For some reason when I'm trying to call methods using a main method or try changing variables declared outside the main method I get forced into having to change everything to static. This is fine in places but when it comes to needing to change values later in the code for example using a Scanner for input the main method just takes it to a whole new level trying to make me change the Scanner library etc.       I have never faced an issue like this before when writing java code I've tried recreating the classes/ project files etc but nothing works. I've tried looking everywhere for a solution but I can't seem to find one probably due to the fact that I don't know what to search for. I've probably made myself look like a right idiot with my title haha! Any suggestions people?? Thanks in advance!  Maisy

To be specific, I was trying this code:  package hello;  public class Hello {      Clock clock = new Clock();      public static void main(String args[]) {         clock.sayTime();     } }   But it gave the error      Cannot access non-static field in static method main   So I changed the declaration of clock to this:  static Clock clock = new Clock();   And it worked. What does it mean to put that keyword before the declaration? What exactly will it do and/or restrict in terms of what can be done to that object?


a) Prove that {∨, ∧, ¬} is functional complete b) Prove that the singleton sets {|} and {↓} where $$ \begin{array}{cc|ccccc|c} x & y & x \mid y & & x & y & x \downarrow y \\ \hline 0 & 0 & 1 & & 0 & 0 & 1 \\ 0 & 1 & 1 & & 0 & 1 & 0 \\ 1 & 0 & 1 & & 1 & 0 & 0 \\ 1 & 1 & 0 & & 1 & 1 & 0 \end{array} $$ are functional complete. The connective | is called Sheffer stroke and the connective ↓ is called Pierce arrow.  c) Prove that the sets {∨, ∧}, {→, ∨}, {→, ∧} are not adequate sets of connectives.

If I know that the set of operators {∨, & , ¬} is functionally complete, how do I go about proving/disproving the functional completeness of the following set of operators?  a) $\{\vee,\neg\}$  b) $\{\to,\neg\}$  c) $\{\to\}$  I have looked at the answer here for (b) :


I had added up English(US), Belgian(alternative), Tamil Keyboard layouts using the GUI.  How do I easily switch between these three layouts from terminal?

I use 12.04 Server in command line mode (no X installed), and I would like to change the keyboard layout. How can I do this?


Like the title, I have seen case where after a program is abnormally finished (because of bug I made usually), the shell doesn't echo my command anymore including the new-line (but I can see it accepts and runs it) so whatevery I type-in, it just prints everything in a single line without new-line. For example if I keep pressing enter key, the prompt string is printed to the right like this. ckim@chan-ubuntu:~/ProjectS/QEMU/qemu-5.1.0/test$ ckim@chan-ubuntu:~/ProjectS/QEMU/qemu-5.1.0/test$ ckim@chan-ubuntu:~/ProjectS/QEMU/qemu-5.1.0/test$ ckim@chan-ubuntu:~/ProjectS/QEMU/qemu-5.1.0/test$ ckim@chan-ubuntu:~/ProjectS/QEMU/qemu-5.1.0/test$ ckim@chan-ubuntu:~/ProjectS/QEMU/qemu-5.1.0/test$   Very annoying.. I have no choice but to exit the shell and open a new tab(which opens a new shell). In this abnormal situation, is there any method I can revive the shell behavior without openning a new shell?

I can issue the clear command or press Ctrl + L to clear the current Ubuntu terminal, but this just shifts previous output upwards and if you use mouse scroll or PgUP and PgDown keys it's hard to distinguish where the output of previous command ends and output of current command begins.  Is there a way to really clear the terminal so I won't see previous command results?


See the image below.  The first table is the actual table.  How to get the expected result in the second table using a procedure when I pass formid as parameter?  example: exec procedure 123

how to convert multiple duplicate columns as single row with appreciated values see the image my actually table and expected result.


Python 2.7.9 (default, Jun 29 2016, 13:08:31) IPython 5.6.0 -- An enhanced Interactive Python. In [1]: import numpy as np  In [2]: np.__version__ Out[2]: '1.14.3'  In [3]: np.arange(1.1, 1.12, 0.01) Out[3]: array([1.1 , 1.11, 1.12])  In [4]: np.arange(1.1, 1.13, 0.01) Out[4]: array([1.1 , 1.11, 1.12])   In both cases, the array gets to 1.12... how would you explain that?

Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


In James Baldwin's essay Everybody's Protest Novel, there is the following sentence:     It must be remembered that the oppressed and the oppressor are bound together within the same society; they accept the same criteria, they share the same beliefs, they both alike depend on the same reality.   I know that repeating the word or phrase at the beginning of a clause is called anaphora. In this case, that word is "they." Also, I know that repeating the last word or phrase in a clause is called epistrophe. Now, is there a name for repeating a word or phrase in the middle of a clause as is the case with "the same" in the sentence above.  Related to the same sentence, the short independent clauses after the semicolon are separated by commas and there is not coordinating conjunction. Is this common grammatical practice or not?  EDIT: The second part of the question has already been answered .

He called her, emailed her, texted her, tweeted her—all to no use.   Strictly speaking, I would need to write texted her and tweeted her, but I'm omitting and to convey a rhythm and sense of urgency. What do you call this kind of construction, and is it accepted grammar (at least for creative writing, if not in an academic context)?


Consider you have 2 sets of numbers A and B of size n and m respectively. Find the number of ways of arranging these numbers such that in the final output the order of numbers present in A and B remains same. Eg A={1,2,3} B = {4,5} One of the ways of arranging them is 1 2 4 5 3 Another way is 4 1 2 3 5 Notice how all the numbers of set A have same order  within themselves and same is true for numbers in B.

Suppose that, for a real application, I have ended up with a sorted list A = {$a_1, a_2, ..., a_{|A|}$} of elements of a certain kind (say, Type-A), and another sorted list B = {$b_1, b_2, ..., b_{|B|}$} of elements of a different kind (Type-B), such that Type-A elements are only comparable with Type-A elements, and likewise for Type-B.  At this point I seek to count the following: in how many ways can I merge both lists together, in such a way that the relative ordering of Type-A and Type-B elements, respectively, is preserved? (i.e. that if $P_M(x)$ represents the position of an element of A or B in the merged list, then $P_M(a_i)<P_M(a_j)$ and $P_M(b_i)<P_M(b_j)$ for all $i<j$)  I've tried to figure this out constructively by starting with an empty merged list and inserting elements of A or B one at a time, counting in how many ways each insertion can be done, but since this depends on the placement of previous elements of the same type, I've had little luck so far. I also tried explicitly counting all possibilities for different (small) lengths of A and B, but I've been unable to extract any potential general principle in this way.


Everytime I make meatballs they fall apart during cooking them. I used a several recipes such as a chinese lionshead meatballs and an indonesian recipe  and even a recipe from  a michelin 3-star restaurant. Always they fall apart. please give me tips. I like to make lions heads or indonesian meatballs. But they fall apart all the time. it drives me nuts. I use the recipes to the letter so it must be technique or something.  The meatballs look oke when i construct them, but during cooking they all apart.

I tried cooking meatballs as a change to what I usually cook but I found that they didn't stay together when being fried.  I made the meatballs with about 500g of mince, a chopped onion, some herbs and a beaten egg. I then mixed everything up in a mixing bowl and then fried.  After I realised that they weren't saying together when being fried I tried adding another egg, but it still didn't help.  Does anyone have any suggestions as to what I did wrong, or what I could try next time?


Consider the following example:  In [1]: lst = list(range(10)) * 2  In [2]: lst Out[2]: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]  In [3]: for i, x in enumerate(list(lst)):    ...:     if i > 10 and x % 2:    ...:         lst.remove(x)    ...:           In [4]: lst Out[4]: [0, 2, 4, 6, 8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]   So this strategy doesn't work, as it removes the first occurrence of item in the list, which is not what I want.  In [5]: lst = list(range(10)) * 2  In [6]: for i, x in enumerate(list(lst)):    ...:     if i > 10 and x % 2:    ...:         del lst[i]    ...:          --------------------------------------------------------------------------- IndexError                                Traceback (most recent call last) <ipython-input-6-bbec803a1844> in <module>()       1 for i, x in enumerate(list(lst)):       2     if i > 10 and x % 2: ----> 3         del lst[i]       4   IndexError: list assignment index out of range   My other strategy doesn't work either, because the copy of the initial list eventually has larger index, as the original list has items constantly removed from it.  The following does work:  In [7]: lst = list(range(10)) * 2  In [8]: idx = 0  In [9]: for i, x in enumerate(list(lst)):    ...:     if i > 10 and x % 2:    ...:         lst.pop(i-idx)    ...:         idx += 1    ...:           In [10]: lst Out[10]: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 2, 4, 6, 8]   And also this one:  In [11]: lst = list(range(10)) * 2  In [12]: idx = 0  In [13]: for i, li in enumerate(x for x in lst.copy()):     ...:     if i > 10 and li % 2:     ...:         lst.pop(i-idx)     ...:         idx += 1     ...:           In [14]: lst Out[14]: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 2, 4, 6, 8]   Is any of the working methods better than the other? Is there a better way to achieve what I want? What if I have or statement in the if test?  In [15]: lst = list(range(10)) * 2  In [16]: idx = 0  In [17]: for i, x in enumerate(list(lst)):     ...:     if i > 10 and (x % 2 or x // 5):     ...:         lst.pop(i-idx)     ...:         idx += 1     ...:  In [18]: lst Out[18]: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 2, 4]

Is there a built-in that removes duplicates from list in Python, whilst preserving order? I know that I can use a set to remove duplicates, but that destroys the original order. I also know that I can roll my own like this:  def uniq(input):   output = []   for x in input:     if x not in output:       output.append(x)   return output   (Thanks to  for that .)  But I'd like to avail myself of a built-in or a more Pythonic idiom if possible.  Related question:


If K and L are finite Galois extensions of F, then show that the intersection of K and L is Galois over F.  I was trying to use Galois group of the intersection and show that if the fixed field is NOT F then we can extend an automorphism to K and get some contradiction.  Any help?

I have finite Galois extensions: E/K and E/L. $$M:=K \cap L$$ I am trying to prove that if the extension E/M is finite then it is also Galois. Any suggestions? Thanks


I've tried proving the statement using that $x^2\equiv -1\pmod p$, and someone told me that this actually just implies that $p\equiv 1\pmod 4$. But I don't see it. Can anyone help me with this problem?

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


I'm playing Capture the Flag (on Turbine), and the enemy's team has a group of about five level-3 sentries right outside the door to our base. I've tried being a Soldier, Heavy and Demoman, and destroying them, but all five gun me down before I have the chance. The Scout's essentially useless and he'll be destroyed almost instantly, as will the Pyro and Medic. As a Spy, I am either blown up by grenades or sticky bombs before I even get near the sentries, or, if I'm lucky enough to get to them, as soon as I sap them, another Engineer comes along and removes my sapper (and I obvious can't backstab him as other Sentries will quickly shoot at me).  What is the best thing to do in this situation (in order to destroy lots of sentries), where coming into contact with them is inevitable (What is an ideal class to use, and what is the best strategy)?

Now that the Engineer update has come, there will be lots of Engineers building up everywhere.  How should this best be handled?


It has been bugging me for a very long time and I'm really sick of it. For example there's a script called testscript that compares two directories. In class the prof can just type   testscript dir1 dir2   to get the output, but I have to add ./ before the testscript and hit enter. Then enter dir1 and dir2 next line  How did the prof do that? Is it something with the bashrc thing? I never get how it works. If it's related please explain in plain simple language since I'm new to Linux. Thank you!

Why do we use ./filename to execute a file in linux?  Why not just enter it like other commands gcc, ls etc...


I have been trying to edit the blockquote formatting in the question,  on SE Arduino.  The issue I am having is with this piece of markup:        which ends up looking like this:        The final line in bold is appended to the previous line, and the newline is ignored.  It is not actually the blockquoting causing the issue. Working on that snippet in isolation, if the blockquotes are removed, the issue still occurs:        I have been playing with this for about an hour now, and can't find a solution.  I have tried copying and two pasting the previous line and writing in the Position... part, within it, manually, but as soon as I type the first space after the colon, the line appends itself to the previous one, like so:  OK        Not OK        I have added blank lines at the end of the blockquote, still nothing. IS it something to do with the CSV output upsetting the following line?  I have given up trying now, and need a pointer as to what I am missing, or doing wrong.    Here is the actual markup, if anyone wants to try themselves:  Here is the output:  $GPGSA,A,3,14,20,21,18,29,15,10,,,,,,2.59,1.13,2.33*0E $GPGSV,4,1,13,29,63,172,35,40,59,241,34,15,45,039,43,18,44,324,51*7A $GPGSV,4,2,13,21,42,350,46,10,27,284,46,24,27,116,19,14,25,209,17*76 $GPGSV,4,3,13,20,24,037,46,193,23,064,39,25,10,180,16,26,08,268,*44 $GPGSV,4,4,13,16,01,294,*42 $GPRMC,003218.000,A,1301.6703,N,07740.9225,E,0.02,0.00,010316,,,D*6D Position: GPRMC,003218.000,A,1301.6703,N,07740.9225,E,0.02,0.00,010316,,,D*6D Position: lat: 1******8 lon: 7*****42

Possible Duplicate:          In markdown a <br> is inserted if you end a line with a double space I find this feature particularly confusing.   Is there a reason why markdown swallows new lines?  Should SO make a modification so new lines are treated with respect without the double space hack?


When I saw $$\int_0^\infty\frac{|\sin t|}{t}\;dt$$ integral I remembered Laplace transform and complex analysis but I couldn't find anything. Is this integral bounded (convergent) and if it is what is it's value? I cannot do anything.

Improper integral $\sin(x)/x $ converges absolutely, conditionaly or diverges?  We have that $$\int_1^{\infty}\frac{\sin x}{x}dx$$ $$u=\frac{1}{x}$$ $$du=-\frac{1}{x^2}dx$$ $$dv=\sin xdx$$ $$v=-\cos x$$ $$\int_1^{\infty}\frac{\sin x}{x}dx=-\cos(1)-\int_1^{\infty}\frac{\cos x}{x^2}dx$$ $$\int_1^{\infty}\frac{\cos x}{x^2}dx<\int_1^{\infty}\frac{1}{x^2}dx$$ So it converges. Now I need to find out if $\int_1^{\infty}|\frac{\sin x}{x}|dx$ converges or diverges.


I am a research student from India working in European funding project in University of Pisa, Italy.  My Schengen visa will expire on Jan 8 2017. But I have scheduled to stay until February 8 2017 in Italy.  I am travelling from Pisa to Delhi via London Heathrow on February 8th 2017. Transit time of 2 hours 30 minutes before I catch the connecting flight via British airways. I don't even need to cross immigration area or leave the airport. Though my visa will expire, I still hold the valid residence permit issued by Italy until February. Having this card am I eligible to be exempted from needing a transit visa or air transit visa? I am using British Airways.

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


One of my database server running mysql/debian is out of memory. I added a swap file but as far as I know it's not used by the system.  I can confirm that the swap is enabled when I execute the free -h command:               total       used       free     shared    buffers     cached Mem:          497M       489M       7.5M         0B       432K       285M -/+ buffers/cache:       203M       293M Swap:         1.5G       2.7M       1.5G   When I look at the memory usage I can see that my system is out of ram but the swap is untouched.  MemTotal:         508944 kB MemFree:            6300 kB Cached:           292064 kB SwapCached:           32 kB SwapTotal:       1535996 kB SwapFree:        1533240 kB   I tried to increase the swappiness from 60 to 100 but it didn't change anything.  I'm out of ideas, am I missing something?

This is a  about how Unix operating systems report memory usage.   Similar Questions:                    I have production server that is running Debian 6.0.6 Squeeze  #uname -a  Linux debsrv 2.6.32-5-xen-amd64 #1 SMP Sun Sep 23 13:49:30 UTC 2012 x86_64 GNU/Linux   Every day cron executes backup script as root:  #crontab -e  0 5 * * * /root/sites_backup.sh > /dev/null 2>&1   #nano /root/sites_backup.sh  #!/bin/bash str=`date +%Y-%m-%d-%H-%M-%S` tar pzcf /home/backups/sites/mysite-$str.tar.gz /var/sites/mysite/public_html/www mysqldump -u mysite -pmypass mysite | gzip -9 > /home/backups/sites/mysite-$str.sql.gz cd /home/backups/sites/ sha512sum mysite-$str* > /home/backups/sites/mysite-$str.tar.gz.DIGESTS cd ~   Everything works perfectly, but I notice that Munin's memory graph shows increase of cache and buffers after backup.  Then I just download backup files and delete them. After deletion Munin's memory graph returns cache and buffers to the state that was before backup.  Here's Munin graph:  Externally hosted image was a dead link.


My truffle won't move in I have beaten ocram even and it still hasn't moved in. I made an overground mushroom biome but nothing is happening. It just keeps saying "maitake would like to settle in". SOS PLS HELP! I don't have pics but I can describe it to you: it is a skybridge 3 blocks thick around 150 blocks really really long has 2 house still vacant and the truffle won't still move in!   Please help once again. I have been trying for 2 days

I currently find myself in a pickle because even after I've built the mushroom biome and met all other requirements, the Truffle NPC won't move in.   I've defeated not only the Wall of Flesh but Ocram already. Created a surface mushroom biome. Built a house made out of mushrooms with mushroom furniture.   I have no idea how long it takes for the NPC to move in or if I'm wrong in any of the steps.


I'm currently trying to justify the removal of the rule in findbugs/sonar that classifies making a class serializable, or in most of our cases, extending our base class that makes the classes serializable without the dev realising, then not defining a SerialVersionUID a critical error! This of course makes our muggle management (read management that are not developers) panic, thinking we have critical bugs that must be fixed!  My argument is that in the current versions of Java, you do not need to provide a SerialVersionUID as the JVM will do that for you in cases where you serialize a class, but can anybody point any reasons why in todays day and age we should still provide a UID ourselves rather than leave it to the JVM? Looking on the web, the only reasoning I can really find for providing a UID nowadays is that not doing it is 'bad practice'.  Any ideas?

Eclipse issues warnings when a serialVersionUID is missing.       The serializable class Foo does not declare a static final   serialVersionUID field of type long   What is serialVersionUID and why is it important?  Please show an example where missing serialVersionUID will cause a problem.


I may not remember enough for this question to be answered.  I read this book 2 years ago; I grabbed it from a classroom library because I needed a book to read. It was definitely on the older end - at least, the copy looked like it had seen better days. I remember enjoying it, which is odd because I dislike most dystopian books - I think I grabbed it because the cover was interesting? I don't remember. It was definitely a middle grade or YA book - for kids, anyway.  It was very short (150 pages or less) and a cheap paperback. The protagonist was a younger teenager, who was living on the streets for some significant percentage of the novel. He met up with a much older man who taught him stuff (I think how to read) in this hut/hovel thing. I remember books being very important (but in a different way than Fahrenheit 451 - no one really knew how to read, I think). I think the main character narrated in first person, and it was in a sort of slang, along the lines of that in The Moon is a Harsh Mistress, though again, not entirely sure.     The novel ends with the older man being burned alive/tortured to death, I think, and the boy just runs off into the darkness.   I keep kind of associating this book with Freak the Mighty for whatever reason, but I don't know why, as I know they have very different plots.

I read this story in middle school or high school and I cannot for the life of me remember the name of it. I think it started off in a small clan of people, there was a young boy who had just come of age and he had some kind of gift that related to the books? Also I think the injecting was illegal, because I vaguely remember the boy encountering an old man who had a bunch of books that he had to keep hidden. There was also a city and he met a girl there that was Special some how. I may just be merging memories but I think at some point the boy and girl went to an underground city?  Does anyone know what I'm talking about?


I am told that I can AUTOMATICALLY (not manually) forward my Facebook messages to my email account but I can't find how to do that in the Facebook settings.  1) Can Facebook messages be automatically forwarded? 2) How do I do that?  (YES someone asked this very same question but the answers were to the question  "How can I manually forward messages." so I'm asking again.)

I can create email addresses that forward to other email addresses.  Likewise, can I automatically forward Facebook messages to either my email or phone?


I am using Ubuntu 18.04 on Dell Vostro 3546 uname -a  Linux <host-name> 4.15.0-122-generic #124-Ubuntu SMP Thu Oct 15 13:03:05 UTC 2020 x86_64 x86_64 x86_64 GNU/Linu  I am having severe wine dependency problems. This started when I did sudo apt-get purge wine*. I am not able to install it back. Please help, wine is very essential for me.  32-bit architecture is enabled  Output of sudo apt-get update, just for you to look at my repositories list :   Output of normal winehq-stable installation:   Output of winehq-stable installation using my favourite dependency tool: . If I choose "Y" in the first prompt it will do nothing and just exit. Then, in the second prompt if I choose "Y" it completely ruins my system by removing everything. If I choose "n", then it will ask again and again to do the same thing. Had to "q" abort.  Using synaptic:    EDIT: apt-cache policy winehq-stable wine-stable   winehq-stable:   Installed: (none)   Candidate: 5.0.2~bionic   Version table:      5.0.2~bionic 500         500 https://download.opensuse.org/repositories/Emulators:/Wine:/Debian/xUbuntu_18.04 ./ Packages wine-stable:   Installed: (none)   Candidate: 5.0.2~bionic   Version table:      5.0.2~bionic 500         500 https://download.opensuse.org/repositories/Emulators:/Wine:/Debian/xUbuntu_18.04 ./ Packages      3.0-1ubuntu1 500         500 http://es-mirrors.evowise.com/ubuntu bionic/universe amd64 Packages         500 http://es-mirrors.evowise.com/ubuntu bionic/universe i386 Packages  sudo apt install --install-recommends winehq-stable   Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:   The following packages have unmet dependencies:  winehq-stable : Depends: wine-stable (= 5.0.2~bionic) E: Unable to correct problems, you have held broken packages.  Output of apt-cache policy $(apt-rdepends winehq-stable 2>/dev/null | grep "^[a-zA-Z]" | sort | paste -s -d" ") =  Output of apt-cache policy $(apt-rdepends wine-stable 2>/dev/null | grep "^[a-zA-Z]" | sort | paste -s -d" ") =

After upgrading from 10.04 to 12.04 I am trying to install different packages.  For instance ia32-libs and skype (4.0).  When trying to install these, I am getting the 'Unable to correct problems, you have held broken packages' error message.   Output of commands:  sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.   After running this:  sudo dpkg --configure -a foo@foo:~$ sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.


How is it possible to suggest a change to a default site icon? I noticed a lot of sites with a default one.

Who is responsible for defining a site logo? I mean, there are moderators of the site that define it, or stackexchange defines it?


As title suggest, wondering what the literary rule is for "A unit." Unit being a noun would need an article. I have generally understood that the a/an decision is if the vowel sound if the lead sound ex: "an hourglass, but a glass".  it seems to me very clearly the "U" sound is the lead here, but for word that start with the 'you-enn' sound (unit, uniform, unabomber), we use "a".

Usually when a word starts with a vowel, we will use "an" before it. But for union, it is "a union" not "an union." It is not explained in the previously mentioned  why union is an exception. It explains how to know exceptions for h like hotels.   Also are there any exceptions for the opposite side, where there should be an "a" but is an "an" instead? (Unfortunately I have no example of a case like this.)


Looking at the question  it appears that you can either have a tool that can derive keys or bits, or can be used to sign and verify something. Is there an EC way to do both with the same keypair?

Are there any security risks using a single key-pair for both key-exchange and signing?  I'm mainly interested in using Curve25519 for key-exchange and Ed25519 for signing. But similar combinations, such as EC-DH and EC-Schnorr or even EC-DSA with the same key pair would be interesting too.   Curve25519 hashes the output of an x-coordinate only Diffie-Hellman key exchange Ed25519 is a slight variant of EC-Schnorr signatures.   I saw some recommendations to avoid using a single key for multiple purposes, but I couldn't find anything concrete.


I am using Ubuntu server 16.04 LTS in MacOS device through VirtualBox.  How can I open more than one terminal and navigate through them?  I already came across a similar question asked  but it didn't work with me. I believe it is because I am running the Ubuntu server from mac in VirtualBox.

I have installed Ubuntu 12.04 LTS server .  How can i run more than .sh file in the same time  (opening more than terminal)  I can use it on desktop version but i use server version.  Is it possible? if yes how can do?


This question is the result of a discussion in . If I publish an article, solving a problem, or finding relevant data, and subsequently another article gets published, explicitly stating that the problem is unsolved, or that there are no relevant data, what should I do?  Should I contact the editor of the journal where the second paper was published, to inform him that the paper is faulty? Would authors take exception to the fact that I didn't bring up the matter with them first? And would the right thing to do be to talk to the authors first, even if they can't find out who brought the matter to the editor's attention? Do I owe it to the editor, or to the academic community as a whole, to try to get the paper changed as quickly as I can by going directly to the editor? And does the answer depend on whether I believe that the authors acted in good faith or not?    Anything below this line is not part of my question and just justification for asking it.  Note that this question is about a specific bit of advice given in an answer in the other question, which I find questionable. As such, obviously this question has an answer in the other question. My question is whether that specific bit of advice is correct. Obviously the answer that prompted me to ask this question says so.  However, the point of the the other question is not to find out whether that specific advice is correct, and so there is no mechanism there for  a) showing agreement or disagreement for this bit of advice or any rival advice as to how to proceed (since the question is not about how to proceed in the first place.)  b) posting answers and/or thoughts about the correct way to proceed (since that question is not about how to proceed in the first place.)  So there is no way to extract any useful information from the fact that that answer has X votes: Was it given the votes because of or inspite of that bit of advice? Would people upvote the opposite course of action? Who knows. So I see some value in posting it as a separate question.  Feel free to remove this part once it has been decided whether this question is valid or already answered.    Another line: Why this is not a duplicate of : That question deals with the issue of plagiarism and asks for specific advice if you suspect this happening. The answers there advise to do nothing. My question is for the case that the authors explicitly and wrongly state that there is no research or data available, and I have (for good or for ill) chosen to take action to get this factually incorrect point to be corrected. My question is not "What should I do if people don't cite me?", my question is "If I already have decided to make it known that the paper is wrong in claiming that it offers the first, or only, solution to a problem, and am trying to get that changed, would the correct way of going about be alerting the authors that the claim they made is wrong, or should I write directly to the editor." I have edited the question a bit to make that clearer, but even with the old question I don't see how people can construe this as the same question (and could consider any answer in the other question to be a valid answer for this question.)

Before I start my PhD I worked in a group that researched on the application of a particular area to a particular domain. No other research group published work in this area+domain. So I can safely say that my previous group is among the first if not the first to research in the application of that particular research area on that particular domain.   Now I find a paper published at an IEEE conference where a major part of its contribution is introducing a system that does something I did in a previously published paper, and it does it in the exact same way and even gives it the same name!   I know that some conferences could accept non-novel contributions. Also the paper talks about other aspects so I find it perfectly fine that this paper has been accepted and published. But what I find annoying is that they do not cite my relevant work which was published a year earlier and fairly visible online; A simple (unpersonalized) search on Google would show up at least three links to my work.   This is the second time I face this problem, but the first time this happened it was actually by the same group I worked with before; they published a related paper without citing the paper I co-authored with them.   I try to give the maximum possible exposure to my work by making it publicly available on my personal website, ResearchGate, making sure it appears on Google Scholar, etc..   I find it worrying that my work misses citations, I am keen on improving my h-index and citations count. So my questions are:   Is there anything I can do regarding that already-published paper?  Is there anything I can do to prevent this from happening in the future?


I'm trying to dual boot Ubuntu 18.04 with Windows 10 on my Lenovo laptop, but have run into some problems :)  Specifically, my problems seem to come from choosing UEFI or Legacy as the Bootmode in the BIOS.  Here is what I have found so far:  Windows 10 needs to boot using UEFI and doesn't work in the Legacy mode while Ubuntu needs to boot using Legacy mode.  So how I uninstall ubuntu from my Legacy mode?  Currently both Windows and Ubuntu are installed on my laptop and disk partitioning type is GPT.

How to install Ubuntu 18.04 alongside Windows 10?  I have tried different process to install Ubuntu 18.04 in my PC in dual boot mode alongside Windows 10. But it turned out that most of the process didn't worked for my PC. My PC's configuration is 500 HDD, 3.5GHz Intel processor, 4GB RAM, 1GB Intel graphics & supports both BIOS & UEFI.


I want to interpolate daily climate data available from 3 locations. I am not sure how to interpolate the data for daily values for 30 years from the available 3 locations.

I have three location points with weather data. It's a 10-year composite of temperature values which means I only have three values for three locations for ten years. The distance between points is approximately 100 kilometers.  I want to interpolate these points to create a temperature map for the area. So, which method should I use and how?


In The Econometrics of Financial Markets by Campbell, Lo and MacKinlay -- a beautifully typeset book -- I have found gorgeous cross correlation matrices of the style below.    What is an elegant way to typeset these labels for the rows and columns in LaTeX (ideally in conjunction with the amsmath matrices)?

I need to write a complicated matrix, that has a structure as in the attached picture.


Subgaussian norm of a random variable $X$ is defined as: $$ \|X\|_{\psi_2} = \inf\left\{t > 0: \mathbb{E}\left[e^{\frac{X^2}{t^2}}\right] \leq 2\right\}. $$ For $L_2$ norm of a random variable we can write $\|X - \mathbb{E}[X]\|_2 \leq \|X\|_2$ which is called centering inequality. It is easy to prove that a similar inequality holds for subgaussian random variables as well. Namely, $$ \|X - \mathbb{E}[X]\|_{\psi_2} \leq C\|X\|_{\psi_2} $$ for some $C \geq 1$ which does not depend on $X$. I would like to see if this inequality holds for $C = 1$?

Specifically, define the sub-gaussian norm for a r.v. X as  $$ \|X\|_{\psi_2}=\inf\{t>0:e^{X^2/t^2}\leq 2\}. $$  How do we prove that the centering inequality with $C=1$ does not hold in general? i.e. $$ \|X-\mathbb{E}X\|_{\psi_2}\leq C\|X\|_{\psi_2}.  $$ A counter example would work too. Thanks in advance!


I  but it was closed despite the link being non-applicable to my question. I need help solving the below basic modular problem,  Show that $39$ divides $17^{48}-5^{24}$  My course has NOT covered Fermat's Theorem. The only properties of modular arithmetic I know are additivity, multiplicativity, symmetry, and transitivity. My professor wants me to solve this question only using these basic properties, but I have honestly no idea how to do so. I don't know what pattern I'm supposed to recognize.

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


I find it ironic that the  tag has 794 questions. I am curious though as to where someone can go to ask "developers" questions on the GPL especially since tons of lawyers don't know how to read those licenses very well. Where to go?  Example: I had to argue over the junit and eclipse licenses quite a while back and finally convinced the lawyer that we could use it internally at a very large telecom company. Developers need to ask developers and gain understanding from peers before talking to a lawyer. (And talking to other developers helped me to talk to that lawyer.)  I am guessing that questions on licenses will continue be asked on SO primarily because this is where developers are.  When developers leave SO, that is when licensing questions will stop being asked.  Personally, I like developers asking licensing questions on here and I respond with what knowledge I do have to those questions as we are all on SO to help our peers.

Is it appropriate to ask questions about software licenses/licensing on ? Or is the appropriate place  ? Or is there no appropriate site currently and we should suggest such a site on ?


I'm using SPOMOD and have used it in the past, but I think it might be broken forever. I'm getting the following error when trying to connect:  Exception calling "ExecuteQuery" with "0" argument(s): "Cannot contact web site '' or the web site does not support SharePoint Online credentials. The response status code is 'Unauthorized'. The response headers are 'X-SharePointHealthScore=0, SPRequestGuid=5aa8a59d-8092-2000-15b6-124fb12347a3, request-id=5aa8a59d-8092-2000-15b6-124fb12347a3, X-MSDAVEXT_Error=917656; Access+denied.+Before+opening+files+in+this+location%2c+you+must+first+browse+to+the+web+site+ and+select+the+option+to+login+automatically., MicrosoftSharePointTeamServices=16.0.0.5708, X-Content-Type-Options=nosniff, X-MS-InvokeApp=1; RequireReadOnly, Content-Length=0, Content-Type=text/plain; charset=utf-8, Date=Tue, 20 Sep 2016 16:06:01 GMT, P3P=CP="ALL IND DSP COR ADM CONo CUR CUSo IVAo IVDo PSA PSD TAI TELo OUR SAMo CNT COM INT NAV ONL PHY PRE PUR UNI", Server=Microsoft-IIS/8.5, X-Powered-By=ASP.NET'." At C:\Users\jfedorowicz\sharepoint\SPOMod.psm1:3209 char:3 +   $ctx.ExecuteQuery() +   ~~~~~~~~~~~~~~~~~~~     + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException     + FullyQualifiedErrorId : NotSupportedException    Any idea?

I'm a global admin on my O365 tenant. I get the below error when I try to access anything:  Exception calling "ExecuteQuery" with "0" argument(s): "Cannot contact web site 'https://domain.sharepoint.com/' or the web site does not support SharePoint Online credentials. The response status code is 'Unauthorized'. The response headers are 'X-SharePointHealthScore=0, SPRequestGuid=664da69d-002a-2000-15b5-db84f0677cb9, request-id=664da69d-002a-2000-15b5-db84f0677cb9, X-MSDAVEXT_Error=917656; Access+denied.+Before+opening+files+in+this+location%2c+you+must+first+browse+to+the+web+site+ and+select+the+option+to+login+automatically., MicrosoftSharePointTeamServices=16.0.0.5708, X-Content-Type-Options=nosniff, X-MS-InvokeApp=1; RequireReadOnly, Content-Length=0, Content-Type=text/plain; charset=utf-8, Date=Thu, 22 Sep 2016 16:10:24 GMT, P3P=CP="ALL IND DSP COR ADM CONo CUR CUSo IVAo IVDo PSA PSD TAI TELo OUR SAMo CNT COM INT NAV ONL PHY PRE PUR UNI", Server=Microsoft-IIS/8.5, X-Powered-By=ASP.NET'." At line:1 char:1 + $Context.ExecuteQuery() + ~~~~~~~~~~~~~~~~~~~~~~~     + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException     + FullyQualifiedErrorId : NotSupportedException


I have already looked at , but I'm not looking for references. I'd like to know how to check if two objects, or two arrays, two maps, two sets, etc, have the same values as another. Edit Not only the same values, but also keys! For example; var a = {foo: "bar"}; var b = {foo: "bar"}; a == b // I'd like true, but this returns false  Above code will return false, because of object reference. I do know that "foo" == "foo" will return true, because that's how strings work, but how's that for objects, arrays, maps, etc?

A strict equality operator will tell you if two object types are equal. However, is there a way to tell if two objects are equal, much like the hash code value in Java?  Stack Overflow question  is similar to this question, but requires a more academic answer. The scenario above demonstrates why it would be necessary to have one, and I'm wondering if there is any equivalent solution.


My bicycle has a front derailleur. It's a hybrid. I use it to commute and would like to fit a chainguard.  Is there any chainguard that can be fitted when there is a front derailleur?

I've been slowly going through the process of converting my old hardtail mountain bike into a commuting bike. One of the things that I'd like to do is to fit a chain guard so that I can ride the bike while wearing long trousers and not have to worry about chewing up the trouser cuffs.  A complication is that the bike (like most mountain bikes) is fitted with both front and rear derailleur gears. I'm not keen to replace these with an internally geared hub system as I have been trying to keep the changes relatively modest in their cost.  Are there chain guards that you can add to bikes with derailleur gears?


When in openGL and cycles as the rendering engine, i see black lines at the bottom when zoomed. I use RX 570 4gb as my gpu.

I'm new to blender and have been studying and starting with low poly modeling. Recently I changed my GPU from a GTX 960 to an RX 580. I uninstalled the drivers and installed new ones using DDU.  Problem: Rendering using OpenCL produces these unwanted lines. The attached image is a product of CPU + GPU render then the GPU only render, respectively. When I render using only the CPU the results are as expected, no unwanted black vertical lines, using only the GPU adds more lines on the image.  Any help is appreciated, thank you!


With the sun radiating so much energy every millisecond can nuclear fusion keep up with that pace? And if it can’t keep up isn’t the sun losing energy every second and therefor losing mass? Which leads to a smaller curvature of space time around it and therefor pushing the earth further away. And if this is true, isn’t this a huge problem? Or are the effects so small that it won’t be a problem until millions of years?

$M$ = mass of the Sun  $m$ = mass of the Earth  $r$ = distance between the Earth and the Sun  The sun is converting mass into energy by nuclear fusion.   $$F = \frac{GMm}{r^2} = \frac{mv^2}{r} \rightarrow r = \frac{GM}{v^2}$$  $$\Delta E = \Delta M c^2 = (M_{t} - M_{t+\Delta t}) c^2 \rightarrow \Delta M = \Delta E / c^2$$  $$\rightarrow \frac{\Delta r}{\Delta t} = \frac{G}{v^2 c^2}.\frac{\Delta E}{\Delta t}$$  Sun radiates $3.9 × 10^{26}~\mathrm W = \Delta E/\Delta t$  Velocity of the earth $v = 29.8 \mathrm{km/s}$  There is nothing that is stopping the earth from moving with the same velocity so for centripetal force to balance gravitational force $r$ must change.   Is $r$ increasing? ($\Delta r/ \Delta t = 3.26070717 × 10^{-10} \mathrm{m/s} $)


I am receiving an error when manually running this function: function updateCells() {   var ss = SpreadsheetApp.getActiveSpreadsheet();   var spreadsheetSummary = ss.getSheetByName('Summary');   const columnsWithData = () => {     const range = spreadsheetSummary.getDataRange()     const values = range.getDisplayValues()     const transposeCheck = values[0].map((_, iCol) => values.map(row => row[iCol]).some(cell => cell))     const countBoolean = transposeCheck.filter(Boolean).length        return countBoolean     }   var spreadsheetCommunityGroups = ss.getSheetByName('Community Groups');   var cellValueCommunityGroups = spreadsheetCommunityGroups.getRange('A12').getValue();   var summaryCommunityGroups = CONCATENATE('B', countBoolean++);   spreadsheetSummary.getRange(summaryCommunityGroups).setValues(cellValueCommunityGroups); }   Error: ReferenceError: CONCATENATE is not defined  I've turned on "API GOOGLE APP SCRIPT" for my account: . Is countBoolean not being output in the CONCATENATE function?

Using the following Google Sheets script:   var currentMonth = MONTH(TODAY);  I receive the error ReferenceError: MONTH is not defined. Why is MONTH not defined?


I'm writing C++ code on a mac. Why do I get this error when compiling?:     Undefined symbols for architecture i386:   "Log::theString",   referenced from:         Log::method(std::string) in libTest.a(Log.o) ld: symbol(s) not found for architecture i386 clang: error: linker command failed with   exit code 1 (use -v to see invocation)   Not sure if my code is wrong or I have to add additional flags to Xcode. My current XCode configurations are the default ones for a 'static library' project.  My code:    Log.h------------  #include <iostream> #include <string>  using namespace std;  class Log{ public:     static void method(string arg); private:     static string theString ; };   Log.cpp ----  #include "Log.h" #include <ostream>  void Log::method(string arg){     theString = "hola";     cout   << theString << endl;  }   I'm calling the 'method' from a test code, in this way: 'Log::method("asd"):'  thanks for your help.

Can anyone explain why following code won't compile? At least on g++ 4.2.4.  And more interesting, why it will compile when I cast MEMBER to int?  #include <vector>  class Foo {   public:       static const int MEMBER = 1;   };  int main(){       vector<int> v;       v.push_back( Foo::MEMBER );       // undefined reference to `Foo::MEMBER'     v.push_back( (int) Foo::MEMBER ); // OK       return 0; }


This has been raised many times, and marked duplicate, but  (I believe), and it is time to revisit the question with a different perspective... especially since there was debate in the linked MSO question as to whether the MSO question itself is/was appropriate. It seemed appropriate at the time, but, in retrospect, a lot of trouble, and a quicker and more appropriate response would have been available if a flag-the-moderator option in a logical place was available....  Without the flag-the-moderator, is the right answer to post to MSO?        Possible duplicates that have been previously closed as duplicates:    (Good question!)    (declined, not duplicate)  others.   In most cases (all?), the duplicate links point back to this question:         In that question, it is suggested that the 'flag user' is missing , and that moderators have the ability to flag the users, and not 'general' users.  The problem is: how do you get moderators to flag the user, when you can't easily notify the moderators?  The answer given in the question is that you should flag one of the 'abusive' things the user has done, a comment, post, chat message, etc. The assumptions are that:   the profile itself will not be the actual problem. there is some activity of that user to flag. the 'volume' of these incidents is small.   if there is no 'action' to flag, then flag a random post and give the details in the message. This seems convoluted.  Unfortunately, it is possible to use  tool.  The result is that, to report this problem, you have to flag some random post (another user's post), and then provide complicated details in the 'reason'.  There should be a better way to do this.... and a flag on the offending profile page is the right way. Even if the only option is: flag for moderator attention. Provide reason: .....  Special things to consider:   the offending person/profile can join any chat room regardless of their profile home-page so the profile's effect stretches beyond the home-site jurisdiction. They don't need to 'say' anything to be offensive the flag-user may be part of the 'privilege' escalation process, presumably like the existing flag-posts @ 15 threshold.   FYI:  Removed Image showing chat rooms since it is not appropriate in all places.... you can find the image at http://i.stack.imgur.com/aq4bW.png

I think the community does a great job policing questions/answers, etc. and the community has some good tools available to do this.  Between flagging questions with some reasons behind it and editing posts, closing them, and deleting them, the only thing that seems to be missing to me is the ability to flag a user.  Reasons to flag a user as abusive:   Duplicate User Abusive Behavior Offensive user name or profile User profile consists of spam Others?


Why does the direct sum of infinitely many groups require only finitely many are nonzero?  Is it just a case that the direct sum and direct product are two different things, and those are their names?  Or is there a logical connection between the idea of a sum and a product that governs one permitting infinitely many nonzero elements and the other not?

One can see on every text (book, lesson, comments) that a direct sum/coproduct of abelian groups is the same as a finite product but in the infinite case, the direct sum/coproduct is only a subgroup of the product.  Why does an element in an infinite direct sum only have finitely many components different from the neutral elements?  I don't see where the "finite" comes from when I look at the universal property.  Also, in another situation, a condition of "finiteness" appears and I think that is because of the same structure: a freely generated group, vectors space, algebra etc... has elements that are finite product/sum of generating elements. Because, if one really wants an infinite "sum" (or sequence) one may just take a formal serie. That is a ring, hence also an abelian group.


My study is a prospective observational study. My dependent variable (outcome) is development of surgical site infection (SSI) after surgery and my independent variables (predictors) are many factors containing socio-demographics, pre-operative, intra-operative and post-operative factors.   Outcome is dichotomous: SSI: 0=No , 1=Yes  Predictors are dichotomous as well as polychotomous( 3 or more categories), e.g. ASA score: 0=Class_1, 1=Class_2, 2=Class_3, 3=Class_4  I have already done the cross-tabulation (Chi square test) and i have also done univariate analysis using Enter method of binary logistics for every single variable.   Now i want to perform a multivariate analysis using all the predictors who came out to be significant in the univariate analysis (P= <0.25 as significant). I am now a bit confused which method i have to use in order to get more authentic results. I have seen literature similar to my study using simple logistic regression or forward step-wise regression as well. The references are as below:  Reference 1:   Reference 2:   My questions:   1) For polychotomous variables, i transformed them into dichotomous variables for one single category. e.g. I made 4 seperate columns for 4 classes of ASA score. and put them all individually in Univariate? and those who come out to be significant will be put in multivariate with 0=No as the reference category? Is this method acceptable?  2) Which method regarding binary logistics is the best as per my study?  i want to find out independent risk factors of SSI with Odds ratio?

I would like to implement an algorithm for automatic model selection.  I am thinking of doing stepwise regression but anything will do (it has to be based on linear regressions though).   My problem is that I am unable to find a methodology, or an open source implementation (I am woking in java). The methodology I have in mind would be something like:   calculate the correlation matrix of all the factors pick the factors that have a low correlation to each other remove the factors that have a low t-stat add other factors (still based on the low correlation factor found in 2.). reiterate several times until some criterion (e.g AIC) is over a certain threshold or cannot or we can't find a larger value.   I realize there is an R implementation for this (stepAIC), but I find the code quite hard to understand. Also I have not been able to find articles describing the stepwise regression.


It seems like there's something taking up a chunk of extra space and I have no clue what it is or how to check.

I am wondering about the pie chart in the properties basic tab. I can see blue is used space and white free space but what does the gray part mean. I have been searching with no luck. Thanks in advanced!


I have following crontab entry which does not work. Please can anybody help?  @midnight scp /home/xxx/file.txt xxx@yyy:~/zzz/file.txt_`date +"%m-%d-%y"`   This command works very well when run from command line. This is trying to backupo file to another machine every day with current date appended to it.

I am trying to make a crontab that makes a new .tar file each minute every business day by using the following code:  */1 * * * 1,2,3,4,5 tar -cf /home/user/Archiv/$(date +"%Y%m%d%H%M").tar /home/user/Textverarbeitung/ -P   This doesn't work. Why?


I am planning to buy a Nexus 4 from US and want to use it in India.  Should I expect any issues with this? Is that phone compatible with all carriers in India? Are there any power related problems?

Possible Duplicate:          I plan to purchase the LG Nexus 4 from the US on the release date (13th November). The phone claims to be unlocked. But will it be compatible with Airtel in India for both data and call services?


When solving many equations you usually stuff them in matrices and solve them using Gauss-Jordan elimination. Where I come from, we write it like this and this is what should appear in my document:    The gray parts of image are there for clarity and are not part of what I need. I just need (n+1) x n matrix with separation line. I will also need to display multiple of the matrices next to each other to show the GEM process:    How can I do it?

When studying systems of linear equations, it's nice to remind people that the last column of the coefficient matrix holds the constants.  This is often done in books by putting a vertical line between the last column and the next to last column.  What is a good way to do this in LaTex?


For instance, if we use [,æmplɪfɪ'keɪʃən] [,æmpləfə'keʃən] to indicate how to read "amplification", the practice is called phonetic notation or phonetic transcription, and the symbol is called International Phonetic Alphabet.   My questions are  1) How shall I describe the following practice: "amplification is read as am-pluh-fi-key-shun" Is there a name for the kind of phonetic notation?   2) what's the difference between [IPA] and [this kind of phonetic notation (am-pluh-fi-key-shun for amplification)] in terms of the degree of formality and/or which one is more commonly used?  3)Is it unanimous to use, for intance, -uh- for [ə] in this kind of notation? Maybe other people would write it as am-pli-fi-ki-shion or anything else?

What's this notation for marking up pronunciation?      analgesic: ann-ull-JEE-zick   What's a good introductory article or book to learn it?


Hi guys could you help me with this:  proof if $\sum a_{n}^{2}$ convergs then $\sum \frac{a_{n}}{n}$ convergs absolutely.  i tried:  if $\sum a_{n}^{2}$ convergs then exists m $\geq n\geq n_{0}$ ; given $\varepsilon > 0$   so.  $| a_{n+1}^2 + a_{n+2}^2 + ... + a_{n+m}^2| < \varepsilon $  i was goona use triangular inequality but it doesn't helps.  and i can't keep continue. Maybe i've taken the wrong way to solve this problem.

Suppose $\sum{a_n}$ converges. How do I prove that $\sum{\frac{\sqrt{a_n}}{n}}$ converges.  So I know that just because  $\sum{a_n}$ converges, do not mean I can say anything about the converges of its square root. So I know that I can prove that if  $\sum{\sqrt{a_n}}$ converges then $\sum{\frac{\sqrt{a_n}}{n}}$ converges by Abel's Test, but I do not know where to start for the case where  $\sum{\frac{\sqrt{a_n}}{n}}$ diverges


I have the following code which I compiled with g++ 6.1 on windows using the MinGW compiler.  unsigned char test_uc[8] = {0, 0xaa, 0xbb, 0xcc, 0x11, 0x22, 0x33, 0x44};  uint64_t* p64 = (uint64_t*)test_uc; __m256i res = _mm256_cvtepu8_epi32 (_mm_cvtsi64_si128(*p64)); uint32_t* u32 = (uint32_t*)&res; for(int i = 0; i < 8; i++)     printf("%d.0x%x\n", i, u32[i]);   When I run the program with optimization level -O1, I get the expected output as shown below.  0.0x0 1.0xaa 2.0xbb 3.0xcc 4.0x11 5.0x22 6.0x33 7.0x44   However, if I switch to optimization level -O3, I get this strange output.  0.0x0 1.0x0 2.0x0 3.0x0 4.0x8 5.0x0 6.0x41027f 7.0x0   What is going on here?

When asking about , people sometimes refer to the strict aliasing rule. What are they talking about?


A Salesforce instance change (refresh) will take place in production overnight from Saturday to Sunday. Salesforce will be "read-only" during the refresh period. What are the impact of a Salesforce Instance refresh or migration on the Marketing Cloud Connect Integration? What are the impacts regarding synchronization, Synchronized data extensions, Journeys, automations, any else on Marketing Cloud (SFMC) ? Will the connexion between SFMC and CRM still work correctly after that ? Do we need to make any changes or check anything that ? thank you Regards Ludivine

I have a connection between Salesforce sandbox and Marketing Cloud instance. There are some journeys configured in Journey Builder. In the documentation I see  Disconnecting does the following:  Removes the connection between your Marketing Cloud account and Sales or Service Cloud org. Removes the Salesforce system user’s credentials and resets the connection at the account level. Removes user mappings in the disconnected business unit and synchronized data extensions. Cancels tracking subscriptions. Any tracking for previous sends is not pushed to the previous Sales or Service Cloud org. Tracking is not affected in the Marketing Cloud   I have two questions. The first question is: Will work my journeys and other configured functionality if I disconnect my Sandbox org, connect Production org and configure synchronized data extensions? Or I need to create all my functionality again? The second question is: Will work my journeys and other configured functionality if I refresh Sandbox org?


I have a variable defined as:  var o = new String("0");   In console when i write:  o === o   it returns true but when i write:  new String("0") === new String("0")   it returns false  I don't understand why is it working on variable references but not on objects?  I tried it as:  (new String("0")) === (new String("0"))   because the problem may arise due to operator precedence, but it still returns false

A strict equality operator will tell you if two object types are equal. However, is there a way to tell if two objects are equal, much like the hash code value in Java?  Stack Overflow question  is similar to this question, but requires a more academic answer. The scenario above demonstrates why it would be necessary to have one, and I'm wondering if there is any equivalent solution.


We are trying to restore a backup file in Azure SQL MI using SSMS. the issue is we are trying to overwrite an existing database and we notice this feature is not present in SSMS for Azure SQL MI but available for SQL Server. Is it possible to overwrite the database using SQL scripts.

We're working on migrating some SQL Server VMs to Azure SQL Managed Instances.  We did an initial backup/restore without a problem:  RESTORE DATABASE [xxx]      FROM URL = 'https://<account-name>.blob.core.windows.net/<container-name>/<filename>.bak'   After doing testing, we now need to do a fresh restore from our SQL VMs.  We started doing the same process we initially did but when restoring, we got an error:  Msg 1801, Level 16, State 1, Line 1 Database 'xxx' already exists. Choose a different database name. Msg 3013, Level 16, State 1, Line 1 RESTORE DATABASE is terminating abnormally.   So I tried the WITH REPLACE option.  Unfortunately:  Msg 41901, Level 16, State 2, Line 1 One or more of the options (replace) are not supported for this statement in SQL Database Managed Instance. Review the documentation for supported options.   Reviewing the documentation just tells me that WITH REPLACE isn't available on a Managed Instance.  I can't find any documentation on doing an in-place restore/overwrite of an existing managed instance database.  Am I forced to drop and re-create the database?


I have recently installed Windows 10 and Ubuntu (Linux Mint). I was able to boot into both  systems, but I had to restart Windows. After this, Windows does not boot. It shows the black screen with the small wheel, and then it gets black, but the computer is running (I have to force shutdown).   I am able to work start Linux correctly, but it is not able to mount them unless I first use ntfsfix.  I have Fastboot disabled. I am able to run Windows in safe mode, from where I checked that hibernation is disabled.  EDIT: I suspect it has something to do with the hibernation files that Windows creates, because I need to delete them (using ntfsfix) in Linux in order to use the drives. However, hibernation is disabled in Windows.  Also, if this helps I am able to boot Windows into safe mode (I get the menu after trying to boot it 3 times).  Thank you!

I installed Windows on my computer, followed by an installation of Ubuntu. However, now I'm unable to boot into my Windows install.  What can I do to fix this?


It'd be nice if answers which are an exact copy of an existing (possibly upvoted) answer or contain large substring of such an answer and few own text - which should be a comment on the copied answer - are hard to spot in review because only the question and the answer is displayed.  A warning that the above described similarity has been detected (by an algorithm which can be quite simple for starters) would be helpful and avoid that those unwanted answers get into the system/stay in there for long time as easy as possible.

There have been many cases where on-site plagiarism has been coincidentally discovered by  good citizens either while looking for , or while answering questions merely to find out one of their  etc.   Most of the cases have been identified as verbatim copy-paste of the original answer.  I understand plagiarism is considered very offensive and can't be tolerated. It is very unprofessional and unfair. So here are my questions (and possibly a feature request):   Could verbatim plagiarized content be automatically detected?  Should it be pushed into a review queue similar to low quality posts for other users to confirm?


I have Windows 7 and Ubuntu dual-booted on my hard drive. My Ubuntu installation became kind of messed up and I don't know how to fix it. So it would just be easier for me to just do a fresh install of Ubuntu over the existing partition. Is there a way for me to do this without reformatting the whole drive and having to reinstall Windows?

I am trying to install a fresh version of Ubuntu in my computer without touching the windows 10 dual boot! In the Installation Type, the first option seems exactly what i wanted to do.  My question is, is this feature is safe to use? because i don't want to lose any windows files and other NTFS partitions on the hard-disk. Please eliminate my confusion. Note as that i dont need any files or media which are in the ubuntu partition, Thanks.


I'm using this to generate values between 5 to 13   int randomGeneratedLevelValue = ThreadLocalRandom.current().nextInt(5, 13);   How to make same matches fewer?

How do I generate a random int value in a specific range? I have tried the following, but those do not work: Attempt 1: randomNum = minimum + (int)(Math.random() * maximum);  Bug: randomNum can be bigger than maximum. Attempt 2: Random rn = new Random(); int n = maximum - minimum + 1; int i = rn.nextInt() % n; randomNum =  minimum + i;  Bug: randomNum can be smaller than minimum.


I'm trying to clear a player's inventory of an unstackable item if they have two of them in their inventory. This is a system to prevent duplication, while at the same time guaranteeing they still have this item and can't get rid of it.  The problem is: using an NBT tag selector for if the player has this item in their inventory only works for one item. Writing another entry within this NBT tag selector (like {Inventory:[{id:"minecraft:example"},{id:"minecraft:example"}]}) still treats it like one item and using {id:"minecraft:example",Count:2b} doesn't work either since these items can't be stacked.  How can I make this work the way I want it to? I'd rather not make 600+ different NBT tag selectors for each combination of possible {Slot:#b}'s if I can avoid it.

So, I need o give players one arrow every two seconds, but with a maximum of two arrows in the inventory. To do this, I tried adding a scoreboard objective called  ArrowN and setting the score to 1 if the player has one arrow and to 2 if the player has two arrow. Then every two seconds replacing with two arrows if the player has an ArrowN score of 1 and not replacing if he has a score of 2. Now, I couldn't get how to set a score of 0 for a player that has no arrows, to replace him one arrow. Something like this just works for a half:  scoreboard objectives set @a[score_ArrowN=!1,score_ArrowN=!2] ArrowN 0   I think operation could be useful, but i can't use that command.  Note: it must be multiplayer friendly  Edit:probably using /give is a lot easier but I don't like having arrows popping on your face every two seconds


I would like to reproduce the "Save site as template" action with the client object model. Can someone give me a hint how to do this?

For creating a list template programmatically by using server object, I'm using the SaveAsTemplate() function.  SPSecurity.RunWithElevatedPrivileges(delegate {   using (SPSite oSPsite = new SPSite(strSiteURL))   {     oSPsite.AllowUnsafeUpdates = true;     using (SPWeb oSPWeb = oSPsite.OpenWeb())     {       oSPWeb.AllowUnsafeUpdates = true;        SPList list = oSPWeb.Lists[strListName];       string bkpTemplateName = "bkp" + strListName + ".stp";       list.SaveAsTemplate(bkpTemplateName, bkpTemplateName.Replace(".stp",""), "Description", true);        list.Update();       oSPWeb.AllowUnsafeUpdates = false;     }     oSPsite.AllowUnsafeUpdates = false;   } });   But, is there a way to do the same by using CSOM?


Let $x\in \mathbb{R^n}$ be a nonzero columns vector. Define $A=xx^T\in  M_n( \mathbb{R})  $. What is the necessary and suffcient condition for $I-2A$ to be an orthogonal matrix?  Should I use $AA^T=I$?

Let $x$ be a non zeo (column) vector in $\mathbb{R}^n$. What is the necessary and sufficient condition for the matrix $A = I-2xx^t$ to be orthogonal?


Is there a meaningful difference between  if self.pk is not None:   and   if self.pk:   when checking a model field in python django?  Other languages have all kinds of differing 'correct' ways to check for a variable being null, empty, nonexistant, whatever.   a) I don't know how python handles the check  b) I don't know if this is important and / or meaningful in the context of django model fields

I've seen several examples of code like this:  if not someobj:     #do something   But I'm wondering why not doing:  if someobj == None:     #do something   Is there any difference? Does one have an advantage over the other?


I have a Lenovo Ideapad S510p (59-411351) Laptop (4th Gen Ci3/ 8GB/ 1TB/ Win8.1/ 2GB Graph). Can I install Ubuntu 12.04 LTS on it? Any specific steps I need to follow?

I would like to see a full how-to guide on how to install Ubuntu.


t = [[a, b], [c, d], [a, e], [f, g], [c, d]]   How can I get the a unique list of lists, so that the output equals:  output = [[a, b], [c, d], [a, e], [f, g]]   [c,d] is present twice so it needs to be removed.  [a,b] and [a,e] are unique lists regardless of the duplicated 'a'.  Thanks!

Is there a built-in that removes duplicates from list in Python, whilst preserving order? I know that I can use a set to remove duplicates, but that destroys the original order. I also know that I can roll my own like this:  def uniq(input):   output = []   for x in input:     if x not in output:       output.append(x)   return output   (Thanks to  for that .)  But I'd like to avail myself of a built-in or a more Pythonic idiom if possible.  Related question:


After a painful conversation with the reviewer I was asked to remove our biggest USP and resubmit, however there is already a very popular app that blatantly offer the very same feature.  I didn't bring this up with the reviewer on the call as she was very VERY aggressive and this could potentially have made matter worse. Which option do I have now?

Apple has refused my app, but I can not accept reason. They said it is not able to fully loaded, but on all device, conditions etc. work well for me.    Do you think is it any chance they read my complain, and tries to recheck my app, or better to submit and wait an other 1 week for review?     We discovered one or more bugs in your app when reviewed on iPad running iOS 8.2 and iPhone running iOS 8.2 on both Wi-Fi and cellular networks. Specifically, we found that your app is unable to fully load and function.


One among the few shops in London that offer or offers designer clothes.

One of the things that makes him great is he brings it every night.   I'm pretty sure it should be that make him in the plural, because one of the things is referring to a lot of things and a lot of things should take a plural verb. But I always hear native speakers in America say it in the singular, so with an s.  Another example:     This is one of the responsibilities that comes with greatness and he understands that.   Native speakers always use the verb in the singular (here, comes) even though [I believe] it is grammatically incorrect to use the singular form of the verb there.


The real line with the countable complement topology is not compact.  I create an open cover of $\mathbb R$ by: Let $\mathbb Q$ denote the rationals. Let an open cover be defined be the set of $\mathbb Q-\{q\} $, where $q \in \mathbb Q$. Then this set is countable. I am unsure how to proceed from here. And is this a good example of an open cover that doesn't have a finite subcover? Which will lead to my conclusion of not compact?

Is $(\mathbb{R},\tau_{co})$ compact where $\tau_{co}$ is the cocountable topology on $\mathbb{R}$?  I have the answer of my teacher but I'd like to see another one so I can understand better how people find the answer intuitively. He says:     $\mathbb{N}-\{n\}$ is infinite countable for all $n\in\mathbb{N}$.   Then $V_n = \mathbb{R}-(\mathbb{N}-\{n\})=(\mathbb{R}-\mathbb{N})\cup\{n\}\in\tau_{co}$ for all $n\in\mathbb{N}$.      Then $U=\{ V_n : n\in\mathbb{N}\}$ is a open covering of $(\mathbb{R},\tau_{co})$.      $U$ does not contain a countable subcover since $V_n\cap\mathbb{N}=\{n\}$ for each $n\in\mathbb{N}$ and $\mathbb{N}$ is infinite.   How would you solve that problem?


I'm working with a large SDK codebase glommed together from various sources of varying quality / competence / sanity from Linus Torvalds to unidentified Elbonian code slaves.  There are an assortment of styles of code, some clearly better than others, and it's proving an interesting opportunity to expand my knowledge / despair for the future of humanity in alternate measures.  I've just come across a pile of functions which repeatedly use a slightly odd (to me) style, namely:  void do_thing(foo) {     do {         if(this_works(foo) != success)             break;         return(yeah_cool);     } while (0);     return(failure_shame_death); }   There's nothing complicated being done in this code (I haven't cut 10,000 lines of wizardry out for this post), they could just as easily do:  if(this_works(foo) == success)     return(yeah_cool); else     return(failure_shame_death);   Which would seem somehow nicer / neater / more intuitive / easier to read.  So I'm now wondering if there is some (good) reason for doing it the other way, or is it just the way they always do it in the Elbonian Code Mines?  Edit: As per the "possible duplicate" links, this code is not pre-processed in any sort of macro, it is just in the normal code. I can believe it might be due to a coding style rule about error checking, .

In many C/C++ macros I'm seeing the code of the macro wrapped in what seems like a meaningless do while loop.  Here are examples.  #define FOO(X) do { f(X); g(X); } while (0) #define FOO(X) if (1) { f(X); g(X); } else   I can't see what the do while is doing.  Why not just write this without it?  #define FOO(X) f(X); g(X)


I've searched all over the internet and cannot seem to factorise this polynomial.  $x^4 - 2x^3 + 8x^2 - 14x + 7$  The result should be $(x − 1)(x^3 − x^2 + 7x − 7)$  What are the steps to get to that result? I've tried grouping but doesn't seem to work...

This might seem like a basic question but I want a systematic way to factor the following polynomial:  $$n^4+6n^3+11n^2+6n+1.$$  I know the answer but I am having a difficult time factoring this polynomial properly. (It should be $(n^2 + 3n + 1)^2$). Thank you and have a great day!


I'm trying today to build a regex to make it match to email adress.  I've made one but not working in all the cases I want.  I would a Regex to match with all email address finishing with 2 characters after the dot or only the .com.  I hope to be clear enought,   aaaaaa@bbbb.uk --> should work aaaaaa@bbbb.com --> should work aaaaaa@bbbb.cc --> should work aaaaaa@bbbb.ukk --> should not work aaaaaa@bbbb. --> should not work   this is my code:  #include <stdio.h> #include <stdlib.h> #include <regex.h>  int main (void) {   int match;   int err;   regex_t preg;   regmatch_t pmatch[5];   size_t nmatch = 5;   const char *str_request = "1aaaak@aaaa.ukk";    const char *str_regex = "[a-zA-Z0-9][a-zA-Z0-9_.]+@[a-zA-Z0-9_]+.[a-zA-Z0-9_.]+[a-zA-Z0-9]{2}";              err = regcomp(&preg, str_regex, REG_EXTENDED);   if (err == 0)     {       match = regexec(&preg, str_request, nmatch, pmatch, 0);       nmatch = preg.re_nsub;       regfree(&preg);       if (match == 0)     {           printf ("match\n");           int start = pmatch[0].rm_so;           int end  = pmatch[0].rm_eo;           printf("%d - %d\n", start, end);     }       else if (match == REG_NOMATCH)     {           printf("unmatch\n");     } }   puts ("\nPress any key\n");   getchar ();   return (EXIT_SUCCESS);  }

Over the years I have slowly developed a  that validates MOST email addresses correctly, assuming they don't use an IP address as the server part.  I use it in several PHP programs, and it works most of the time.  However, from time to time I get contacted by someone that is having trouble with a site that uses it, and I end up having to make some adjustment (most recently I realized that I wasn't allowing 4-character TLDs).  What is the best regular expression you have or have seen for validating emails?  I've seen several solutions that use functions that use several shorter expressions, but I'd rather have one long complex expression in a simple function instead of several short expression in a more complex function.


I have some binary mask image with 255 and 0 values and I want 0 values become transparent.  How can I do this?    Seems it work, but I'm not sure if it the best method:   gdal_translate -a_nodata 0 -of PNG src.png dst.png

Is there a way to set all the 0 value pixels on a raster to nodata using GDAL?  I would like to use fillnodata to fill some holes, but holes are set to 0, so I need to delete them first


NOTE: L'Hopital's and Taylor series not allowed!  Taking the log and exponenting the entire thing I get $$\lim_{n\rightarrow\infty}\left(\frac{1+\sqrt[n]{a}}{2}\right)^n=\lim_{n\rightarrow\infty}e^{n\ln\left(\frac{1+\sqrt[n]{a}}{2}\right)}=\lim_{n\rightarrow\infty}e^{n\ln\left(\frac{1+\sqrt[n]{a}}{2}-1+1\right)\cdot\frac{\frac{1+\sqrt[n]{a}}{2}-1}{\frac{1+\sqrt[n]{a}}{2}-1}}.$$  Letting $k=\frac{1+\sqrt[n]{a}}{2}-1$ we see that the RHS can be simplified to  $$\lim_{n\rightarrow\infty}e^{nk\frac{\ln\left(k+1\right)}{k}}.$$  It follows that $k\rightarrow0$ as $n\rightarrow\infty,$ and $\ln(k+1)/k$ then tends to $1$ (standard limit). So we can write  $$\lim_{n\rightarrow\infty}(e^{k})^n=\lim_{n\rightarrow\infty}\left(\frac{e^{k}-1+1}{k}\cdot k\right)^n=\lim_{n\rightarrow\infty}\left( \frac{e^k-1}{k}\cdot k+1\right)^n=(1 \cdot0+1)^n=1.$$  The answer should be $\sqrt{a}.$ Why is my method wrong?

Let $a$ and $b$ be positive reals. Show that $$\lim\limits_{n\to\infty} \left(\frac{a^{\frac{1}{n}}+b^{\frac{1}{n}}}{2}\right)^n =\sqrt{ab}$$


I have a Mac iBook G4, which is not booting at all and it requires 'OS X Recovery CD', which i do not have. So I wanted to install Ubuntu on, which I already use on another system.   A step by step guide, for burning the .iso image, or a bootable USB version guide for Ubuntu 13.10 for my iBook is highly appreciated.

If you select "USB" and "Mac" on , it gives a series of command line instructions to make a USB key which the MacBook will boot into Ubuntu from.  I've followed them to the letter two or three times on different USB keys, and it doesn't work. There's a very great deal of technical discussion about EFI etc. but this set of instructions seems to suggest it should just work, but it doesn't.  Help? I'm increasingly unhappy with the more locked-down approach Apple is taking, and I'd quite like to start using Linux with a view to transitioning over to using it as my main operating system, but booting from the CD takes forever, runs slowly and I'm really hoping to get it moving off USB.  Can anybody help me?


I've got a table with tows that are clickable via:   $(".clickableRow").click(function() {     console.log('Row Clicked');     window.document.location = $(this).attr("href"); });   That works perfectly after the page is loaded. However, we have added a search function that adds rows dynamically after a Ajax call.   After the call is done, the rows aren't clickable any more.   $('#carName').changeOrDelayedKey(function(e) {     var carSearch = $(this).val();     console.log(carSearch);     var carRows = $('#carTable tr[id^="product-"]');     $(carRows).each(function () {             console.log('This:'+this);             $(this).remove();     });       //Get new data     $.post("search.php", {s: carSearch}, function (data) {             console.log(data);             $.each(data, function (index) {             if ($('#product-' + data[index].externalProductId + '').length == 0) {                     $('#carTable').append('
' + data[index].title + '
');             }     });      }, "json");    }, 400, 'keyup');      $(".clickableRow").click(function() {             console.log('Row Clicked');     window.document.location = $(this).attr("href");                     });

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


I'm working with some python code, and I can't seem to figure out how to get a byte representation, and a string variable to work together.  I have:  secret = b'a very secret message'   if I redefine this as:  myrealsecret = 'Hey there this is a real secret' secret = b+myrealsecret   Why is that? and how can I get whatever value is in myrealsecret to play nicely with secret as a byte representation?  Thank you.

I'm using this code to get standard output from an external program:  >>> from subprocess import * >>> command_stdout = Popen(['ls', '-l'], stdout=PIPE).communicate()[0]   The communicate() method returns an array of bytes:  >>> command_stdout b'total 0\n-rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file1\n-rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file2\n'   However, I'd like to work with the output as a normal Python string. So that I could print it like this:  >>> print(command_stdout) -rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file1 -rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file2   I thought that's what the  method is for, but when I tried it, I got the same byte array again:  >>> binascii.b2a_qp(command_stdout) b'total 0\n-rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file1\n-rw-rw-r-- 1 thomas thomas 0 Mar  3 07:03 file2\n'   How do I convert the bytes value back to string? I mean, using the "batteries" instead of doing it manually. And I'd like it to be OK with Python 3.


I would like a better understanding of the famous birthday paradox.  "What is the probability that, in a set of n randomly chosen people, some pair of them will have the same birthday?"  I understood the first part, where the probability reaches 100% when the number of people reaches 367 by the pigeonhole principle. But I am not understanding the explanation beyond that. How do they say that the probability is 99.9% with 70 people and 50% with 23 people? And how do you further generalize the answer? And why is it a "paradox"?

I recently read about the Birthday Paradox which states that in a group of 23 people, there's a probability of 50% that 2 people share their birthday, probability wise.  I calculated and don't think it's possible that it's true in any case (unless my math is wrong). So, can anyone please tell me how to prove or disprove it mathematically ?


Although I’m rather new to physics and this site, I wanted to ask a question because it’s been sitting on my mind recently and I can’t figure it out... Forgive me if I’m missing something but here goes. It is said that when an object approaches the speed of light, it’s mass increases very, very much. However, If an object travelling nearly light speed is also not a black hole seen as how it is not a black hole in its reference frame, what happens to the mass gained by the object due to this speed? What I mean is, although it is not a black hole in its reference frame, thereby not allowing it to be a black hole in any other reference frame, it will still be a very heavy object when seen in its own reference frame, with tons of mass relative to volume due to the approaching of light speed. Doesn’t this mean that, in the object’s frame of reference, it will become a black hole, thereby allowing it to become a black hole in all frames of reference.. Provided I’m not missing anything, this means that objects approaching near light speed will produce a black hole in all frames of reference. I say this because: A.) if we say that the object isn’t stationary because of how heavy it is, this means that the near light speed velocity of the object is absolute because, in the object’s own reference frame, it has a definite velocity that is non-zero, thereby meaning that the object can become a black hole at near-light speeds; B.) if the gained mass is of the object in its own reference frame is seen as “not there” due to the lack of velocity of the object in the current reference frame, that means that mass is as referentially dependent as velocity, which doesn’t make sense to me. I apologize if this didn’t make sense, I tried my best and please forgive my lack of experience with this information.

I'm a big fan of the podcast Astronomy Cast and a while back I was listening to a Q&A episode they did. A listener sent in a question that I found fascinating and have been wondering about ever since.   From the show :      Arunus Gidgowdusk from Lithuania asks: "If you took a one kilogram mass and accelerated it close to the speed of light would it form into a black hole? Would it stay a black hole if you then decreased the speed?"   Dr. Gay, an astrophysicist and one of the hosts, explained that she'd asked a number of her colleagues and that none of them could provide a satisfactory answer. I asked her more recently on Facebook if anyone had come forward with one and she said they had not.  So I thought maybe this would be a good place to ask.


I need help running python in ubuntu  I can run python without a problem in my terminal but when I create a .py file I can't get it to run.

Trying to learn how to run my scripts through Ubuntu's terminal regularly.  That being said I am familiar with bash, wget, and awk being called but how do I call python files to run in the terminal?  I would like to learn this but I am unsure on where to research it.  I have a .pyw file that references several .py files in a folder.


I was using my PC in darkness.Brightness of PC was too shiny. I downloaded  software. I scanned it on . It says 1 threat detected(STOPzilla). I searched on Google that what is it.I got nothing except anti-STOPzilla. I visited the following page but it was not understand-able to me cause I am not too professional at english:  Can Anybody help me that what virus is it?

What should I do if my Windows computer seems to be infected with a virus or malware?  What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware?   This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits.


I am trying to select a portion of a message in Messages.app : however I get emojis when clicking inside of it:  This may be expected behavior on an iPhone but it certainly is not on macOS . Is there any way to select a portion of the message and copy it to the clipboard?

I am pretty sure I used to be able to select and copy text in Messages.app like in any other app (click + drag, double-click, etc.)  Right now I don't seem to be able to do this.  I am not sure what updated last, I am on macOS 10.14.6, Messages.app 12.0  Use case:    How do I copy the code from the message?


On the site for puzzels, we always use the invisible text to hide spoilers. Unless hovered over, the text is yello, just as is the background.  However, I noticed that this feature doesn't work in the question itself, only in the answers.  Can I somehow make it work even in the answers's body?      This text should not be visible.   and also...     !Neither should this. Do not edit.   * We're looking for a common everyday object.   * It's not anything abstract as love or energy.   * It's not symbolic as the letter A or peace sign.

The spoiler markdown is sometimes cough messed up. Today's edition: Spoiler doesn't work with numbered lists.  >! 1. Foo    2. Bar    3. Baz  renders like     ! 1. Foo      2. Bar      3. Baz   I could instead do  >! 1. Foo >! 2. Bar >! 3. Baz  but that also turns into      1. Foo  2. Bar  3. Baz   Sheesh, it's ugly! I could also insert two spaces in the second version and get "bar" and "baz" in new lines, but that's still not proper or enough indentation.  Can this be fixed please? Are there any good and un-ugly workarounds? (preferably using markdown)


Hello I am having some troubles with linking header files that contains templates. I have heard that using namespace could resolve this linking issue, but I could not get it to work. Thanks in advance.  //utility.h #ifndef _UTILITY_H_ #define _UTILITY_H_ #include<iostream> #include<string> #include<vector> using namespace std; namespace utility { template<typename T> void space_b4(T &value, int &max_num_length); template<class T> string doub_to_str(T &d);   //Converting double to string. } using namespace utility; template<class T> string doub_to_str(T &d)    //Converting double to string. {     stringstream ss;     ss << d;     return ss.str(); } template<typename T> void space_b4(T &value, int &max_num_length)    //This function adds space    before an element if the number of digits of this element is less than the maximum number. {     int d = max_num_length -  doub_to_str(value).length();     for (int a = 0; a < d / 2; a++)     {         cout << " ";     } } #endif   Here is my main cpp file: Data management.cpp   //Data management.cpp  #include <iostream>  #include"utility.h"  using namespace std;  using namespace utility;  int main()  {      double a;      int max;      max = 10;      utility::space_b4(a, max);  }   Here are the error messages:  1>Data management.obj : error LNK2019: unresolved external symbol "void __cdecl utility::space_b4<double>(double &,int &)" (??$space_b4@N@utility@@YAXAANAAH@Z) referenced in function _main 1>C:\Users\liuxi_000\Documents\C++\Final project_test\Final Project\Debug\Final Project.exe : fatal error LNK1120: 1 unresolved externals

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


I know this has been asked several times. I've read the responses. I'm still very confused.   What are the legal requirements for using samples from SO in other projects? If there are requirements, how should we go about removing them?  Case in point: a user whose question I answered was concerned about the CC license. I had to email him the solution to remove his fears of licensing. That's stupid, I don't want to give out my email address to work around legal issues.   So can someone at this organization clarify this is the intent?  If so, what is a legally sufficient means of bypassing the license?  One related answer suggested a profile message that source posted would be considered public domain and free of licensing. Is this sufficient?  Regardless of the answer above I'd like to make a recommendation that a 'Public Domain Content' checkbox be added for answers. Since I may pull code from an already public domain source the license does not apply anyway.  UPDATE   actually clears it up a little, my apologies for being a twit and not finding this first.  Most of my confusion comes from  where the basic consensus among answers was to 'consult an attorney' which is IMO counterproductive.    PS: I still think a "License Free" option for posts would be an ideal solution.

I was wondering about the copyright of code snippets from answers. Let's say you ask a question and the solution consists of ten lines of code, which are given in an answer. Are there any restrictions about the use of that code?   It seems that the content of this page is under the . So does one have to attribute the author if code is used in an open source project? Can it be legally used in closed source projects at all?  I guess ten lines of code are not really problematic, but is there a critical number of lines?


I am using Miktex2.9. I added \usepackage{signalflowdiagram} to draw block  diagrams. Then an error message appeared  "file signalflowdiagram.sty not found"   Where do I place the .sty file? Please show me how to do step by step!

I know how to define a package or a class, but how do I make it available (to myself) at all times?  Say I have the package file commonstuff.sty (or myprettyclass.cls), that I want to be able to include in any .tex file I create on my computer. Where do I put it? Do I need to run some installer on it, or is it enough to keep it in a certain folder?  Note: I know I can just place it in the same folder as the .tex file, but that's not what I'm after here. I'm looking for a way to "install" the package centrally on my computer.


Let $f$ be a real valued continuous function defined on $[0,1]$ so that $f(0) = 1,$ $f(1/2) = 2,$ $f(1) = 3.$ Show the limit,  $\lim_{n \rightarrow \infty} \int_0^1 f(x^n)\,dx$ exists and compute its limit.   It seems as if we can use continuity to say if $x_n$ goes to $x,$ then $f(x_n) \rightarrow f(x) = f(0) = 1$, but I don't know why they give $f(1/2)$ and $f(1)$, plus $x^n$ is not uniformly continuous on $[0,1]$ so I'm a little unsure.

Let $f$ be a real, continuous function defined for all $0\leq x\leq 1$ such that $f(0)=1$, $f(1/2)=2$, and $f(1)=3$. Show that  $$\lim_{n\rightarrow\infty} \int_0^1 f(x^n) dx$$  exists and compute the limit.  Attempt:   Since $f$ is real-valued continuous on $0\leq x\leq 1$ and the boundaries $f(0)=1$ and $f(1)=3$, $f$ is bounded on the interval  and the integral $\displaystyle\int_0^1 f(x^n)dx$ exists for any positive $n$. Thus, we can interchange the limit and the integral and compose the limit, \begin{align*} \lim_{n\rightarrow\infty} \int_0^1 f(x^n)dx&=\int_0^1\lim_{n\rightarrow\infty}f(x^n)dx\\ &=\int_0^1 f\left(\lim_{n\rightarrow\infty} x^n \right)dx\\ &=\int_0^1 f(0)dx=1. \end{align*}  Questions: So, my first question concerns whether interchanging the limit and the integral is correct. It seems it would be justified by the dominated convergence theorem, where $f(x^n)$ is dominated by a function $g(x)=\displaystyle\sup_{0\leq x\leq 1} f(x^n)$ and $f_n(x^n)$, on $0\leq x\leq 1$, converges pointwise to a function $f$ that takes value 1 for $x\neq 1$ and 3 for $x=1$.  My next question is whether the interchange between the limit and composition of the function is allowed. Since the function is continuous and the limit exists at that point, it seems the interchange would be justified.


We can prove that circle is not contractible (homotopic equivalent to a point). But is there an intuitive explanation of why this is so?

I am familiar with the proof that the fundamental group of the unit circle $S^1$ is $\mathbb Z$, yet I couldn't develop intuition for why it is true. For example, why would I fail if I try to find homotopy from a path that circles $S^1$ once to the path that stays at one point all the time? What brakes the continuity of such a homotopy?


My employment provides me with a W-2 at the end of the year, and I currently have taxes withheld from my paychecks. In the opposite of this question, , I'd like to know if I can elect to have zero withholdings from my paycheck and instead make estimated payments with a 1040-ES.  In this case, I have a generally good idea of my exact tax liability, so I can easily make quarterly payments without trying to predict fluctuating income. I'd just like to make sure it's legal to make quarterly estimated payments if you have income that would ordinarily pay taxes through withholdings.

As a consultant, I got used to paying quarterly taxes. Now that I'm a regular w2 salaried employee, I'm subject to normal withholding on each pay statement. I would like to keep making exact quarterly payments instead of having a (generally incorrect) amount held back each paycheck.   I haven't been able to find any information on the 1040-es that would make me think I'm ineligible to do so, but I suspect that it may be the case. I'd have to stop paycheck withholdings by updating my w4 to either have a high number of exemptions or mark myself as exempt from taxes, which I assume is where the rub lies.   So, as a regular salaryman, is it possible for me to pay taxes exclusively through quarterly payments in lieu of traditional withholdings?


Since, the sentence has "never" it must be present perfect, but whereas it's simple past. Why is it so?

I have this example in my practice book where I need to use the Past Simple or Present Perfect:     My grandfather died before I was born. I have never met him.   The right answer is "I never met him".  Shouldn't we use the Present Perfect with "never"?


I can't understand what is 'consecutive' in my profile on stack overflow. Thanks

What does the expression "consecutive days" mean with respect to badges?  Does it mean that you have to revist the site within 24 hours? Or does it allow that you might visit in the morning and the next day just before you finish work — e.g. over 24 hours, but say under 26 hours?


I'm using Sketch 51 on a macOS High Sierra. The Instagram icon looks great in Sketch but when I export as PNG it loses a lot of quality.    To the right we can see the icon in Sketch with zoom in good quality, and to the left we can see the image once exported.   I export the image with these options: - First I create an Artboard and adjust it to the image - Icon size is 45x45 - I export the artboard and choose PNG

I have noticed that my exports are not as sharp as they look in the Artboard. To give an example am trying to export the Google Play Badge from this dribble file:   But the text seems to be blurry.


I am new to jQuery and have been trying to create a dynamic drop-down-menu using select. However I am unable to use onChange in appendTo. Any Suggestions ?  <script> $(function() {     var addDiv = $('#content');     var n = 1;     jq144('#add_match').live('click', function() {         $('<p ><select onchange = "showUser(this.value, "select_team_' + (n) + '")" name="select_team_' + (n) + '" id="select_team_' + (n) + '"><option value = "">Team 1</option><option value = "a">A</option> <option value = "b">B</option><option value = "c">C</option></select> </p>').appendTo(addDiv);     ++n;      }); }); </script>   I also tried using on() but am unable to pass parameters to it.  Here is showUser:  <script>     function showUser(str, select_name) {         var num = parseInt(select_name.substr(select_name.length - 1));         alert(num + 1);         if (window.XMLHttpRequest) {             xmlhttp=new XMLHttpRequest();         } else {            xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");         }         xmlhttp.onreadystatechange=function() {             if (xmlhttp.readyState==4 && xmlhttp.status==200) {                 $("select[id='select_team_" + (num + 1) + "']").html(xmlhttp.responseText).selectmenu( "refresh");             }         }         xmlhttp.open("GET","getplayers.php?q="+str.value,true);         xmlhttp.send();     } </script>   Finally I was able to solve the problem using .on().

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.