Download multiple packages in parallel from a single repository with apt?

I'm painfully watching my apt dist-upgrade command download each package in a very long list, and what makes it painful is that packages are downloaded one-by-one. I fail to see why this process couldn't be sped up by downloading multiple packages simultaneously!  For example, if apt is downloading Chrome (PPA), Syncthing (PPA), and Ubuntu system updates (non-PPA), three simultaneous downloads will begin, one for Chrome, one for Syncthing, and one for the Ubuntu system updates.  Since all update packages are downloaded before any installation even begins, I don't see any reason why multiple packages for Ubuntu system updates coming from a single repository can't be downloaded in parallel.  I would really like to know if anyone knows a way to make this happen? Can I downloaded multiple package upgrade files in parallel from a single repository when running apt dist-upgrade or apt upgrade?


Searching stackexchange.com displays "Loading" and doesn't

The content of the page just says "Loading".  The URL I tried to load was:   Am using Chromium browser Version 43.0.2357.81 Built on Ubuntu 14.04, running on LinuxMint 17.1 (64-bit).  The developer tools console shows the error:     Mixed Content: The page at   '' was loaded over HTTPS,   but requested an insecure script ''. This   request has been blocked; the content must be served over HTTPS.   Screenshot:   Further important details: I had just recently logged in, with that browser tab, using my Google account. Looking at the browser history, the https comes from that point. I didn't initially try to load the site through https.


I am not a native speaker and it sometimes surprise me how many different meanings some words have. An example is the word call - when I was learning English I thought it was only "shout" or "to ring someone" but the list of meanings is almost endless:  .  What are some other such words so that I can be careful when interpreting their meaning? As if I could execute the query "give me a top ten list of words with most definition lines on TheFreeDictionary".


Why isn't it possible to view this user's profile?

Someone , but it's not possible to click their name to view their profile. Why is that?  I've seen this sort of thing when a user has been deleted. But I looked at this answer literally one minute after it was posted. Could the user have been deleted within that one minute? It seems unlikely.


Why do Windows XP desktops have 4 wire CPU fans while Windows XP laptops have 3 wire CPU fans?

Take a look at this cooling fan from a Dell D630:  Another cooling fan, from an XP desktop:  Notice that only the desktop's cooling fan has the 4th wire. Why is that so?


I've tried finding an answer for this but without success. Most people just say "don't drink it" without telling one why. The only reason being "it's bad".  As one having studied biology and chemistry I find the answers unacceptable and I wonder if anyone know why it's bad?    The water at my hotel looks fine, smells fine, tastes fine and doesn't make me sick.


how to clean the memory termed as 'others' in iphone 4s

since a couple of days iam facing the problem with internal memory of my apple iphone 4s device so can you help me to find a solution for this. my ios software is 7.1.2 and not the jailbroken piece


Terminate function call if it takes over 1 millisecond python

I have a list of black-box functions (no critical data handling, no side-effects from calling, okay to terminate prematurely) which need to be executed and their return values aggregated:  aggregate = [result for fn in seq for result in fn()]   The functions generally return within a few microseconds, however there are edge cases which I cannot influence which cause some of them to occasionally raise exception, return invalid type (e.g. None instead of iterable), or hang indefinitely.  To handle invalid output and exceptions, I wrote a decorator:  def safe_call(fn, valid_type, default, error_handler=None):     try:         val = fn()         if isinstance(val, valid_type):             return val         if error_handler is not None:             error_handler(TypeError("Invalid return type"))     except Exception as e:         if error_handler is not None:             error_handler(e)     return default   Now the only problem are hangs. Entire expression above should always be evaluated within milliseconds, and to ensure that I'm trying to implement a 1ms timeout for each function in the sequence.  I tried threading and multiprocessing, but I cannot properly terminate problematic threads, and overhead of starting a new process is too high and by itself exceeds the timeout value of 1 millisecond.  I tried using signals, benchmark indicating a 25% overhead on each call which is acceptable, but the evaluation is being done from a django's view which doesn't run in main thread, so signals don't work properly.  My current workaround is to have a separate process for each function constantly synchronizing with its parent process through a Queue, waiting to be called. This way, the parent can trigger the call on demand, wait 1ms, then check if the result has been sent back - saving the result if it has, or terminating the process otherwise.   It does work as far as performance is concerned, but there is 1400-1700% memory overhead from this solution which is not acceptable.  So how do I timeout a function call with a <1 ms precision without a huge memory overhead?


How to properly initiate combat when leading with an assassination as an Assassin Rogue?

I'm somewhat new to the game so sorry if this question is a stupid one and my english isn't the best either so pls excuse that as well ^^.   That being said, I'm unsure how initiating combat with an assassination (rogue assassin) really works.   If i successfully sneak up on someone/something and declare an assassination (or attack), my target and me roll for initiative and combat proceeds. Right?  But that seems kinda weird to me. There could be the possibility of my target rolling a better initiative, going first (but not doing anything bc it is surprised), losing its surprised status on the end of its turn and giving me the turn to attack. This means I wouldn't get advantage (Assassinate ability) bc my target had its turn before me meaning I also wouldn't get my sneak attack bonus (Sneak attack ability) and since the target isn't surprised anymore I also wouldn't do crit damage (Assassinate ability). That just doesn't make any sense to me since I would have attacked from a totally advantageous position an enemy that wouldn't even be aware of me. Did I miss something?  Is my thinking of how this works correct or am I right in suspecting that I missed something?   Thanks alot!


Why do we assign probability to theta even though we consider it constant in frequentist statistics?

i am trying to understand the differences between bayesian and frequentist statistics. I read that in frequentist statistics the unknown population parameter theta is considered a constant but in DerSimonian and Laird method the assign for example a Normal Probability distribution theta ~ N[μ,τ^2]. Can anyone clarify how a quantity is considered a constant if it has a probability distribution?


Why do quantum tunneling consume energy, if not then why it must pay back borrowed energy quickly?

I understand that quantum tunneling is a pure example of the uncertainty principle but clearly transistor had to be powered to work properly, anyhow I like to know if it is true that particle must borrow energy to quantum tunnel then quickly pay it back? I thought this is supposed to be probabilistic phenomenon so how does energy come into play?


I received a text from a number. My contact list had that number saved as well as 3 other numbers in the same contact card.   How do I get to know which number had sent the text, when it shows only the name?  (the “recent” thing, in Phone app does not seem to work.)  I worked around it by deleting each number from the contact card and seeing how the “sender” changed.  There ought to be an easy way for the same.


Is it possible to create a windowed identity column that automatically initializes and increments in SQL Server 2017 or later?    I would like the conceptual functionality of SelectedSubsetId below.  CREATE TABLE dbo.SelectedSubset (     ItemSetId INT NOT NULL FOREIGN KEY REFERENCES dbo.ItemSet(ItemSetId),     SelectedSubsetId INT NOT NULL IDENTITY(1,1) OVER(PARTITION BY ItemSetId),     PRIMARY KEY CLUSTERED (ItemSetId, SelectedSubsetId ) )   Where SelectedSubsetId would start at 1 and increment by 1 for each ItemSetId entered.  Another table would would foreign key this primary key and add the item ids of the set  CREATE TABLE dbo.SubsetItems (     ItemSetId INT NOT NULL,     SelectedSubsetId INT NOT NULL,     ItemId INT NOT NULL,     FOREIGN KEY (ItemSetId, SelectedSubsetId) REFERENCES dbo.SelectedSubset(ItemSetId, SelectedSubsetId),     FOREIGN KEY (ItemSetId, ItemId) REFERENCES dbo.ItemSetItems(ItemSetId, ItemId),     PRIMARY KEY CLUSTERED (ItemSetId, SelectedSubsetId, ItemId) )   In this concept SelectedSubsetId is only defined by its ItemIds. It has no attributes of its own that warrant creating a table to hold additional information.


Internal direct product of two subgroups

Problem: Find $A$ and $B$ subgroups of $S_4$ such that $S_4$ is an internal direct product of $A$ and $B$. Sol: As we know that $S_4=\{I, (1 2), (1 3), (1 4), (2 3), (2 4), (3 4), (1 2)(3 4), (1 3)(3 4), (1 4)(2 3), (1 2 3), (1 3 2), (1 3 4), (1 4 3), (1 2 4), (1 4 2), (2 3 4), (2 4 3), (1 2 3 4), (1 3 2 4), (1 4 2 3), (1 4 3 2), (1 2 4 3), (1 3 4 2)\}$ and we can see that $|S_4|=24$. Subgroups of order 2: Subgroups of order 3: Subgroups of order 4: Subgroups of order 6: Subgroups of order 8: Subgrougps of order 12: How to find its solution by using the strategy of 3×8=24, 4×6=24,2×12=24. Can anyone provide exact full solution? I am trying to solve it. But it is too lengthy for me. Because of head to trial method. I cannot guess A and B.


Why is work defined with respect to distance rather than time?

The common way of finding the work done on some object is by applying the equation: force*displacement.  However, suppose we apply a force of F newtons on an object of mass M for a duration of T seconds. We can then express the work done in terms of T and F, by expressing the change in velocity in terms F and T and then by applying the work-energy theorem.   If we do some further substitutions (Express displacement in terms of F, initial velocity and T), we can show that the above 2 methods produce the same result for a given force (according to what I calculated, do correct me if I am wrong).  Why is the equation force*displacement used instead of the latter case? To me, calculating the work done with respect to time is more intuitive because the increase in momentum of an object (under a constant force) is the same per unit of time. On the other hand, the increase in momentum per unit of displacement of an object gets progressively smaller due to the acceleration of the object.


When I'm editing a stack snippet, I often want to copy code from the original question into the snippet. But while the snippet editor is on display, there's no way to access the question, other than opening another tab/window. What I often do instead is copy all the code in the question to the clipboard, open the snippet editor, then paste it all in and revise it to what I want. But when the original code is poorly designed, that ends up being more work than just copying the bits and pieces that I want.  There could be a "View Question" button that pops up the question over the snippet editor and allows copying. Or maybe the Snippet Editor could be draggable and resizable, so you can reveal the question and copy from it; but this would require that it not be purely modal.


Problems with configuring figure and table counters in LaTeX

I'm typesetting a series of documents with the article class which present a series of problems with figures and/or tables, using the amsthm package. There are no sections in the document. What I'm aiming to do is to number each figure and table by the problem number, followed by the figure/table number. For example, the 3rd figure in the 4th problem would be numbered 'Figure 4.3', and the 2nd table in the 5th problem would be numbered 'Table 5.2'. For this purpose I wrote the following code (trimmed down to a MWE): \documentclass[12pt]{article} \usepackage{amsthm} \usepackage{graphicx} \usepackage{hyperref}  \theoremstyle{definition} \newtheorem{problem}{Problem}  \renewcommand{\thefigure}{\arabic{problem}.\arabic{figure}} % custom figure numbering \renewcommand{\thetable}{\arabic{problem}.\arabic{table}} % custom table numbering \newcommand{\newproblem}{\setcounter{figure}{0} \setcounter{table}{0}} % reset figure and table counter  \begin{document} \title{Minimum Working Example} \author{R. J. Drofnats} \maketitle \begin{problem} Lorem ipsum dolor sit amet, consectetur adipiscing elit. Pellentesque quis est at lacus auctor semper sit amet nec orci. Sed ultricies felis aliquam leo auctor aliquet. Vivamus eget metus et ligula aliquet hendrerit vitae ac nisl. Aenean eget diam ut nisi condimentum bibendum. Sed nulla magna, mollis in blandit a, finibus eu risus. Aliquam justo felis, tristique at diam sed, blandit ullamcorper nunc. Mauris non diam et purus convallis dapibus. Morbi eget egestas ligula, ornare cursus odio. See Figure \ref{fig:mwe_1-1}. See also Figure \ref{fig:mwe_1-2}. \begin{figure}[ht]     \centering     \includegraphics[width=0.4\textwidth]{mwe_1-1.png}     \caption{A first figure in Problem 1.}     \label{fig:mwe_1-1} \end{figure} \begin{figure}[ht]     \centering     \includegraphics[width=0.4\textwidth]{mwe_1-2.png}     \caption{A second figure in Problem 1.}     \label{fig:mwe_1-2} \end{figure} \end{problem} \newproblem \begin{problem} Curabitur cursus vitae diam sit amet imperdiet. Pellentesque eleifend libero ut dui venenatis faucibus. Proin iaculis ligula nisi, vitae rhoncus enim ultrices quis. Donec quis lacus sit amet lacus posuere feugiat. Vestibulum in condimentum nulla. Sed ornare velit sit amet eros dignissim egestas. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. In luctus condimentum elementum. Duis quis volutpat lacus. Fusce finibus enim eget turpis hendrerit, sed lacinia lectus efficitur. Maecenas vel libero metus. Cras quis placerat lacus. Donec ac sapien eu tellus elementum egestas non dictum diam. Donec a posuere neque, non euismod dolor. See Figure \ref{fig:mwe_2-1}. \begin{figure}[ht]     \centering     \includegraphics[width=0.4\textwidth]{mwe_2-1.png}     \caption{A first figure in Problem 2.}     \label{fig:mwe_2-1} \end{figure} \end{problem} \end{document}  You may wish to copy the MWE to your machine and typeset it there to better understand my question. The idea is that the figure and table counters would reset after every problem. The downside was that I would have to type in \newproblem or \newproblem* after every single problem, which obviously is very inelegant. This was originally a stopgap method to be used until I was better acquainted with the float system and hyperref. The method worked for a while. However, very recently I tried to click on the hyperlink for Figure 2.1 in the MWE above, and it redirected me to Figure 1.1 instead. It appears that hyperref could only read the figure counter and not the problem counter, so it linked the references to Figure 1.1 and Figure 2.1 in the copy all to Figure 1.1, as they shared the same figure counter. What I am looking for is a method to remedy this issue, i.e. design a method to allow figures and tables to be numbered as described above, while still linking references to figures with the same figure counter but different problem counters to the correct figures. Any advice to avoid having to manually type \newproblem after every problem would be welcome as well.


Ubuntu 16.04 On Choosing an Repository I have 3 choices for this country and all gave this error. Could not download all repository indexes  The repository may no longer be available or could not be contacted because of network problems. If available an older version of the failed index will be used. Otherwise the repository will be ignored. Check your network connection and ensure the repository address in the preferences is correct. An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://dl.google.com/linux/earth/deb stable Release: The following signatures were invalid: KEYEXPIRED 1555048520  KEYEXPIRED 1555048520  KEYEXPIRED 1555048520  KEYEXPIRED 1555048520Failed to fetch http://dl.google.com/linux/earth/deb/dists/stable/Release.gpg  The following signatures were invalid: KEYEXPIRED 1555048520  KEYEXPIRED 1555048520  KEYEXPIRED 1555048520  KEYEXPIRED 1555048520Some index files failed to download. They have been ignored, or old ones used instead.  Can some one help to fix this?


Java null pointer exception. Though an object has been created

I am only beginning to learn Java and my first project is a simple version of a sea battle. Currently when compiling my project i get the following problem:  Exception in thread "main" java.lang.NullPointerException     at SinkGame.PlaceDotComs(SinkGame.java:310)     at SinkGame.<init>(SinkGame.java:19)     at FirstVersion.main(FirstVersion.java:9)  Here are the relevant parts of the code: This is a part of SinkGame class  public class SinkGame  {    int gess_num;    DotCom dotcoms[];    Dot[] dots;    boolean gameover;         public SinkGame()    {        gess_num = 0;        gameover = false;        dotcoms = new DotCom[3];        dots = new Dot[49];         PlaceDotComs (); //Problem is here    } ...   PlaceDotComs method:  public void PlaceDotComs () {     boolean dotcom_set = false;     int dot_num = 0;      //Sets all the board dots coordinates     for (int i = 1; i < 8; i++)     {         for (int j = 1; j < 8; j++)         {                dots[dot_num].SetRow(i); // Problem is here             dots[dot_num].SetColumn(j);             dot_num ++;         }     }     //Sets dotcoms coordinates     for (int i = 0; i < 3; i++)     {         dotcom_set = false;         while (!dotcom_set)         {             dotcom_set = PlaceDotCom ((int)(Math.random()*GetActiveDotNumber()), i);             if (dotcom_set)                 ExcludeFilledDots();         }     } }   And my test class:  public class FirstVersion  {    public static void main (String[] args)    {        SinkGame new_game = new SinkGame(); //Problem here        new_game.Game();    }  }   As far as i know Null pointer exception appears when an object has been declared but not created. But in this example i have created an object in constructor: dots = New Dot[49] before calling PlaceDotComs function. Could you please explain me what the problem is and how to solve it? Thank you very much!


the unicode gets inserted in database through query in phpmyadmin bt doesnt gets inserted through php (CI)

i am building a nepali site ... it works fine with browser...now i am trying to insert the words in mysql database ..first i tried by changing collation to UTF-8_general_ci..It didn't work..after doing hours of google i found a way ..  In the file /usr/share/phpmyadmin/libraries/dbi/mysqli.dbi.lib.php at the end of function PMA_DBI_connect() just before the return statement I added:  mysqli_query($link, "SET SESSION CHARACTER_SET_RESULTS =latin1;"); mysqli_query($link, "SET SESSION CHARACTER_SET_CLIENT =latin1;");   that worked in phpmyadmin when i did a small query..it gets inserted in the table with nepali words..  bt when i tried simply from php (CI ) though generating last_query().. its doesnt get insert in table...the view i can get is ?????? where the nepali words should be...  note : my last_query generates  INSERT INTO `scheme` ( `functioning`) VALUES ( 'बन्द भएको ') ..


Utilizing the words "may" or "can" in vocabulary

My grandmother is slowly teaching me aspects of proper grammar. Sadly, I sometimes question her judgment since we both live in the southern United States. However, I would like to clarify when is the correct way to use the words: may or can. May I open this door? or Can I open this door? I am under the impression one means capability, but some movies that use such words are contradicting what my grandmother is saying is incorrect grammar. She stated, which I agree may is asking permission and can will be acknowledging if possible to do so, this is my own understanding. Is this a correct analysis?


What makes a good physics/engineering poster?

A more general form of this question has been answered  for example, but I want to know what makes a good poster presentation in physics and/or engineering conferences.  Obviously the poster must be visually appealing as discussed in various posts here, but I have seen cases where the most stunning posters (looks really good and well-written) did not win poster prizes when judged by professors at the conferences. Can you give reasons as to why this happens? Are there some special conditions or requirements in physics/engineering for such presentations?


Calculate: $$\int \frac{\sqrt{1 + x^4}}{1 - x^4} dx$$  I've been thinking about a good substitution, but I haven't found any yet. Integration by parts doesn't gave me anything meaningful.  Thank you!


Overlap between two kernel densities in ArcGIS for Desktop?

I have two different kernel reclassified raster files and I would like to find the overlap area between them, what I should do?   I have tried Boolean operators and map algebra and it does not work.


Remove elements from object in Javascript/Angular

I have an object let myObj = {"info1": "", "info2": "", "info3": "", ......}  Here I want to remove info1 and info2. I tried splice, but it is throwing error. The pop method is also not working. How can I achieve that?


Automatic vacuum fails with `ERROR: XX000: cache lookup failed for type 0`

I've been noticing something like this popping up every 15 seconds in my server logs:  2020-01-30 21:10:30 UTC::@:[24969]:ERROR: XX000: cache lookup failed for type 0 2020-01-30 21:10:30 UTC::@:[24969]:CONTEXT: automatic vacuum of table "myschema.mytable" 2020-01-30 21:10:30 UTC::@:[24969]:LOCATION: get_typlenbyval, lsyscache.c:2036   When I manually run a VACUUM ANALYZE myschema.mytable; it runs without any error, and the error in my logs goes away. However, inevitably, it returns again at some point.   The table in question is defined as follows:  tfs_dev=> \d myschema.mytable;                                                    Table "myschema.mytable"    Column    |   Type    | Collation | Nullable |                                  Default -------------+-----------+-----------+----------+---------------------------------------------------------------------------  level       | text      |           | not null |  id          | integer   |           | not null | nextval('myschema.mytable_id_seq'::regclass)  text_id     | text      |           |          |  name        | text      |           |          |  geom        | geometry  |           |          |  valid_dates | tstzrange |           |          | tstzrange(NULL::timestamp with time zone, NULL::timestamp with time zone)  adjacent    | integer[] |           |          |  valence     | integer   |           |          |  color       | smallint  |           |          | 0 Indexes:     "mytable_pkey" PRIMARY KEY, btree (level, id)     "mytable_text_id_key" UNIQUE CONSTRAINT, btree (text_id)     "mytable_gix" gist (level, geom, id, text_id, name)     "mytable_spgix" spgist (geom)     "mytable_text_id_ix" btree (text_id, level, id, name) Referenced by:     TABLE "otherschema.othertable" CONSTRAINT "othertable_mytable_fk" FOREIGN KEY (level, level_id) REFERENCES myschema.mytable(level, id)     TABLE "otherschema.othertable2" CONSTRAINT "othertable2_mytable_fk" FOREIGN KEY (level, level_id) REFERENCES myschema.mytable(level, id)   Many other posts with a similar error seem to be about a foreign data wrapper, which is present in this database, but not with this table/schema.


I’m rewatching TNG, and twice have noticed that objects from the holodeck are able to exit the holodeck. Wesley gets wet and stays wet when leaving; and also has a snowball fight, throwing a snowball which exits the holodeck and hits Captain Picard. How?


Why did Voldemort kill a muggle tramp and Albanian peasant to create Horcruxes?

I read somewhere (apologies, I cannot find the source) that Voldemort put high importance on creating Horcruxes. They were all kept in objects of meaning to him and almost all of the deaths were significant.  However it puzzles me that he'd murder people as trivial as a Muggle tramp and an Albanian peasant to create a Horcrux.  In summary, why did Voldemort kill such trivial people (Muggle tramp and an Albanian peasant) to undertake such a serious and significant task as creating a Horcrux?


One Function Expanding into Another Function?

How can one expand the function $f_1(x) = x$ on $(−π, π)$in terms of the functions $\cos nx, n = 0, 1, 2, ...$ and $\sin nx, n = 1, 2, ...,$ I read the below function - $$f_2(x) = a_0 + \sum_{n=1}^{\infty}(a_n \cos nx + b_n \sin nx)$$ is the expansion of the $f_1$, how is that? Main Question: Is $f_1$ equivalent to $f_2$ in some way? If so, plz provide a detail proof which is easily comprehensible. I have attached the excerpt below -


Are rejected migrations ever automatically deleted from the destination site? Should they be?

Now that rejected migrations , the list of them can be . Browsing them, I noticed that some questions persist in the rejected-closed-locked state for many months; e.g., here is a .    I read that "[rejected migrations] are deleted automatically after a month", but the evidence says otherwise. (Possibly, the writer was thinking of the migration stubs, which are indeed auto-deleted).  Most rejected migrations are rejected because they are off-topic for the destination site. Yet they remain on the site, being protected from deletion by the lock.  In most cases, their copy on the source site is long gone, having met the criteria for auto-deletion. The whole thing just doesn't seem logical.   Last year, Shadow Wizard raised this same question in a , receiving no answer.


Eclipse: Iteration's count while Debugging a for each loop

Can we know the count of the iteration (that is whether it's the first, second, third ... iteration ) while we are stepping over the code in a for each loop, in the eclipse debugger? Eclipse must be holding a count but how to get it show it to us. Apart from the workarounds of introducing an index in the code can we utilize something in built in eclipse.


I have Data stored in DataTables and I'm trying to write that data into a .xlsx file, with multiple sheets. I don't how to go about it. Thanks


I've created a shell script but I don't know how to do a loop that prints the number of lines in every file you pass to the script as argument. So that the output would be something like this:  2 lines in hello.sh 33 lines in /var/log/syslog


"as essential a part of the weekly shop"

To the Dutch, milk and cheese are staples, as essential a part of the weekly shop as rice is for a Chinese shopper or teabags are for an Englishman.   This is a sentence from an article on CNN. I don't understand why it is not "an essential part of the weekly shop".  Can you tell me about any rules or grammar in this phrase, please?


Let's consider the following integral $$\int \limits_{-\infty}^{\infty} \frac{\cos2x}{(x^2+4)^2} \, dx. \tag{1}$$  I would like to compute $(1)$ using residue theory. Let's consider a complex function $$f(z) = \frac{\cos2z}{(z^2+4)^2} = \frac{\cos2x}{(z-2i)^2(z+2i)^2}.$$  Of course $\text{Im}(-2i) < 0$ thus I am to calculate residue only in the point $z_0 = 2i$.  Noting that $z_0$ is a double pole we have $$R = \text{res}_{z_0}f(z) = \lim_{z \to 2i} \frac{d}{dz} \bigg((z-2i)^2 \frac{\cos(2z)}{(z-2i)^2(z+2i)^2} \bigg).$$  After some calculations we get $$R = \frac{i \big(-5 + 3 e^8 \big)}{64 e^4}.$$ That implies $$\int \limits_{-\infty}^{\infty} \frac{\cos2x}{(x^2+4)^2} \, dx = 2 \pi i \frac{i \big(-5 + 3 e^8 \big)}{64 e^4} = -\frac{(-5 + 3 e^8) \pi}{32 e^4}.$$  According to  $(1)$ is equal to $$\frac{5 \pi}{16 e^4}.$$  What am I doing wrong?


I want to solve the integral $$\int_{0}^{+\infty}\frac{t \sin(t)}{t^{2}+b^{2}}dt$$ Which function and contour should I consider ?


How can I convert a html book (consisting of a number of html files linked to each other) to a pdf file on Ubuntu?   Hope the resulting pdf file can have bookmarks according to the structures of the html book.  The html book can be downloaded from . Extract it, and go to help, and the directory manual is the html book.


How to upgrade or downgrade the Kernel in Ubuntu (to any stable or testing release)

When I report a bug I may be asked to "try out the latest upstream Kernel", how do I do that?  I see a lot of version specific answers to this question here on ask ubuntu, what are the general instructions?


Is a superconductor really a super conductor?

It is known that a superconductor is a material with electrical resistance zero. My question is, it is exactly zero, a theoretical zero, or for practical realistic reasons it is effectively zero?


Is 20 eyes an expression that means 20 person

The book slipped from his hands and fell on the floor with loud noise, 20 eyes looked up at him and his face turned red..... Q: approximately,how many persons where at the library? •10 •20 •40


Shell script runs two functions as child processes (via &). Both of them went to sleep (via sleep command).  Is it possible to wake them?  I have their pids.  P.s.  I don't want to run sleep with & and wait


Combining style numeric with style authoryear in BibLaTeX

I haven't had a lot of experience with biblatex so far and I decided to use the numeric style for citations in the text. However, the authoryear style for the bibliography is much nicer. I know, I can't actually combine numeric citestyle with authoryear bibstyle.  That brings me to my question: How can I achieve using the numeric citestyle and the formatting of authoryear in the bibliography?


How to declare class array inside another class in java?

I am trying to create an array of an object inside a class. Unfortunately I am keep running into nullpointerexception. This is my code, what could be wrong?    /////Init Buttons/////     //      button[] Buttons=new button[nButtons];    for (int i=0; i<nButtons-1; i++)       Buttons[i]=new button();     /////End/////       /////Set Button information/////       for (int n=0; index < nButtons*4-1; index+=4, n++) {        ////////       if (debug)         print("Index ");         println(index);         print("N ");         println(n);       ////////           String[] pieces = split(lines[0], ' ');        ////////       if (debug)       {         print("Button name ");         println(pieces[index]);         print("Button X ");         println(pieces[index+1]);         print("Button Y ") ;         println(pieces[index+2]);         print("Button size ");         println(pieces[index+3]);       }       ///////        Buttons[n].setInfo(pieces[index], Float.parseFloat(pieces[index+1]), Float.parseFloat(pieces[index+2]), Float.parseFloat(pieces[index+3]));     }


Steam wasn't opening, so I looked at another post

There it said that I should edit the environmental variable in front of the Ssteam desktop application How?  I really want to be able to just click on the icon on my desktop as opposed to opening terminal every time and typing a long command. Help? Please?  Also, I don't know anything about coding/Linux.


Is there a direct proof of this lcm identity?

The identity  $\displaystyle (n+1) \text{lcm} \left( {n \choose 0}, {n \choose 1}, ... {n \choose n} \right) = \text{lcm}(1, 2, ... n+1)$  is probably not well-known.  The only way I know how to prove it is by using  that the power of $p$ dividing ${a+b \choose a}$ is the number of carries needed to add $a$ and $b$ in base $p$.  Is there a more direct proof, e.g., by showing that each side divides the other?


why is the math calculations in java are not precise?

i have an XYSeries that holds Lat and Lon position of points. in some point i calculate the center point of all those positions. the code is very simple:  for(int i = 0; i < pnts.getItemCount(); i++){                 avgLon += (double)pnts.getX(i);                 avgLat += (double)pnts.getY(i);             }             cntrMass = new Vector2D(avgLon/pnts.getItemCount(), avgLat/pnts.getItemCount());   however this average calculation is not precise. when i calculate the same thing using excel sheet and the same data set there is a difference in the center point. I am using the exact number of significant digits for both calculations. the differences is of a 1e-6 magnitude, when converted to meters it gets pretty significant. any idea of how to fix this problem? any help would be appreciated.


I am writing a bash script to automate several actions:  #!/bin/bash           echo "Hello, World" NAME="${1}" PATH="${2}" echo $NAME echo $PATH eval "ls"   I am going to call ls, ffmpeg and a lot of other commands.  However running my script gives me the following error:  /var/www/html# ./life.sh test midhand.mp4 + ./life.sh test midhand.mp4 Hello, World test midhand.mp4 ./life.sh: line 9: ls: command not found   How come? why not found? Maybe I should import a directory with scripts?


Quantum entanglement for faster-than-light (FTL) network communication?

Quantum entanglement is 2 atoms that are paired together and when you stop one from spinning the other also stops with the same spin. Can you use these pairs to have faster-than-light (FTL) communication between 2 computers?


I write a test class for a batch that make a callout. So I wrote test class with a mock that I call in my batch test class. Here is the test class :  @isTest private class y_batch_Test {     @isTest static void batchTest(){         String query = 'SELECT Id FROM Mission__c';          Contact c = new Contact(LastName = 'Test', Email = 'mail@mail.com');         insert c;          Mission__c[] missionsList = new List<Mission__c>();         for (Integer i = 0; i < 10; i++) {             Mission__c m = new Mission__c(Name = 'Mission class test ' + i,                                           Description__c = 'test');             missionsList.add(m);         }         insert missionsList;          Test.startTest();         Test.setMock(HttpCalloutMock.class, new y_batch_Mock());         y_batch y = new y_batch();         Database.executeBatch(y);         Test.stopTest();      } }   And the mock class :  @isTest public class y_batch_Mock implements HttpCalloutMock {     public HTTPResponse respond(HTTPRequest req) {          // Create a fake response         HttpResponse res = new HttpResponse();          res.setHeader('Content-Type', 'application/json');          res.setBody('{"body":"test","group_id":"1234"}');          return res;     } }   When I run the test class I got this error :      System.CalloutException: You have uncommitted work pending. Please commit or rollback before calling out   However I got 76% of code coverage... But the test class can't pass.  EDIT - change in the batch test class I try to use the method in this post  but it throw me the same exception. Here is the batch test class after the modifications :  @isTest private class y_batch_Test { @isTest static void batchTest(){     String query = 'SELECT Id FROM Mission__c';      Contact c = new Contact(LastName = 'Test', Email = 'mail@mail.com');     insert c;      Mission__c[] missionsList = new List<Mission__c>();     for (Integer i = 0; i < 10; i++) {         Mission__c m = new Mission__c(Name = 'Mission class test ' + i,                                       Description__c = 'test');         missionsList.add(m);     }     insert missionsList;      Database.BatchableContext bc;     y_batch mbc = new y_batch ();     Database.QueryLocatorIterator iter = mbc.start(bc).iterator();     List<Mission__c> batch = new List<Mission__c>();     Integer batchsize = 10;     while (batchsize-- > 0 && iter.hasNext())     {         batch.add( (Mission__c) iter.next());     }      Test.startTest();     Test.setMock( HttpCalloutMock.class, new y_batch_Mock());     mbc.execute( bc, batch);     mbc.finish( bc);     Test.stopTest();  } }   But maybe my error comes from my mock class ?


If I ready the cantrip Gust to push back the first enemy that tries to use a (melee) attack against my party, what happens if the push back was successful?     Does it interrupt the attack? Does the attack simply fail through the push back? Does it allow the enemy to walk forward again and attack anyway?   What exactly happens?


I don't know how to make the diagonal line at the top left.


Open a sub-directory using something rather than its name

I wonder if it's possible to open a sub-directory using something rather than its names, because some names are long and also sometimes they have meaningless parts(acronyms or etc.). Is there something like an index number(after entering ls) and a special command I can use for this purpose? Or do you have another solutions? Thanks.


whitelisting some domains & some users on specific domains as destinations for Zentyal/Postfix

I have been using sendmail as MTA & SquirrelMail for webmail. I used to have following setup to restrict recepient in SquirrelMail. SquirrelMail had a plugin called Recepientrestrictions which can check two php files   Config.PHP - contains list of different domains where my domain user can send mails (sysadmins & Directors of company can send mails to anybody) recepientrestrictions.php - contains list of specific addresses such as user@gmail.com or user1@yahoo.com to whom my domain user can send mail.(again sysadmin & Directors of company can send mails to anybody)   Now the problem is:  I am migrating to Zentyal as email server. Zentyal uses Postfix in background & Roundcube for webmail.  I have got a partial solution which is a general rule for all users in my domain (couldn't seperate sysadmin/ directors to send mail to anybody on internet)  which restricts mails delivered to specific domains which is as follows.    Add this into main.cf:   smtpd_recipient_restrictions = check_recipient_access              hash:/etc/postfix/recipient_domains, reject   /etc/postfix/recipient_domains is the whitelist file:   mycompany.com OK  anotherdomain.com OK   Generate hash file: postmap /etc/postfix/recipient_domains Restart postfix service.    Even after this it doesn't block a mail sent to anybody@gmail.com or anybody@yahoo.com . Also I want to enable sending mail to few mail id's on webmail providers with the help of a whitelist file. e.g.  somebody@gmail.com OK somebody@yahoo.com OK foo@gmail.com OK   In short the scheme is :   Group1 sends mail to anybody on the planet. Group2 sends mail thro' two whitelists 1) domain wise 2) specific users of webmail.   Question is how to achieve this scheme?


How to denote number of summands below the expression?

If we want to write for example $\mathbb{N}=\mathbb{N}\times\dots \mathbb{N}$ and below the RHS write "n copies" how we will do it in Latex?


Preferred languages: C/C++, Java, and Ruby.  I am looking for some helpful books/tutorials on how to write your own compiler simply for educational purposes. I am most familiar with C/C++, Java, and Ruby, so I prefer resources that involve one of those three, but any good resource is acceptable.


SLEEP WINDOWS 10 Using CMD (command prompt)

All suggested  for Windows XP/7/8  PUTS WINDOWS 10 in  HIBERNATION (not in Standby).   1) so, for WINDOWS 10, how to put PC into from CMD (batch file)?  2) is there correct keyboard combination (without "choosing this and that", just direct keyboard combination.)


The conditions $a^2b^2=b^2a^2$ and $a^3b^3=b^3a^3$ make the group $G$ abelian?

Let $G$ be a group. Assume that $a^2b^2=b^2a^2$ and $a^3b^3=b^3a^3$ for all $a, b \in G$. Prove that the group $G$ is abelian.   Also please tell me whether there is any standard approach in proving commutativity of groups like this problem.


Coloring a certain side of a cell in a table

I have a standard LaTeX table and want to color a certain side of a cell, like I can do in Excel. Is there a way to do this?  Example of what I mean:    Thanks!


Having a problem with my recently purchased refurbished 2017 15" MacBook Pro. Yesterday it suddenly shut down and after rebooting, I noticed the battery was at 1% despite being plugged in. Now if it gets unplugged, the system shuts down instantly. When I click on the battery icon in the menu bar, it says:   Battery Is Not Charging  Power Source: Power Adapter   No warning about servicing or replacing the battery. The interesting part comes up when I check the system information. Under power, it lists:  Charge Information:   Charge Remaining (mAh): 0 Fully Charged:  Yes Charging: No Full Charge Capacity (mAh):   6736   Health Information:   Cycle Count:  4 Battery Installed:    Yes Amperage (mA):    0 Voltage (mV): 12904   The fact that the charge remaining is 0 but that it's still thinks it fully charged leaves me to believe that this is what is preventing it from charging properly. I've Googled the problem pretty thoroughly but everyone I've come across with a similar issue has Charge Remaining: 0/Fully Charged: No.   So far I have tried resetting SMC, different outlets & leaving it unplugged with the clamshell open all night in an attempt to fully drain the battery. Does anyone have any  other suggestions short of taking it in for servicing? I bought this thing like 4 weeks ago so I'd rather not have to spend more cash on it already. According to the Apple website, this computer has had the battery recall issue taken care of already. Could the new one be calibrated incorrectly?  System Specs:   MacBook Pro (15-inch, 2017) 2.9 GHz Quad-Core Intel Core i7 16 GB 2133 MHz LPDDR3 Intel HD Graphics 630 1536 MB   Thanks in advance for any help you might be able to offer


Mod deletion after a review deletion is attributed incorrectly

I just deleted  in response to a disputed review flag:    After seeing the deleted-by label, I assumed that review had somehow beaten me to the deletion.  disproves that:    It looks like the deletion label on the post is picking up on the later timestamp, but the earlier deleters. Looks like a bug.


Prove Involving Mean Value Theorem for $x \rightarrow a_+$

Let $g:[a,b] \rightarrow \mathbb{R}$ be continuous on the compact interval $[a,b]$. Also, assume that $g$ is differentiable on the open interval $(a,b)$. Assume that there exist a number $c \in \mathbb{R}$ so that $$g'(x) \rightarrow c$$ for $x\rightarrow a_+$. Show that $g$ is indeed differentiable in the point $a$ with $g'(a)=c$. I am having troubles with the generel cases of proving such a statement. I know that this is hinting for me to use the mean value theorem as it is continuous on the closed interval and differentiable on the open interval. But what is there to prove? Or rather how would I prove that it is differentiable? Do I have to use the direct definition of a derivative?


Proof that for all $x,y \in \mathbb{R}$: $$|x+y|+|x-y| \geq |x| + |y|$$  My (failed) attempt: $$|x + y| \leq |x| + |y|$$ $$|x - y| \leq |x| + |y|$$ $$|x + y|+|x - y| \leq 2(|x| + |y|)$$  Thank you


How would I show the result below using contour integration? $$\int_{-\infty}^{\infty} \frac{\cos bx - \cos ax}{x^2} dx = \pi (a-b)$$ where a>b>0 using contour integration. Any help would be greatly appreciated, thanks!


Consider the sequence $x_0 =\cos 0$, $x_{n+1} =\cos x_n$, how do I show it converges?

I know that this sequence is bounded and also that if it converges, then it should converge at $x$ such that $x = \cos x$. Assuming I am not allowed to use calculator (and hence not able to solve $x = \cos x$ numerically), how would I prove the convergence?


Java BufferedReader error: NullPointerException

I have a small assignment for uni which I seem to be stuck with. The application is suppose to be a quiz program which reads questions and answers from a text files and stores them like a flash card. My problem is that my buffered reader seems to be returning the nullPointer exception when it tries to read from the file. I'm unsure why this is. I will provide all code and highlight the error in bold. After doing a bit of debugging I found that the readLine method was returning null. Any thoughts? Thanks a lot. Error is at String[] line = getLine().split(":");  text file is in the format question:answer  import java.io.IOException; import java.util.ArrayList; import java.util.Scanner;  public class Quiz {     private ArrayList<FlashCard> flashCards;     public static void main(String[] args){         Quiz quiz1 = new Quiz();     }     public Quiz(){         FlashCardReader cardReader = new FlashCardReader();         try {             if(cardReader.isReady()==true){             flashCards = cardReader.getFlashCards();             play();             }         } catch (IOException e) {             e.printStackTrace();         }     }     private void play(){         Scanner userInput = new Scanner(System.in);         String answer = userInput.nextLine();         for(FlashCard card: flashCards){              System.out.println(card.getQuestion());             System.out.println("********************");             sleep(10000);             System.out.println("Enter your answer:");             answer = userInput.nextLine();             if(card.getAnswer() == answer){                 System.out.println("Correct.");             }else{                 System.out.println("Incorrect. The correct answer is " +     card.getAnswer() + ".");             }          }     }     private void sleep(int x){         try {             Thread.sleep(x);         } catch(InterruptedException ex) {             Thread.currentThread().interrupt();         }     } }     import java.io.BufferedReader; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.IOException; import java.util.ArrayList;  public class FlashCardReader {     BufferedReader reader;     public FlashCardReader(){         try {             reader = new BufferedReader(new FileReader("Questions.txt"));         } catch (FileNotFoundException e) {             System.err.println(e.toString());         }       }     public String getLine() throws IOException{         return reader.readLine();     }     public Boolean isReady() throws IOException{         return reader.ready();     }     public ArrayList<FlashCard> getFlashCards(){         ArrayList<FlashCard> flashcards = new ArrayList<FlashCard>();         try {             for(int i = 1; i <= reader.lines().count(); i++){                 **String[] line = getLine().split(":");**                 System.out.println(line[0]);                 flashcards.add(new FlashCard(line[0],line[1]));             }         } catch (IOException e) {             System.err.println(e);             e.printStackTrace();         }             return flashcards;      } }     public class FlashCard {     private String question;     private String answer;     public FlashCard(String question, String answer){         this.question = question;         this.answer = answer;     }     public String getQuestion(){         return question;     }     public String getAnswer(){         return answer;     } }


"Your delete vote has been recorded" message for undelete vote

When I have voted for undeletion, the system showed me message about deletion.        And looks like it isn't the localization problem, 'cause in traducir everything is fine:   Looks like the system shows incorrect message for undeletion vote.  Discussion on SOru:


Can I skip the last leg of my domestic return flight?

I've seen some comments on 'hidden city' ticketing, but am not sure if what I'm considering falls under that description.  My original tickets were MKE-CLE-IAD and back IAD-CLE-MKE.  The airline (United) changed my tickets after confirmation -- no idea why -- they must have taken one of the legs out of their scheduled flights because I can't find it anymore.  So now they have me flying MKE-ORD-IAD and back IAD-ORD-MKE. I live midway between MKE and ORD and the only reason I chose to use MKE was because I need to be in Milwaukee the evening of my return.  So now if I use the full ticket, I'll arrive in Chicago at 2:32, sit around for 2 hours, and hope that the ORD-MKE flight stays on schedule so that I arrive at MKE at 5:30 as planned so I can attend the 7 p.m. event.     or -- I can get picked up at ORD on arrival and be sure of making it to the concert.  Not checking bags.    Is there any reason I couldn't do this?   I've paid for the ticket and don't expect any part of it refunded.


Quantum vacuum thruster and conservation of momentum

I have been  and I think I understand the idea of virtual particles being created and destroyed but what I don't understand is how this is different from just shining a light and moving due to momentum from the light in the opposite direction.  Just to make sure I am understanding the concept correctly, here is a summary of what I think is going on:   Particles and antiparticles are continuously being created and destroyed in the quantum vacuum.   The thruster uses energy to exert a force on these particles.   An equal and opposite force pushes the thruster forward.   The particles annihilate each other.   If any of this is wrong please correct me.  It seems to me that in the end, only energy in the form of electromagnetic radiation exits the thruster. If momentum is conserved then the momentum imparted on the thruster must be due to the momentum of the electromagnetic radiation. How then, is this different from just creating this electromagnetic radiation in a more traditional way and using its momentum for thrust?  Thanks for the explanation


[[ 0*10%300 ]] works on AIX 6.1 but not on AIX 7.1 (ksh)

I have a ksh93 script that I'm migrating from AIX 6.1 to AIX 7.1  It's failing on 7.1 but works fine on 6.1.  Here's a snippet of the important parts.  integer f_count=0    . . .     . . .     . . .  if [[ ($f_count*$sleep_interval%$alarm_interval -eq 0 ) && $f_count > 0 ]]        then   When it hits the "if" I get  line 191: *10%300: arithmetic syntax error  I decided to simplify it by typing this at the command prompt.  AIX 7.1> integer x=1           AIX 7.1> [[ $x*10%300 -eq 0 ]] AIX 7.1> print $? 1 AIX 7.1> integer x=0           AIX 7.1> [[ $x*10%300 -eq 0 ]] -ksh93: *10%300: arithmetic syntax error   AIX 6.1> integer x=1           AIX 6.1> [[ $x*10%300 -eq 0 ]]  AIX 6.1>  print $?                                                                                1 AIX 6.1>  integer x=0                                                            AIX 6.1>  [[ $x*10%300 -eq 0 ]]  AIX 6.1>  print $?                                                                                0   To show it's ksh93 on AIX 6.1 I did this.  asdlkfjasd -ksh93: asdlkfjasd: not found.   If I move the 0 value so it's not first, it works as expected.  AIX 7.1> integer x=1             AIX 7.1> [[ 10*$x%300 -eq 0 ]]   AIX 7.1> print $?              1 AIX 7.1> integer x=0            AIX 7.1> [[ 10*$x%300 -eq 0 ]]   AIX 7.1> print $?              0   This will fix my issue as I know the 2nd and 3rd variables in my original equation will never be 0.  Is this showing an AIX 7.1 bug?


Why is it that FileInputStream read is slower with bigger array

If I read bytes from a file into a byte[] I see that FileInputStream performance worse when the array is around 1 MB compared to 128 KB. On the 2 workstations I have tested it is almost twice as fast with 128 KB. Why is that?  import java.io.*;  public class ReadFileInChuncks  {     public static void main(String[] args) throws IOException      {         byte[] buffer1 = new byte[1024*128];         byte[] buffer2 = new byte[1024*1024];          String path = "some 1 gb big file";          readFileInChuncks(path, buffer1, false);          readFileInChuncks(path, buffer1, true);         readFileInChuncks(path, buffer2, true);         readFileInChuncks(path, buffer1, true);         readFileInChuncks(path, buffer2, true);     }      public static void readFileInChuncks(String path, byte[] buffer, boolean report) throws IOException     {         long t = System.currentTimeMillis();          InputStream is = new FileInputStream(path);         while ((readToArray(is, buffer)) != 0) {}          if (report)             System.out.println((System.currentTimeMillis()-t) + " ms");     }      public static int readToArray(InputStream is, byte[] buffer) throws IOException     {         int index = 0;         while (index != buffer.length)         {             int read = is.read(buffer, index, buffer.length - index);             if (read == -1)                 break;             index += read;         }         return index;     } }   outputs   422 ms  717 ms  422 ms  718 ms   Notice this is a redefinition of an already posted question. The other was polluted with unrelated discussions. I will mark the other for deletion.  Edit: Duplicate, really? I sure could make some better code to proof my point, but  does not answer my question  Edit2: I ran the test with every buffer between 5 KB and 1000 KB on Win7 / JRE 1.8.0_25 and the bad performance starts at precis 508 KB and all subsequent. Sorry for the bad diagram legions, x is buffer size, y is milliseconds


As i dependent on my father so my source of income is my family and spend 20,000 PKR each month in my living as i already submitted my university fee of full semester. so my question is that what should i mention in regarding to above question they asked  Do you have regular source of income or savings? how much money you spend each month?


Evaluation of integral involving trigonometric functions

Evaluate $$\int_0^{\pi}\frac{x\sin x}{1 + \cos^2x}\,dx$$   I've tried many substitutions like $u = x\sin x $, $u = \cos x$ and $u = 1+\cos^2 x$ but they didn't work.


Does the implications of double slit experiment contradict the "law of conservation of information"?

Not sure if I framed below question properly, let me know if anything you want me to clarify in the comments.  Implications of double slit experiment show concious observation affect the 'reality as we know it' on bigger scale of Einsteins relativity.  Consider below scanarios(Lets assum the detector of type magnetic needle detector)  Scenario 1. Detectors Off + Recording Off(No paper for recording, needle movement On) => Interference pattern  Scenario 2. Detectors On + Recording On => Expected two band pattern  Scenario 3. Detectors On + Recording Off(No paper for recording + Needle movement On) => Interference pattern  When we perform the experiment with the "detectors on" but the "recording off" shows the same results as if detectors are off.    Now when recording if off(no paper for recording) the needle still moves and has effect on correcponding air molecules come in contact with the needle and as per law of conservation of information, information can still be recovered.  If law of conservation of information is correct then we would have seen the same effect for Scenario 2 and Scenario 3. So do above result contraict the law of conservation of information?  ====Update  If we say magnectic needle affecting air molecules cannot be recovered that means information is lost which is against conservation of information theory.   Also if system decides(whether to produce defraction pattern or two band pattern) based on our capabilities of recovering the information then how does system know our capability of what information can be recoverd by us ? If in future we become advanced enough to be able to recover that information will the scenario 3 produce defraction pattern ?  -- The question "The Double Slit Experiment - delayed measurement " does not deal with law of conservation of information which is specifically I am acking about.


A term used in a contract stated this "Specialist oils or spark plugs may be required for your vehicle's service.  Specialist oil is at a set cost of £24 whilst if recommended Spark Plugs will be quoted to you on the day of your service.", In the first sentence, does "Specialist" describe only "oils" or both "oils" and "spark plugs"? Does the second sentence clarify anything in the first?


I have a doubt about the following sentence how it should be made correctly.     "I'm happy when you're beside/s (of) me"   Beside or besides, me or of me?


I was a victim of serial downvoting 2 days ago. Is it possible to know the username, IP address or similar of the person who down-voted me? What happens to such people? Will they be banned/warned?


Does there exist a function $f(x)$ such that $f'(x)$ exists for all $x \in A$ but $f'(x)$ is not continuous on $A$?

I don't think this can be the case, since the derivative is defined as a limit $$f'(x) = \lim_{a\to x} \frac{f(x)-f(a)}{x-a}$$ And a function that equals its limit is by definition continuous but this feels like a non-rigorous proof so I do not want to depend on it. If a function does exist such that $\forall \, x \in A \,\, \exists \,y : f'(x) = y $, a good answer would give an example of such a function, or if such a function does not exist, a good answer would give pointers as to how I could prove its non existence


Both sentences are in the past, what is the difference?  Mr X had driven them home.  Mr X has driven them home.


Does the pilot of a rocket ship experience an asymptotic approach to the speed of light?

A question has recently come up that goes beyond my knowledge of special relativity.  Suppose a pilot has his foot on the gas pedal of a rocket ship and keeps it applied to achieve a constant acceleration, and he has a magical engine that can maintain the thrust needed to accomplish such acceleration even as the vehicle acquires mass.  He measures his acceleration at periodic intervals and sums it up as he goes.  Observers perceive the rocket to increase in speed and gradually approach the speed of light (but never reach it). Two possibilities are being debated for what the pilot observes, and my preference is for the first:   Time dilation gives him the impression that the summation of his readings are approaching light speed at a constant rate, but there is an asymptote involved here even in the inertial frame such that he never actually perceives himself to reach, let alone exceed, $c$, because time slows down to a crawl (as seen from the reference frame) before this can happen. Although to observers he is only approaching $c$, it is possible for the summation of the measurements on his accelerometer to indicate that he has surpassed $c$ and is now traveling faster than light.  From the reference frame he is approaching $c$ and his instruments in the inertial frame tell him that he has surpassed it.   I assume (1) is true beyond a doubt?  If so, is there a straightforward explanation for this?


I downloaded ubuntu but I also had to download WinZip in order to complete the download?

I downloaded Ubuntu and in order to complete the download I had to download WInZip. I am so confused on why I had to that and what I have to do.  I'm on windows.


How would I write a T-SQL query to concatenate and group text

I have a table with the following structure:  PERSON   Sequence    TEXT   1        1         John ran   1        2         across the field   2        1         Bill also   2        2         ran across the field after John     I would like to write a query that produces the following result:   PERSON   TEXT  1        John ran across the field  2        Bill also ran across the field after John   Is something like this possible with T-SQL


Morphisms $X\to\text{Spec }A$ are in natural bijection with ring morphisms $A\to\Gamma(X,\mathscr O_X)$.

$\newcommand{\Spec}{\operatorname{Spec}}$I'm working on the following problem from Vakil's notes:     Show that (scheme) morphisms $X\to\Spec A$ are in natural bijection with ring morphisms $A\to\Gamma(X,\mathscr O_X)$.   Of course, any map $X\to\Spec A$ induces a map of global sections $A\to\Gamma(X,\mathscr O_X)$. I am working out the other direction. It is certainly true if $X$ is affine, because affine scheme morphisms $\Spec B\to\Spec A$ are in bijection with ring maps $A\to B$.  In the general case, we cover $X$ with affine open sets $\Spec B_i$. Then for each $i$ we get a map  $$A\to\Gamma(X,\mathcal O_X)\overset{\text{res}}{\to}\Gamma(\Spec B_i,\mathcal O_X)=B_i$$  which in turn gives a map $\pi_i:\Spec B_i\to\Spec A$ (in particular, if we let $\pi_i^{\#}$ be the map $A\to B_i$, then the map is given by $\pi_i(p)=(\pi_i^{\#})^{-1}(p)$).  How can I show that these glue correctly to give a morphism of schemes $\pi:X\to\Spec A$?


How To Remove Textbox Using Jquery On Button Click

Here i want to add new textbox on click of button i.e btnAdd and and also want to remove those newly added textbox by clicking the button i.e btnRemove which is also added along with the new added textbox on a click of btnAdd .Now the problem is that as i click the add button i.e btnAdd new textbox along with remove button i.e btnRemove is also added as required but as i click on remove button i.e btnRemove the respective textbox and that respective remove button is not removed.Below is what i have done  <!DOCTYPE html> <html> <head> <title></title> <meta charset="utf-8" /> <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script> </head> <body> <div id="a">     <input id="Text1" type="text" /> </div> <input id="btnAdd" type="button" value="Add" /> <script>     $(document).ready(function () {         $("#btnAdd").click(function () {             $("#a").append('<input type="text" id="Text1" value="" />'+'<input type="button" id="btnRemove" value="Remove"/>');         });         $('#btnRemove').click(function () {             $('#Text1').remove();             $(this).remove();         });     }); </script> </body> </html>


How can I download macOS Sierra installer

The latest macOS version at the moment is High Sierra (10.13), and I can't find the installer for macOS Sierra (10.12) at the App Store. How/where can I download the installer for macOS Sierra?


Click triggers two onclick events at the same time

I have a span on top of a div. The div has an onclick event, and the span also has an onclick event. If I click on the span, I want only the span-onclick event to be triggered, unfortunately, both the onclick of the div and the one of the span are triggered. How can this be fixed?
                                                   Slett


Is it possible to install pure Android on any Android phone?

As the title says, is it possible? What is AOSP (Android Open Source Project)? I want to install a pure Android operating system, nothing else. Full control (root access), no bloatware and all.   Is there any possible way, as Android is said to be an open source, so why we are bounded by these restrictions?


Recall that $GL_2(\mathbb{R})$ is the group of all invertible 2x2 matrices with real entries. Let:  $G = (\begin{pmatrix} a & b \\ 0 & c \end{pmatrix} \in GL_2(\mathbb{R}) : ac \neq 0$)  and  H = ($\begin{pmatrix} 1 & x \\ 0 & 1 \end{pmatrix}: x\in\mathbb{R}$)  H is a subgroup of G.   Show that every left coset of H in G is equal to the right coset of H in G.  First, I thought of assuming that G is abelian. But clearly that failed for me because G isn't abelian. So the other thing I thought of trying was to show $ghg^{-1}\in H$ where $g\in G$ and $h\in H$. Now with this idea, I'm stuck in showing that $ghg^{-1}\in H$. Can anyone help me out?


grep dates in a text file to less than 30 days old and move to a new file

A script that should look out for texts with a date inside the file thats 30 days older than the current date then move to another file like the $ awk '$NF <= "2018-05-01"' ip.txt but need a command to get text with dates 30 days older than the system current date automatically without having to manually change the script everyday


Robust mean estimation with O(1) update efficiency

I am looking for a robust estimation of the mean that has a specific property. I have a set of elements for which I want to calculate this statistic. Then, I add new elements one at a time, and for each additional element I would like to recalculate the statistic (also known as an online algorithm). I would like this update calculation to be fast, preferably O(1), i.e. not dependent on the size of the list.  The usual mean has this property that it can be updated efficiently, but is not robust to outliers. Typical robust estimators of the mean, like inter-quartile mean and trimmed mean cannot be updated efficiently (since they require maintaining a sorted list).  I would appreciate any suggestions for robust statistics that can be calculated/updated efficiently.


I found it in an old dictionary and I'm not sure what it means. It looks like the number "3", but the top of the three has been flattened(and slightly curved). I've only seen this in three or four words. []


How can I set conditional formatting on a particular cell that depends on another cell's value?

In my example I would like to conditionally format column B cells. Those marked with x should be formatted according to value in column A (in the example the value is 1):  A | B 1 | x 2 |  3 |  1 | x 1 | x 4 |  8 |  // x can be any value and is here merely to mark the cell that should be formatted   IMPORTANT 2014 NOTE: Conditional formatting based on formula that may include other cells is now possible in Google Sheets, and works very similarly to how Excel spreadsheets work.  explains its use.


I'm trying to write an iterator for results from a PDO statement but I can't find any way of rewinding to the first row. I would like to avoid the overhead of calling fetchAll and storing all the result data.  // first loop works fine foreach($statement as $result) {     // do something with result }  // but subsequent loops don't foreach($statement as $result) {     // never called  }   Is there some way of reseting the statement or seeking the first row?


Select an element by a class that multiple elements share with jQuery

I want to select an element with the class 'submenu-expand', and add another class to it.  $('.menu-item').on('click',function(){ $('.submenu-expand').toggleClass('expanded') })   This code works, but the problem is that multiple elements share that class, so jQuery selects all of them. I tried to do it this way since '.submenu-expand'is inside of 'menu-item':  $('.menu-item').on('click',function(){ $('this>.submenu-expand').toggleClass('expanded') })   HTML:
 אודות <button class="submenu-expand" tabindex="-1"></button>
   What is the correct way to do that?


Is there a way to set a keyboard shortcut to toggle layer visibility in Photoshop (CS3)?


How to speed-up boot by disabling few dev-loox.device?

When I checked my system's boot logs, I noticed that each of the dev-loopx.device takes a good 3-5 seconds to boot, and I have a total 20 such loopx devices lines up during my boot, which ultimately slows down my boot.  To get further details on these loopx devices, I ran the following command  $ df -a -h -T  And the most important part of the output was:    Why are some applications (or part of them) is being loaded during boot, which I don't even use in every session?  For example, the gaome-calculator application, the gtk-common-themes, the gnome-system-monitor.  Why are there multiple entries of some of the applications (and each one of takes a good 3-5 seconds, and even more)?  How can I disable and/or remove some of these loopx devices when I don't use the associated application/services very often? This would definitely speed up my boot process!  Any help and guidance are really appreciated.  Abbas.


How can a Python script detect if it is being run in Virtualbox or some other VM?

Ideally, I'd like a isRunningInVirtualbox() function that returns True or False.  I'm specifically looking at getting this detection in Python. Is there a Python module or some way that can detect if the Python script is being run in Virtualbox (or ideally detect if it's being run in VMware or some other VM.)  (I'm writing a script that will warn the user if it's NOT running in a VM, so I don't really care about elaborate hacks or tricks that will try to give false positives.)


Help finding the fundamental group of $S^2 \cup \{xyz=0\}$

let $X=S^2 \cup \{xyz=0\}\subset\mathbb{R}^3$ be the union of the unit sphere with the 3 coordinate planes. I'd like to find the fundamental group of $X$.  These are my ideas:  I think the first thing I should do is to retract all the points outside the sphere to the sphere (is that possible? how?)  then using spherical coordinates I could make the following deformation:  $(1,\phi,\theta)\to ((\sin\phi \sin\theta \cos \phi\cos \theta)^t,\phi,\theta)$. This collapses all the point in $S^2 \cap \{xyz=0\}$ to $0$ obtaining $8$ deformed spheres touching each other in $0$ (how can I prove rigorously that they are simply connected), using Van Kampen theorem we can say that $X$ is simply connected.


This came up in a friend's exam and it must be one of those ${\epsilon},N(\epsilon)$ arguments I could do in a snapshot in my twenties but now I can't figure out how the proof should go: For a positive non-increasing sequence $\{a_k, {k \in \mathbb{N}}\}$ if $$\sum_{k=1}^{\infty}a_k$$ converges then $b_n=na_n{\to}0$.  Thanks in advance!


What to do when forward declaration isn't able to resolve circular dependency?

I have these files:  pi_utilities.h      #ifndef UTILITIES_H_ #define UTILITIES_H_  #include <set> #include <vector>  typedef unsigned short int MYTYPE2;  namespace pi {    class dfa; }  using namespace std;  struct ir_statistical_measures {     // True positive, and so on.     int tp = 0;     int tn = 0;     int fp = 0;     int fn = 0;      int dim_positive=0;      int dim_negative=0;       double accuracy  = 0; //(number in [0 1])     double precision = 0;     double recall = 0;     double f_measure = 0;     double matthews = 0;     double specificity = 0; //this is recall- or true negative rate     double bcr = 0; };   void compute_ir_stats(const pi::dfa* dfa1 ,const pi::dfa* target,const set<vector<MYTYPE2>> &test_set,ir_statistical_measures &stats); #endif   pi_utilities.cpp   #include "pi_utilities.h"  void compute_ir_stats(const pi::dfa* dfa1 ,const pi::dfa* target,const set<vector<MYTYPE2>> &test_set,ir_statistical_measures &stats) {    bool result;    result = dfa1->mq(true);    result = target->mq(false); }   pi_dfa.h      #ifndef DFA_H_ #define DFA_H_  #include <string> #include <vector> #include <set>  #include "pi_utilities.h"  typedef unsigned short int MYTYPE;  using namespace std;  extern struct ir_statistical_measures &stats; //I say to compiler that definition isn't here  namespace pi {    class dfa    {         public:         bool compare_dfa(const dfa *dfa_to_compare,string method,ir_statistical_measures &stats1,ir_statistical_measures &stats2) const;          bool m_q(bool flag) const;      }; } #endif   pi_dfa.cpp  #include "pi_dfa.h"    bool pi::dfa::compare_dfa(const dfa *dfa_to_compare , string method , ir_statistical_measures &stats1 , ir_statistical_measures &stats2) const {    set<vector<MYTYPE>> test_set;    compute_ir_stats(dfa_to_compare,this,test_set,stats1);      return true; }  bool pi::dfa::m_q(bool flag) const {    return flag; }   main.cpp  #include "pi_dfa.h" #include "pi_utilities.h"  int main() {    pi::dfa* L_dfa=NULL;      L_dfa = new pi::dfa();    pi::dfa* O_dfa=new pi::dfa();     bool value_return;    struct ir_statistical_measures test_set_ir_statistical_measures; //struct defined in pi_utilities.h    struct ir_statistical_measures test_set_ir_statistical_measures2;    value_return = L_dfa->compare_dfa(O_dfa,"method",test_set_ir_statistical_measures,test_set_ir_statistical_measures2); }   There is a circular dependency problem. To resolve I used forward declaration, but with the pointer of the class dfa I have to call a function of the class too, thus the definition there isn't and the compiler goes into trouble, I get these compile errors:      pi_utilities.cpp: In function ‘void compute_ir_stats(const pi::dfa*, const pi::dfa*, const std::set<std::vector<short unsigned int> >&, ir_statistical_measures&)’: pi_utilities.cpp:6:17: error: invalid use of incomplete type ‘const class pi::dfa’     result = dfa1->mq(true);                  ^ In file included from pi_utilities.cpp:1:0: pi_utilities.h:11:10: error: forward declaration of ‘const class pi::dfa’     class dfa;           ^ pi_utilities.cpp:7:19: error: invalid use of incomplete type ‘const class pi::dfa’     result = target->mq(false);                    ^ In file included from pi_utilities.cpp:1:0: pi_utilities.h:11:10: error: forward declaration of ‘const class pi::dfa’     class dfa;   Thus forward declaration isn't enough. How could I fix it?  I'm using C++11 (The code here is rearranged to a minimal executable version)


What was the URL for the Ready Player One competition website?

In the printed version of  lies an "easter egg" hidden in some misspellings from which readers can deduce the site where a competition took place.  I read the book last and then gave it away to a friend who was interested, so I cannot get back to it. Can anyone scan me that page or tell me where it is so that I can ask my friend to send me a photo? I've gotten really curious, so much that I'd read the book again, which I cannot do.


How does resist all apply to an attack that deals two types of (non-combined) damage?

Resist all applies to all damage types (including untyped damage), reducing the damage by the resist amount. What happens when a single attack deals two different kinds of damage? Not combined damage, like "1d6 fire and cold damage", but two separate kinds of damage, such as "1d6 fire damage plus 1d6 cold damage"? Consider the following example: A creature with the following power...  Rimehound Bite Melee 1 Attack: +X vs AC Hit: 1d12+6 damage plus 1d6 cold damage  ... attacks a player wearing , which grants "resist 1 all". Does the Rimefire Plate reduce the damage by 1, or by 2?


How to get Images post ID (to use with Enfold gallery)

I made a blog with posts, and i would like to show the attached images in a post in a gallery in the single.php. But I get this error when opening a post.. A critical error has occurred on this site. Here i get all the images and their ids functions.php: function prefix_get_img_ids($atts) {     global $post;     $images = (array) get_post_meta($post->ID, 'wpcf-listing-pictures', false); // cast to array in case there is only one item     $ids = array();     global $wpdb;     foreach($images as $img) {         $query = "SELECT ID FROM {$wpdb->posts} WHERE guid='$img'";         $id = $wpdb->get_var($query);         $ids[] = $id;     }     return implode(",",$ids); } add_shortcode("get-image-ids", "prefix_get_img_ids");  Here i use the shortcode with the shortcode in the 'ids' tag. Single.php: <?php      echo do_shortcode("[av_gallery ids="[get-image-ids]" style='big_thumb' preview_size='portfolio' crop_big_preview_thumbnail='avia-gallery-big-crop-thumb' thumb_size='portfolio' columns='5' imagelink='lightbox' lazyload='avia_lazyload']");  ?>  Anybody know a way to solve this issue? Thanks


New badges for the increased flag-weight

Because the , and (if I understood it right) you'll get less and less weight with every flag towards 750, I'd like to suggest two new Badges:   Sheriff (Silver): Achieved a flag weight of 700 Clint Eastwood or Marshal1 (Gold): Achieved a flag weight of 749   1: As suggested by .  Edit: I've started this bounty, because now that there are people actually getting a flag weight of 750 in multiple sites, don't you think it would be a good idea to implement this brilliant idea which is so popular with many users? Jeff? please?


I am trying to determine the right frame size for myself before purchasing a hybrid bike. My height is 174 cm and I have an inseam size of 85 cm. If I go by the height it should be a medium frame between 43-47 cm but if I go by the inseam height, recommended frame size is 58 cm! Apparently, the latter is wrong but I wonder why there is so much difference between two calculation methods.


Is it possible to array a group of objects?   For example, if I have three objects in a group, (I want to keep them as separate objects) is it possible to easily duplicate them as if I pressed AltD for every single one?


What are some questions that seem easy but aren't?

I've only just started to study a degree in Mathematics and I find it extremely satisfying to have a seemingly easy question that is incredibly difficulty or tricky to work out. I've looked into heaps of competition exams (although they aren't really what I'm looking for - seeing that they don't usually seem easy). A good example are the so called 'Coffin Problems' (you can find some ). I'm reaching out here to hear any original problems that fit into this category. Here's an example of mine:  If $\sin \theta + \cos \theta + \tan \theta = -1$, find the values of $\sin \theta + \cos \theta - \tan \theta$ for $\theta$ not being a multiple of $\pi$.  From memory, one of the answers I got for that problem was $\sqrt{2}-1$, although I know that there are plenty of other answers. Also, I appologise if this question does not belong on this site. This was the only site I thought of to ask a question like this. Thanks!


How do I specify whether a given number has a whole number square root?

How do I amend what I have written to specify whether the user-input number is a perfect square?   I have tried placing various % placements, to no avail. The solutions I have found online don't use the M.O I desire.  I will include one solution I have found online, which I believe is ironically inefficient given the book's emphasis on avoiding brute force techniques, and doesn't seem to produce the desired results.  This problem is from Art And Science of Java Chapter 5, Programming Exercise number 7.  /**  * This program tells the user whether the number they've entered returns a perfect square. *  */  import acm.program.*; import java.lang.Math;  public class Squares extends ConsoleProgram {      public void run() {         println("This program determines whether the number you're about to enter is a perfect square");         int s = readInt("Enter a positive number here: ");         switch (s) {          }          if (isPerfectSquare(s)) {             ;         }         {             println((int) Math.sqrt(s));         }     }      private boolean isPerfectSquare(int m) {         int sqrt = (int) Math.sqrt(m);         return (sqrt * sqrt == m);     } }   And here's the solution I believe to be deficient:  /*  * File: PerfectSquare.java  * -------------------------  * This program test the isPerfectSquare(n)   * that returns true if the integer n is a   * perfect square.  */ import acm.program.*; import java.lang.Math;  public class Book extends ConsoleProgram {      private static final int MIN_NUM = 1;     private static final int MAX_NUM = 100000000;      public void run() {         int cnt = 0;         for (int i = MIN_NUM; i <= MAX_NUM; i++) {             if (isPerfectSquare(i)) {                 cnt++;                 println(cnt + ": " + (int) Math.sqrt(i) + ": " + i);             }         }     }      private boolean isPerfectSquare(int n) {         int sqrt = (int) Math.sqrt(n);         return (sqrt * sqrt == n);     } }


How can I prove that the open interval $(c,d)$ is not of measure zero?

I am currently trying to prove this theorem. I know how to do the closed interval case, it is a contradiction proof that uses the heine-borel theorem. Does anyone know how I can do the open interval case? I suspect it uses contradiction too, but dont know where to obtain the contradiction from (in closed case it was from the heine-borel theorem).  Thanks!


Can a finite number have an uncountable infinite amount of non-zero terms?

For example, $e=\dfrac{1}{0!}+\dfrac{1}{1!}+\dfrac{1}{2!}+\dfrac{1}{3!}+\dfrac{1}{4!}+\cdots$ has infinite terms when treated with this form, but it is a countable one, because the cardinality of natural numbers is countably infinite, and my question is if a number can have uncountably infinite terms. Thanks.  My thought is that it is impossible because it must be valid to enumerate the terms, which in uncountably infinites you cannot. Is this true? I need some aclarations.  Edit:  I only need non-zero terms, as sugested in the comments, and the number the terms sum to has to be a finite number.


Prove that $A_n$ is the only subgroup of $S_n$ with index 2.

For the $n=3$ and $n \geq 5$, $A_n$ is simple, and suppose for a contradiction $H\leq S_n$ has index 2 and $H\neq A_n$, then since $H\cap A_n \unlhd A_n$ and $A_n$ is simple, $H \cap A_n$ must be trivial.   Since $H$ has order equal to that of $A_n$ and $|A_n|>3$, there must exist at least two non-identity elements in $H$. Let $h_1 \neq h_2 \in H$ be non-identity elements of $H$. Then $h_1$ and $h_2$ must be odd permutations, hence $h_1 h_2 \neq h_1^2$. But the product of two odd permutations is even, so $h_1h_2 \in A_n$, so $h_1h_2 \in H\cap A_n = 1$, so $h_1h_2=h_1^2=1$, which is a contradiction.   Therefore $A_n$ is the only subgroup of $S_n$ with index 2 for $n=3$ and $n\geq 5$.  Also note that $A_1$ and $A_2$ are trivial, so we only have to prove the case for $A_4$. But then I'm stuck.


I've created a room in blender (one floor plane+ 3 wall planes) by duplicating the floor plane.  However, when I change the floor plane colour in materials all the other planes change also. How do I stop this and just assign a colour to one plane in view in 2.8.


Allow moderators to see failed audits that haven't led to an automated review ban

Moderators have access to a user's profile/history to look at things necessary to perform our role - one of those is reviewing stuff. The system currently now only records on a user's profile if they were banned from review - but not if they failed audits.  We can work it out of course - but it's a lot of clicking through and combining stuff from other screens together.  Can we add to a user's profile "failed audit"?


Micro SD card shows wrong capacity and files disappear. Can it be fixed?

I have two PCs and one micro SD card. What I did was copy some files (1.1 GB) onto micro SD card. But I replaced some files. So everything was perfect, until I tried to use the SD card for Raspberry Pi, when did not work.   I checked the micro SD card again, and most files had disappeared! I connected it to my mac and formatted the micro SD card. It was good for mac but not Ubuntu. It said that 1.1 GB is used! But there are no files.   I re-formatted again, but this time in Ubuntu. And now the total capacity has dropped, and it is unreadable in mac.   Why has this happened? Is there any hope that I can fix it?


GF(q) is a finite field of order q, where q is odd. Prove that $a\in GF(q), a\neq0$ has a root in $GF(q)$ iff $a^{(q-1)/2}=1$.  I tried to prove it this way:  Suppose a has a root in $GF(q)$, so there is some $b\in GF(q)$ so that $b^2=a$. There is a primitive element $g$ in $GF(q)$, so that $g^x=a, g^y=b$. Therefore $(g^y)^2=g^x\to 2y=x$. Furthermore $a^{(q-1)/2}=(g^x)^{(q-1)/2}=g^{(x/2)*(q-1)}=g^{y(q-1)}$ and since $y$ is an integer, $g^{y(q-1)}=1^y=1$. Now suppose $a^{(q-1)/2}=1$, then again $(g^x)^{(q-1)/2}=1\to g^{(x/2)*(q-1)}=1$. That means that $x/2$ is an integer (or else $g^{(x/2)*(q-1)}\neq 1$), and therefore $0\le x/2\le q-1$ being an integer, $g^{x/2}$ creates a certain element $b\in GF(q)$ so that $b^2=a$.  I am a bit unsure of this proof - first of all since I don't use the fact that $q$ is odd, which means I am wrong somewhere. Second of all, I feel extremely 'weak' with my argument regarding $x/2$ being an integer, yet I have no idea how to strengthen it. Any hints/directions will be extremely appreicated!


How can I add a bumpy glowing surface to my model?

How can I achieve this surface and light on sphere's? Picture below:    I appreciate help, thank you.


Are these correct ways to use very with a noun?  She is the very girl I want. On the very year of 2012, comes the end of the world. This is the very company everyone wants to work for.  What I understand is that very can be used to emphasize the importance of a noun.


Where can I find good ConTeXt documentation

Where would be a good place to start learning ConTeXt if you haven't got a lot of experience under your belt yet? Any place online or in a bookstore is welcome, provided that the reading is well-structured, well-written and beginner-friendly.  I know there is quite a heap of "official documentation", including "ConTeXt, an excursion", the official handbook and the contextgarden.net Wiki.   Still, often ConTeXt novices find it very difficult to get a good start with the documentation provided -- the command syntax seems to work sometimes, sometimes not; some commands work well with each other, others only in a specific order (which isn't documented anywhere) and some don't work with each other at all etc. The consequence is that there is a lot of experimenting with the code while the focus should be on the topic to be published itself.  This question would love to get RTFM answers, so please point out any Ms which should TF be R.


Floating point division error [Thread Closed]

Can anyone explain the following. What is exactly causing the following problem?  int main() {   double a;   double b;   int i = 2115;   a = 77.0*i/1000*100;   printf("%.20f\n", a);    b = 77.0*i/10;   printf("%.20f\n", b); }   I expect both outputs to be 16285.50000000000000000000 but it prints 16285.49999999999818101060 then 16285.50000000000000000000  I understand that numbers are represented in binary and which is why many decimals cannot be represented correctly in computer systems. However, specifically, why does 77.0*i/10 work but not 77.0*i/1000*100? How is 77.0*i/10 always able to be represented correctly? (Please dont explain using i = 2115 only, what about all REAL number i?)  And if so, what other variations of this multiplication/division can work?


We say "I will contact you by letter", but we say "He was knocked down by a bus". Why is "letter" not preceded by an article?


Boundedness and convergence of $x_{n+1} = x_n ^2-x_n +1$

Suppose that $x_0 = \alpha \in \mathbb{R}$ and $x_{n+1} = x_n ^2-x_n +1$.  I am asked to study the boundedness of $(x_n)$ and then asked if $(x_n)$ converges. How can I show that $(x_n)$ is bounded?  I have noted that $$x_{n+1}-x_n = (x_n-1)^2\geq 0$$ so $x_n$ is increasing.  Suppose that $(x_n)$ converges, then $l = l^2-l+1$ so $l = 1$. This means that the sequence converges only when $\alpha \leq 1$. And so $(x_n)$ is bounded above by $1$ if $\alpha\leq 1$ (since an increasing sequence converges to its supremum) otherwise the sequence is not bounded above.  Is my reasoning correct?


I am creating a pager component and faced a problem. I simplified the code to show the problem :  @for (int i = 0; i < 10; i++)         {
UpdatePager(i)" class="waves-effect">@(i+1)
                   } @code{      public void UpdatePager(int iCurPage)     {         Console.WriteLine(iCurPage);     }  } // when click on 1  console result is 10 // when click on 2  console result is 10 // ... // when click on 10  console result is 10  My expectation is when I click any of lis the corresponding number(i) should be logged in the console but what is actually happen is for all of the lis the number 10 ( final value of i) is printed. What is the problem and how should I pass different values for each rendered elements?


Get stacktrace for crash, without running the app in a debugger

I normally use GDB (in Linux, with the Qt Creator debugger GUI) to debug. But right now I have a crash that refuses to ever happen when running under the debugger, yet happens easily when running outside of it.  How do I get a stack trace of my crash, in these circumstances?  A linux-specific solution is OK.  Note: I'm talking about running a debug build only, even when it's run outside the debugger.


Given $\sum a_n $ convergent, are $\sum n^{1/n} a_n$ and $\sum a_n/({1+ |a_n|})$ convergent?

Let $\sum a_n $ be a convergent series. Is  $\sum n^{1/n} a_n$ convergent? $\sum a_n/({1+ |a_n|})$ convergent?  If not, provide examples in the contrary.  I feel like 1 is maybe convergent, however I cannot seem to prove it or come up with an example to contradict. Please help.


Where can I download older versions of Blender?

I was trying to re-download the original Blender 2.8, however it goes directly to the 2.81 download page instead.  How can I access downloads for previous versions of Blender and installers for older releases?


Will a 50mm EF lens give the same result as a 50mm EF-S lens?

edit: ^^ the answer to that question talks about the lens being the same and but not how or why this is the case, and does not answer the question about resultant image,   First of all, to let you know what I understand:   I am aware that focal length is focal length, and that doesn't change* (that's usually the first line of every answer I've read), the difference between full frame and smaller sensors and the effect that the same lens will have on different bodies (with different frame sizes), the difference between focal length, crop factor and field of view angle, what some are calling "effective" focal length as compared to FOV, cropping and multiplication factor.   (* see second question)  I know this question sounds the same as  and   (and a whole heap of others **) but they all seem to go off in slightly different tangents, namely what I will see on different bodies (I don't care about this, I have only one body type), they also cover things such as the effect of (say) an EF-S lens on a FF body (I'm not doing that either).   Put very specifically, here is my question broken into (now) four parts:   Does mounting an EF vs an EF-S lens produce the same results on a camera body that has an APS-C frame size? (my thinking is NO because of the design of the lens and "short back focus" of the EF-S, and the fact that the EF lens produces a picture for a FF sensor and the fact it is further away—when directly comparing 50mm EF and 50mm EF-S—do they have the same field of view, which then leads onto the next question), (this is probably where my confusion lies, but) aren't the EF-S range of lenses physically closer to the sensor whereby the focal length IS actually shorter?   If EF-S lenses (as a whole unit) are shorter and have a shorter back focus plane, wouldn't that make the FOV wider (ergo not producing the same image)?   edit:   is it the case that Canon have labelled their EF-S 50mm lens as 50mm to the focal plane AS IF the focal plane was a FF 35mm plate at 50mm? Or is the focal distance 50mm to the actual smaller frame? (I think my confusion here is that a 50mm EF lens sits further forward than a 50mm EF-S lens, which to me seems to indicate that one of them isn't 50mm :)   (** others):


How to monitor a folder for changes, and execute a command if it does, on Windows?

There are similar questions for  and , but I'm after a Windows solution here.  The problem is as follows: I want to write several (js) script files in a folder, and have a  program monitor that folder for file changes and new files being added, and run a command whenever that happens (to compile them all into one single file).  The solution has to:   Monitor both file changes and new files being added, in a folder. Run a command only if there is any change.   It would be best if it either is a built-in solution (like a JScript or VBscript snippet), or something that does not require installation.


In the card game "Projective Set": Compute the probability that $n$ cards contain a set

In the game of , it turns out that any seven cards contain a projective set. For fewer than 7 cards, how can we determine the probability that one or more sets exist (in terms of the number of cards)?  For those not familiar with Projective Set, here's a description from the wikipedia page linked above:   A Projective Set card has six binary attributes, or bits, generally represented by colored dots. For each color of dot, each card either has that dot or does not. There is one card for each possible combination of dots except the combination of no dots at all, making $2^6 - 1 = 63$ cards total.  Three cards are said to form a "set" if the total number of dots of each color is either 0 or 2. Similarly, four or more cards form a "set" if the number of dots of each color is an even number.  A card and itself could be said to form a two-card set, but as the cards in the deck are all distinct, this does not arise in actual gameplay.


Perform parameter expansion before brace expansion?

Bash manual says that brace expansion is performed before any other expansions.  I am writing a script which accepts two arguments:  #! /bin/bash  for b in {$1..$2}; do echo $b; done   I run it like:  $ ./myscript 0002 0010 {0002..0010}   The output isn't what I hope.  I hope to perform parameter expansion before brace expansion.  The expected output of my example is 0002 0003 0004 0005 0006 0007 0008 0009 0010, not 2 3 4 5 6 7 8 9 10. What would you  replace {$1..$2} with?  I hope that the solution works even when $1 and $2 are strings not just made of digits, but also made of letters and digits.  Note that the values $1 and $2 can only be given as arguments to the script. I think it is clear from the beginning, but point it out in case not.


How to handle with multi buttons on Setclick?

How to handle with multi buttons?  I´m using this code to change SoundOff to soundOff ON click  I dont now how to fix the error  @Override protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);       setContentView(R.layout.gameover);      //setting the orientation to landscape     setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);        ImageView medaille = (ImageView) findViewById(R.id.medaille);     //adding a click listener      //Define Logout     ImageButton LogOut = (ImageButton) findViewById(R.id.imageButton8);      //Define SoundOn      ImageButton SoundOn = (ImageButton) findViewById(R.id.imageButton9);      //Define SoundOff      ImageButton SoundOff = (ImageButton) findViewById(R.id.imageButton10);      //getting the button     ImageButton ButtonOk = (ImageButton) findViewById(R.id.imageButton11);      LogOut.setOnClickListener(this);     SoundOff.setOnClickListener(this);     SoundOn.setOnClickListener(this);     ButtonOk.setOnClickListener(this);      // Version      //define     TextView txtView = (TextView) findViewById(R.id.tv_current_score);      TextView txtsView = (TextView) findViewById(R.id.tv_current_score_value);     txtsView.setText(String.valueOf(GameView.score));      //Value     TextView myText = (TextView) findViewById(R.id.tv_best_score_value);     myText.setText(String.valueOf(GameView.Highscorer) );      TextView txtViews = (TextView) findViewById(R.id.tv_best_score);   }    @Override       public void onClick (View v){      //Define Logout     ImageButton LogOut = (ImageButton) findViewById(R.id.imageButton8);      //Define SoundOn      ImageButton SoundOn = (ImageButton) findViewById(R.id.imageButton9);      //Define SoundOff      ImageButton SoundOff = (ImageButton) findViewById(R.id.imageButton10);      //getting the button     ImageButton ButtonOk = (ImageButton) findViewById(R.id.imageButton11);     switch (v.getId()) {              case R.id.imageButton11:                 //starting game activity                 startActivity(new Intent(this, GameView.class));                 break;              case R.id.imageButton4:                 //Logout                 startActivity(new Intent(this, GameLogout.class));                 // do your code                 break;             case R.id.imageButton8:                 startActivity(new Intent(this, GameLogout.class));                 break;             case R.id.imageButton9:                 play = false;                 SoundOn.setVisibility(View.GONE);//set visibility to false on create                 SoundOff.setVisibility(View.VISIBLE);                 break;             case R.id.imageButton10:                 play = true;                 SoundOn.setVisibility(View.VISIBLE);//set visibility to false on create                 SoundOff.setVisibility(View.GONE);            }      }   I´m getting an error in NullPointerException in the "SoundOn.setVisibility(View.GONE);//set visibility to false on create"


Vector Infographic - Why does it render differently in the web browser?

I made an infographic in Adobe Illustrator, and saved it as a .svg file. But then when I tried to open it in the Google Chrome browser, some of the fonts and some italicized fonts were not even italicized. Why is this happening and what is the solution?  It was 600*1100 pixels because I had read somewhere that it is a good size to start with.   It actually turned out to be pretty ugly!


How long has the apocalypse been going on?

In The Walking Dead, the outbreak starts in an unknown year, but we know that Carl had to have been at least ten and the show has been going on for six years now and then by the time it's season six Carl is a teen.  So my question is how long has everything been happening for?


How to change radius/weight of curve bezier?

try scaling, change radius, but its dont work


Long time ago, like 45 years ago or more, I read a book where Earth had been invaded by an alien space empire. Problem was, for the aliens, that on average humans were more intelligent than the aliens. Humans spread out throughout the empire and cause all kinds of chaos and confusion. The book ends with the empire having crushed all rebellion with the help of a now independent Earth and the humans confronted, together with the aliens, are now confronted with a third alien race that is more intelligent than humans.


Why does ohms law not work on transformers?

The voltage for transformer is given by  $\frac{V_1}{V_2} =\frac{N_2}{N_1}$  if we use ohms law and assume resistance are same for both inductors,  $\frac{I_1 R} { I_2 R}=\frac{N_2}{N_1}$  but   in my book they derive using power equivalence $I_1 * V_1 = I_2 V_2$ which gives  $\frac{V_1}{V_2}=\frac{I_2}{I_1}$  where have I made the mistake?


Why does the ending -ough have six pronunciations?

There are cough, tough, bough, through, and though (and "hiccough", if you're not from the U.S.); each of which has a different pronunciation for the ending "-ough".  Why is this?  Edit for clarification: I'm trying to figure out why cough is spelled with an "-ough", if it's pronounced with an "-off".  And then tough, pronounced "tuff".  Why is that not spelled "tuff"?  Bough, through, and though should be spelled "bow", "thrue" (or "thru"), and "thoe".  Where did "-ough" come from?  And then hiccough.  Since that derives from cough, it should be pronounced "hickoff", but it isn't.