seen a detailed explanation of it?  We could not make it work in other bases--any suggestions?


I want to change the CMD startup directory when I launch it via Start+R Currently, it points to my users folder. I need it to point to C:\Windows\System32\ When I navigate using explorer to C:\Windows\System32\ and run CMD from there (Shift+RightClick on an empty area), it starts in the desired path. When I run from Win+R, it starts from the users folder. I suspect I need to change the registry or an environment variable. Anyone knows how to ? THIS QUESTION IS DIFFERENT FROM THE OTHERS FOR THE REASON EXPLAINED BY @KARAN (READ THE THIRD COMMENT FROM THE ANSWERS BELOW) DIFFERENT ANSWERS ONLY WORK FOR SHORTCUTS Edit: Found the right answer hidden on the pit of the provided links, kilometers away from the supposed "right answer" [HKEY_CURRENT_USER\Software\Microsoft\Command Processor] "Autorun"="cd C:\Windows\System32\"

So, I know you can create a shortcut to an administrator-level command prompt (as described in ), but what I'm seeing is that whenever I use such a shortcut, it always drops me into c:\windows\system32\ path.   I've tried specifying that shortcut's properties to set the "start in" path I need, but to no avail. It seems any time I run cmd.exe "As Administrator," it completely disregards the shortcut's paths and sticks to c:\windows\system32\  Any suggestions on how to get Windows 7 to respect the shortcut's "start in" path?


I would like to move my current installation of Ubuntu 11.10 to a bigger harddisk, since the old one is failing.  I would like to avoid solutions like dd block copying (since there would be unused space at the end) with something cleaner, but I'm open to suggestions.  Partitions info:  Size  Used Avail Use% Mounted on Partition type Encrypted 19G  9.9G  7.6G  57% /           ext4 59G   50G  6.2G  90% /home       ext4           Yes   What is the best way to accomplish such a task, preferably with advantages/disadvantages of any given approach.

The HDD I have my Ubuntu installed is about to fail. I would rather not lose 3 years worth of data, customisation and apps. I am looking for a way to move the complete system (SWAP included, because I'm not sure if I can relink the system to a new SWAP partition) to another HDD. But not the complete HDD< only the partition containing Ubuntu, to a partition on a different HDD. Basically I'd like to do what I've been able to do with Norton Ghost for my Windows install. I thought about using Clonezilla but I think I would have issues with GRUB (Especially trying to boot from a different UUID than what is in the conf file). do you know of any way this could be done?  PS, my home directory is encrypted but that's not really an issue, because I can work around that.  EDIT: changed the explanation to make it clearer


I have a shapefile which looks like this (this is a snippet of it):    I would like to create a grid in a new shapefile which will be overlaid (that's not a technical term, I'm just not sure how to describe it) on this map.    The grid should be comprised of equal sized polygons, except by the borders where they can (and in all likelihood will) be smaller. It should look like this:    I have tried using the Create Fishnet tool in ArcMap to accomplish this, but this gives me a grid which is always rectangular and does not stop at the borders of the original shapefile.  How do I create this shapefile?

I have created a fishnet grid (3km x 3km) over a vector polygon.   I now want to clip the fishnet over the vector polygon retaining all grid squares within the boundary of the polygon.   Therefore I want all squares that would typically be clipped into partial squares to remain as whole squares.   Does anybody know how to do this?


$\displaystyle\sum_{i=0}^{k-1}2^i=2^k-1$ for all $k \in\Bbb N$.  Clearly, the first step here is easy. You can start with k=1 and solve to get  $2^0=2^1-1$.  What is a bit more challenging is the induction step. I don't even know where to begin here. Where would I even begin?

Prove mathematical induction $$\sum_{i=0}^{k-1} 2^i = 2^k-1$$


There are many types of CPUs, like Pentium, Atom, core 2 duo, core iX (X = 3,5, ....), But I always don't look at them this way! I always look at their speed which in GHZ unit and then compare them with each other. For example when some CPU is in type of 'X' with 2 GHZ of speed and another one is in type of 'Y' with 2.2 GHZ of speed, I say the second one ('Y') has better speed and also better performance.  Is it a correct way?

Today, comparing processors is obviously not just looking at the frequency and the number of cores.  When choosing a new PC, how do you compare processors? Is there some resource, like a site or something that does (not necessarily super-precise) processor comparisons?  Thanks.


I do not understand the concept of pass by value in C. Here is my function:   void add(int x){    x = x+1; }   and when I call the function:  int y=3;   add(y);   but when I compile, I still get 3. I've been told it has something to do with pass-by-value but I still do not understand? Can anyone explain why?

What is the difference between    a parameter passed by reference a parameter passed by value?   Could you give me some examples, please?


I deleted a post today on Hinduism SE and am not able to see the deleted post for undeleting or editing it. Reputation is not yet adequate.

Today, I saw -50rep added to my reputation in my Movies.SE account, as a result of deletion of a user. So definitely one or more answers to his question(s) was/were deleted. So is there a way to see the deleted posts?


I'm travelling from Singapore to Lucknow (India) with transit at Bangkok. Here are the flight details:  Singapore - Bangkok : Thai Airways Bangkok - Lucknow : Thai Smile  Do I need a transit visa at Bangkok? I am getting mixed info that's why seeking more info if someone had travelled this route before.  I have travelled from Singapore to other Europe, India and Japan before and both legs were on Thai Airways and I didnt require a transit visa at BKK.  But in this instance, my second leg is on Thai Smile so not sure probably they follow the same rules.

Im an Indian citizen. Do I need a transit visa in Thailand while going to Angkor Wat from Kolkata (India), and can I stay in Thailand for two days on this transit visa?


I need the latest version of HPLip on my computer to fully support a new printer. I already have HPLip and HPLip GUI installed from the Ubuntu repositories. HP offers a .run based installer to be run in bash. Should I remove the HPLip deb packages before I run the HP installer, or will the HP installer update current version? I am afraid to just try since I may mess up the printer sub system not knowing how to fix it.

Let's assume that one has some HP printer and/or scanner and checked its support status on the corresponding page of HPLIP site - .  So one have the following information: the device Model name, Min. HPLIP Version and Driver Plug-in need.   What should one install to make Ubuntu fully support the HP printer and/or scanner?


In the derivation it is assumed that all the rays meeting at a point are parallel but then parallel rays don't meet at a point and no interference can take place if they don't meet at a point. So if they meet at a point then they are not really parallel if they aren't parallel that means that subsequent rays coming to the same point would nat have the same path difference of exactly lambda thus no bright spots would be seen. So its crucial for us to assume the rays to be parallel but in reality its not possible and even a small difference can not be neglected here as a lot of rays are interfering at the same point so the rays need to be exactly parallel so How is it justified to assume that the rays are parallel in the derivation?

In learning to derive the diffraction grating equation to form an interference pattern on a screen parallel to the diffraction grating, this kind of image is used extensively:    Then as normal, $AB = d$, $AC = n\lambda$ then $d\sin\theta = n\lambda$  This assumes the lines are parallel. However, in every derivation I've searched, it states this, but not if this is an approximation as my intuition states:  My possibly flawed understanding is that these 3 light rays shown in the picture would converge onto a single point and constructively interfere, creating a maxima, however this means that these light rays aren't parallel.  Is there something I'm missing? Are they parallel enough to ignore the small differences in angles, or are they actually parallel?


I was viewing the solution provided by StubbornAtom in the following question:   Specifically, some of the steps aren't clear to me:    When computing $\lambda(\bf{x}) = \frac{sup_{\theta_1 = \theta_2} L(\theta_1, \theta_2)}{sup_{\theta_1,\theta_2} L(\theta_1, \theta_2)}$, as outlined by the user, one can show that the MLE under $H_0$ is given by $\hat{\theta} = \frac{\sum_{i = 1}^{n_1}x_i + \sum_{i = 1}^{n_2} y_i}{n_1 + n_2} = \frac{n_1\bar{x} + n_2\bar{y}}{n_1 + n_2}$, and the MLEs of $\theta_1$ and $\theta_2$ are given by $\hat{\theta_1} = \bar{x}$, $\hat{\theta_2} = \bar{y}$, so that one gets likelihood ratio given by $\lambda(\bf{x}) = \frac{L(\hat{\theta}, \hat{\theta})}{L(\hat{\theta_1}, \hat{\theta_2})}$. However, the user then claims that, after simplification, this likelihood ratio becomes $\lambda(\bf{x}) = \text{constant} \cdot(\frac{n_1\bar{x}}{n_1\bar{x}  + n_2\bar{y}})^{n_1}(\frac{n_2\bar{y}}{n_1\bar{x}  + n_2\bar{y}})^{n_2}$. How does the user get this simplified version of the likelihood ratio ?  How does the user see that $2n_1\bar{X}/\theta_1 \sim \chi_{2n_1}^2$ and $2n_2\bar{Y}/\theta_2 \sim \chi_{2n_2}^2$ ?  Where does the conclusion that $\lambda(\bf{x}) < c \iff$ $v < c_1$ or $v > c_2$ come from ? Also, in a formal hypothesis test, does this give us our rejection region ?    Edit: To expand upon my first question, here is what I get when computing the likelihood ratio :   $$\lambda(\bf{x}) = \frac{\bar{x}^{n_1}\bar{y}^{n_2}}{\left( \frac{n_1\bar{x} + n_2\bar{y}}{n_1 + n_2}\right)^{n_1} \left( \frac{n_1\bar{x} + n_2\bar{y}}{n_1 + n_2}\right)^{n_2}}$$  Thank you for your time!

I am trying to solve this complicated Generalised Likelihood Ratio Test problem for 2 samples as part of my independent study course. However, the book that I am using does not talk about 2 samples at all; all the examples provided are 1 sample questions.  The question:      Assume that $X_1, ...,X_m$ is a random sample from $\theta_1e^{-\theta_1x}I_{(0,\infty)}(x)$ and $Y_1, ...,Y_n$ is a random sample from $\theta_2e^{-\theta_2y}I_{(0,\infty)}(y)$. If we assume the samples are independent. What is the GLR for testing   $H_0:\theta_1=\theta_2$  vs. $H_0:\theta_1\ne\theta_2$?   So far I just got to $$\Lambda=\frac{L(\theta,\theta)}{L(\theta_1,\theta_2)}=\frac{\theta^{m+n}\exp[-\theta\sum x_i+\sum y_i]}{\theta_1^m\exp[-\theta_1\sum x_i]\theta_2^n \exp[-\theta_2\sum y_i]}$$  However, I don't know what I should do for the next step. They say it should be an F test but I just can't see it.   I appreciate your time and help!


If I flag a moderator's own content as rude/offensive, is there a possibility that very same moderator will handle the flag (i.e. be able to dismiss it), or is it guaranteed another moderator will be handling it?  I'm hoping the answer will be "another moderator handles it", because the ability of a moderator to dismiss flags against themselves when they may be violating community standards would be concerning.  I understand that the idea of flagging a moderator's own content this way is probably pretty serious. Since this is naturally sensitive, I would rather not discuss details to prove I'm not mod-hating, so please take my word that I am treating this seriously.  Previously asked was , but this doesn't appear to reflect whether the moderator in question can do anything about that flag.

This is related to .  Bill the Lizard informed us that mods know who flagged a post, but does this include them?  If a mod gets flagged, do they get to see who flagged them?  Not that any of these wonderful mods would ever think of doing anything untoward, but you never know.  Bill might suddenly lose his mind one day and, if I have to flag him, madness plus "modness" could equal mayhem.


I download with Firefox (in the section Information-->View Page Information-->Media) a picture without extension (I attach it). How can I open it? I tried with windows picture viewer and with Chrome. The last give a page which is full of codes.    Thank you in advance.

I have an open source application that i can edit any files on it. Now i want to edit some pictures that have no Extension! (Just the picture name can shown). and when i open them with any Picture-Editors (like Paint, Ashampoo, GIMP), it says "Unknown Extension.". but i have to Edit this non-Extension picture My Question: How can i Edit an non-extension picture file?


If I have an int array:  int *array;  array = malloc(5 * sizeof(int));   and I malloc to it as above, I can then access it and set values to it. Everything is fine.  But if I create that int pointer and pass to it a function and malloc inside the function, I can't access/set values to the array unless I pass it to the array as a pointer to a pointer?  some_void_function(int *array) {     array = malloc(5 * sizeof(int)) }  int *array; some_void_function(array);  *(array + 3) = 5; // DOES NOT WORK   To fix it I can make the array accept (int **array) as a parameter and pass in the address of the pointer (so a pointer to a pointer), dereference it, and assign it with malloc:  some_void_function(int **array) {     *array = malloc(5 * sizeof(int)) }  int *array; some_void_function(&array);  *(array + 3) = 5; // WORKS    Could someone explain this to me? Am I not doing the same thing in both situations? Pass the address and then just dereferencing it is the same thing as just pass in the single pointer in the first place right?

I think I've got it down to the most basic case:  int main(int argc, char ** argv) {   int * arr;    foo(arr);   printf("car[3]=%d\n",arr[3]);   free (arr);   return 1; }  void foo(int * arr) {   arr = (int*) malloc( sizeof(int)*25 );   arr[3] = 69; }   The output is this:  > ./a.out   car[3]=-1869558540  a.out(4100) malloc: *** error for object 0x8fe01037: Non-aligned pointer                          being freed  *** set a breakpoint in malloc_error_break to debug >   If anyone can shed light on where my understanding is failing, it'd be greatly appreciated.


Determine the structure of the ring $R_0$ obtained from $\mathbb{Z}$ by adjoining an element $\alpha$ satisfying each set of relations:   $$ \begin{cases} 2x-6 &= 0\\ x-10 &=0 \end{cases} $$   I know that the solution is just $\mathbb{Z}/14$. I am struggling to reach that conclusion.  I understand that finding a linear combination and setting this equal to zero, we find that $$2x-6-2(x-10)=14=0,$$ so we much be in $\mathbb{Z}/14$.  What I am confused about now is how $2x-6$ and $x-10$ simply just go away? Any help on this would be great. Thanks

This is an exercise in Artin,     Describe the ring obtained from $\mathbb{Z}$ by adjoining an element $\alpha$ satisfying the two relations $2\alpha - 6 = 0$ and $\alpha - 10 = 0$.    I have seen examples in the text where one relation is imposed on a ring, but not two. I would very much like to see how this is done. Thanks!


The protagonist, a Human, flew an 'S20' Spacecraft. The area of the solar system covered was the asteroid belt to Earth, i.e. the Inner Solar System. After sleeping on this I have dredged up the following. The S20 came from Mars to Earth to kidnap people. I think the Mars colony was splitting/rebelling from earth. Mars had a secret HQ embedded in an Asteroid. I may have read this in the 1980's. The S20 may have been para-military and the pilot was male.

I read this book in high school too many years ago for me to think about. Martian colonist are raiding earth's oceans for water and because of the conditions on Mars where only male children are conceived, they are also on the look out for young women as potential mates. Our main character while on a raid, bags not only a young woman but her brother as well. Returning to Mars they find that Earth has attacked Mars can't remember much more.


I've been here for a while, and sometimes I see people answering questions related to shutdown or restart problems with this : "delete "quiet splash" from the /etc/default/grub file". My question is: what is "quiet splash" for?

What do Kernel command line parameters (also also known as boot options) mean?  When you go to Ubuntu (or better, GRUB) options, you have things like nomodeset, quiet and splash. What do these options mean?  I am also interested in other parameters and would be interested to see descriptions of any kernel parameter (like acpi), but these are not essential.


VLC, a program I use only rarely, has an entry in the sound indicator. I can remove it using dconf by following instructions from , but each time I start up VLC, despite it being in the "blacklisted-media-players" section, it reappears. I also tired some things listed , but that didn't help either.  The entry "vlc.desktop" keeps appearing under "interested-media-players":   Is it possible to either prevent VLC from showing up in the sound indicator menu entirely, or, preferably, only show up when I'm actively using it?

I don’t use VLC that much to have it there, so I would like to remove it from the sound menu in the top right. I found a small image to show what it looks like (the sound menu is open and shows VLC along with other music players).    Sorry for giving a very low resolution image.


I'm relatively new to Linux and Ubuntu (about 3 months now), and have been pretty impressed with the whole experience, until now. Shortly after an upgrade about 2 weeks ago, (not sure if it's linked), whenever I try to launch any program from the unity launcher, whatever windows are open, and all icons, flicker briefly, then disappear from the screen (leaving only the desktop screensaver). The lapse lasts a few seconds, then the screen returns to the state it was in before I tried clicking. I have to click another 3-4 times (best case scenario) to get the program to launch. The same thing happens when the cursor simply hovers over the unity icons. This problem does not occur when launching from shortcuts on the general desktop, but then I have to go through the same nonsense when trying to switch from, say, thunderbird to firefox, or the vlc player, from the unity launcher.   PS: An accompanying issue (don't know if related) that is not constant, is the cursor not activating whatever's right under it. Writing this, if I want to click somewhere to, say, correct a mistake elsewhere in the text, I have to point to a line over the mistake, to get the cursor to land a line beneath (not sure this is clear). This issue doesn't occur systematically, but happens in & out.  PS2: This doesn't seem to be necessarily hardware-related, as when I reboot with Windows (from bootable external HDD), no such issues.  Any idea what might be causing this?

Yesterday (Jan. 3, 2018), I installed an OS update (Ubuntu 16.04), using the Software Center. My system isn't working correctly now. When my mouse rolls over the Launch bar, it disappears, then any open window disappears, leaving me with only the desktop screensaver showing. I can't even shut the computer off using the settings button on the top.  I went into the Terminal and attempted to fix it using the following commands:  sudo apt-get dist-upgrade sudo apt-get autoremove   But I'm still having the same problem.  I have reinstalled Ubuntu 16.04 and when I accepted the update on install had the same problem.  I have reinstalled it a second time but have not done an OS update and everything seems to be working fine.    Found another user with the same problem:    Is it possible that the Meltdown security update is at fault?  I've read the update has been issued for 64-bit x86 architecture ();  I'm running a 32 bit i386 architecture.  Could that be an issue and is there a way to correct it?


I know about Daily Vote Limit, I thought it was 40 iff your question-upvotes to answer-upvotes ratio is high I've been on MathSE since this morning (I'm in India).  You need to take a look at this image.     Why is my vote count 41 ?

And by someone, I mean that evil feline WesleyDavid:        That screenshot was taken just before 4pm PST, i.e. just before 0000 UTC.  That shows KittehHead's votes for the month, which is the same as for the day since it's March 1st.  Just to be sure it wasn't that SE had the time wrong, I tried upvoting something and got the expected "Daily Vote Limit Reached, Please Vote Again in 6 minutes."  So how did Kitteh^H^H^H^H^H^HWesley get 42 votes in one day?  ADDED: It's getting worse... Now it's March 2nd, and Wesley/Cat has 3 extra votes:        Now I finally got an extra vote (take that evil kitteh!), but it hasn't helped me understand why:


A follow-up question of $\frac{1}{2}\otimes\frac{1}{2}=0⊕1 $ : If I have 4 spin-1/2 particles in my system, how can I use a series of direct sums to represent  $\frac{1}{2}\otimes\frac{1}{2}\otimes\frac{1}{2}\otimes\frac{1}{2}$ ? How to determine how many singlets, total spin 1 (I think that's 3), and total spin 2s are there? Thanks!

I am looking at the tensor product of $n$ spin halfs (fundamental of $SU(2)$): \begin{equation} \left(\frac{1}{2}\right)^n = \frac{1}{2} \times \frac{1}{2} \times ... \times \frac{1}{2} = \frac{n}{2} + ... \end{equation} For example, for $n = 3$ \begin{equation} \frac{1}{2} \times \frac{1}{2} \times \frac{1}{2} = \frac{1}{2} \times \left(1 + 0\right) = \left(\frac{3}{2}\right)_1 + \left(\frac{1}{2}\right)_1 + \left( \frac{1}{2} \right)_0 \end{equation} where lower indexes on the right hand side specify from which tensor product representation came from. My question is how do I read off if a certain term on the right is a symmetric, antisymmetric or a mixed symmetry representation of $SU(2)$? I came up with two ways of approaching the problem.  First is Young Tableaux. As far as I understand rows of Young Tableaux correspond to symmetric indexes while columns to antisymmetric ones. So, for example, a diagram with just one row (like one that corresponds to the highest spin $\frac{3}{2}$ from the example - three boxes in a row) describes a totally symmetric representation. A diagram that has one column (maximum 2 boxes since we are dealing with $SU(2)$) describes totally antisymmetric representation. Everything that has both rows and columns is a mixed symmetry representation. Following this logic it looks like only the highest representation in the product can be totally symmetric, singlet is antisymmetric and everything in between has mixed symmetry. So, for the example \begin{equation} \left(\frac{3}{2}\right)_1: \text{symmetric rep}\\ \left(\frac{1}{2}\right)_{0,1}: \text{mixed symmetry reps}\\ \end{equation} Is this is a correct logic?  Another way to think about this is the following. Let's build representation the way we do in QM starting from the highest one, when all the spins are up. Then all components of the highest multiplet can be generated by applying lowering operators to the highest state. So, all the relative signs in the expressions are "+" and thus the highest representation is always symmetric as 1. also suggests. Then all the other representations must be constructed by writing down expressions orthogonal to components of the highest multiplet, so they will necessary get some "-" signs and as a result must be either antisymmetric or have mixed symmetry, but can not be totally symmetric.   Is this correct logic? Is it true that only the highest representation in the product can be symmetric and all the others have mixed symmetry or antisymmetric?


I'm quite confortable with definitions such as a derivative or an integral because i get to see why they are the way they are and that feels really natural, there is a fundamental question to be solved such as "What is the slope at a certain point of the curve" and so on...  I can't see why someone would come up with the idea of a determinant, don't tell me that gives some area , I don't see why giving an area or a volume solves the kind of problems determinants do, is there a nice line of reasoning for determinants? Thank you guys !

While I basically understand what a determinant is, I wonder how this idea was developed?  What was the principal idea behind its origination?  I would like to know this so that I can have a better conceptualization of the determinant.


I'm doing the Memory Game for school using JQuery and JS. When the game ends, I'd like to redirect automatically to another HTML page but I can't... I tried many ways but none of these works.  I've already tried many commands like   $(location).attr("href", "Page.html"); window.location(...); window.location.href(...); location.href(...); $("body").load("Page.html");   .  if (j==2) {     setTimeout(function() {       if(images[0].attr("src")!=images[1].attr("src")) {         $(images[1]).hide();          $(images[1]).next().show();          $(images[0]).hide();          $(images[0]).next().show();          contatore = contatore + j;          if(contatore > 16) $("body").load("Win.html");       }     }, 200);      j=0; }   The expected results would be the automatically redirect to the secondary HTML page (Win.html) but the actual results are that when the game ends nothing happens.

How can I redirect the user from one page to another using jQuery or pure JavaScript?


I use LaTeX for writing books. I would like to extend my working environment and, I was wondering if it is possible to read (or much better - edit) tex files containing text only on an ipad? I know that there are a few LaTeX editors for the ipad out there. But, I use Aquamacs as my main writing editor and, LuaLaTeX as the writing medium. I do not want the file format changed in any way. Does anyone have any ideas? I thought of using say, Dropbox and then being able to open the file on the ipad, add a sentence or two, correct a few spelling errors say then, send the file back to Dropbox. Is this possible?

Is there a (La)TeX distribution running on iPad?


Is there a way to set the default position option for floats?  I want all float to by default to use the option H. Then I only need to set position parameter for those floats that I do not want to use H.

In a document I'm writing, I'm using the familiar  option for my floating tables, and I  them. I'd like to avoid repeating that every time I'm creating a table. I assume it's easy to add something in my preamble that makes sure that these two options are used every time I begin a new table environment?  \documentclass{article} \begin{document} \begin{table}[hbt] \centering \begin{tabular}{*3{l}} 1 & 2 & 3\\ a & b & c\\ \end{tabular} \end{table} \end{document}


Just thinking about "galactic habitability zones." Is this even a valid question?

How can one get the eccentricity of the orbit of the Sun around center of the Milky Way? Can it be measured?


There are a number of continuous but nowhere-differentiable functions, none of which (to my knowledge) are bijections. I am wondering if continuous bijection $f:\mathbb{R} \to \mathbb{R}$ is necessarily everywhere-differentiable. I would think so, but am not sure how to formally approach this problem and have not found a similar question on MSE.

I am aware of a few example of continuous, nowhere differentiable functions. The most famous is perhaps the Weierstrass functions  $$W(t)=\sum_k^{\infty} a^k\cos\left(b^k t\right)$$  but there are other examples, like the van der Waerden functions, or the Faber functions. Most of these "look like" some variation of:    (Weierstrass functions from Wolfram)  Specifically, they are clearly not invertible. Since these functions are generally self-similar at many scales, this non-invertability would seem to hold essentially everywhere.  I'm wondering if it's possible to construct such a function which is invertible. Intuitively, maybe this would be "jittery" in the same way as the Weierstrass function, but if it had a slope which always increased, it would be invertible. Or perhaps there is at least an example in which the function is invertible over some segment of the range.


Let $A$ be an $nxn$ matrix with characteristic polynomial    $$f(t)=(-1)^nt^n+b_{n-1}t^{n-1}+\cdots+b_1t+b_0$$      Show that $tr(A)=(-1)^{n-1}b_{n-1}$   I think I should be able to get this from the characteristic polynomial given however I don't know where to start.  My thinking is to start by trying to replace $f(t)$ with $det(A-\lambda I)$ and attempting to work backwards to get to A, and then solve for trace.  My other thought is to use the Pattern Method to try and get $f(t)$

Let $A$ be an $n\times n$ matrix. Then its characteristic polynomial is  $$\phi_A(x) = \det(xI - A) = x^n - (\operatorname{tr} A)x^{n-1} + \cdots + (-1)^{n-1}(\operatorname{tr}(\operatorname{adj}A))x + (-1)^n\det A,$$  where $\operatorname{adj}A$ denotes the  of $A$.     My question: Why are the coefficients of $\phi_A$ those shown above?   I can see why $(-1)^n\det A$ is the constant term, since $$\det(A) = \phi_A(0) = (0-\mu_1)\cdots(0-\mu_n) = (-1)^n\mu_1\cdots\mu_n,$$  where $\mu_i$ are the roots ($i=1,\dots,n$).  I also see why the coefficient of $x^{n-1}$ is minus the trace, since by Laplace expansion (along the first row):  \begin{align*}     &\det(xI-A)\\[10pt]    &= \begin{vmatrix}          x-a_{11} & -a_{12} & \cdots & -a_{1n}\\          -a_{21} & x-a_{22} & \cdots & -a_{2n}\\          \vdots & \vdots & \ddots & \vdots\\          -a_{n1} & -a_{n2} & \cdots & x-a_{nn}     \end{vmatrix}\\[10pt]     &= (x-a_{11})\begin{vmatrix}          x-a_{22} & \cdots & -a_{2n}\\          \vdots & \ddots & \vdots\\          -a_{n2} & \cdots & x-a_{nn}     \end{vmatrix} + \underbrace{a_{12} \begin{vmatrix}          -a_{21} & \cdots & -a_{2n}\\          \vdots & \ddots & \vdots\\          -a_{n1} & \cdots & x-a_{nn}     \end{vmatrix} + \cdots}_{\text{at most polynomial of degree $n-2$}}\\[10pt]    &=(x-a_{11})\bigg((x-a_{22})\begin{vmatrix}         x-a_{33} & \cdots & -a_{3n}\\        \vdots & \ddots & \vdots\\        -a_{n3} & \cdots & x-a_{nn}     \end{vmatrix}     +\underbrace{\underbrace{a_{23}\begin{vmatrix}         -a_{32} & \cdots & -a_{3n}\\        \vdots & \ddots & \vdots\\        -a_{n2} & \cdots & x-a_{nn}     \end{vmatrix}+\cdots}_{\text{at most polynomial of degree $n-3$}}      \bigg) + \cdots}_{\text{at most polynomial of degree $n-2$}}\\     &\kern10pt\vdots\\[10pt]     &=(x-a_{11})(x-a_{22})\cdots(x-a_{nn}) + \underbrace{\cdots}_{\text{at most polynomial of degree $n-2$}}\\[10pt]     &= x^n - (a_{11}+a_{22}+\cdots + a_{nn})x^{n-1} + \cdots\\[10pt]     &= x^n - (\operatorname{tr}A)x^{n-1} + \cdots \end{align*} (Let me know if there is a more elegant way to obtain this).   But what I cannot seem to prove is that the coefficient of $x$ is $ (-1)^{n-1}\operatorname{tr}(\operatorname{adj}A)$. Attempting to work with the Laplace expansion (as I did to obtain the trace above) is leading me nowhere.


In the past late 2000s/early 2010s, the villainous character of Red Hulk was brought to the Marvel comics universe, to mixed reception. Later on, it was revealed that this character was       General Thunderbolt Ross, longtime nemesis of the Hulk   and man with an impressive moustache. When Red Hulk was introduced, he had no moustache, and in various appearances, when transforming, his moustache disappears. Why does the moustache disappear instead of just growing with Red Hulk?

Red Hulk doesn't have a mustache. But as seen in , he has a mustache in mere-mortal mode. Why? Doesn't "Hulking out" scale up your normal body? Is he using a mustache-wig in normal mode?  Yes, I know that I'm writing about a character that violates mass/energy conservation but only complaining about him also violating hair conservation.


@DavidMarciel the code is now supposed to store the received value in the corresponding variable after checking that some condition is true, but when the program doesn't  enter the body of if-condition even though the condition is true. I put an example in this code for the "male" variable being true, and placed a print statement inside the body of the if to show it. Below is my code.  public class j { static String sss = "male,O+,45,saudi,brain_diseases"; static String male = ""; static String blood = ""; static String age = ""; static String nat = ""; static String dis = ""; static void func() {     String[] pieces = sss.split(",");     male = pieces[0];     blood = pieces[1];     age = pieces[2];     nat = pieces[3];     dis = pieces[4];      System.out.println(male);     System.out.println(blood);     System.out.println(age);     System.out.println(nat);     System.out.println(dis);     // if(male=="male"){ System.out.println("hello male"); } }  public static void main(String[] args) {      func();         }}

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?


my problem is with JavaFX.  I've created Login Panel (first scene) and when someone put correct login and password and click the button -> the scene should be changed to another one.   Everything compiles properly but when click the button it throws exception. (It is something about invoke or something) but in the end there is something like that:   Caused by: java.lang.NullPointerException at Login.LoginController.Login(LoginController.java:50)   So the problem is in my Controller, in method Login,  here it is:  @FXML public void Login(MouseEvent event) throws SQLException, IOException {      DatabaseConnection polaczenie = new DatabaseConnection();     polaczenie.selectDataFromDB("select * from logowanie");      if(tfLogin.getText().equals(polaczenie.getLogin()) && pfPassword.getText().equals(polaczenie.getPassword())) {             lblStatus.setText("Udalo sie zalogowac.");          Parent window1;         window1 = FXMLLoader.load(getClass().getResource("/Menu/Menu.fxml"));          Scene newSceneWindow1 = new Scene(window1);          Stage mainStage;         //mainStage = (Stage)  ((Node)event.getSource()).getScene().getWindow();         mainStage = Main.getPrimaryStage();         mainStage.setScene(newSceneWindow1);         mainStage.show();     }     else {         lblStatus.setText("Logowanie nie powiodlo sie.");     }   And two lines with problem:  mainStage.setScene(newSceneWindow1); mainStage.show();   When i delete these two, everything compiles properly BUT it doesn't change scene.  I don't know how to repair this, I checked almost everything.   PS  My Main:  private static Stage primaryStage;  private void setPrimaryStage(Stage stage) {     Main.primaryStage = stage; }  static public Stage getPrimaryStage() {     return Main.primaryStage; }  @Override public void start(Stage primaryStage) throws Exception{     FXMLLoader firstPaneLoader = new FXMLLoader(getClass().getResource("LoginPanel.fxml"));     Parent firstPane = firstPaneLoader.load();     Scene firstScene = new Scene(firstPane);      primaryStage.getIcons().add(new Image("file:C:///Users/Bartek/Desktop/HarcerzSystem-master/test.png"));     primaryStage.setTitle("Harcerz System");     primaryStage.setScene(firstScene);     primaryStage.show(); }  public static void main(String[] args) {      launch(args); }

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'm using Chromebook C720 and I installed Ubuntu, but when it restarts/reboots it enters into Chrome OS and not Ubuntu. How can I get Ubuntu working?

I have installed Ubuntu 13.04 on my desktop (runs like a charm). Then I used Crouton to install Ubuntu 12. 04 on my chromebook samsung (ARM). It also works quite well.  Here comes my question. Can we have a true Ubuntu (preferably 13.04) on my ARM chromebook?  It seems that the Crouton/Ubuntu is not 100% the real thing.  The best option would be to have the full Ubuntu 13.04 and remove the Chrome OS.


I am in need of creating a Windows 8.1 Pro USB bootable. I've tried googling for solutions and all returned Winusb. Upon installing winusb, these errors shows up on the CLI input sudo apt-get update:  W: Failed to fetch http://ppa.launchpad.net/colingille/freshlight/ubuntu/dists/trusty/main/binary-amd64/Packages  404  Not Found W: Failed to fetch http://ppa.launchpad.net/colingille/freshlight/ubuntu/dists/trusty/main/binary-i386/Packages  404  Not Found   Thus, when I enter this CLI input sudo apt-get install winusb, this message is shown E: Unable to locate package winusb.  I was wondering is there another way to install/create a Windows8.1 USB Bootable using Ubuntu 14.04 LTS with the source of the Windows installer is coming from an .iso file.

I'd like to create a Windows bootable USB stick, but I don't have a Windows machine with me at the moment to do so. How could I achieve the same using Ubuntu?


Adding the anbox repository gives me these weird issues. i used the --allow-insecure-repositories but that only works for my update Please help. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. E: The repository 'http://ppa.launchpad.net/jconti/gnome3/ubuntu groovy Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. E: The repository 'http://ppa.launchpad.net/morphis/anbox-support/ubuntu groovy Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. E: The repository 'http://ppa.launchpad.net/peppermintos/p9-release/ubuntu groovy Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. W: GPG error: http://deb.fdmpkg.org bionic InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 38832685B6D09383 E: The repository 'http://deb.fdmpkg.org bionic InRelease' is not signed. N: Updating from such a repository can't be done securely, and is therefore disabled by default.```

When updating, I get the following error message:   W: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial Release' does not have a Release file.   Here, I find another statement on this error:   This recommends removing certain PPAs; and, I'm not sure if I should do that since it might mean not getting the updates that I need.    Is this what I should do?


How can I remove an element from an object list?  I wish to remove the element Kristian from someList. For example:  someList = {"Kristian":"2,5,10",              "John":"1,19,26,96"};   I want to achieve:  someList = {"John":"1,19,26,96"};   This is similar to , but it's implemented differently and the solutions does not work.

Say I create an object as follows: let myObject = {   "ircEvent": "PRIVMSG",   "method": "newURI",   "regex": "^http://.*" };  How should I remove the property regex to end up with new myObject as follows? let myObject = {   "ircEvent": "PRIVMSG",   "method": "newURI" };


I used   % sudo apt-get update  % sudo apt-get install vlc browser-plugin-vlc     I am getting   Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package vlc E: Unable to locate package browser-plugin-vlc

Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc


I was trying to upload a gif file (4MB) into a post. I get the following error:     For security reasons, framing is not allowed. Click OK to remove the frames.   See this gif screenshot (click  if it doesn't play):    Why I am getting this error? Is the size of the file a reason?  Same story is here, on meta, when trying to upload same file.

Ok first, there's that lugubrious use of the semicolon; not necessary.  Second, I didn't open a frame!  You did!  Alls I tried to do is upload a 5MB animated .gif file via Imgur.    Looking further into this, Imgur actually posts an error when you upload an animated .gif larger than 2MB.    Go figure!


How to show that if X is a nonnegative integervalued random variable with distribution F,then  $$E(X)=\displaystyle\int_0^\infty \overline{F}(X)dx$$  and  $$E(X^n)=\displaystyle\int_0^\infty n*X^{n-1}\overline{F}(X)dx$$  where $F(X)=P(X\leq x)$ and $\overline{F}(X)=(X > x)$.  My attempt:  I am working on this question.  Meanwhile if any member knows the answer to this question may reply with correct answer.

Is it possible to calculate the expectation of a function of a random variable with only the the r.v.'s CDF? Say I have a function $g(x)$ that has the property $\int_{-\infty}^{\infty}g(x)dx \leq \infty $ and the only information I have about the random variable is the CDF.  For example, I have a scenario where there are three timers that can be modeled as exponential random variables $X_1,X_2,X_3$ with rate parameters $\lambda_1,\lambda_2,\lambda_3$ respectively. For each moment in time I earn a reward according to some reward function $g(x)$. That is, my reward for waiting until time $t$ can be written as $\int_0^tg(x)dx$. However, $g(x)$ experiences diminishing returns so the the marginal reward received from waiting one second at $t=0$ is greater than one second at say $t=27$. This 'game' ends when one of two things happens. Either both timers $X_1$ or $X_2$ must ring or timers $X_1$ or $X_3$ must ring. I'm trying to find the expected reward of playing this game.  Currently I can calculate the the CDF of the random variable modeling the time until the game ends, but I dont know how to use this information to when what I really need is reward associated with this time.  So far I have the additional random variables: $$ W_{12}=\max(X_1,X_2) \quad W_{13}=\max(X_1,X_3) \quad Z=\min(W_{12},W_{13})$$ Also let $F_i(x), i\in \{1,2,3\}$ denote the CDF of $X_i$ The CDF of $Z$, can be written as: $$F_Z(t) = F_1(t)F_2(t) + F_1(t)F_3(t) - F_1(t)F_2(t)F_3(t)$$  I know when a random variable takes on non-negative values, you can use a shortcut to calculate the expectation using the CDF. That is, $E[X] = \int_0^\infty F(X\geq x)dx$. Is there something similar I could use for a function of a random variable, or is it necessary to compute the pdf of $Z$ first to compute $\int_0^\infty g(t)f_z(t)dx$


As you may be aware, the Schengen visa area of Europe allows for Canadians to visit all of the countries under the Schengen treaty, without need for a visa, and for a period of 90 days out of any six month period.   I am a Canadian citizen currently visiting Spain.  In 2014, I entered the Schengen area in Paris, France, on October 25th.    As of April 25th 2015, it will be six months since my initial entry into the Schengen area.  As of April 25th 2015, my stay in the Schengen area will come to a total of approximately 70 days.  It is my intention to stay in the Schengen area beyond April 25th, if I am allowed to initiate a new six month period per the Schengen agreement.  My question is: am I allowed to initiate a new six month period without need to exit and re-enter the Schengen area?

I have searched the web a lot and could not find an answer that fits my situation. Here are two links that are quite contradictory:       My situation:  I've visited Portugal in December 2012 for 29 days on a Schengen visa valid from December 1st, 2012 to February 1st, 2013 for research purposes (I am a Ph.D. student). I want to visit Sweden from February 10th, 2013 to May 10th, 2013 (89 days). I have applied for a Schengen visa again (for research). How will the 90/180 rule work in my situation?


It is well known that the power set of a countably infinite set is uncountable. Therefore, if a power set is countable, then the cardinality of the set must below "countable". Formally, if $2^A$ is $\aleph_0$, then $A$ must be below $\aleph_0$.  However, I think $\aleph_0$ is the lowest possible cardinality? Are there any possible cardinalities between a finite set and a countable set?      From existing information we can only conclude that if $2^A$ is countable, then $A$ is “below countable”. How to prove that if $2^A$ is countable, then $A$ must be finite?

Let $A$ be a set.  If $A$ is finite then so is $\mathcal{P}(A)$.  If $A$ is not finite then it has a countably infinite subset $B$, in which case $\mathcal{P}(B)$ is uncountable and thus so is $\mathcal{P}(A)$.  Can I say that given an arbitrary set its power set may be finite or uncountably infinite but never countably infinite?


In my CV, I have following type of information.      Gave a talk on "Tits System, Monomial Matrices and BN pairs" as a part of ’Late Night   Seminar Series’ in IISER Mohali     Attended a Workshop on ’Hyperbolic Knot Theory’ oraganised at IISER Pune from 7   December to 17 December 2015    Should I add a full stop at the end? My instincts says yes becasue although it is written in bullet points format, they are complete sentences.

In a 'bulleted' list should items that happen to be complete sentences end with a period?


The description of the monk's  feature states:     Starting at 13th level, you learn to touch the ki of other minds so   that you understand all spoken languages. Moreover, any creature that   can understand a language can understand what you say.   While the ability is useful in social situations, it can occasionally be detrimental. For example, communicating tactics in Common while fighting Duergar (who only speak Dwarvish and Undercommon) is a situation where the Monk would prefer not to be understood.  Is a Monk capable of "turning off" the Tongue of the Sun and Moon class feature?

The rules for the monk ability Tongue of the Sun and Moon state:     Starting at 13th level, you learn to touch the ki of other minds so that you understand all spoken languages. Moreover, any creature that can understand a language can understand what you say.   PHB, pp.79   The text says that this ability is something you learn to do, not something that simply happens to you, so it's not necessarily always on. Further, it seems logical to say that this is something you would do actively. That is, you could choose not to touch someone's mind, thereby excluding them from understanding you. You could also choose not to understand someone yourself, just in case they're telling , or using a subliminal trigger.  Assuming you can choose not to touch someone's mind, let's reason further. Suppose you're speaking and don't know that there is someone listening in nearby. Would they understand you, i.e. is the default that you are or aren't touching someone's mind? Similarly, if you are speaking to a large group of people, would you have to focus on all of them at once for them to understand you? Would this take effort? Is there a range?  My questions are:   Can you exclude some characters from understanding you while allowing others to do so? Can you decide not to understand someone who is speaking?   Basically, these boil down to: Can you choose not to touch someone's mind?  Then, assuming that the answer to the above is yes:   Do you have to know someone is listening in order for them to understand you? Is there a limit to the number of people you can affect? A range?


Since Lucid's packages where moved from archive.ubuntu.com to old-releases.ubuntu.com I'm a bit worried about availability of the repository and want to provide a full local mirror.  Are you aware of a way to download the whole Ubuntu package repository (lucid, lucid-backports, lucid-security and lucid-updates) other than wget -r? I cannot connect with rsync or ftp to old-releases.ubuntu.com.  Edit: This question is not a duplicate of  since the question is about how to mirror from old-releases.ubuntu.com without knowing which packages to mirror (otherwise I could have simply used apt-proxy).

I would like to build my own local repository on my LAN, so that machines on the LAN can update and upgrade from it. I want to download the packages and store them on my local server so that I can update, upgrade, install, etc, from it without using the internet.


Determine all $z \in \mathbb{C} $, so that:   $$ \left| \frac{z-a}{1-\bar{a} z} \right| = 1,$$ where $a \in \mathbb{C}$, $|a| < 1$.   Let $ w =  \frac{z-a}{1-\bar{a} z} $. As $|w| = 1$, I though of multiplying $w* \bar{w} (=1)$ but I got stuck at the step $|z|^{2} = \frac {1- |a|^{2}}{1+|a|^{2}}$. Any hint helps!

Prove that $\left|\dfrac{z-w}{1-\bar{z}w}\right| = 1$ where $\bar{z}$ is conjugate of $z$ and $\bar{z}w\ne 1$ if either $|z| = 1$ or $|w| = 1$.  I used $|c_1/c_2| = |c_1|/|c_2|$ and multiply out with $z = x + iy$ and $ = a+ib$ but I am getting stuck near finish.


From Artin's Algebra:  The definition of isomorphism given in the book:  An isomorphism $\varphi$ from a vector space $V$ to a vector space $V'$ both over the same field $F$, is a bijective map $\varphi:V\rightarrow V'$ compatible with the laws of composition, that is, a bijective map satisfying $$(a)\space\varphi(v+v')=\varphi(v)+\varphi(v')\space\text{and}\space(b)\space\varphi(cv)=c\space\varphi(v),$$ for all $v,v'\in V$ and for all $c\in F$.    Question: Let $V=F^n$ be the space of column vectors. Prove that every subspace $W$ of $V$ is the space of solutions of some system of homogeneous linear equations $AX=0$.  Note: We are not allowed to use the concept of basis, span etc. Attempt: First I thought if I change the definition of isomorphism by $\varphi$ is any map(not only bijective), we must get the definition of homomorphism. Now choose any subspace $W$ of a vector space and consider the map $$\varphi_0:W\rightarrow \{0\}$$ Then $\varphi_0$ is a homomorphism and surjective. Then we can define $\varphi^{-1}_0(0)=\{v\in W: \varphi_0(v)=0\}=W$ Then how to show $\varphi_0(v)=Av$?

For $n \in \mathbb{N}$ and $W \leq \mathbb{F}^n$, show that there exists a homogeneous system of linear equations whose solution space is $W$.  Here's my work: Since $W \leq \mathbb{F}^n$, $k = dim(W) \leq dim(\mathbb{F}^n)$. Let's say that $\{w_1,w_2,...,w_k\}$ is a basis of $W$. Now, construct a matrix $A$ (of size $k \times n$) such that its rows are elements from the basis of $W$, stacked together. The row space of $A$ is $W$, so the row space of its row-echelon form is $W$ too. At this point, I'm stuck! I'm trying to come up with a homogeneous system with the help of $A$, though there may exist other easier ways of approaching this problem. Could someone show me the light? P.S. $W \leq \mathbb{F}^n$ stands for $W$ is a subspace of $\mathbb{F}^n$. P.P.S. Isn't this equivalent to saying that $W$ is the null-space of some matrix? Can we go ahead along these lines, and construct a matrix $P$ such that $Pw = 0$ for all $w \in W$?


In the TikZ manual, version 3.00, the "double" option for line styles is discussed on pages 170 and 171 immediately before the section "Adding Arrow Tips to a Path". We see an example of an arrow tip, "implies", that looks good combined with the "double" option, but it is not clear to me whether other arrow tips may be made to work well with "double". Here is a document that tries four ways to get a double line with arrow head, and the output I got (zoomed in a bit).  The bottom one is the one that best shows off what I want to achieve, but it is also the least easy to understand from the code. If you are wondering where the different \sep values are from, the first is the default value specified on page 199 and the second was arrived at by trial and error.  Is there a better way than what I came up with here, of getting a double line with matching arrow head?  \documentclass[margin=1mm]{standalone}  \usepackage{tikz} \usetikzlibrary{arrows.meta}  \begin{document}     \begin{tikzpicture}         \draw [very thick, red, double = white, -{Stealth}] (0, 3) -- (1, 3);          \foreach \thickness/\colour in {ultra thick/red, very thick/white} {             \draw [\thickness, \colour, -{Stealth}] (0, 2) -- (1, 2);         }          \draw [ultra thick, red, double = white, -{Stealth[fill = white]}] (0, 1) -- (1, 1);          \foreach \thickness/\colour/\sep in {ultra thick/red/0.88pt .3 1, very thick/white/1.8pt .3 1} {             \draw [\thickness, \colour, -{Stealth[sep = \sep]}] (0, 0) -- (1, 0);         }     \end{tikzpicture} \end{document}     I apologise if this question has been asked and answered already. When looking for questions that relate to "double" and "arrows", a lot of unrelated questions relating to double-ended arrows are found.

I want to create with TikZ a yellow arrow with black margin (border, edge). I thought I could do this by using two arrows which lie on the top of each other, e.g. with:  \documentclass[12pt,twoside, a4paper]{report} \usepackage{tikz}  \begin{document} \begin{tikzpicture}[yscale=0.25]% \draw[->,black,very thick](-1974*0.107pt,119*0.107pt) -- (-2258*0.107pt,820*0.107pt);%first layer, black arrow \draw[->,yellow,thick](-1974*0.107pt,119*0.107pt) -- (-2258*0.107pt,820*0.107pt);%second layer, yellow arrow \end{tikzpicture}% \end{document}     But I am not so satisfied with the result because the black arrow should be a bit longer.  I know I could play with the end point coordinates of the black arrow so that it fits well. But if I want to change the coordinates of my black-yellow arrow, this means I have to play again with the coordinates of the black arrow, which would cost a while.  Does anyone have a better solution? I would be glad to hear any hint.:-) Thanks in advance!


I have noticed in my inbox that a number of companies have their avatar/logo displayed next to their address/message snippet.  This is true in a number of email clients that I have used - Gmail, Outlook, Thunderbird, Blue mail...  I have searched online and all info seems to be relating to Gmail.  I am keen to find out for my own business...  Gmail appears easy and there is a lot of literature on the web showing how to do this.  I am keen to find out how to have my avatar show on the other email clients: blue mail, Thuderbird, Outlook etc   Where do they pick up my companies email avatar from?  Any help surrounding this would be much appreciated.

As a bulk sender, is there a way to make Gmail show my avatar?    I would like to obtain this without creating a Google Account.  Maybe embedding my vCard? Or maybe ?


I would like send an email alert on a specific day of every month (say 15th of every month). What is the best way to achieve this?

I have rejected Workflow Rules, since email alerts can't be sent at the exact same time every week. I have rejected schedulable Reports/Dashboards since emails can't be sent to email fields of records and the email content can't be customized.   What are the Apex topics I should look into, to send weekly emails (every Monday) to email-fields of records of a custom object? Can you provide me with code snippets?


How to order by StartDate and UserLikeProduct? I need to sort by StartDate but show by UserLikeProduct first.  public IEnumerable<Check> GetHomeCeeck() {         return this.Query()                .Where(c => c.IsPublish && c.IsHomepageProduct)                .OrderBy(c => c.StartDate)                .Take(30)                .ToList(); }

I have two tables, movies and categories, and I get an ordered list by categoryID first and then by Name.  The movie table has three columns ID, Name and CategoryID. The category table has two columns ID and Name.  I tried something like the following, but it didn't work.  var movies = _db.Movies.OrderBy( m => { m.CategoryID, m.Name })


I see various spellings of the same, which one is correct?  I have considered that the spelling might differ if it is British or American English, but as English isn't my native speak I have no clue.

Do I need to put a "-" between "non" and an adjective? As an example in physics we say "a non isolated photon", "non tight photon"... The context is very formal (paper publications and similar). Is there a general rule? Are there some differences between countries?


I see a lot of implementation of maximum entropy. Can someone explain why it is possible to estimate the parameter based on maximum entropy?

I have used the principle of maximum entropy to justify the use of several distributions in various settings; however, I have yet to be able to formulate a statistical, as opposed to information-theoretic, interpretation of maximum entropy. In other words, what does maximizing the entropy imply about the statistical properties of the distribution?   Has anyone run across or perhaps discovered yourself a statistical interpretation of max. entropy distributions that does not appeal to information, but only to probabilistic concepts?  As an example of such an interpretation (not necessarily true): "For an interval of arbitrary length L on the domain of the RV (assuming its 1-d continuous for simplicity), the maximum probability that can be contained in this interval is minimized by the maximum entropy distribution."  So, you see there is no talk about "informativeness" or other more philosophical ideas, just probabilistic implications.


Here is the formula for the variance : $\sigma^2=\dfrac{\sum(X-\mu)^2}{N}$.  My question is why do we SQUARE the difference between the mean and the variable, why don't we use absolute value ...The result will be different!  I saw online that it's to make the value positive, but like why don't we choose 4 or 6 as exponent?   Hope someone can enlighten me!   Thanks :) Ayman

Let's take the numbers 0-10.  Their mean is 5, and the individual deviations from 5 are -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5 And so the average (magnitude of) deviation from the mean is $30/11 \approx 2.72$.  However, this is not the standard deviation.  The standard deviation is $\sqrt{10} \approx 3.16$.  The first mean-deviation is a simpler and by far more intuitive definition of the "standard-deviation", so I'm sure it's the first definition statisticians worked with.  However, for some reason they decided to adopt the second definition instead.  What is the reasoning behind that decision?


Struggling with something very simple  I have a blender file open and need to import my character in there. That file is also a blender file. Can import blender file into blender file?

In blender, Import has no .blend option..so how can I import .blend file in my current blend file?


I've been searching for a  for quite a while now. I have reached right to left and top to bottom of the jungle and it still hasn't shown up. I don't know how large it is, but I don't think it's that small and I'm worried that my world has spawned without one.

On my 1.2 Terraria Map I have been mining from left to right in my large underground jungle using my rocket launcher. Despite this, I have had no luck on finding the Underground Jungle Lihzahrd Temple. I have been searching the layer above where lava constantly spawns. Have I simply spawned in a world without one or am I searching in the wrong place? I have also considered using the clentimator with Dark Blue ammo to provide light, should I do that?


x = 10 f1: for i in range(x):     for j in range(x):         print(j)         if j == 6:             break f1   1.How to break from outer loop in python?

Given the following code (that doesn't work):  while True:     #snip: print out current state     while True:         ok = get_input("Is this ok? (y/n)")         if ok.lower() == "y": break 2 #this doesn't work :(         if ok.lower() == "n": break     #do more processing with menus and stuff   Is there a way to make this work? Or do I have do one check to break out of the input loop, then another, more limited, check in the outside loop to break out all together if the user is satisfied?


I am stuck looking for a way to test for an item in a player's inventory so far nothing has worked  any help would be nice

This question was recently split into different questions for each workaround. See   meta posts for more information.   Can you use NBT tags in commands? I’ve tried commands that normally work in Java Edition like: give @s minecraft:planks 30 1 {display:{Lore:["Wooden planks"]}} give @s stone_pickaxe{Unbreakable:1b} give @s item_frame{EntityTag:{Invisible:1b}} summon villager ~ ~ ~ {Offers:{Recipes:[{buy:{id:"emerald",Count:5b},sell:{id:"diamond_sword"}}]}} summon tnt ~ ~ ~ {Fuse:20s}


My laptop Lenovo z50-70 with Ubuntu 14.04 has wifi issue.  Wifi gets connected after restarting the laptop. But after sometimes it stops functioning though the wifi icon shows proper connected status. After getting disconnected, it never reconnects before I restart the laptop.  uname -a     Linux  Lenovo-Z50-70 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

I'm new to ubuntu and i'm having all sorts of problems,   My wifi connection is super slow and intermittent, sometimes it randomly disconnects so I was wondering how do I go about to update the drivers for the adapter?  Also, it keeps blinking when transfering data which I find extremely annoying, I have read and tried diferrent solutions about editing the wlan.conf file and adding options iwlwifi led_mode=1 but it doesn't work for me, and I'm guessing it has something to do with the driver, I feel like i'm missing a line or using a setting for an intels adapter rather than an atheros.  I'm using Ubuntu 14.04 64 bits in a HP Pavilion DV7-1245dx.   *-network                       description: Wireless interface        product: AR242x / AR542x Wireless Network Adapter (PCI-Express)        vendor: Qualcomm Atheros        physical id: 0        bus info: pci@0000:09:00.0        logical name: wlan0        version: 01        serial: 00:24:2b:21:93:d7        width: 64 bits        clock: 33MHz        capabilities: pm msi pciexpress msix bus_master cap_list ethernet physical wireless        configuration: broadcast=yes driver=ath5k driverversion=3.13.0-29-generic firmware=N/A ip=192.168.2.7 latency=0 link=yes multicast=yes wireless=IEEE 802.11bg


I'm reading Partial Differential Equations, by L. Evans, and in section $4.3$ is a definition of the Fourier transform for functions in $L^2(\mathbb{R}^n)$. He starts considering a function $u\in L^2(\mathbb{R}^n)$, and a sequence $\{u_k\}_{k=1}^\infty \subset L^1(\mathbb{R}^n)\cap L^2(\mathbb{R}^n)$, with $u_k\rightarrow u$ in $L^2(\mathbb{R}^n)$.  So my question is: why there exists such sequence $\{u_k\}_{k=1}^\infty$ for every function in $L^2(\mathbb{R}^n)$? Is $L^1(\mathbb{R}^n)\cap L^2(\mathbb{R}^n)$ dense in $L^2(\mathbb{R}^n)$? Thank you!

In Lieb and Loss's Analysis, I saw that they mentioned  $L^1(\mathbb{R}^n) \cap L^2(\mathbb{R}^n)$ dense in $ L^2(\mathbb{R}^n)$ (dense wrt the $L^2$ norm, I think). But I didn't find its proof in the book. So I wonder why it is?    Does this conclusion hold for $L^1(\Omega, \mathcal{F}, \mu) \cap L^2(\Omega, \mathcal{F}, \mu)$ for any measure space $(\Omega, \mathcal{F}, \mu)$?  Are there similar statements if replace $L^1$ with $L^p$, and  $ L^2$ with $L^q$ for $p \leq q \in (0, \infty ]$ or $\in [1, \infty]$?  Thanks and regards!


Currently, my form looks like this:  Comment: <textarea name="comment" id="comment" rows="6" cols="20"></textarea>
  Check the box: <input type="checkbox" name="checker" id="checker" value="ON" />   Should these then be converted to
/
 since they're somewhat definition lists, or am I taking this too far?

I've come across a few examples recently that do things like:

Full Name:

<input type="text" name="fullname">

Email Address:

<input type="text" name="email">

   for doing HTML forms.  Why is that?  What is the advantage over using tables?


In current quantum models, name one or more objects that collapse an entangled waveform into a single classical particle other than a complete living human person.  The "duplicate" I just read has an accepted negative score answer that starts with "An observer is a person...", so I don't know how to make this simpler. If you are interested in jokes related to the issue, continue reading, but otherwise you may begin formulating an answer now.  Here are some examples of solid answers that, while not true, would answer my question if they were in a modern quantum model:   Anyone with a full head of hair is an observer.  Receding hairlines have a reduced probability of collapse.   Wigs count too. Anything with a phone number is an observer; it doesn't matter to the quantum state if anyone picks up.  The classical result and its delta T depends on your carrier, and all possible states use the data plan simultaneously.  Anything that walks on two legs is an observer.  Sorry dolphins.  And you can't just do it sometimes, it has to be your primary mode of transport, so no weasling your way in, dogs. It doesn't quantize until it's published in Nature.  PNAS doesn't work, and we all know the news can be both true and false simultaneously now. God (not yours, the other one) decided that some things should act classical, and entangled quantum stuff is so impressed with the endorsement when they come into contact, it acts like a classical thing from that point forward. The electron over there on your keyboard and/or phone is actually the one and only observer.  Its potential paths look like observers now, but as soon as you touch it, we all disappear.   Include as much math as it takes.  A greek letter with a hat that does the job is fine.  Just no humans in your theory.  Like teaching it to a millenial, one might say.  There may be follow up questions, but it is not necessary to answer them to my satisfaction to receive check mark.

My question is not about (pseudo) philosophical debate; it concerns mathematical operations and experimental facts.  What is an observer? What are the conditions required to be qualified of observer, both mathematically and experimentally?


How do I give counter example to this?  Prove or find a counter example to the following claim:     For all sets $A$, $B$, $C$ if $A\cap B\cap C=\varnothing$, then either $A\cap B=\varnothing$ or $A\cap C=\varnothing$ or $B\cap C=\varnothing$.

Show that $A∩B∩C= ∅$ is only true when  $A∩B = ∅, A∩C = ∅$ or $B∩C = ∅$ or show a counterexample.   My answer: True, Let set A={a,b,c,...}, set B={1,2,3,...} and set C={-1,-2,-3...}. Then there is not common elements in A, B or C. Thus, A∩B∩C= ∅. A∩B = ∅, A∩C = ∅ or B∩C = ∅.  Is my prove right?


Before I start, this is going to be a general question but with specific cases. I've been trying to understand GIS tools and applications to achieve the following:   Build my own basemap Publish the basemap online Add my own data layers to the online basemap Perform analysis (on-the-fly)  Add interactivity to the map   So, In my first attempt, I built a spatially enabled database on PostGIS, queried this using PHP, overlayed it on google maps using their API and added interactivity using their api itself. I carried out analysis like area, denisty etc. on the fly using postGIS functions.  For my next attempt, I downloaded TileMill and rendered some really beautiful maps and added zoom level functions to it. I also exported my MBtile files. When I came across trying to publish this online, I hit quite a few names, but got lost and confused:   TileStache TileCache TileStream Mapserver Mapnik GeoServer Mapbox   So, I understand these are mapservers. But what exactly does a mapserver do? Why is it used? Why can't i server my tiles from a normal web Apache server? And for MBtiles, how many servers are out there which lets you publish it directly?  I can also export my basemap as a png/vsvg format. Can these formats be used to make a basemap through a mapserver?  When researching interactivity I came across:   Leaflet ModestMaps OpenLayers Mapstraction   I understand these are Javascript Mapping API's. But on what base map can I use these? Can it be used on Google maps? Can I use them on my own base maps too?   I basically want to understand the differences between these tools and which would be the best software stack to build a fully customized, interactive map with my own basemap.  Sorry if my question sounds to general. I will definitely be here to clarify my questions

I want to start working on a web map at work to map some of our statistics by city.    I have an idea, but I'm not exactly sure where to start.   Are there any definitive resources that provide step by step guidance on how to do this?


If $W = \frac{X + YZ}{\sqrt{1 + Z^2}}$ where all variables involved are standard-normally distributed and independent, what is the distribution of $W$?  The solution I am reading begins with $$P(W \le w) = \int \int \int 1_{(-\infty, w)} ( (x+yz)/(1+z^2)) \frac{1}{2\pi} \exp^{- (x^2 + y^2)/2} \ dx dy \frac{1}{\sqrt{2\pi}} e^{-z/2} dz $$  but I don't find that particularly helpful. What happened?

Let $X,Y$ and $Z$ be three independent real valued random variables. All with finite second moment and all with mean $0$ and variance $1$. Define $$     W= \frac{X+YZ}{\sqrt{1+Z^2}} $$  Find the distribution of $W$ under the additional assumption that $X,Y$ and $Z$ all have a marginal $\mathcal{N}(0,1)$-distribution  Hint: Compute $P(W \le w )$ by Tonellie, integrating out of the joint distribution of $(X,Y)$ first.   I believe that $P(W \le w )$ can be written as  \begin{align} P(W \le w )&=P\left(\frac{X+YZ}{\sqrt{1+Z^2}}\le w\right)\\ & =P(X+YZ \le w\sqrt{1+Z^2})\\ & =P(X \le w\sqrt{1+Z^2})+P(Y\le w\sqrt{1+Z^2})P(Z \le w\sqrt{1+Z^2}) \end{align} But I am not totally sure. Further I do not know how to proceed from here.


I am trying to creat dynamic buttons and click event. Creating dynamic button is working but when I cliked it I am getting undefined message. What is my wrong? Sorry my lang. Thx in advance. My code is below:  $(function(){    var i = 1;  $('button').on('click',function(){       var r= $('<input type="button" class="dinamik" value="new button '+ i +' "/>');       $("body").append(r);       i++;    }); });      $(function(){         $(document).on('click', '.dinamik', function(){            var valueDeger = $(this).find('.dinamik').attr('value');            alert("Value değeri: " + valueDeger);     }); });

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


Let $z_1, z_2, z_3,$ ...be a sequence of independent random variables s.t. $P(z_i=1)=P(z_i=-1)=\frac 1 2$. Does this sequence converge almost surely?  I am still bothered by the definition of almost sure convergence. If we define a RV Z($\omega_1$=negative sign)=-1, Z($\omega_2$=positive sign)=1  with sample space {$\omega_1$, $\omega_2$} doesnt this sequence then converge to Z? Since P(lim n→∞ Zi(w))=Z(w)=1? But the answer should be no, so I am confused bout this defintion (apology in advnace as I am new to this.)  I think i know how to use second bernoulli to prove it since sum of probabilities which is 1/2 will be infinite meaning that the sequence does not converge. But would some one please explain the above definition?

Let $z_1, z_2, z_3,$ ...be a sequence of independent random variables s.t. $P(z_i=1)=P(z_i=-1)=\frac 1 2$. Does this sequence converge almost surely?  My intuition is telling me that the sequence will approach the random variable Z? i.e. $z_n->Z$ as $n->\infty$ and Z is just another RV s.t. $P(Z=1)=P(Z=-1)=\frac 1 2$.  Here is my confusion, if a sequence converges almost surely, then $z_i$ should be different for each term s.t. it approaches Z in the end; but in this sequence $z-i$ is the same for every term. So I dont udnersntand.


I attempted to suggest an edit to . After typing, I tapped Preview and got the “changed too much” error. I reduced my changes and tried again, but still got the error.  After testing, I found that changing 0–5 characters gives the “changed too little” error (as expected) and changing 6+ characters gives .  I suppose that's a bug in the validation, unless it's a Kafkaesque way of telling me I can't edit.

I came across  on hold question and decided to edit it to keep it open. It is very badly written and therefore the edit took quite a bit of an effort to write. My suggested edit is now in the question comments.  When I was done writing, I tried to submit the edit for approval as my rep is rather low on this site. I was told my edit changes too much. I don't understand why this should refrain me from submitting this edit for approval by a moderator.  Can anyone explain to my why this message exists? I feel this should go into the moderator queue like any other edit.  Edit: I managed to edit the question at a later time, which is even weirder.


Let us have two numbers, a, b, so that gcd(a,b)=d. Let us have two prime numbers k,l so that gcd(ak, bl)=d. Is this valid for all prime numbers or is there any conditions that must be met? I guess that it is valid for all prime numbers except those that are divisors of a and b, i.e. kcannot be the prime number which is also divisor of b and lcannot be the prime number which is also divisor of a, but I do not know how to prove it. Could anyone help? Thank you.

Given that $\gcd(a,b) = 1$ and $\gcd(c,d) = 1$, show that $\gcd(ac,bd) = \gcd(a,d) * \gcd(b,c)$.  The work that I have done so far goes as follows.  We write  $$\gcd(ac,bd) = acv + bdu$$ then  $$\gcd(a,d) = ax + dy\quad\text{and}\quad\gcd(b,c) = bs + ct$$ and so \begin{align} \gcd(a,d) * gcd(b,c) &= (ax + dy) * (bs + ct) \\ &= axbs + axct + dybs + dyct \end{align} I tried to factor out some terms, and get $ax(bs+ct) + dy(bs+ct)$  but then I am stuck here. I don't know what else to use to prove the answer.


Sick of checking  page every X days, I really would like to solve my problem with the disk space and the Ubuntu updates. So, there is a way to automatize this process?    Of course I can create a script that does it, but would be awesome if the Ubuntu update center would have a config value like: Amount of Ubuntu images to keep in memory.   In my case, I would save only 1, always having the same amount of disk used, so free.  So, my question is: There is a native/automated solution that keeps the amount of images to certain number without any 'human' action? when a new one is installed, the last one is removed.

I'm getting an error in software updater when I try and do my daily updates. it says:  The upgrade needs a total of 25.3 M free space on disk `/boot`. Please free at least an additional 25.3 M of disk space on `/boot`. Empty your trash and remove temporary packages of former installations  using `sudo apt-get clean`.   I tried typing in sudo apt-get clean into the Terminal but I still get the message. All of the pages I read seem to be for experienced Ubuntuers. I'm running Ubuntu 12.10. I want to upgrade to 13.04 but understand I have to finish these first.  This is the output from typing in cat /etc/fstab into the Terminal:  # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # <file system> <mount point>   <type>  <options>       <dump>  <pass> /dev/mapper/ubuntu-root /               ext4    errors=remount-ro 0       1 # /boot was on /dev/sda1 during installation UUID=fa55c082-112d-4b10-bcf3-e7ffec6cebbc /boot           ext2    defaults        0       2 /dev/mapper/ubuntu-swap_1 none            swap    sw              0       0 /dev/fd0        /media/floppy0  auto    rw,user,noauto,exec,utf8 0       0 matty@matty-G41M-ES2L:~$    Output of df -h:  Filesystem               Size  Used Avail Use% Mounted on /dev/mapper/ubuntu-root  915G   27G  842G   4% / udev                     984M  4.0K  984M   1% /dev tmpfs                    397M  1.1M  396M   1% /run none                     5.0M     0  5.0M   0% /run/lock none                     992M  1.8M  990M   1% /run/shm none                     100M   52K  100M   1% /run/user /dev/sda1                228M  222M     0 100% /boot matty@matty-G41M-ES2L:~$    And dpkg -l | grep linux-image gives:  ii linux-image-3.5.0-17-generic 3.5.0-17.28 i386 Linux kernel image for version 3.5.0 on 32 bit x86 SMP ii linux-image-3.5.0-18-generic 3.5.0-18.29 i386 Linux kernel image for version 3.5.0 on 32 bit x86 SMP ii linux-image-3.5.0-19-generic 3.5.0-19.30 i386 Linux kernel image for version 3.5.0 on 32 bit x86 SMP ii linux-image-3.5.0-21-generic 3.5.0-21.32 i386 Linux kernel image for version 3.5.0 on 32 bit x86 SMP ii linux-image-3.5.0-22-generic 3.5.0-22.34 i386 Linux kernel image for version 3.5.0 on 32 bit x86 SMP ii linux-image-3.5.0-23-generic 3.5.0-23.35 i386 Linux kernel image for version 3.5.0 on 32 bit x86 SMP ii linux-image-3.5.0-24-generic 3.5.0-24.37 i386 Linux kernel image for version 3.5.0 on 32 bit x86 SMP ii linux-image-3.5.0-25-generic 3.5.0-25.39 i386 Linux kernel image for version 3.5.0 on 32 bit x86 SMP ii linux-image-3.5.0-26-generic 3.5.0-26.42 i386 Linux kernel image for version 3.5.0 on 32 bit x86 SMP iF linux-image-3.5.0-28-generic 3.5.0-28.48 i386 Linux kernel image for version 3.5.0 on 32 bit x86 SMP


2 quick questions i wanted to ask on here , I was denied a US Visa this March, before i applied for another country (still waiting Visa decision) Now I have been looking out for possible reasons why the visa was refused, I have not come to a reasonable conclusion , so i wanted to ask on here what could be the possible reason.  Now, here is what. He (V.O) asked me if I was married and If I have traveled out of the country before , i replied both in the negative and he handed me a blue paper. I started to think my marital status was the worry, I have been engulfed with work, hence, I do not see leaving the country as a Must in this case.  Should I have to fill the DS-160 again (If i have to re-apply again at this point), could I enter that I am in a Civil Union / domestic partnership with someone (Of which I am presently, although it did escape my mind as I am apparently not married to her yet.) And secondly, does anyone think the travel issue is a barrier as well?

How can I prove the immigrant officers that I have significant ties in my home country?  Are there any documents that I need?


I have found Ctrl+Shift+U+unicode+Enter quite too long for «quoting the things», or   • bulleting  • it  • up.  However, on Windows another OS, it is quite cool: just hold Alt, type your code on a numpad, and it appears.  The question is if it is possible to:   Change the shortcuts to just Alt? If yes, where it can be changed? Automatically Enter unicode after stop holding the main shortcut?

I'm using Ubuntu 13.10, but I think the keyboard shortcut wasn't bound in 12.10, but could be wrong.  It's not in the shortcuts tab of keyboard settings. How can I change the Unicode input from Ctrl+Shift+U to other?


one of my friend travel to UK and was done 12 month prison and he availed voluntary return scheme can he go back to UK again or not.

As I understand it, there are two mechanisms for throwing somebody out of the UK: deportation and removal. Informally, people seem to call both of these "deportation".  What are the differences between them? Who do they apply to? Do they have different effects on the person's ability to return to the UK later?


I have an integer 100, how do I format it to look like 00000100 (always 8 digits long)?

How do you left pad an int with zeros when converting to a String in java?  I'm basically looking to pad out integers up to 9999 with leading zeros (e.g. 1 = 0001).


Being the buff of lore that I am, I come across a lot of Sci-Fi and Magic based stories.  But, my question is simple.  Because of how spells and charms are used in the Harry Potter world, would it not be more appropriate to call Wizards Warlocks?  I mainly ask because to the items used and the health for spells reference in almost every book.  To Clarify: A warlock has always been someone who uses both mana and life to preforms spells, trade offs, or anything resulting in use of Mana, life or both. While a wizard mainly uses a mana pool.  While some do have the knowledge to tap ones life or not merely depends where you are.

One of Dumbledore's titles is "Chief Warlock of the Wizengamot".   What is the difference between a Wizard and a Warlock in Potterverse? As we don't see the term Warlock used often in the books, my impression is that a Warlock is somehow officially different from a Wizard.  Please no Wikipedia, HP Wikia, or dictionary.com answers. I'm looking for a canon-based¹ explanation.  ¹Any of the ten HP books or a quote from JKR


The below code takes 3 words on 3 different lines. The first word should be changed like all vowels should be replaced by %. The second word should be changed like all consonants should be replaced by #. The third word should be changed like all char should be converted to upper case. Then concatenate the three words and print them. For eg 1st, 2nd, 3rd` words are respectively: how, are, you  Then, the result should be: h%wa#eYOU  However, I get the result as: [C@4769b07b[C@cc34f4dYOU  My code is: Scanner sc = new Scanner(System.in); String fword = sc.nextLine(); String sword = sc.nextLine(); String tword = sc.nextLine().toUpperCase(); char[] arr1 = fword.toCharArray(); char[] arr2 = sword.toCharArray(); for (int i = 0; i < arr1.length; i++) {     if (arr1[i] == 'a' || arr1[i] == 'e' || arr1[i] == 'i' || arr1[i] == 'o'             || arr1[i] == 'u' || arr1[i] == 'A' || arr1[i] == 'E'             || arr1[i] == 'I' || arr1[i] == 'O' || arr1[i] == 'U')         arr1[i] = '%'; } for (int i = 0; i < arr2.length; i++) {     if (arr2[i] != 'a' && arr2[i] != 'e' && arr2[i] != 'i' && arr2[i] != 'o'             && arr2[i] != 'u' && arr2[i] != 'A' && arr2[i] != 'E'             && arr2[i] != 'I' && arr2[i] != 'O' && arr2[i] != 'U')         arr2[i] = '#'; } String res1 = arr1.toString(); String res2 = arr2.toString(); System.out.println(res1 + res2 + tword);

In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the  of the array, as defined by Object.toString():  int[] intArray = new int[] {1, 2, 3, 4, 5}; System.out.println(intArray);     // prints something like '[I@3343c8b3'   But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:  // Array of primitives: int[] intArray = new int[] {1, 2, 3, 4, 5}; //output: [1, 2, 3, 4, 5]  // Array of object references: String[] strArray = new String[] {"John", "Mary", "Bob"}; //output: [John, Mary, Bob]


I currently have an Acer Aspire dualbooting with Windows 7 and Ubuntu 10.10. I would like to have the advantage of Long Term Support that 12.04 provides and would like to upgrade the Ubuntu 10.10. My computer's memory is partitioned so that it is roughly 90gb for windows, 90 for ubuntu, and the rest(roughly 120gb) i use as a sort of "Shared space" so I can save and access files from both OS. I just want to know how to do the upgrade without ruining this set-up.

What are the different ways I can use to upgrade Ubuntu from one release to another?


I have a question how do I get nubmber between 2 different dates using JS. I currently have booking calendar wich works fine but I have no idea how could I make when someones clicks leave date on calendar that it would change price to days between arrival and leave date and * 45$ (let's say 45 is the price/night).  Here's my code of datepicker:       $(document).ready(function(){       var array = <?php echo json_encode($seznamkoncni); ?>;              function DisableDates(date) {                             var string = jQuery.datepicker.formatDate('dd.mm.yy', date);                      return [dates.indexOf(string) == -1];                  }                     $('#date1').datepicker({         minDate: 0,         changeMonth: true,          changeYear: true,       beforeShowDay: function(date){           var string = jQuery.datepicker.formatDate('dd.mm.yy', date);           return [ array.indexOf(string) == -1 ]         },       onSelect: function(dateStr) {              var newDate = $(this).datepicker('getDate');              if (newDate) {                       newDate.setDate(newDate.getDate() + 1);              }              $('#date2').datepicker('setDate', newDate).datepicker('option', 'minDate', newDate);                    }                                });              });  $(document).ready(function(){     var array = <?php echo json_encode($seznamkoncni); ?>;                function DisableDates(date) {               var string = jQuery.datepicker.formatDate('dd.mm.yy', date);              return [dates.indexOf(string) == -1];          }         $('#date2').datepicker({     minDate: 0,     changeMonth: true,      changeYear: true,   beforeShowDay: function(date){       var string = jQuery.datepicker.formatDate('dd.mm.yy', date);       return [ array.indexOf(string) == -1 ]   }                });      });

How do I get the number of days between two dates in JavaScript? For example, given two dates in input boxes:  <input id="first" value="1/1/2000"/> <input id="second" value="1/1/2001"/>  <script>   alert(datediff("day", first, second)); // what goes here? </script>


when i render arabic text from my oracle DB it looks like this:  ������� ������  even though i use windows-1256 encoding.  btw: arabic text that doesn't come from the DB is rendered correctly

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


I have made a mesh with mirror- and subsurface modifiers but when I apply them and switch to sculpt mode, it says "the object has non-uniform scale, sculpting may be unpredictable".     When I try to sculpt, the result is with any sculpting tool this:    Sculpting works with any object/mesh but this and if I try to recreate it with the same methods as this one, it does the same thing.

I ran into a problem I have never seen before and that is when I try to sculpt on a mesh, it sculpts like this:  Instead of this: I am using dyntopo with these settings:   I feel like theres a very obvious solution to this, but I have no idea what it is.


Can anyone please explain, why the outputs are printing two different boolean values. why aren't strings being compared not equal in this case. while simply comparing two strings with '==' operator does compare the strings. For example,     System.out.print("paper" == "paper") prints true. Thanks in advance. :)    package my_pack;      import java.util.Objects;     import java.util.Random;     import java.util.Scanner;       public class game {         public static void main(String[] args) {             //get the user input get_input()             Scanner scn = new Scanner(System.in);             System.out.println("Rock Paper or Scissor? Enter Your choice: ");             String user_choice = scn.nextLine();             user_choice = user_choice.toLowerCase();              //get the random number             Random rand = new Random();             int random_num = rand.nextInt(3) + 1;              //assign the number to specified method             String comp_choice ="";             switch (random_num){                 case 1:                     comp_choice = "rock";                     break;                 case 2:                     comp_choice = "paper";                     break;                 case 3:                     comp_choice = "scissor";                     break;             }             System.out.println(comp_choice);             System.out.println(user_choice == comp_choice); //paper == paper (false)             System.out.println(Objects.equals(user_choice, comp_choice)); //paper == paper (true)          }      }

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?


We have learned the following fundamental correspondence relations from basic quantum mechanics: $$E\rightarrow i\hbar\dfrac{\partial}{\partial t} \tag{1}$$  $$\vec{p}\rightarrow-i\hbar \nabla \tag{2}$$  My question is why we take a minus sign in formula $(2)$? I mean we should not take the minus sign from the viewpoint of space-time symmetry.  Is there any relationship with special relativity? If we don't take the minus sign in the replacement for momentum, what will happen in quantum mechanics?

My book on quantum mechanics suggests a derivation of the wave equation  $$\left(\Delta - \frac{1}{c^2} \frac{\partial^2}{\partial t^2} \right) \psi(\bar{r},t) = 0$$  from the photon energy-impulse relation  $$E^2 = c^2p^2$$  using the substitutions  $$\bar{p} \to -i\hbar \nabla$$ and $$E \to i \hbar \frac{\partial}{\partial t}$$  I suppose the $\hbar$s are there for the non-photon generalisation, but is there a reason for the minus sign in the $p$ substitution? Removing it would yield the same result.