In the Harry Potter universe, how do dementors communicate?

We meet the dementors in 'Prisoner of Azkaban'. I've noticed that dementors are implied to be able to communicate 'off-screen' so to speak, but do not do so on-screen.  In the book, the first time a dementor appears is on the Hogwarts Express. Lupin says "None of us is hiding Sirius Black under our cloaks", but they don't listen to him. It's unclear if they even understand him.  Similarly, they repeatedly violate instructions throughout the book, maybe knowingly, but at no point is it indicated that they actually comprehend what others are saying.  Later, they are described as having no eyes and "something like a mouth", which they use to perform the kiss. It is unclear if they do or even can use it to talk. They are also described as being able to sense emotions. Whether they have other senses like hearing isn't clear.  Now, the 'off-screen' part. Fudge, on multiple occasions says "I've got to talk to the dementors", like after Black escapes from Hogwarts. (How? How does he talk to them?)  And the totally troubling part: In the beginning, Arthur Weasly tells his wife that guards at Azkaban (which I assume to be dementors, since there is no evidence of anyone else guarding Azkaban), have stated that Black keeps muttering "He's at Hogwarts." That implies they can hear, understand and communicate to others what Black said.  So which one is it? Can they talk or not. If they can, why don't they listen to Lupin or even Dumbledore?  PS - It's been a while, but I have read the entire series. Don't worry about spoilers.


Can I install El Capitan on a new 2019 MacBook Pro 16"?

I have some legacy 32-bit software that I'd really like to keep running on my brand new MBP (odds and ends, but mainly Keynote 5.3 — i.e., from the iWork 2009 suite). On my (2015) iMac, I have two partitions: one for El Capitan and one for Catalina. I'd like to create the same setup on the MBP, but I believe that the IT folks at my organization have deployed the computer so that I can't create a new partition to give it a whirl. They tell me that it won't work anyway — the computer's too new, but it's not like the chips are that different. (Is Apple really crippling older OSes in this way?!) Anyway, before I ask them to create a second partition to let me try, I thought I'd double-check that it's in fact hopeless. Their view does get some support from the fact that when I attempt to boot from an external carbon-copy-cloner-cloned volume of ElCap, the boot halts with the message: "A software update is required to use this startup disk" (with options of choosing another disk or "updating", which does nothing). Has anyone been down this road before. Any other ideas? I've tried Parallels and can finagle an installation of ElCap there, but Keynote's graphics are broken in it. It runs most of the other apps I need, though, so maybe I just cut bait and deal with the crappy new version of Keynote. Thanks much!


Why doesn't the owning group get the executable bit?

Playing with ACL's:  [root@rex web]# pwd /media/web [root@rex web]# ll -d drwxr-xr-x. 2 root root 4096 Jan  1 14:31 . [root@rex web]# setfacl -m d:g::rwx . [root@rex web]# setfacl -m g::rwx . [root@rex web]# touch newTest [root@rex web]# getfacl newTest # file: newTest # owner: root # group: root user::rw- group::rw- other::r-- [root@rex web]# getfacl . # file: . # owner: root # group: root user::rwx group::rwx other::r-x default:user::rwx default:group::rwx default:other::r-x   Simple question I'm just not able to answer it. If the executable bit is in the group's default ACL why isn't it showing up in the resulting file. I thought my umask setting was at fault but got the same result there:  [root@rex web]# umask 0022 [root@rex web]# umask 0000 [root@rex web]# touch anotherTest [root@rex web]# getfacl anotherTest # file: anotherTest # owner: root # group: root user::rw- group::rw- other::r--   I'm sure it's intentional, I just don't understand it.  Tried to see if it was just something specific to the primary group but then a mask started showing up in my ACL's for some reason:  [root@rex web]# setfacl -m g:web:rwx . [root@rex web]# setfacl -m d:g:web:rwx . [root@rex web]# touch newer [root@rex web]# getfacl newer # file: newer # owner: root # group: root user::rw- group::rwx                      #effective:rw- group:web:rwx                   #effective:rw- mask::rw- other::r--   I'd imagine this is why it isn't showing up above, but my questions are:  1) Why doesn't "mask" show up before I specify a group other than the primary group?  2) Where is this mask coming from? I'm not seeing it on any parent directory.


I cannot find a way to change chapter style with babel included (for hungarian language). Here is the example:  \documentclass[a4paper]{report} \usepackage[magyar]{babel} \usepackage{titlesec}  \titleformat{\chapter}[hang] {\normalfont} {\LARGE\thechapter.} {10pt} {\LARGE\MakeUppercase} [\normalfont] \titlespacing{\chapter}{0pt}{0pt}{30pt}[0pt]  \begin{document} \chapter{First chapter} \end{document}   If I comment out the \usepackage[magyar]{babel} line, everything works as expected, however, with babel it does not work. Is it possible to style chapters (and sections, etc.) while using babel?


Is the class of algebraic extensions distinguished?

In paragraph V.1 of Algebra proposition 1.7 Lang claims that the class of algebraic extensions is distinguished. I know that if $F/k$ and $E/F$ are algebraic extensions than so is the $E/k$ - that is easy to prove. However, the second required property is that if $E/k$ is algebraic and $F/k$ is arbitrary, then (assuming the compositum is defined) $EF/F$ is algebraic. Lang more or less skips the proof of this, only saying that "an element remains algebraic under lifting, and hence does the extension."  However, there are no finiteness conditions here and no element given in advance. Although $EF$ is generated over $F$ by a set of elements which are algebraic over $F$ (namely, all the elements of $E$), there are no facts known (up to this point in the book at least) about the infinitely generated extensions.  What am I missing?  Thank you.


I'm a bit new to bash scripting, and I'm wondering if there is a program or built-in command to pipe to that will print in a specified color? Or is there an echo argument to do so?  Like I could do:  echo Hi | commandhere -arguement blue   and it would print "Hi" in the color blue?


Adding MS Access Table as X,Y Points using QGIS?

Can you add an MS Access table as X,Y points in the same way you can Add X,Y data in ArcMap using:  File --> Add Data --> Add X,Y Data


How to apply UV map texture while keeping node shaders?

How would I apply the UV map texture I have here to the object (in place of what's currently the colour) whilst still keeping my diffuse and glossy shader?


How do you connect to multiple MySQL databases on a single webpage?

I have information spread out across a few databases and want to put all the information onto one webpage using PHP.  I was wondering how I can connect to multiple databases on a single PHP webpage.  I know how to connect to a single database using:  $dbh = mysql_connect($hostname, $username, $password)          or die("Unable to connect to MySQL");   However, can I just use multiple "mysql_connect" commands to open the other databases, and how would PHP know what database I want the information pulled from if I do have multiple databases connected.


If a question is modified is it proper to respond to the essentially new question with a new answer

There is a question that was clarified by the asker enough so that putting a comment to my question may not be the best approach.  If the clarification substantially changes the question is there any problem with just writing a second complete answer?  Here is the question in question.


What decides that "it (mass energy) " is going to become mass or energy?

Mass and energy are two faces of one same thing. Energy and mass are not two but one( something)  They can be related as :  $$E = mc^2 $$  I want to ask that what decides that "something" is going to become mass or stay in the form of energy (like dark energy, or some other kind)


Two-predictor regression vs partial correlation

Say I want to see whether two variables y and x1 are linearly related, while controlling for the effect of an x2 "nuisace" variable. What is the difference between  (a) regressing y over x1 and x2 and just looking at x1's coefficient; and  (b) doing a partial correlation for y and x1 while controlling for (co-varying) x2?


If a photon is exists in 'timeless' state, how can objects around it move?

My understanding is that light does not experience time. In attempting to understand what the universe would be like from the perspective of a photon, the answer I get is that the universe would be essentially 'frozen'. Answers I've seen describe the photon in a universe where it can move through space, but with events around it not moving at all in time.  So...from my frame of reference, it takes about 4 hours for light to go from Neptune to where I am on Earth. Conceivably I could move somewhere during that time to dodge the photons. But if from the photons perspective I don't have time to move out of the way, then there is a paradox of sorts.  Therefore I must be missing something here. Can someone explain how the motion of other things is possible from the perspective of a photon?


How can I write a macro which enters math mode when called in text mode but when called in mathmode doesn't break?

I'm using the package braket for my physics notes, and this speeds things up a great deal but I'm constantly writing \ket{\psi} or \bra{\psi}, and because this specific pair of bra and ket appears so often, this gets repetitive and I would like a macro to speed this up.  However since the braket package works only in math mode, my attempt \newcommand{\ketp}{$\ket{\psi}}$ work when I'm writing in text mode, but when I'm writing in mathmode it breaks (unsurprisingly).  Is there any way I can get this command to work in both mathmode and textmode without having to define two different macros, one for each?    Thanks in advance for any help.  P.S. I'm certain this is a very simple question but I could find little to no explanation of this feature.


How to use /give commands to create a written book in Minecraft Pocket/Bedrock (iOS)?

I am running the latest version of iOS Minecraft. Education mode and cheats are enabled. I've got command block and trying to apply the following command there - give @p minecraft:written_book{pages:["[\"\",{\"text\":\"The art of rituals is of vital importance to the player.\"}]","{\"text\":\" It is a matter of life and death,\\na road either to safety or to ruin.\"}]","{\"text\":\"Hence it is a subject of inquiry which can on no account be neglected.\"}"title:"Magick Moste Evile",author:Herobrine,display:{Lore:["Of the Horcrux, wickedest of magical inventions, we shall not speak nor give direction —"]}}  But it doesn't work. I get the following error -  Syntax error. Unexpected "minecraft:written_book" at "/give @p >>minecraft:written_book<<{pages:[''["  (some other commands like teleport work well) What could be wrong here? Are there some limitations applied to iOS version?


Does anyone know where android save the details (Mac, etc.) of devices that connected to my phone ?! (When my device is used as a  mobile hotsop)


I was given this problem (I have to prove) and not sure if I use fermat's theorem  $24^{31} ≡ 23^{32} (mod 19)$  If I do use fermat's is this right:  I would do the LHS first:  $24^{18}·24^{13} ≡ 1·24·24^{12}$  RHS:  $23^{18}·23^{14} ≡ 1·23^{14}$  I am not sure where to from here or if it is correct thus far. I have looked at some other posts but they have not helped with this problem.


Why don't they use the transporter in the final fight in Star Trek Into Darkness?

When Spock was chasing, and beating, Khan over a transport in San Francisco, Uhura orders them beamed both back  to the Enterprise, while Chekov says something like:     Its impossible, they are moving!                                   But in the first movie, it was Chekov that transported back to Kirk and Sulu, avoiding hitting the Vulcan planet when trying to disable the Romulan drilling platform.


Can one call oneself a PhD ABD (All But Dissertation) after completing all of the course work and working on the dissertation?


Adding user to a group - Why had to reboot?

I was not able to access the VirtualBox shared folder, so I made the user part of the vboxsf group. But, still not able to access it. Rebooting the guest resolved the problem. Is it a bug? A reboot is not required to add a user to a group.   sudo usermod -a -G vboxsf praveensripati   There was similar query .  I am using 11.10 and don't remember seeing similar behavior in 11.04.


whenever i login into the app ,I am starting sync adapter.It will sync data for every 12 hours.Right now  it is working fine in android kitkat and lower versions but when i login into my app and current os android lollipop,it is crashing please help me  error Log:   12-03 10:56:10.205: E/AndroidRuntime(10000): FATAL EXCEPTION: IntentService[Sync service]     12-03 10:56:10.205: E/AndroidRuntime(10000): Process: com.sample.example, PID: 10000     12-03 10:56:10.205: E/AndroidRuntime(10000): java.lang.IllegalArgumentException: error unparceling Bundle     12-03 10:56:10.205: E/AndroidRuntime(10000):    at android.content.ContentResolver.validateSyncExtrasBundle(ContentResolver.java:1835)     12-03 10:56:10.205: E/AndroidRuntime(10000):    at android.content.SyncRequest$Builder.build(SyncRequest.java:490)     12-03 10:56:10.205: E/AndroidRuntime(10000):    at com.sample.example.BeatsSyncAdapter.configurePeriodicSync(SampleSyncAdapter.java:129)     12-03 10:56:10.205: E/AndroidRuntime(10000):    at com.sample.example.sync.BeatsSyncAdapter.onAccountCreated(SampleSyncAdapter.java:177)     12-03 10:56:10.205: E/AndroidRuntime(10000):    at com.sample.example.sync.BeatsSyncAdapter.getSyncAccount(SampleSyncAdapter.java:168)     12-03 10:56:10.205: E/AndroidRuntime(10000):    at com.sample.example.sync.BeatsSyncAdapter.initializeSyncAdapter(SampleSyncAdapter.java:190)     12-03 10:56:10.205: E/AndroidRuntime(10000):    at com.sample.example.service.SampleSyncService.onHandleIntent(SampleSyncService.java:22)     12-03 10:56:10.205: E/AndroidRuntime(10000):    at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:65)     12-03 10:56:10.205: E/AndroidRuntime(10000):    at android.os.Handler.dispatchMessage(Handler.java:102)     12-03 10:56:10.205: E/AndroidRuntime(10000):    at android.os.Looper.loop(Looper.java:135)     12-03 10:56:10.205: E/AndroidRuntime(10000):    at android.os.HandlerThread.run(HandlerThread.java:61)     12-03 10:56:10.205: E/AndroidRuntime(10000): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.util.Set android.os.Bundle.keySet()' on a null object reference     12-03 10:56:10.205: E/AndroidRuntime(10000):    at android.content.ContentResolver.validateSyncExtrasBundle(ContentResolver.java:1819)     12-03 10:56:10.205: E/AndroidRuntime(10000):    ... 10 more


Error on "Attempt to invoke virtual method 'double java.lang.Double.doubleValue()' on a null object reference"

I have just been having an issue with displaying a map by accessing the Latitude and Longitude from the SqliteDatabase.   When I run this I get the above error on the line .target(new LatLng(latitude, longitude)). Any help would be appreciated.    import android.content.Intent;     import android.os.Bundle;     import android.support.v4.app.FragmentActivity;     import android.support.v4.app.FragmentManager;     import android.support.v7.app.ActionBarActivity;     import android.support.v7.app.AppCompatActivity;      import com.google.android.gms.maps.CameraUpdateFactory;     import com.google.android.gms.maps.GoogleMap;     import com.google.android.gms.maps.OnMapReadyCallback;     import com.google.android.gms.maps.SupportMapFragment;     import com.google.android.gms.maps.model.BitmapDescriptorFactory;     import com.google.android.gms.maps.model.CameraPosition;     import com.google.android.gms.maps.model.LatLng;     import com.google.android.gms.maps.model.MarkerOptions;      import static com.example.kod45.refapp.R.id.lat;     import static com.example.kod45.refapp.R.id.longitude;      public class Map extends FragmentActivity implements OnMapReadyCallback {         Double latitude;         Double longitude;         private GoogleMap mMap;          @Override         protected void onCreate(Bundle savedInstanceState) {             super.onCreate(savedInstanceState);             setContentView(R.layout.activity_map);             // Obtain the SupportMapFragment and get notified when the map is ready to be used.             SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()                     .findFragmentById(R.id.map);             mapFragment.getMapAsync(this);         }          @Override         public void onMapReady(GoogleMap googleMap) {             mMap = googleMap;              // Add a marker in Tallaght and move the camera              CameraPosition cameraPosition = new CameraPosition.Builder()                     .target(new LatLng(latitude, longitude))      // Sets the center of the map to Mountain View                     .zoom(17)                   // Sets the zoom                     .bearing(90)                // Sets the orientation of the camera to east                     .tilt(30)                   // Sets the tilt of the camera to 30 degrees                     .build();                   // Creates a CameraPosition from the builder             mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));              Intent intent = getIntent();             intent.putExtra("latitude", latitude);             intent.putExtra("longitude", longitude);     //        LatLng sydney = new LatLng(latitude, longitude);          }     }


I use a Canon EOS Rebel T3i (600D) with the kit lens. I have experimented a lot with different settings and modes, but I feel like I have wasted many good shots that could have looked amazing, if only they were a little bit sharper.  I use auto-focus on most of my pictures and make sure to choose the right focus point, but all of my photos are still a little bit out of focus. When I zoom in, I can see that the pixels are not very crisp or well-aligned.  I am not sure if this issue is caused by my equipment or skills.


Cyrillic letter-highlighting differs in preview and in post, while identical for latin characters

I found that the rendering xxx**yyy**zzz as xxx*<i>yyy</i>*zzz is by-design, but for latin letters it works identical both in preview and after posting. But this is not so for cyrillic letters.  In  I marked two letters inside a word using double asterisks:  (this is like sailors say комп**а**с, while non-sailors say к**о**мпас).   In edit preview it is shown as bold:        But in the post itself it is shown as italic between asterisks:        Changing double-asterisks to double-underscore yields the same result both for preview and after posting:        So this looks like a bug with processing the highlighting of cyrillic characters in preview mode.  Note: This is not a duplicate of  post. This post is about bug, linked post is about (1) removing the feature on non-programming sites or (2) different processing of ** and __ highlighting.


Calculating the p-value of two independent counts?

My simple experiment:  Two equally-sized patches of the night sky are observed:   Patch A contains $100$ stars Patch B contains $110$ stars   My null hypothesis is that stars are randomly distributed in the sky. The random distribution means that there will be some natural variation from patch to patch.   My question:   How is the p-value (or at the very least, a test statistic) calculated for rejecting the null hypothesis that there is no significant difference between the two patches of sky?


Save slide numbers for further use in a document

I want that multiple things appear simultaneously on a same slide, but I don't want to calculate the number of this slide. I try to save it for futher reuse.  I want to do that several times.  For example, tikzpicture stuff simultaneously with a list.  Hre is my non working try.  \documentclass{beamer}  \newcommand{\Slide}[1]{%  \expandafter\newcommand\csname Sl#1\endcsname{\thebeamerpauses}% }  \begin{document} \begin{frame}  \begin{enumerate}[<+->]  \item  \item \Slide{A} \item   \end{enumerate}  \onslide<\SlA->{Appears on slide 2;}  \end{frame} \end{document}


Please tell me how we can solve the problem of jumping cursor while typing. I am using Ubuntu 16.04 LTS and have Dell inspiron 5559.  At least tell me how to change sensitivity of touchpad.


Is it possible to avoid recording the time you play CS:GO on Steam? My friend and I had a deal that we would spend the same amount of time playing it so it would be fair. Now I have like 30 hours more on record.   I want to play more and get better but I don't want everyone to see I spend almost all day playing it.  Can I play without getting my time recorded on Steam?


How far can a sub-light-speed particle travel? And how fast will it arrive?

If we send a photon away from earth, it would eventually reach a comoving distance of about 16.5 billion light years (the universe's event horizon). I'm interested in how far (in comoving distance) particles moving below $c$ can eventually travel and at what velocity they would arrive if they were to reach a distant comoving galaxy near the end of this journey.  A simple answer to both would be that a particle moving at $kc$ (where $0<k<1$) could eventually travel $k$ times as far as light could. This is what I get if I assume $v_{peculiar}$ is always equal to $kc$ and $v_{recessional} = H(t) \cdot distance(t)$ (both in proper coordinates) and take the integral of velocity over time to get the distance.   However, I've also heard that the momentum of a particle reduces as it travels, resulting in redshift for photons (since they can't lose velocity) and in velocity loss for other particles. It seems that this could affect the above calculations. For example,  says $\frac{\dot{p}}{p}=-H$.  Does this mean that a particle launched at $kc$ would instead travel less than $k$ times 16.5 billion light years and arrive at a galaxy near that limit with a relative (proper) velocity near zero?  (Bonus points if you could derive an equation for the the maximum distance as a function of $k$.)


How can I track my progress towards a tag badge?

A tag badge criterion says      Earned X upvotes for at least Y answers in the Z tag   . How can I track this?


Syntax highlighting fails to highlight "abstract" correctly

I've just noticed that the syntax highlighting no longer highlights C# "abstract" keyword correctly:        I think it used to work correctly before. Anything changed?


Showing marker symbol even when no value in field using QGIS

In QGIS, I have been learning a few expressions to style my trail maps but still know little and am stumped on what to use to filter my symbol data. I am showing Parking locations on my map. I use a marker symbol as a background element, so I can do callouts. I created a data field and added values to display beside this symbol a number that references a list of parking addresses in the book's text. All good except if the field has no number to display, it is NULL, it does not display my marker symbol. I need to filter this, so it does show even when there is no value in the field.


Why is my textured material showing up as a solid color?

I'm trying to use a simple oak texture on this cube but it just shows up as a solid color.  I tried every option in the image texture (linear, cubic, flat, etc.) none of them worked in fact  I saw no difference between them.


If a set of $k$ random variables $x$ is drawn from the same normal distribution with mean $μ$ and standard deviation $σ$, then:   the mean of the distribution of $Σx$ is $kμ$ the mean of the distribution of $Σx²$ is $k(μ²+σ²)$   Is there a similar closed-form expression for the mean of the distribution of $Σx³$ ?  Sorry if I've got the terminology wrong!


I have these lines in my program:  printf("%-29s\n",("%s, Capital", CO)); printf("%-29s\n",("%s, Drawing",CO));   and when I run the program, it only shows the %s equivalent (CO) instead of "%s, Drawing"  Please help?


Providing a "flag-to-queue" option for moderators

Currently, posts deemed by someone in the community to be in need of being closed or reopened are sent to the close/reopen review queues by clicking a link below the post. However, if a moderator selects to close or reopen from a post, their vote is -- as in the queues themselves -- binding.   Currently, moderators only have limited choices when they come across a post in need of a close/reopen vote:   Provide a binding close/reopen vote (in seeming opposition to the ) Hope some other user chooses to initiate a close/reopen vote for the community to react to.  (3. Provide a comment and hope someone reacts by initiating a vote)   Moderators are often some of the most active members on various SE sites. In small enough sites or those with relatively few members that actively perform review tasks, many posts fail to be flagged for closing or reopening when appropriate.    I propose the addition of a way for moderators to "flag-to-queue" VTC and vote to reopen posts. In other words, instead of ignoring a post in need of community moderation or providing a binding vote, mods should be able to "flag" the post so that it enters the appropriate review queue to receive community input/voting.   Perhaps an additional action can be provided under the mod tools popup menu to "send to queue."


I have an array of 1000 or so entries, with examples below:  wickedweather liquidweather driveourtrucks gocompact slimprojector   I would like to be able to split these into their respective words, as:  wicked weather liquid weather drive our trucks go compact slim projector   I was hoping a regular expression my do the trick.  But, since there is no boundary to stop on, nor is there any sort of capitalization that I could possibly key on, I am thinking, that some sort of reference to a dictionary might be necessary?    I suppose it could be done by hand, but why - when it can be done with code! =)  But this has stumped me.  Any ideas?


Careers Top X% - Should be able to choose which (multiple) SE sites are shown

I'm a system administrator. While my Stack Overflow tags are applicable to my career skills, I'd also like to show my top tags on Server Fault and possibly other SE sites.  Could additional sites be user selectable to show in the Top X% section on our Careers 2.0 listings?


Which user input validation approach is better: preventing or explaining?

Scenario: let's say we are talking about a simple form, which contains the following field types:   All fields are mandatory. Number: only digits are allowed. Text: text must not exceed the maximum length. Email: must be a valid email address 'xxx@xxx.xxx'.   Preventing: make it impossible to enter an incorrect value by only allowing a valid input that follows the pattern, the submit button is only enabled once every field is entered correctly.  Explaining: allow submitting the form, check all the fields and generate a list of validation errors if there are any.  (On failure, user isn't forced to re-enter data. I guess everything should be preserved, since incorrect values could be really long and only require minor changes to be corrected.)


How can I create launchers on my desktop?

In older versions it was easy to create a launcher on my desktop. All I had to do is right click on my desktop and select the "create launcher" option.  How can I create such launchers now?


I can temporarily disable screen reader using super+alt+s, but it gets enabled again after some time.  Q: How to completely disable the Screen Reader?


Link in tag subscription e-mail is not correctly formatted

I'd like to report that the link to this site is not rendered correctly in tag subscription emails.


What account should own the files on a shared ubuntu webserver?

I have multiple users with FTP access to my ubuntu server, each running their own website.  Apache is running as default after installed through apt-get. I believe www-data is the apache user. If the user owns their files, apache cannot modify them (ie: wordpress). If apache owns the files, the users cannot FTP in and modify them.  What is the best practice to solve this?


How to create an infrastructure Wi-Fi network from Yosemite with no Internet connection?

How to create a Wi-Fi hotspot (infrastructure network, not ad-hoc) on a Mac without any Internet connection?  In Windows, we can easily create an infrastructure wifi LAN hotspot with:  netsh wlan set hostednetwork mode=allow ssid=MyWifi key=12345678 netsh wlan start hostednetwork   It is compatible with most devices like Android/Windows/Mac/iOS, and it does not require an available Internet connection.  So, is there a similar solution on OS X 10.10 (Yosemite) that:   can create a Wi-Fi hotspot; compatible with most devices; does not require an Internet connection?


I'm modelling a bottle shape. And when I add the subdivision modifier the top and rear of the bottle has its surface seem pinched non smooth (although I have added shade smooth). So I delete the top face, select the vertices and do a grid fill which can be seen in the image attached. But when I increase the viewport quality in my subdivision modifier the top of the bottle seems more square than circle.  What's the best modelling tip so the top of the surface doesnt make that pinched surface?  Thank you.


Please charge rep for questions after threshold

There was a suggestion on uservoice - now down, that really illustrate the need to stop users from gaming the system by simply asking meaningless, ridiculous question after question to gain rep. We have users who have gamed the system enough to actually have moderation capabilities.   These users do not deserve the system's trust and instead cause nothing but problems.   My solution is to enforce a threshold for how many questions you may ask and receive reputation on based on your answers or other activities.  Please stop these people from becoming trusted members of the community. It will not be good for anyone.


I have a program which generates random numbers. How can I test if the random number generator is generating actual random numbers?


I've studied quite a bit of group theory recently, but I'm still not able to grok why normal subgroups are so important, to the extent that theorems like $(G/H)/(K/H)\approx G/K$ don't hold unless $K$ is normal, or that short exact sequences $1\to N \stackrel{f}{\to}G\stackrel{g}{\to}H\to1$ only holds when $N$ is normal.   Is there a fundamental feature of the structure of normal subgroups that makes things that only apply to normal subgroups crop up so profusely in group theory?  I'm looking here for something a bit more than "$gN=Ng$, so it acts nicely".


Deskop shows green dots and skip some letter after upgrading from Ubuntu 19.10 to 20.04

After upgrading from Ubuntu 19.10 to 20.04, software looks working fine, but the main GNOME desktop screen is showing these green lines. Also Gedit text icon in the Dock has some buggy look and some characters are missing in upper clock as seen in the below screenshot. In Ubuntu 19.10 everything worked fine. When the screen image changes the green lines disappear, but after rebooting they come back again.  If I don't find out how to fix it, I'll have to downgrade back to Ubuntu 19.10. I am disappointed, because this is the first problem I've had with Ubuntu after four years of using it.


Proving a limit as x approaches positive infinity

Prove that $$ \lim_{x \to +\infty} \frac{x}{e^x} = 0$$ The highest degree is one so I divided both the numerator and denominator by $x$: $$= \lim_{x \to +\infty}\frac{\frac{x}{x}}{\frac{e^x}{x}} $$ $$= \lim_{x \to +\infty}\frac{1}{\frac{e^x}{x}} $$ And I argued that the denominator approaches a big value as x approaches $+\infty$, thus the limit approaches zero. If this is true, what is more mathematical way of doing this?


I'm trying to get all the factors of a number provided by a user and after a button click displaying all the factors on a MessageBox.   This is what my code code taken from  answer by  looks like, I thought I was pretty close, but I'm displaying the number of factors not the actual factor numbers.   For example if the user types in 10 and uses a button click, the MessageBox displays the number 4, but i'm wanting it to display the actual factors of 10 which should be 1,2,5,10.  *how can I display the factors?  public int Divisors(int fact)     {         int number = int.Parse(textBox2.Text);         int factorCount = 0;         int sqrt = (int)Math.Ceiling(Math.Sqrt(number));          for (int i = 1; i < sqrt; i++)         {             if (number % i == 0)             {                 factorCount += 2; //  We found a pair of factors.             }         }          // Check if our number is an exact square.         if (sqrt * sqrt == number)         {             factorCount++;         }          return factorCount;     }  private void ShowallButton_Click(object sender, EventArgs e)     {         int input = int.Parse(textBox2.Text);         double output = Divisors(input);          MessageBox.Show(+output + "");     }


(revision 2) on SU renders the markdown incorrectly:    This might be a duplicate of , but as I don't want to clutter SU's review queues I did not try out the answer.


How to NOT become a root user? Are administrators root?

I installed Ubuntu on my PC. To log in, I use the username and password I created during installation. Does this mean I am a root user? If yes, then how do I become non-root? It looks like non-root user is more secure than admin user.


How can I repeat a Linux command every minute?

I'd like to get a Linux command which runs in the background and writes something to the terminal screen every one minute. I am trying to keep ssh session alive, I am using Cygwin for connection to the server but the connection is resetting every short time if nothing is written to the screen.  I already tried with sshd_config option to solve the short connection time by changing ServerAliveInterval 0 to ServerAliveInterval 60 but this does not solve the problem.


For comment in  , Rizier123 mentioned the question poster @tim. But I received the notification in my inbox due to the fact that my display name has "tim" as prefix.  My understanding is that when there are multiple participants with the same username prefix specified in a comment, the current behavior is to notify the most recent one.   However, when there is indeed a participant whose username perfectly matches the specified name, matching the most recent one instead of the perfectly matched one is counter-intuitive. Could the current behavior be changed?


How to delete tomcat8 and related files like docs examples admin?

I installed tomcat8 and then tried to use tomcat8-docs webapp manager but link did not work.  Can you please guide me to uninstall completely tomcat8 along with docs examples admin and other files.


References on the History of Linear Algebra

I have an aggregated understanding of the history of linear algebra compiled from friends, teachers, and coworkers. It may have several errors. It goes something like this:   Even ancient cultures like the Chinese used the idea of row reduction to solve systems of linear equations, even if the format looked somewhat different. In medieval times, Arabic cultures kept this idea alive. In the 18th century, European mathematicians developed matrix notation to represent a linear system. There was even now the idea of inverting that matrix. By the mid 19th century, matrices were fully understood as derivatives of multivariable functions, and hence understood as transformations between finite dimensional vector spaces.   Still at this point there was limited applicability for practical problem solving. If a matrix was even moderately large, it was a nice theoretical tool, but practically impossible to compute with. So the most recent chapter is   In the 1940s and 1950s, with the advent of modern computing technology these limitations were overcome, and for example, Leontiff could solve a system of 500 equations.   I suppose my first question is: is any part of this significantly inaccurate? But my main question is: is anyone aware of a good historical reference emphasizing the last chapter, where computers sparked renewed interest in linear algebra? I can't seem to find any good histories that focus on this era. Most of what I find focuses on the theory developed up to the mid 19th century.


How does Miller's planet in Interstellar have such huge time dilation yet such a small gravitational force?

In Interstellar, the crew of the Endurance experience extreme time dilation (7 years to an hour) on Miller's planet, due to its proximity to a black hole. However, they only feel 130% of Earth's gravity when on the planet. How does a gravitational field powerful enough to create that kind of time dilation not also manifest as a huge physical force?


For which prime numbers $p$ is $\cos(2\pi/p)$ irrational?

I am beginner in field extension theory. But I have not learnt Galois theory. I need to solve the following problem:  For which prime numbers $p$ is $$\cos\left(\frac{2 \pi}{p}\right)$$ irrational?  I have spent some time on this question. But I did not make much progress. If someone could provide a full solution, that would be great. But hints will be appreciated as well. Thanks so much.


Consider the polynomial ring $F\left[x\right]$ over a field $F$. Let $d$ and $n$ be two nonnegative integers. Prove：$x^d-1 \mid x^n-1$ iff $d \mid n$.  my tries:  necessity, Let $n=d t+r$, $0\le r<d$ since $x^d-1 \mid x^n-1$, so, $x^n-1=\left(x^d-1\right)\left(x^{\text{dt}+r-d}+\dots+1\right)$... so,,, to prove $r=0$? I don't know, and I can't go on. How to do it.


Flag declined, link-only answer subsequently deleted

I flagged  as very low quality on the grounds that it was an answer consisting only of links, and was notified:     very low quality – 18 hours ago   declined - a moderator reviewed your   flag, but found no evidence to support it   However, I now see that the answer has been "deleted by Robert Harvey♦ 12 hours ago"  What did I get wrong here? I thought link-only answers were discouraged? Also, the fact that the answer was deleted, suggests that I did not get it wrong.   It is getting somewhat confusing working out what to flag and what not to flag.


Why does Quantum Field Theory use Lagrangians rather than Hamiltonians?

Why does Quantum Field Theory use usually Lagrangians rather than Hamiltonains?  I heard many reasons, but I'm not sure which is true.   Some say it's just a matter of beauty, so Lagrangians are more beautiful because they don't break/separate the space-time variables (so space-time is a single variable, like in the Klein-Gordon Lagrangian and Hamiltonian).  Some say that Hamiltonians are not always Lorentz invariant.  Could someone explain in a little bit more details?


Outlook 2013: Hotkey to show just unread messages

When I'm looking at my inbox in Outlook 2013, there are two convenient buttons called "All" and "Unread". When I press "Unread", it shows just the unread items, and I can toggle back to "All" to see all my messages.  My question: Is there a hotkey for pressing these buttons? I prefer to avoid using the mouse wherever possible.


Ignoring the normalising constant in Bayesian MCMC

This post relates to my original question , but this time focusing on a more fundamental misunderstanding of how MCMC actually works.  When using Bayesian MCMC for parameter inference with a single model, it is usual to ignore the "evidence" integral and write:  $$P(\theta | D) \propto P(D | \theta) P(\theta)$$  For numerical reasons, it is also common to work with logarithms:  $$ln[P(\theta | D)] \propto ln[P(D | \theta)] + ln[P(\theta)]$$  I've used this successfully on a number of occasions, typically using Python and . However, for reasons explained in my , I've recently been wondering about "normalising" my likelihood by dividing it by the number of observations (I realise this probably sounds odd, but please see my other question for why I thought it was worth a try).  My likelihood assumes i.i.d. Gaussian errors, so my log-likelihood is just the sum of the individual data likelihoods. My prior is uniform and I'm currently using an improper log-prior function, which simply returns zero if the parameter values are "within range" and '-inf' otherwise.   I initially assumed that dividing by the number of data points wouldn't make any difference, because the RHS is still proportional to the log-posterior:  $$ln[P(\theta | D)] \propto \frac{1}{n}ln[P(D | \theta)] + ln[P(\theta)]$$  (My prior only ever returns 0 or '-inf', so multiplying that by $1/n$ makes no difference).  However, when I re-run my MCMC, I get very different results. As a sense check, I tried a simple OLS linear regression using the same code.   With my original (not normalised) likelihood, I get sensible results: the MCMC recovers the "true" parameters and the 95% CI broadly agrees with the Frequentist results from 'statsmodels':    However, with the "normalised" likelihood, I get very different (and obviously wrong) results:    I think I understand why this is, at least from the point of view of a simple Metropolis algorithm. The probability of accepting the proposed jump, $x_{i+1}$, compared to the current location, $x_i$, is:  $$\alpha = \frac{P(x_{i+1})}{P(x_i)}$$  Which, re-writing in terms of my log-posterior, $L$, becomes:  $$\alpha = \frac{exp(L(x_{i+1}))}{exp(L(x_i))} = exp(L(x_{i+1}) - L(x_i))$$  On the other hand, for my "normalised" version, all the likelihoods are divided by $n$, so this becomes:  $$\alpha = [exp(L(x_{i+1}) - L(x_i))]^\frac{1}{n}$$  which is different, and might explain why my uncertainty bounds suddenly become much larger. (I understand that emcee is more sophisticated than just basic Metropolis, but I guess a similar principle applies?).  My question:  What am I missing/misunderstanding to reconcile these two results, please? On the one hand, it's OK to ignore the "normalising constant" in Bayes' equation, because anything proportional to the log-posterior is sufficient. On the other hand, multiplying the log-posterior by a constant $\frac{1}{n}$ seems to have a dramatic effect on my results?  Thank you!


My applications for PhD in Neuroscience got rejected? How to be an extraordinary candidate for PhD?

Please take time to read this, I appreciate any advice from any Ph.D. student or mentor, an advice from a neuroscience or health science field person is more useful to me.  I am an international student from India, pursuing my master's degree in Pharmacology at a US university (a private university not classified as a research university).   Hopefully, I will graduate in May 2018. I have a serious and never-ending interest in doing research in the neuroscience field. I planned to do Ph.D. in neuroscience and took care of all requirements.  My undergrad was in Pharmaceutical Sciences from India, I made an evaluation of my undergrad transcripts and converted into US GPA score by WES, and it is 3.23/4.0.   My maser's GPA as of now (3 semesters) is 3.64/4.0.   GRE: 151 Verbal, 153 Quant, 3.0 Analytical writing TOEFL: Reading - 27, Listening -29, speaking -20, writing -28 (Total - 104)  I don't have any published research papers yet.  I wrote a cohesive Statement of purpose explaining my research experience in my master's program and also my future research interests and mentioned the names of potential advisors that I searched in the respective university faculty websites.  Sent all documents before deadlines.   I applied to a total of 10 Universities, they are:    Univ of Alabama Birmingham - rejected Univ of Texas Austin - awaiting decision Rockefeller University -awaiting decision Univ of Illinois Urbana Champaign - rejected Univ of Iowa - Awaiting decision    Univ of Kansas - selected for an interview, but got rejected few days after the interview    Univ of Michigan - Awaiting decision Icahn School of medicine - rejected Univ of North Carolina - Awaiting decision Yale University - rejected    So, I got rejected from 5 universities, out of which one university interviewed me but rejected later. Now, I am waiting for the decision from 5 more. I feel that my confidence levels are dropping already.   I am not worried about falling, I have failed many times at many things, and I am sure that I will apply next year or in two years to the same program.  But one thing I noticed was, many of the Universities that rejected me replied: "because of so many extraordinary applications, we could not give admission to an excellent application like your's".  I don't know whether this reply from them is generalized one or specific to me. But I don't know how to be the extraordinary applicant. One bad thing in my application that I am aware of is my GRE. If there are any experienced Ph.D. students here, please suggest me what to do.   Thank you


If greater than javascript into XSLT doesn't work

I have javascript code into xslt which should check image dimension. If width is greater than height to rotate img.  <script language="javascript">     var a = 3;     var b = 1;     if (a > b) {       document.getElementById("img1").style.transform = "rotate(90deg)";     }    </script>     I tried:  1) &gt;  2) <![CDATA[ --code --]]>  3) disable-output-escaping="yes"   But nothing works. In console see an error message    Thanks


How I delete all files in a directory with specific extensions except the last 5 of them

The directory contains files with different extensions. I would like to delete all files with extensions .gz, zx, ext4 except the last 5 files. I can list all those files with   ls -l | grep '\.gz\|xz\|ext4$'   and I could just show the oldest 5 of them:  ls -l | grep '\.gz\|xz\|ext4$' | head -5   Or list the last 5 files:  ls -l | grep '\.gz\|xz\|ext4$' | tail -5   But I don't know how delete all of them except these 5 files that are listed in the above command.


Clarification on useful questions getting closed

I had asked a question some time ago and noticed that it has been closed.  I was rather (VERY) surprised that it had been closed as it seems pretty darn legit.  A programmer asking other programmers a question related to programming with a new framework...  Is this question highly subjective?  You bet.  Could a spammer or someone looking to make money on this type of thing ask this question?  You bet.  Could these types of questions theoretically impact the positive experience of Stack Overflow users?  Maybe... I know I'm way late to this game and there are probably 1002 threads here on meta about this topic already.  But, what the heck is going on here?  Seriously? Stack Exchange is a business that charges us absolutely nothing to come and use their Q&A platform.  They make their money through advertisements and sponsorships, not through us.  This particular question received 8 upvotes and 0 downvotes since it was asked in June of 2009.  The question has also been viewed over 6300 times since then with the vast majority likely coming from search engines. I thought the purpose of the Q&A platform being a Wiki format was to allow living questions that have answers that change over time.  I actually pulled this question up to start tweaking it now that MVC3 is out and 4 is well along the way. Can someone please explain why questions like this that are obviously NOT SPAM yet are very helpful have been getting closed? EDIT 5 answers to this question, the most helpful are voted down like no other.  This is simply disgusting.  While I did answer that question with the use of the Telerik controls, things have changed.  More controls exist today.  The question should be edited, new answers given.  This question is very helpful to anyone looking to use grids in MVC.  Just because some users on StackOverflow seem to have an issue with this, the entire community gets punished.  I'm completely disgusted.  It feels to me that Spolsky and others have given the keys to the prisoners.


Split the files on a directory and move them to another newly created directory

I have 1000 files in a single folder and I need to split them into counts of 100 files each. After this, I need to automatically move the 100 files to a new folder which is automatically created.  I use this command for manually moving the files.  for file in $(ls -p | grep -v / | tail -100); do  mv "$file" NEWFOLDER; done   But, this will be hard enough if I had around 10000 files in a single folder.


Zeros of bounded analytic function on unit disk -- infinite Blaschke product

Suppose we have $f: \mathbb{D} \rightarrow \mathbb{D}$ analytic and not identically zero. In order to prove $f$ has an infinite Blaschke product representation (where of course the product defines an analytic function on the disk), I need to show that $f$ necessarily has countably many zeros $a_j$ in $\mathbb{D}$, and that they satisfy $$\sum_{j=1}^{\infty} (1-|a_j|)<\infty.$$ This condition seems necessary because the Blaschke product formed by the zeros of $f$ converges locally uniformly on the disk if and only if they satisfy the summation condition, which is how one would show the product is analytic.  Assuming this crucial step, I am able to prove that $f$ has a representation $f(z)=B(z)g(z)$ where $B$ is a product as above and $g$ is a never vanishing analytic function. Any help is appreciated.


I am a new Linux user and I have ubuntu 20.04 running in Lenovo laptop. It was working fine all of sudden it started giving authentication error. I tried restarting the system and since then I am getting the below error. Its stuck forever and not moving anywhere. Please can somebody help me. Below is the screenshot of the error


When do we double the last letter in the past tense? Is there any rule for that?


In this video:   3:18 into the video. I'm curious about Server Jacks and possibly ballpark costs for them.


I have been given the following:  If X is a positive random variable with E(X) = 0, find P(X=0).  I am guessing this is 1 but how do i prove this?


Practical way to implement prevention of IP Spoofing

I am an undergraduate Computer Science student and was hoping to gain some knowledge of ways to help prevent IP spoofing but all the resources I have tried out elaborate this concept in a theoretical way. I want to try out my hands at one of the techniques like:      How do I simulate this whole situation in my own system were I myself am the attacker and I myself have to defend it? And once I have gained an understanding of it, then how do I start translating that into programming terms?


How to place three pages on one larger page?

I seek advice how to place three pages on one larger page. I would like to place front cover page, spine and back cover page on one page. It is not obvious from the MWE, but the images on front / back cover should be placed in pair under each other. Pictures illustrated the desired placement (the whale should not be there :)). Thank you in advance.  Edit: The solution should preferably include the possibility to stretch / shrink the spine according to the real width of pages.    Here is my attempt but it places pages under each other.  \documentclass[8pt]{extbook}     \usepackage[paperwidth=400mm, paperheight=280mm, top=0cm, headsep=0cm, bottom=0cm, left=0cm, right=0cm]{geometry} \usepackage[icelandic, latin, czech]{babel} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc}      \usepackage{tikz} \usetikzlibrary{calc}   \usepackage{color} \usepackage{mwe}  %\usepackage{lscape} % for printing \usepackage{pdflscape} %for viewing \usepackage{pagecolor} \usepackage{afterpage}     \usepackage{adjustbox} % loads also graphicx \usepackage%[showframe]            {geometry}             % Basic geometry of document \geometry   { layoutsize = {360mm,240mm}   , layoutoffset = {2cm,2cm}   , showcrop   }  \graphicspath{%   {/images/}}  % #################################################################### COLORS #  \definecolor{darkgreen}{rgb}{0.4, 0.01, 0.24} \definecolor{title}{RGB}{16, 13, 32}  % #################################################################### #  \newcommand\makebookmarkfront{  \begin{landscape} \begin{center} \vspace*{\fill}  {\Huge\scshape\color{darkgreen}%    \dictnameCZ\\\dictnameIS}  \vspace*{\fill} \end{center} \end{landscape} \clearpage  }  \def\dictnameCZ{islandsko-český studijní slovník} \def\dictnameIS{íslensk-tékknesk stúdentaorðabók}  \renewcommand{\baselinestretch}{0.7}   \newcommand\makebookmarkfrontd{  \vspace*{0.3cm}%{\fill}  \begin{figure}[ht]\centering%  \setlength\fboxsep{0pt}\setlength\fboxrule{0pt}%  \fbox{\includegraphics[width=4cm]{example-image-b}}  \end{figure}   \vspace*{0.90cm}%{\fill}  %\begin{minipage}{0.6\textwidth}   \begin{center}\Huge\scshape\color{darkgreen}%    islandsko-\\    český\\    studijní\\    slovník   \end{center}      \vspace*{0.1cm}%{\fill}     \begin{center}\Huge\scshape\color{darkgreen}%    íslensk-\\    tékknesk\\    stúdenta-\\    orðabók    \end{center}  %\end{minipage}   \vspace*{10cm}%{\fill}  \begin{center} {\color{darkgreen}www.hvalur.org} \end{center}   \vspace*{\fill} \clearpage  }   % #################################################################### COVERS # \newcommand*{\frontcoverimages}{%   example-image-b,   example-image-b,   example-image-b,  example-image-b,  example-image-b,   example-image-b,   example-image-b,   example-image-b}  \newcommand*{\backcoverimages}{%   example-image-a,   example-image-a,   example-image-a,   example-image-a,   example-image-a,   example-image-a,  example-image-a,   example-image-a}  \newcommand\makecoverwith[1]{  %\pagecolor{title}\afterpage\nopagecolor  \begin{center}  \vspace*{0.3cm}%{\fill}  {\Huge\scshape\color{darkgreen}%    \dictnameCZ\\\dictnameIS}  \vspace*{1em}                        % I think this is necessary  \begin{figure}[ht]\centering%    \setlength\fboxsep{0pt}\setlength\fboxrule{0.5pt}%    \foreach \file in #1{      \fbox{\includegraphics[width=5.5cm]{\file}}}  \end{figure}  \vspace*{\fill}  \end{center} }   % ############################### Document  \begin{document}  \pagenumbering{gobble} %    \pagecolor{title}     \makecoverwith\frontcoverimages     \makebookmarkfrontd{}   \makecoverwith\backcoverimages  \end{document}


Figures with [h] position in multicols environement

I usually work with the normal article latex environment, with one column, and I usually introduce figures using the position given by [h] (with means "place the float here, i.e., approximately at the same point it occurs in the source text (however, not exactly at the spot)".  However, in multicols (in this case, in two columns), the only way I know to introduce graphics is by means of float package and it only works with the position given by [H] ("put exactly here"). The problem is that I have several graphics and using the position given by [H] there are lots of empty spaces that looks quite bad.  The question is if there is some way to use [h] position or something equivalent in the multicols package. Thanks in advance.


Given that B is a symmetric matrix how can I show that if B can be diagonalized then there exists an orthonormal basis of eigenvectors of B?

Suppose that $B \in R^{n \times n}$ is a symmetric matrix.  How do I prove that if $B$ can be diagonalized, then there must be an orthonormal basis ($v_1,v_2, \dots, v_n$) of eigenvectors of $B$?  This is different than the question tagged as duplicate because I am asking for a proof for that there must be an orthonormal basis rather than just proving vectors are orthogonal.


Can't use window controls on maximized windows

When I maximise a window and hover my mouse where the window controls should be, they do not appear however if I hover my mouse over the file menu bar, they do appear but as soon as I move my mouse back, it disappears as if my mouse was elsewhere. This is only on maximised windows and I'm using Ubuntu 13.04.  Mouse over menu:   Mouse over window controls:


Setting variables in /etc/environment not having an affect but setting them in command line is

I am setting certain environment variables for the command pyspark to work. When I set the variables in /etc/environment and source it, it doesn't work. However, when I set them in command line they do work but ofcourse only for this session. My intent is to set them globally so that even if I re-open the session I can just type pyspark  Setting in /etc/environment  [root@localhost ~]# more /etc/environment [root@localhost ~]# echo "export SPARK_HOME=/srv/spark" >> /etc/environment [root@localhost ~]# echo "export PATH="$SPARK_HOME"/bin:"$PATH >> /etc/environment [root@localhost ~]# echo "export JAVA_HOME=/usr/lib/jvm/jre-1.7.0-openjdk" >> /etc/environment [root@localhost ~]# source /etc/environment [root@localhost ~]# pyspark --version -bash: pyspark: command not found   Setting on command line  [root@localhost ~]# export SPARK_HOME=/srv/spark [root@localhost ~]# export PATH=$SPARK_HOME/bin:$PATH [root@localhost ~]# export JAVA_HOME=/usr/lib/jvm/jre-1.7.0-openjdk [root@localhost ~]# pyspark --version Welcome to       ____              __      / __/__  ___ _____/ /__     _\ \/ _ \/ _ `/ __/  '_/    /___/ .__/\_,_/_/ /_/\_\   version 1.6.1       /_/  Type --help for more information.


Does $a_n \le b_n \implies \lim a_n \le \lim b_n$ hold?

For two sequences $\{a_n\}$ and $\{b_n\}$ with $a_n\le b_n,\forall n \in\mathbb{N}$, it is true that $\lim a_n \le \lim b_n$, right? I need this result to prove something but I can not find it  anywhere.


I am trying to learn Fibonacci tricks and I have one that I can not prove. I know it works because Ive tried it multiple times but I have not a clue how to prove. Here it is:  f(0)^2 + f(1)^2 + f(2)^2 + f(3)^2 = f(3)f(3+1)   0    +   1    +   1    +   4    =   2  *  3             = 6                          =6    Is there a way to prove this?


Can free humans tell if they are in the Matrix?

Can any of the "free humans" tell if they are in the Matrix or not? Does it feel different? Or is it only context (like if they remembered being put in there, or see familiar Matrix cities, etc.)?


I look for similar questions to this one but my problem is different. I want to join this community:    so I click in     but I got this error:    but then, I found that the community is already in list of communities:    However, if I click on the community, I'm an anonymous member     and even I have the option to join again     but if I click on it, the problem starts again :( what can I do?


How To Export Blender Mesh w/ Shaders to Unity

I am following CG Geek's  and I want to export this tree, shaders and all, to Unity so I can add it to my game. How would someone go about exporting a (Cycles Rendered) mesh To Unity? Thank You In advance! (BTW, I know there are a lot of people that already asked this but I tried them and they don't work. Also (I think), my circumstance is kind of specific)


Changing projection of shapefile in QGIS

How do I change the projection of my shapefile using QGIS? The default projection is set to EPSG:3003, I want to change it to WGS84 EPSG:32632. When I do a reprojection or I change projection in the properties mask I don't have the correct result. On the left, I have the plan coordinates but they are not correct for the EPSG shown on the right:


What is the answer? Amount or Quantity or Number

Try to reduce the .......... of cups of tea you drink a day (amount - Quantity - Number) Some help please


Often in geology & archaeology we listen that they calculated the age of things (bones, pots) using radio active dating. Radioactive dating works using half life of unstable isotopes. And what geologists/archaeologists do is use the fraction of remaining isotopes. But this makes no sense to me. I mean should not it be that those isotopes start decaying right after they were created (probably inside star cores or explosions 💥) instead of when that pot was created?


I deleted my question from Stack Overflow. How can I delete the revision history?

I deleted my question from Stack Overflow having some sensitive information, but I believe the question is not completely removed from Stack Overflow. It also has a revision history, so I want to remove all the data related to it - snapshot everything. Could anyone properly help me to resolve this matter?


how to prove this inequality $(ab+bc+ac)^2 ≥ 3abc(a+b+c)$

Prove that if $a,b,c$ are non-negative real numbers, then   $(ab + bc + ca)^2 \geq 3abc(a+b+c)$.   I tried to compute from $(a-b)^2 + (b-c)^2 + (c-a)^2 \geq 0$.


Converting a single String to a Character before pushing it on a stack

I'm a Java noobie so I'm still not familiar with the tools this language has. What I'm writing is an expression evaluation program, whose only operations are * and +. For input : 2+2*2*2*2*2*2+2*2 I should get an output of 70 but instead, my main throws a java.lang.NullPointerException where I call the function and where I try to push it on the stack. I've tried using Charachter.valueOf() but the outcome is the same. My questions are:   How to convert a primitive type char to a Character? Why is new Character deprecated?   Here is my stack implementation:   public class MainClass {          //ExpressionEvaluator MainClass       public static int evaluateExpression(String expression){          int evaluation = 0, a = 0, b = 0, tmp = 0;          char ch1, ch2, op;          LinkedStack<Character> operand = null;          LinkedStack<Character> operator = null;          for(int k = 0; k<expression.length(); k++){              if(Character.isDigit(expression.charAt(k))){                  op = expression.charAt(k);                  operand.push(new Character(op)); // <----- then error here             }                                           // won't let me push it on the stack             else{                 operator.push(expression.charAt(k));             }         }         if(operator.peek() == '*'){             evaluation = 1;         }         while(!operand.isEmpty() && !operator.isEmpty()){             a = operand.pop();                       ch1 = operator.pop();                    if(ch1 == '*'){                              evaluation *= a*operand.pop();             }             else{                                        tmp = a;                                 a = operand.pop();                       ch2 = operator.pop();                    if (ch2 == '*'){                     evaluation *= a*operand.pop();                 }                 else{                     evaluation += a+tmp;                 }             }         }         return evaluation;     }      public static void main(String[] args) throws IOException {         BufferedReader input=new BufferedReader(new InputStreamReader(System.in));         System.out.println(evaluateExpression(input.readLine()));//  <--------   first error here     }  }


Relation between magnetic moment and angular momentum -- classic theory

How do I prove the relation between the vectors of magnetic moment $\vec\mu$ and angular momentum $\vec L$, $$\vec\mu=\gamma\vec L$$  ?  Many text books and lecture notes about the principles of magnetism show the relation of $\mu$ and $L$ as scalars only and then just state that the relation holds also for the vectors. An example:   $$\mu=I\cdot A = \frac{q}{t}\pi r^2 = \frac{qv}{2\pi rm}m\pi r^2$$  ($I=q/t$: current, $A$: area of a loop, $q$ charge, $t=2\pi r/v$: time of 1 rotation, $v$: velocity of particle, $m$: mass )  The angular momentum is $\vec L = \vec r\times\vec p$ or $L=mrv$ and therefore $$\Rightarrow \mu = {\frac{q}{2m}} L = \gamma L.$$  Why is this also true for the vectors? Is there a general explication by classical physics without the need of quantum theory?


how to wire a 2 way switches with 2 pendants

How do I wire a 2way 2light system. On the upstairs landing I want to switch 2 lights on and off at each end of the corridor.


Convergence of $\sum_{n=0}^\infty \frac{(-1)^n}{z+n}$

I want to find the domain of convergence of the series $\sum_{n=0}^\infty \frac{(-1)^n}{z+n}$ I recently posted a similar question here:  where I was able to use Laurent series and find an annulus in which the series does converge.  However, for this problem, I am not sure if I can do that.  The ratio and root test don't help too much either.  So, I was wondering if there is a way to apply, maybe, Leibniz's criterion to a series of a complex variable?  What would something like that look like?  Maybe there is something else that would work?  Any ideas, hints, etc. are (as always) greatly appreciated!  Thank you.


Exit windows popup messages to be customized with styles css

I want the message "Leaving page will cause loss of data" to be bold. could you please help me?  $(window).bind("beforeunload", function(e) {     return "Leaving page will cause loss of data"; }).unload(function() {     // what if they choose 'leave this page';  });


How do I determine which process is using a serial port?

The company I work for makes hardware that communicates to the computer though a serial port. Third party companies write software that communicates with our hardware.   There are times when I need to diagnose our hardware. However, a third party software app connects to the serial port when Windows starts up, blocking any other connection. I don't know the name of this application/service and it's not always the same one.  Is there any way to either:   Find the name/pid of the app/service that is currently using a given serial port or Steal the serial port connection from another app.   vb.net preferably, but I'll take a language agnostic answer as well.


Can I use ECC for encryption/decryption, just like RSA?

I'm familiar with RSA for asymmetric encryption. I also understand it's only supposed to encrypt small amounts of data (smaller than the key) so for encrypting arbitrary data I would typically generate a one-time random key, encrypt just that random key with asymmetric encryption, and then encrypt the actual data using AES with the random key (and then throw away the plaintext key) Can I also use Elliptic Curve Cryptography for this? And if yes, can I use any common type of curves / keys? For example, can I create a Ed25519 or Secp256k1 or Secp521r1 keypair, and then encrypt something with the public key so it can only be decrypted with the corresponding private key? I sometimes read things like 'Ed25519 is only for signatures, not encryption' or 'ECC is only for authentication'. Suppose I have an RSA keypair MyPrivateRsaKey.pem and MyPublicRsaKey.pem and a small data file secret.txt.I can encrypt secret.txt using MyPublicRsaKey.pem, and then the encrypted data can only be decrypted with MyPrivateRsaKey.pem. Now if I have a keypair MyPrivateEd25519Key.pem and MyPublicEd25519Key.pem for example, can I do the same? Or am I mistaken and are elliptic curve keys fundamentally unsuitable for this? P.S. note that for the context of this question, I'm not dealing with key exchange or signatures or certificates or authentication. Just asymmetric encryption+decryption.


Random variable of multiple random variables question.

Hey guys can you help me with this? The problem setting is that X and Y are independent random variables and Z = Y / X. I want to verify that: $\displaystyle f_ Z(z)\, = \int _0^\infty {{y}} f_ Y(y)f_ X(yz) \, dy$ In other words, is this true? I hope the problem is clear. Thank you in advance. PS I know the answer but I'm looking to understand.


Let's say my string is 10 characters long.   How do I remove the last character?  If my string is "abcdefghij" (I do not want to replace the 'j' character, since my string may contain multiple 'j' characters) I only want the last character gone. Regardless of what it is or how many times it occurs, I need to remove the last character from my string.


Value of a specific q-series / infinite product?

While working on a different problem, I've run into the infinite product: $$\prod_{i=1}^\infty (1-2^{-i}) $$ Which I'm reasonably sure should be equal to $1-\frac{1}{\sqrt{2}}$. EDIT: It definitely doesn't equal this value, nevermind   However, I don't really have any notion of how to work with / prove things about an infinite product of this form. I tried considering the log of the partial products, but that doesn't seem to make the numerical value any easier to evaluate.  Doing some googling, these sorts of products seem to be called Euler products, or q series (see here: ). However, I can't find much or anything online about methods for finding their value. Is there any process that would yield a precise answer in this case?


What is the T-SQL To grant read and write access to tables in a database in SQL Server?

What is the exact SQL to assign db_datareader and db_datawriter roles to a user in SQL Server?  The user name is MYUSER and the database is MYDB.


Two Bibliographies: one for main text and one for appendix

I have a manuscript in which has the following structure:  Main Text Bibliography Appendix   However, there are citations which are only cited in the appendix, and they show up in the main bibliography. I would like to split my Bibliography into two different sections, so that the structure of the paper would look like this:  Main Text Bibliography for Main Text Appendix Bibliography for Appendix   I'm currently using bibtex and a single .bib file, and creating the bibliography with  \bibliographystyle {someBibStyleFile} \bibliography {bibFileName}   I'm interested in a method to split my single bibliography into main bibliography and appendix bibliography with minimal changes to the rest of the document.  I'm aware that biblatex is more powerful than bibtex, but I'm not prepared to make the switch before the deadline of this project. There are many related bibliography-with-multiple-sections type of questions, but I didn't see one that covers this case.


Why does Fort Lauderdale airport Wi-Fi prevent me from submitting certain answers with code?

I am in the Fort Lauderdale airport, waiting for a flight, and connected to the Internet on my computer, which I regularly use for Stack Overflow. The only difference is that I am connected to the publicly available Wi-Fi system.  Certain code combinations are simply not allowed. For instance, the code in  could not be accepted (you will see that someone else edited it after me).  Is there a way to fix this or work around it? I am logged in on a Mac using Chrome.  Edit:  Now I am in the airplane, so this is via a mobile device.  The error is simply that the answer or comment cannot be submitted. This is not a generic problem with all code. I was able to submit partially formatted code, which was then edited.  Also, simply removing the formatting did not fix the problem.  Stack Overflow can do something about it. The first thing would be notifying the submitter about where the error is occurring. Improved error descriptions should be entirely in the spirit of the site.  Second, if we know what the problem is, then perhaps that can be communicated to the people running such sites. Fixing the Internet is not in the purview of Stack Overflow, but on a community moderated site no one individual needs to take responsibility for it. If we know what the problem is, then just maybe it can be fixed.  Is there a way to figure out what the real problem is so such issues can be fixed?  And, I'm just happy that my flight is only 20 minutes late, so this issue no longer affects me.  (If I had missed the flight due to overuse of Stack Overflow, the site might have done me a favor. It is about 50 degrees (F) colder in New York City than down here.)


I have quite a simple question but I can't for the life of me figure it out.  For a set of iid samples $\,\,X_1, X_2, \ldots, X_n\,\,$ from distribution with mean $\,\mu$.  If you are given the sample variance as  $$ S^2 = \frac{1}{n-1}\sum\limits_{i=1}^n \left(X_i - \bar{X}\right)^2 $$  How can you write the following?  $$ S^2 = \frac{1}{n-1}\left[\sum\limits_{i=1}^n \left(X_i - \mu\right)^2 - n\left(\mu - \bar{X}\right)^2\right] $$  All texts that cover this just skip the details but I can't work it out myself. I get stuck after expanding like so  $$ S^2 = \frac{1}{n-1}\sum\limits_{i=1}^n \left(X_i^2 -2X_i\bar{X} + \bar{X}^2\right) $$  What am I missing?  Edit: A similarly equivalent expression is often given that I also can't derive but which may be more obvious is  $$  S^2 = \frac{1}{n-1}\left[\sum\limits_{i=1}^n X_i^2 - n\bar{X}^2\right] $$


I have recently started to dual boot ubuntu 17.04 with Windows 10. I am able to connect to my LAN via a wired connection, but wifi shows "disabled" even after checking "enable wifi."  I have posted the relevant information in the link below.    System: Lenovo Legion y520


Won't emission line spectrum also be observed in absorption spectrum?

In absorption spectrum, we pass white light through the sample of gas or liquid which is to be examined. The electrons in those atoms will will absorb particular wavelengths from the white light and will get excited to a higher energy level. The wavelength which are absorbed by the electrons won't appear in the screen and hence dark lines should be observed in a coloured background if the light is further passed through a prism or a diffraction grating. In this way and absorption spectrum is obtained in which dark lines appear in a coloured background. But we know that electrons don't like to stay in higher energy level. They typically stay there for a time that is of the order of $10^{-8} s$. So they will jump back to the ground level either by one transition or by multiple transitions and thus they will the emit the energy in the form of photons. If they come back to the ground level in one transition they will emit photon which has the exact wavelength of a photon that they absorbed. Thus we won't say see dark lines in a coloured background as the electron emitted the photon of the exact same wavelength with it absorb which we see as dark lines in a coloured background, right?


Try to install ubuntu 18.04 to HP Laptop 1-da0xxx

I'm trying to install the Ubuntu 18.04 to my laptop HP Laptop 15-da0xxx it is possible to my laptop. Thank you


Force.com Site and custom user authorization - Is it allowed and when?

Assume I am going to build a customer facing website where users have some access to Salesforce Standard and custom objects.  Because it's expensive I don't want to give them Salesforce licenses. I also don't want to go with a Full-blown Community. The technical complexities and the costs of Heroku Connect also shy me away from Heroku.  Can I do this?   Force.com Site Custom User and Permission Objects Custom Registration + Login using VF "Authentication" with Custom User object Only a Single Guest licence Giving 50 outside users access to Accounts and Lead using single Salesforce license   So my question is not about technical feasibility. I know that this would be possible. It's about legal stuff. Salesforce is in the License business and circumventing this is probably disallowed.  I need to know if and when I can do this. Can you point me to any documentation, legal material that is prohibiting that?  Maybe it is only prohibited for ISVs and AppExchange packages. Maybe it is prevented by Security review. Are Consulting Partners and PDOs allowed to (help) build such apps? And if not, where is that documented.  I really need some official reference material here.


sed: replace part of text in previous line if match is found

I want to replace create_test in the file with #create_test if the next line contains psfxxx_16_pi. How can I do it with sed for the whole file containing this?  Input file content:  create_test -type hard -outer { 1.0000 } { \     psfxxx_16_pi/psfop/deadline_north_re_0 }  create_test -type hard -outer { 0.0000 } { \     psfxxx_16_pi/psfop/deadline_south_re_1 }   Output file:  #create_test -type hard -outer { 1.0000 } { \     psfxxx_16_pi/psfop/deadline_north_re_0 }  #create_test -type hard -outer { 0.0000 } { \     psfxxx_16_pi/psfop/deadline_south_re_1 }


Sed: Replace ANY IP address with 127.0.0.1

I'm trying to do an in-place replacement of an IP address in a file using sed. I know that . is a wildcard, so I've tried doing the following:  sed -i -e 's/.\..\..\..\./127.0.0.1/g' /.../myfile.txt  however I'm not sure how many digits each section of the IP address could be (1-3), and I'm also not sure if my escape works as well. Any advice? Much appreciated


Calculation of the n-th central moment of the normal distribution $\mathcal{N}(\mu,\sigma^2)$

Since integration is not my strong suit I need some feedback on this, please:  Let $Y$ be $\mathcal{N}(\mu,\sigma^2)$, the normal distrubution with parameters $\mu$ and $\sigma^2$. I know $\mu$ is the expectation value and $\sigma$ is the variance of $Y$.  I want to calculate the $n$-th central moments of $Y$.  The density function of $Y$ is $$f(x)=\frac{1}{\sigma\sqrt {2\pi}}e^{-\frac{1}{2}\left(\frac{y-\mu}{\sigma}\right)^2}$$  The $n$-th central moment of $Y$ is $$E[(Y-E(Y))^n]$$  The $n$-th moment of $Y$ is $$E(Y^n)=\psi^{(n)}(0)$$ where $\psi$ is the Moment-generating function $$\psi(t)=E(e^{tX})$$  So I started calculating:  $$\begin{align}  E[(Y-E(Y))^n]&=\int_\mathbb{R}\left(f(x)-\int_\mathbb{R}f(x)dx\right)^n\,dx \\ &=\int_\mathbb{R}\sum_{k=0}^n\left[\binom{n}{k}(f(x))^k\left(-\int_\mathbb{R}f(x)dx\right)^{n-k}\right]\,dx \\ &=\sum_{k=0}^n\binom{n}{k}\left(\int_\mathbb{R}\left[(f(x))^k\left(-\int_\mathbb{R}f(x)dx\right)^{n-k}\right]\,dx\right) \\ &=\sum_{k=0}^n\binom{n}{k}\left(\int_\mathbb{R}\left[(f(x))^k\left(-\mu\right)^{n-k}\right]\,dx\right) \\ &=\sum_{k=0}^n\binom{n}{k}\left((-\mu)^{n-k}\int_\mathbb{R}(f(x))^k\,dx\right) \\ &=\sum_{k=0}^n\binom{n}{k}\left((-\mu)^{n-k}E\left(Y^k\right)\right) \\ \end{align}$$  Am I on the right track or completely misguided? If I have made no mistakes so far, I would be glad to get some inspiration because I am stuck here. Thanks!


Let $A,B\in M_n(\mathbb{R})$, Prove $\det\begin{pmatrix} A & -B\\ B & A \end{pmatrix}=|\det(A+iB)|^2$

Let $A,B\in \mathcal M_n(\mathbb{R})$, Prove $\det\begin{pmatrix} A & -B\\ B &  A \end{pmatrix}=\bigg|\det(A+iB)\bigg|^2$  My work:  We know:     $$|\det(A+iB)|^2=\sqrt{(\det(A+iB))^2}^2=\det(A+iB)^2=\det(A+iB)\det(A+iB)=\det((A+iB)(A+iB))=\det(A^2+AiB+iBA+i^2B^2)=\det(A^2+AiB+iBA-B^2)$$   Here I'm stuck. Can someone help me?


Reputation tally in profile counts -1 for downvotes but not +1 for deleted downvotes

The profile page shows a number for the total reputation change since you last looked at that tab.  This number seems to include the -1s for downvotes you cast but not the +1s if those posts are later deleted, even though both events show up as highlighted:    The total rep change from the highlighted events is 65; the number in the tab header is 64.  I've seen this consistently across several sites for a while, including MSE with the new Activity page; it's not new or localized behavior.  It's easy enough to figure out what's really going on, but the discrepancy stands out.  Can we make the number in the tab header match reality?  (The deletion didn't immediately follow the downvote, though it was on the same day.  So I don't think I should blame caching.  Besides, I think I've seen these for cases where the events occurred on different days.)


Time/Datetime block of code isn't working

I am a new programmer to Python, and I am trying out a quick datetime/time test piece of code for a bigger project. Upon running it, I get several errors. Here is the code: import datetime, time time = time.localtime() currentTime = time.strftime("%H:%M:%S", time)  I have tried replacing time.strftime with time.strptime but that doesn't work. Any ideas? Thanks, Kizuo


Find $\lim \limits_{s\to 16} \frac{4-\sqrt{s}}{s-16}$

How do you find this limit using algebra?  $$ \lim \limits_{s\to 16} \frac{4-\sqrt{s}}{s-16} $$  By graphing I get 1/8.


How to return an enum by item index as apposed to value index?

How do I index into an enum via "item index" instead of the "value indexing": "Value indexing" (not useful to me with what I am doing): eSerialBauds eBaud = static_cast<eSerialBauds>(1200); // yields eBaud1200  I want "item indexing": ( How to get the following? ) eSerialBauds eBaud = static_cast<eSerialBauds>(3); // to yield eBaud1200   // values (from WinBase.h) #define CBR_110             110 #define CBR_300             300 #define CBR_600             600 #define CBR_1200            1200 #define CBR_2400            2400    enum class eSerialBauds {   eBaud110 = CBR_110,   eBaud300 = CBR_300,   eBaud600 = CBR_600,   eBaud1200 = CBR_1200,   eBaud2400 = CBR_2400, }   Please note that I am given this enum class from another class.  There are many. So I have to work with what is given to me. I did write a work around method but it would be nice to have a more elegant way of getting the result.


addEventListener and classes declared inside

Started to use addEventListener some weeks ago. It is one case i cant understand so far. We are talking about cases where we printing taggs with templet literals and declaring the class inside thos taggs. After that if we going to use thise classes for other EventListener, somethimes we need to have other EventListener inside the first one(the one who is printing/declaring classes) other times we dont have to have another eventListener inside the first one. Why? Somebody have good explanation or can point me in right direction? I am giving exemples under. Thank you in advance //two different Event Listener were the first one making class and second one using that class  const drink = document.querySelector(".drink"); let drinkTxt = ""; MenyModule.getDrink().forEach(drink =>{   drinkTxt +=`   <div class="boks">     <h4>${drink.name}</h4>     <p class="des">${drink.des}</p>     <p class="price">kr ${drink.price}</p>     <a class="button-buy">BUY</a>   </div>   ` }); drink.innerHTML = drinkTxt;   document.querySelectorAll(".boks").forEach(boks =>{   boks.addEventListener("click", (e)=>{       alert();     })   });   //Second exemple where i need to have other EventListener inside the first one or alert() will not be executed  document.querySelectorAll(".button-buy").forEach(button =>{   button.addEventListener("click", ()=>{         valgteRetterTxt+=`<a class="remove1">REMOVE</a>`       valgteRetter.innerHTML=valgteRetterTxt;          document.querySelectorAll(".remove1").forEach(remove=>{           remove.addEventListener("click", ()=>{             alert();           });         });      });   });


Where can I ask a question about an obscure/dialect programming language?

I'm starting to use multiple programming languages and sometimes the syntax for things trips me up. I would like to be able to Google "How to write a for loop in Optoscript" and have a relevant answer show up in Google just like every other major language, but this does not always work. I thought that Stack Exchange would be a good place to ask that kind of question (and post the answer from the manual that takes forever to load) but figured I'd ask on Meta first. Should I post these questions? To what stack should I post them?


$$\lim_{n \to \infty} \sum_{k=1}^{n} \left(\sqrt{1+ \frac{ k}{n^2}}-1\right)$$ I was trying to use Riemann integral method here, but how to find $f(x)$? Any hints?


What is the difference between minimal, desktop & server Editions?

I just want to know, what is the difference between ubuntu Minimal, Desktop & Server Editions? How they differ? is it by performance? If yes which one is recommended for a normal user and which one is recommended for a advanced user ?


How to install source sans pro in ubuntu?

I like this font because its free but i am unable to install it in my ubuntu 14.04. I did a lot of research on this but all results give me source code pro. Which is also developed by adobe but a different font that source sans pro. This is the link for this font


What solutions does the equation 4x≡2mod10 have? (Hint, it will have more that one.) What about solutions to an equation ax≡dmodn, where d=gcd(a,n)?

What solutions does the equation $4x\equiv2\mod10$ have? (Hint, it will have more that one.) What about solutions to an equation $ax\equiv d\mod n$, where $d=\gcd(a,n)$?  This is the question that appeared in our universities last year paper. But it seems very difficult for me like for first part I am able to solve by simplifications I got $x=5\cdot Z +3$ as solution which makes sense and seems fair but for the second one, I have no idea how can I approach that. Can you please help me out with that one. I tried to simplify that by using Euclidean algorithm but still, I didn't get any idea that what actually the solution will be. My final exam is on 2nd of next month and because of covid I am unable to contact in person for any help. So any help from this site will be appreciated. Thank you for looking at this question!


EDITED: I got a script running with a cronjob every day at 1 am: 0 1 * * * /bin/bash /home/performanceRatio.sh  It also appears in the cron.log: Feb  2 01:00:01 inf-education-67 CRON[108963]: (root) CMD (bash performanceRatio.sh) Feb  2 01:00:01 inf-education-67 CRON[108962]: (CRON) info (No MTA installed, discarding output)  Expected behavior is to update a mysql database. Changes appear if it's run manually. Using Ubuntu 20.04 My script looks like: #!/bin/bash PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin  python3 get_weather_data_crn.py && python3 pv.py  * * * * * env > /tmp/env.output shows: HOME=/root LOGNAME=root PATH=/usr/bin:/bin LANG=de_DE.UTF-8 SHELL=/bin/sh PWD=/root


Can a level 1 Oracle use the additional spell slots gained by having a high Charisma to cast the low level spells she knows or are those slots initially wasted?  Can spell slots generally be used to cast a lower spell than their level?


Can Euler's identity be extended to quaternions?

Euler's identity is $e^{i \pi} + 1 = 0$, a special case of the Euler's formula $e^{i\theta} = \cos\theta + i\sin\theta$, where $\theta = \pi$ (half-turn of the unit circle).  It is commonly described as "beautiful" because it is simple and includes a bunch of fundamental mathematical constants and operators, including the complex numbers.    Is there a corresponding Euler's identity for ?  Speculation:    proposes a different fundamental circle constant, $\tau = 2 \pi$, and a corresponding alternate Euler identity, based on a complete turn, the special case of $\theta = \tau$:   $e^{i\tau} = 1$  If both identities are extended to quaternions, is one any simpler or more "beautiful" than the other?


openSUSE - Remove all packages from a repository

I've installed cinnamon in my openSUSE to try it, but I didn't liked and removed cinnamon and cinnamon-session, but I noticed that there were still a lot of packages from this repository installed.  # zypper search --installed-only --repo Cinnamon Loading repository data... Reading installed packages...  S | Name                                 | Summary                  | Type    --+--------------------------------------+--------------------------+-------- i | cinnamon-control-center              | The Control Center for-> | package i | cinnamon-control-center-lang         | Languages for package -> | package i | cinnamon-desktop-lang                | Languages for package -> | package i | cinnamon-screensaver                 | Cinnamon screensaver a-> | package i | cinnamon-settings-daemon             | The settings Daemon fo-> | package i | cinnamon-settings-daemon-lang        | Languages for package -> | package i | cinnamon-themes                      | Default Cinnamon Themes  | package i | cinnamon-translations                | Translations for the C-> | package i | cjs                                  | Javascript module used-> | package i | gtk3-theme-vivagreen                 | openSUSE Cinnamon defa-> | package i | libcinnamon-control-center1          | Shared libraries for C-> | package i | libcinnamon-desktop4                 | Libcinnamon-desktop API  | package i | libcinnamon-menu-3-0                 | A menu system for the -> | package i | libcjs0                              | Shared Libraries for C-> | package i | libmuffin0                           | Muffin shared libraries  | package i | libnemo-extension1                   | Nemo extension shared -> | package i | nemo                                 | File browser for Cinna-> | package i | nemo-compare                         | Context Menu compariso-> | package i | nemo-dropbox                         | DropBox support for th-> | package i | nemo-emblems                         | Change a folder or fil-> | package i | nemo-fileroller                      | Fileroller support for-> | package i | nemo-gtkhash                         | Nemo extension for com-> | package i | nemo-image-converter                 | Nemo extension to mass-> | package i | nemo-media-columns                   | Nemo Media Columns       | package i | nemo-pastebin                        | Pastebin extension for-> | package i | nemo-preview                         | A quick previewer for -> | package i | nemo-python                          | Python bindings for th-> | package i | nemo-rabbitvcs                       | RabbitVCS extension fo-> | package i | nemo-repairer                        | Nemo extension for fil-> | package i | nemo-seahorse                        | OpenPGP encryption/dec-> | package i | nemo-share                           | Samba share extension -> | package i | nemo-terminal                        | Nemo extension to enab-> | package i | python-kaa-base                      | The Kaa Media Reposito-> | package i | python-kaa-metadata                  | The Kaa Media Reposito-> | package i | typelib-1_0-CinnamonDesktop-3_0      | Libcinnamon-desktop AP-> | package i | typelib-1_0-CinnamonMenu-3_0         | Libcinnamon-menu API --> | package i | typelib-1_0-CjsPrivate-1_0           | Cinnamon JS module -- -> | package i | typelib-1_0-MetaMuffin-0_0           | Muffin Introspection b-> | package i | typelib-1_0-Nemo-3_0                 | File Browser for Cinna-> | package i | wallpaper-cinnamon-branding-openSUSE | openSUSE Cinnamon defa-> | package   If I run # zypper rr Cinnamon those packages will be uninstalled? How should I proceed?  Thanks!


Simulate AR(1) process in R with specified nonzero mean and AR coefficient

I need to simulate an AR(1) process with the following equation in R:   $$ X_{t} = 5 + 0.5X_{t-1}+Z_t $$  Where $Z_t$ ~ White Noise(0,1) and $T=500$.  I know I should be using the arima.sim function from the forecast package with parameters n = 500 and ar = c(0.5) but I do not know how to account for the $ \delta = 5$ or the fact that $Z_t$ is white noise with mean 0 and sd 1. I have been unable to find clear documentation on how to do this.


Random variables $X$ and $Y$ are independent and have density $f_x(x)$ and $f_y(x)$:  $f_x(x)=4x^2e^{-2x}\mathbb{1}_{x>0}$  $f_y(x)=\frac{8}{3}x^3e^{-2x}\mathbb{1}_{x>0}$.  Calculate $Var(\frac{X}{X+Y})$ I tried to find density for $\frac{X}{X+Y}$, but from changing of variables I have $T(X,Y)=(\frac{X}{X+Y},Y)$. Jacobian of $T^{-1}(X,Y)$ is complicated and maybe someone can do it easier? Thanks in advance.


Let $\alpha (t)$ be a curve such that $|\alpha'(t)|=1$ for all $t\in\mathbb R$. Assume $k(t)\neq 0$, $k'(t)\neq 0$ (whereas $k=|\alpha''(t)|$ is the curvature) and $\tau(s)\neq 0$, whereas $\tau$ is the torsion.  Prove: The trace of $\alpha$ lies on a sphere $\Leftrightarrow$ $\frac{1}{k^2} +\frac{1}{(k'\cdot\tau)^2}=$const.$>0$.  I know this somehow works by using the Frenet-Serret-equations, but I don't really know how to do this proof. Can anyone help me out? Thanks!


“serious errors while checking the disk drives for /boot” error while booting

When I try to install ubuntu 14.04 I get this error after installing the system and trying to boot for the first time. I saw this article   But, it does not helped me. I cannot boot ubuntu. I'm installing it into my Windows 8.1.  No matter witch option i choose ( (I to ignore, S to skip mounting or M for manual recovery)), cannot boot. Any solution to this ?


Python's logging module not working with ArcPy

I have a Python script imported to an Arc toolbox. It uses Python's logging module for message recording.  import logging import time import os, sys import arcpy  logging.basicConfig(filename='log.log', format='%(levelname)s - %(asctime)s: %(message)s', datefmt='%d/%m/%Y %I:%M:%S %p', filemode='w', level=logging.DEBUG)   When run as a standart Python file it created the log file successfully. However, when I ran it from the Toolbox in ArcMap, the log file was not created. It seems logging is not working with ArcPy. Any idea?


I'll make this short and hopefully I make sense.   Im trying to give a user ssh access, but, he/she must only be able to access /opt and the few subdirectories that live under it. However, here's where it gets tricky, I understand that if they are chrooted in /opt the other directories in there that aren't owned by root wont be accessible. That's a problem for me cause living inside there is /opt/Pentaho which you guessed it, is owned by the pentaho user and when you chown root:root that directory brings our Pentaho app to a grinding halt obviously. SO, is there a way for me to restrict an SSH user to /opt and be able to read and write files within the /opt/Pentaho directory or have I just lost my mind? Any insight would be great, thanks!


What's a word for a positive kind of "envy" without the sense of resentment?

Imagine your college buddy is now running a multi-billion dollar company, while you're still stuck at the same white-collar day job 5 years after graduation. You chat with him and want to express the idea that you're happy for him and fancy having his lifestyle--something like "I wish I could buy a yacht and cruise around the world like you do; I'm glad you're doing really well!"  Basically, it's the feeling of envy when you take out the resentment from it. Is there a word for it?   (I thought about "admire", but found it too strong and broad)


My work uses a locked down DNS to control web browsing.  I get around this by specifying the DNS as 8.8.8.8 and 8.8.4.4.  However, when doing so, I can't connect to my work email server.  Is there a way to set just Chrome to utilize the Google public DNS and allow all other applications to use the default DNS?


How can I disable or reassign the 'Windows' key?

Between Ctrl and Alt, modern keyboards have an abominable key: the 'Windows' key :P    By default, when this key is pressed alone it opens the Start menu. Many applications and a great number of games work in fullscreen mode, and if you press this key accidentally, most of times because you wanted to press the Ctrl or Alt keys, the application usually freezes for a while and  minimizes itself. If you are lucky, your videogame will pause, but sometimes it continues even when it is minimized.  Is it possible to disable the 'Windows' key?  It would be possible to show the Start menu with another combination of keys? I would like to keep combinations that use the Windows key working, like Windows+L, which leaves current session.


Say I've got a thin plate, like a cylinder, that's only 1mm thick - i.e. a disc. I want to bevel the edge all the way around. Whenever I use the bevel tool, it puts the initial slice proportional to the depth of the surfaces. So, the "plate" surface that's get 90% of the bevel while the "edges" that are only .1mm wide get only 10% (making an angle of about 80deg). I want the same bevel on both surfaces - i.e. the initial cut is at 45deg, not 80 ,so that he bevel is a smooth arc of constant curvature. It doesn't seem to matter how I play with the popup setting: width or profile, it always stays at that 90/10 ratio. Alternately, is there a simpler way of just rounding thin "edges"? (My actual shape is more complex than just a cylinder, so any solutions can't be too generic. As long as I can select the edges or faces I want to bevel, and by how much.)


SSH into multiple remote machines through ssh tunnel

I am new to ssh-tunneling.  Basically I want to be able to get ssh access to servers in a remote lab (say subnet 1.2.3.X).  I can log into a machine that is visible say 11.22.33.44  I want to be able to log into machines in 1.2.3.X subnet through ssh tunneling, but I am not sure what exactly needs to be done.  Logging into the machines through the machine I can already log into is an option, but I have my development files on my local pc. So I wanted to use the ssh-tunneling.


How can we prove that a binomial coefficient $n\choose m$is divisible by the ratio of $n$ and $\gcd(n,m)$?

Prove that for every $n\geq m \geq1$ natural numbers, the following number is an integer:  $${\gcd(n,m)\over n}\cdot{n\choose m}$$  Where $\gcd$ is the greatest common divisor.  I tried to make it simpler by cancelling the $n$ from the left side, and making it $(n-1)!$ on the right: $\gcd(n, m) \cdot \frac{(n-1)!}{m!(n-m)!}$, but can't really go further.   This was problem B-2 on the .


Is there a timeframe that needs to pass before you can get shot with a zat gun again without dying?

So right now I'm up to season 6 in Stargate SG1, and I've noticed the main crew gets zapped with a  A LOT. Shouldn't they be dead by now? I thought the second shot kills and the third causes the body to disappear. Did this change somewhere? Is there a period of time where if you don't get shot it wont kill you?