I've been a Stack Exchange contributor for a couple of years now, currently most active on . One thing that keeps coming up is questions that would appeal to audiences on two different Stack Exchange sites but there are almost no features taking advantage of these questions. On travel.SE we have crossover questions most often with  and possibly next most often with  - but it can happen with almost any SE site. Today alone we had  with  and  had . I am absolutely sure that this must happen all the time between arbitrary pairs of Stack Exchange sites but the only feature that takes advantage of it is the possibility of migrating off-topic questions which leaves the original question acting as a redirect across the two sites. I think there is a missed opportunity to build the network between sites where users of one site don't realize they could make valuable contributions to a sister site they have had so far little to do with. At the very least there could be a way to "advertise" a question on a second site that could be interested in it. Probably by listing it in the sidebar where there are also links to meta questions, linked questions, related questions, new blog posts, and But there could also be some kind of features that make some sort of acceptable crossposting. There could be gamification/badges added around building cross-site questions or whatever else you can think up. I think this is a great way for people to spread their expertise from their main site onto other sites, to make the network stronger and more cohesive, to bring more attention to questions that would have a divided audience between two sites. I can think only of positives and no negatives. Does anyone else have some ideas to add or think this is a bad idea for any reason?  Example crossover questions: Here are some links to some crossover questions I've been finding in the Stack Exchange network here. (This was previously posted as an answer, but more people wanted it to be part of the question.)   ▶  :   ▶  :   ▶  :   ▶  :   ▶  :   ▶  :   ▶  :   ▶  :   ▶  :   ▶  :   ▶  :   ▶  :   ▶  :

There is much overlap between the SO, SF and SU sites.  For instance, questions about shell programming are programming related (since they are about programming), about system administration (because they manage the shell) and for single users too, if they want to script their computer.    I suggest allowing questions that overlap sites to be posted to more than one site simultaneously in order to:   avoid duplication between sites get answers from all 3 communities.   I suggest that the answers be visible on all relevant sites, and that any votes apply to all relevant sites.  Edit:  For instance, questions about VIM have appeared in SO (637/222780 questions) and in SF (17/8142 questions).  VIM is a valuable tool for programmers as well as sysadmins.  Where do such questions belong?  I didn't review all the questions in SO but the ones in SF could easily be in SO as well.  How about Perl?  9/8142 on SF and 1772/222780 on SO.  If you're a sysadmin but not a programmer, Perl is most certainly relevant.  These are two cases where there is overlap.  I'm sure there are many more.  Edit: Here are some good examples of questions on SU that are relevant to SF and SO as well:       Edit: Here's another example of such concerns:


I'm not sure where or when I read this.  Probably 1980s or 1990s, but it might have been a magazine or an anthology. The story is set on a post-technological (fallen) world where technological advancement is blocked by an unexplained invisible aura that might be called "shadow."  The aura, which makes people sick, will grow on anything made, but the more artificial it is, the faster the aura grows and the stronger it becomes.  If I'm recalling the back story properly, a colony starship landed, but before they could accomplish anything the entire ship was enveloped, and the colonists had to flee with essentially the clothes on their back.  Generations later, there is a society existing at approximately mediaeval level; they haven't lost all knowledge, but can't use anything more advanced than simple hand-worked metal tools. The protagonist is one of a special guild who fight these auras.  Because he is specially sensitive, he sees the auras as a dark haze around objects, and can easily identify them and tell how strong they are.  He travels from town to town, destroying the auras on people's tools so they can keep using them.  He does this by a psychic effort, fighting the aura into submission; it is very draining and he can only do so much in a day.  I remember a mention of how fighting the aura means taking some of the darkness into yourself, which affects his mental state and maybe his health. In one town he becomes alarmed when he finds they have far too much metal for one of his guild to keep the auras under control.  He is introduced to someone who claims to have a new way to fight them, which I recall as "mindlight."  Instead of dominating the dark aura, this person creates a brightness that drives it away.  When this is demonstrated, the protagonist is temporarily blinded; his connection to the aura has made him sensitive to the brightness too. I'm not sure where the story went after that; I recall one more scene but it may have been from a sequel. In this scene an enemy has managed to create a large number of swords and is threatening to conquer a town.  The swords are stored in a tent in barrels so the people who drive away the auras can keep them clear, and the protagonist's side sneaks in and dumps a huge amount of powdered metal all over everything.  Because of mindlight they can manufacture it, but the other side with the traditional way of dealing with auras is overwhelmed.  (The resulting aura was bigger than the tent and visibly expanding as they snuck away.)

Plot Summary/Details  As best I can remember, the setting for this one was contemporary Earth, or a human off-world colony with contemporary technology. Whatever the exact location, there are creatures of shadow that present a threat to the world.  I can't remember if they are undead creatures, or alien beings, or if their true nature is unknown.  I also can't remember exactly what harm they can do to people.  What I do remember for certain is that the protagonist is of a particular occupation/class that fights these shadows to protect the rest of society.  The method by which the protagonist and his fellows battle the shadows is something of a psychic duel.  The protagonist enters a house, and reaches out mentally against the shadow.  The two entities become locked in a mental struggle, with the task of the protagonist to be able to out-darkness the creature of darkness.  Something like that.   If successful, the shadow is dispelled, and the weary shadow fighter emerges victorious.  The cost of victory, however, is quite high.  The protagonist talks at length the strain of going into the darkness, and the toll fighting shadows takes on a human being.  He and his kind age and become "burned out" far sooner than a human being otherwise would.  Eventually, a shadow-fighter becomes too weak to fight on against the darkness. I think the protagonist is nearing the end of his ability to fight, but is not quite finished yet.  About mid-story, the protagonist encounters a man and several followers.  They claim to have found a new way to destroy the shadows.  The protagonist wearily dismisses the man and his group.  For generations, alternative approaches have been proposed and tried.  Some come from well-meaning fools, while others are snake-oil propositions from con-men.  All, however, have failed.  There is only one way to destroy a shadow, and that is the grueling, debilitating method the protagonist uses.  The story's final act comes when the new man and his followers join hands in a circle.  I believe they do so around and infested house.  They channel positive emotions or something like that.  There is a flash of light, and the darkness from this infested house is gone.   The new method worked, and it did so without any harm or ill-effect to the man or his followers.  The story closes with the protagonist realizing that his entire life has been spent sacrificing himself, his youth, and his vitality.  And now, he and his ways are completely obsolete.  Timeframe of Publication  Not really sure.  I'd say 1980's or earlier.  I think I read it in a sci-fi mag, rather than an anthology of some sort.


I'm trying to allow Root login on my ubuntu server but it just doesn't work. I tried googling for a while now and I only see things like "Set PermitRootLogin yes" but I tried that, saved and restarted and it still didn't work. Keep getting a "Permission denied, please try again". The password is 1234 (temporary) and I don't think I miss typed that this often.   I tried PermitRootLogin yes, UsePAM no, commented things out like StrictMode etc.  I am also able to login as root when I'm doing it on the ubuntu server itself.   Here is my sshd_config  # Package generated configuration file # See the sshd_config(5) manpage for details  # What ports, IPs and protocols we listen for Port 22 # Use these options to restrict which interfaces/protocols sshd will bind to #ListenAddress :: #ListenAddress 0.0.0.0 Protocol 2 # HostKeys for protocol version 2 HostKey /etc/ssh/ssh_host_rsa_key HostKey /etc/ssh/ssh_host_dsa_key HostKey /etc/ssh/ssh_host_ecdsa_key HostKey /etc/ssh/ssh_host_ed25519_key #Privilege Separation is turned on for security UsePrivilegeSeparation yes  # Lifetime and size of ephemeral version 1 server key KeyRegenerationInterval 3600 ServerKeyBits 1024  # Logging SyslogFacility AUTH LogLevel INFO  # Authentication: LoginGraceTime 120 PermitRootLogin yes #StrictModes yes  RSAAuthentication yes PubkeyAuthentication yes #AuthorizedKeysFile %h/.ssh/authorized_keys  # Don't read the user's ~/.rhosts and ~/.shosts files IgnoreRhosts yes # For this to work you will also need host keys in /etc/ssh_known_hosts RhostsRSAAuthentication no # similar for protocol version 2 HostbasedAuthentication no # Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication #IgnoreUserKnownHosts yes  # To enable empty passwords, change to yes (NOT RECOMMENDED) PermitEmptyPasswords no  # Change to yes to enable challenge-response passwords (beware issues with # some PAM modules and threads) ChallengeResponseAuthentication no  # Change to no to disable tunnelled clear text passwords #PasswordAuthentication yes  # Kerberos options #KerberosAuthentication no #KerberosGetAFSToken no #KerberosOrLocalPasswd yes #KerberosTicketCleanup yes  # GSSAPI options #GSSAPIAuthentication no #GSSAPICleanupCredentials yes  X11Forwarding yes X11DisplayOffset 10 PrintMotd no PrintLastLog yes TCPKeepAlive yes #UseLogin no  #MaxStartups 10:30:60 #Banner /etc/issue.net  # Allow client to pass locale environment variables AcceptEnv LANG LC_*  Subsystem sftp /usr/lib/openssh/sftp-server  # Set this to 'yes' to enable PAM authentication, account processing, # and session processing. If this is enabled, PAM authentication will # be allowed through the ChallengeResponseAuthentication and # PasswordAuthentication.  Depending on your PAM configuration, # PAM authentication via ChallengeResponseAuthentication may bypass # the setting of "PermitRootLogin without-password". # If you just want the PAM account and session checks to run without # PAM authentication, then enable this but set PasswordAuthentication # and ChallengeResponseAuthentication to 'no'. UsePAM yes   Any ideas on what else I could try?  EDIT: auth.log:  Dec  8 17:01:41 Testumgebung-Ubuntu login[1554]: ROOT LOGIN  on '/dev/tty1'  Dec  8 17:01:56 Testumgebung-Ubuntu sshd[1568]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=10.211.55.2  user=root  Dec  8 17:01:57 Testumgebung-Ubuntu sshd[1568]: Failed password for root from 10.211.55.2 port 58058 ssh2  Dec  8 17:02:12 Testumgebung-Ubuntu sshd[1571]: Accepted password for seb from 10.211.55.2 port 58060 ssh2   First message is from succesfull login on the ubuntu system, last one is login with user seb via sftp

I´d like to enable the ssh root access on Ubuntu 14.04. Editing the /etc/ssh_config (PermitRootLogin yes) didn't affect anything.


I have been working at this for easily 15 hours now and nothing works. First I had linux installed and I wanted to install windows as a dual boot, which took 8 hours because of all the issues. It finally worked but I had windows as UEFI and Linux as Legacy. So I followed multiple websites on how to convert linux to UEFI and nothing worked so I thought, hey maybe I'll reformat all the drives that I have Linux on and just do a fresh restart. Well in order to create a UEFI boot loader I have to switch legacy mode off in my bios. However anytime I try to run my USB drive with Ubuntu loaded in UEFI mode, I get multiple errors saying, ACPI BIOS error (bug) Faliure creating named object[_SB.PCI0.XC.RHUB.8809._UPC], AE_ALREADY_EXISTS, During name lookup/catalog (2019086/psob.ject-220) Over and over again along with weird colored lines streaking all across the black background and it just sits there. I tried loading it up many times, I made multiple ISO. files on multiple flash drives with different tools and trying GPT, FAT32 etc and nothing works. Now I have no linux and a slow working windows 10 on my HDD and my SSD is empty waiting for linux to get reinstalled. Please help! I don't care what I have to delete I just want this working. Thank you!

This question is asked often in Ask Ubuntu, sometimes with few hints about the situation.   Please provide a list of possible reasons to help troubleshoot the problem.


Have a simple form including few of the input elements that should show up the data (based on the input) on tableselect (part of the same form) through the ajax callback functionality.  //submit button     $form['action'] = [     '#type' => 'button',     '#value' => $this->t('Submit'),     '#ajax' => [     'callback' => '::setMessage',     'prevent' => 'click',     'wrapper' => 'scrollable',     'method' => 'replace',     'effect' => 'fade',      ],     '#suffix' => '

',     ];   and within my ajax callback function:  public function setMessage(array $form, FormStateInterface $form_state) {      $options = array();       $header = [        'subject_id' => t('Subject ID'),        'ct_availability' => t('CT Availability'),        'sex' => t('Sex'),        'race' => t('Race'),        'cardiovascular_disease' => t('Cardiovascular Disease'),        'registration_age' => t('Registration_Age'),         ];      $options = $this->getOptions(); //getting the associative array          dpm($options);  //printing to make sure that the array is filled  //assigning to the table     $form['table']['#header'] = $header;     $form['table']['#options'] = $options;     return $form['table']; }   The header gets assigned fine and the table is displayed only with it. The data doesn't get filled and it seems the #options does not get assigned to the tableselect thus showing no data.    There are no ajax errors from the console  Wondering if it has something to do with 'processTableselect' function or rebuilding the form before returning the table element?  Or if it is a wrong approach to assign form element attributes within the callback function?

I'm trying to add AJAX callback to form element that was previously rendered by AJAX but with no luck. Code below.   A bit of description. There are three main methods here:   buildForm - base form extraField - AJAX callback attached to ['month'] choosePerson - AJAX callback attached to: ['week_day']['hour']   In the buildForm method I create base form with AJAX callback on 'month' select element. In the AJAX callback you can find an extraField method. This method contains form element called 'hour' ($form['week_day']['hour']) and this element renders well. But this element also contains AJAX callback, which doesn't work, it does not generate 'person_container' element and the 'person' select.   Any idea how to ajaxify elements that previously were rendered by ajax?  class ReservationForm extends FormBase {    public function getFormId() {     return 'reservation_form';   }    public function buildForm(array $form, FormStateInterface $form_state) {      $form['month'] = array(       '#type' => 'select',       '#title' => $this->t('Select month'),       '#options' => array($this->t('January'), $this->t('February'), $this->t('March')),       '#ajax' => array(         'callback' => array($this, 'extraField'),         'event' => 'change',         'wrapper' => 'week-day',       ),     );      // Disable caching on this form.     $form_state->setCached(FALSE);      $form['week_day'] = [       '#type' => 'container',       '#attributes' => ['id' => 'week-day'],     ];   }    public function extraField(array &$form, FormStateInterface $form_state) {     $month = $form_state->getValue('month');      $hour_options = array();      if ($month == '0') {       $hour_options[0] = $this->t('08:00');       $hour_options[1] = $this->t('09:00');       $hour_options[2] = $this->t('10:00');     }      if ($month == '1') {       $hour_options[0] = $this->t('12:00');       $hour_options[1] = $this->t('13:00');       $hour_options[2] = $this->t('14:00');     }      if ($month == '2') {       $hour_options[0] = $this->t('18:00');       $hour_options[1] = $this->t('19:00');       $hour_options[2] = $this->t('20:00');     }      $form['week_day']['hour'] = array(       '#type' => 'select',       '#title' => $this->t('Choose hours @month', array('@month' => $month)),       '#options' => $hour_options,       '#ajax' => array(         // tried with that callback too: [ $this, 'choosePerson']         'callback' => array($this, 'choosePerson'),         'event' => 'change',         'wrapper' => 'person',       ),     );      $form['week_day']['person_container'] = array(       '#type' => 'container',       '#attributes' => ['id' => 'person-container'],     );      $form['week_day']['person_container']['person'] = array(       '#type' => 'select',       '#title' => $this->t('Choose person'),       '#options' => ['John', 'Sarah', 'Peter'],     );      return $form['week_day'];   }    public function choosePerson(array &$form, FormStateInterface $form_state) {     $form['week_day']['person_container']['person'] = array(       '#type' => 'select',       '#title' => $this->t('Choose person'),       '#options' => ['John', 'Sarah', 'Peter'],     );     return $form['week_day']['person_container'];   } }


I'm creating a Python3 program that generates SVG images with random circles that I need for a personal project. Right now the program works perfectly, but I'd like to fine-tune some parameters to produce the best results possible. My idea is to have a display window that shows the intermediate result and an interactive shell to change some of the values that generate the position of the circles, without having to create thousands of different images and compare them. When I finish I can simply save the result. And here comes the problem: I don't really know how to achieve this result. I first thought of using Matplotlib, which is usually perfect for these kind of tasks, but it doesn't seem to be able to read SVG files. I also thought of drawing circles directly into a plot, but some of them have to be blurred (Gaussian blur filter in the SVG file), and Matplotlib doesn't seem to be able to blur shapes. Finally I looked for something else able to display either an SVG file or directly the text the program produces to generate the SVG file, but with no luck. Edit: I just tried CairoSVG to convert the SVG file to PNG. It works, but it doesn't support Gaussian blur, so it's a suboptimal solution. I can accept a solution that involves converting the SVG file to PNG or some other format, but I'd like it to support at least Gaussian blur, otherwise I can simply draw every circle with Matplotlib. Thanks in advance for the help!

In a  application, I would like to render resolution-free GUI widgets described in SVG.  What tool and/or library can I use to reach this goal ?  (I like the  toolkit but it seems to be bitmap dependent for its rendering)


Is there a single word for someone who only spends time doing things they like, and shirk their important duties? I am trying to describe Mr. Frederick from Animal Farm, who had "a large, neglected, old-fashioned farm, much overgrown by woodland, with all is pastures worn out and its hedges in a disgraceful condition." It is implied that the farm has gone to such a state because he "spent most of his time in fishing or hunting". I can't think of the right word to describe this, and I'm not even positive there is one. I also want something that emphasizes doing something you enjoy in place of work that needs to get done.

I am looking for one word to describe someone who always does what he loves.   Loving means enjoying something very much, free-spirited means not restrained by convention. Is there a hybrid word?   I mean a word that describes someone who is independent and always does what he loves. Please also try to not make the word too esoteric. Also, the word needs to be positive.  How will it be used?  I am submitting an application for college, and they require me to supply a word to describe myself. I have always done what I love. So, I require a word to describe someone who loves what they want. There is no sentence, in particular, just a prompt asking me to describe myself in one word.


I know the moment of inertia of a filled sphere is $(2/5) Mr^2$. How do you show the moment of inertia of a hollow sphere is $(2/3) Mr^2$?

I've been trying to compute the moment of inertia of a uniform hollow sphere (thin walled) wrt the centre, but I'm not quite sure what was wrong with my initial attempt (I've come to the correct answer now with a different method). Ok, here was my first method:  Consider a uniform hollow sphere of radius $R$ and mass $M$. On the hollow sphere, consider a concentric ring of radius $r$ and thickness $\text{d}x$. The mass of the ring is therefore $\text{d}m = \frac{M}{4\pi R^2}\cdot 2\pi r\cdot\text{d}x$. Now, use $r^2 = R^2 - x^2:$ $$\text{d}m = \frac{M}{4\pi R^2}\cdot 2\pi \left(R^2 - x^2 \right)^{1/2}\text{d}x$$ and the moment of inertia of a ring wrt the centre is $I = MR^2$, therefore: $$\text{d}I = \text{d}m\cdot r^2 = \frac{M}{4\pi R^2}\cdot 2\pi\left(R^2 - x^2\right)^{3/2}\text{d}x $$ Integrating to get the total moment of inertia: $$I = \int_{-R}^{R} \frac{M}{4\pi R^2} \cdot 2\pi\cdot \left(R^2 - x^2\right)^{3/2}\ \text{d}x = \frac{3MR^2 \pi}{16}$$  which obviously isn't correct as the real moment of inertia wrt the centre is $\frac{2MR^2}{3}$.   What was wrong with this method? Was it how I constructed the element? Any help would be appreciated, thanks very much.


strace can monitor only one single processes not all, lsof is not a good way too, it's not a real time tool, maybe I need a real time version of lsof? How to list all the processes which have accessed a particular file?

Is there any way in unix to find out who accessed certain file in last 1 week? It may be user or some script ftp it to some other place. Can I get a list of user name who accessed certain file? How can I find out who is accessing particular file??


Is it possible to have Latex automatically insert a \newline when it encounters a blank line of text? I find putting \newline's everywhere tends to make my text unreadable.

I would like to have my whole document showing a blank line (or space) between paragraphs and no indentation. I know how to do it line by line, but is there a way to change that with just one or a few lines at the beginning of the document? Like a package you can install, or a new command?


I am hoping someone may know this book based upon the plot:  An advanced race visits a planet that is technologically equivalent to the dark ages.  To interact with the inhabitants these visitors allow them to think they are magical.  In particular the daughter of one of the visitors has to pretend to be a magical sorceress. The planet is then also visited by an Earth ship that is not as advanced as the first set of visitors.  Their goal is to deal with the inhabitants for natural resources.  The advanced visitors try to prevent the Earth people from exploiting the planet while remaining unknown to the Earth people.    The story switches between 3 different points of views:   The daughter of the advanced visitors as she pretends to be the magical sorceress A peasant boy who interacts with the "sorceress" and becomes somewhat infatuated with her An earthman who is trying to obtain the deal for the natural resources of the planet.

I'm looking for the name and author of a novel (or possibly novella). I first read this in the seventies, and might be older than that. It might have been written for teenagers.  The story takes place on a planet inhabited by a primitive humanoid race, roughly stone age if I remember rightly. Visiting this planet is a small team from a more advanced race, also humanoid and with spacefaring technology (obviously!). They are either there to help or observe, no nefarious purposes. I think they are avoiding contact with the primitives, at least initially. It's explicitly mentioned that the planet they are visiting is the third one of a medium sized star, just like their own homeworld. Also orbiting round the planet is an even more advanced race, using high tech to remain hidden from both the others. They are observing the whole situation, and again its mentioned that this is a 'third planet', like their own homeworld.  I'm a little bit hazy on the rest of the plot, but I think the super-advanced race end up revealing themselves, even though they are not supposed to.  The story is told from the viewpoints of both the second and third races (maybe also the first, I forget)  EDIT: For the record it turns out my recollection was faulty, and the second race are indeed coming to the planet for nefarious purposes. And the planet is at the medieval stage, not stone age.


Usually in quantum optics, one uses the polarization degree of freedom of the photon to create and manipulate photonic qubits. This, using various linear optics devices, can be coupled with the 'path degree of freedom' inside an interferometer for instance. So far, that makes two 'available' degrees of freedom to store quantum information as qubits.  But what else can we use in photons ? One can immediately discard the angular momentum degree of freedom, since this is just the left or right circular polarization state.  Maybe the wavelength ? But how could it be used, ie how could you create and manipulate quantum superpositions of wavelength states ?  I try to think of others, but I quite lack of imagination and experience in this field.  Thanks in advance,

How many types of qubit encoding on photons exist nowadays? I know only two:   Encoding on polarization: $$ \lvert \Psi \rangle = \alpha \lvert H \rangle + \beta \lvert V \rangle $$ $$ \lvert H \rangle = \int_{-\infty}^{\infty} d\mathbf{k}\ f(\mathbf{k}) e^{-iw_k t} \hat{a}^\dagger_{H}(\mathbf{k}) \lvert 0 \rangle_\text{Vacuum} $$ $$ \lvert V \rangle = \int_{-\infty}^{\infty} d\mathbf{k}\ f(\mathbf{k}) e^{-iw_k t} \hat{a}^\dagger_{V}(\mathbf{k}) \lvert 0 \rangle_\text{Vacuum} $$ Time-bin: $$ \lvert \Psi \rangle = \alpha \lvert 0 \rangle + \beta \lvert 1 \rangle $$ $$ \lvert 0 \rangle = \int_{-\infty}^{\infty} dz\ f\left(\frac{t -z/c}{\delta t_{ph}}\right) e^{-i w_0 (t-z/c)} \hat{a}^\dagger(z) \lvert 0 \rangle_\text{Vacuum} $$ $$ \lvert 1 \rangle = \int_{-\infty}^{\infty} dz\ f\left(\frac{t -z/c+\tau}{\delta t_{ph}}\right) e^{-i w_0 (t-z/c+\tau)} \hat{a}^\dagger(z) \lvert 0 \rangle_\text{Vacuum} $$   Is there anything else?


Visual Studio default implementation for GetHashCode():  class Animal {     public int Id { get; set; }      public override int GetHashCode()     {         return 2108858624 + Id.GetHashCode();     } }   Why "2108858624" is added to Id for GetHashCode compute?  Video: (Gif)

In .NET, the  is used in a lot of places throughout the .NET base class libraries. Implementing it properly is especially important to find items quickly in a collection or when determining equality.  Is there a standard algorithm or best practice on how to implement GetHashCode for my custom classes so I don't degrade performance?


While comparing the content of sms with text, it's not working. Can any one please help me solve this? Here I want the count of a and b based on sms content. If sms content is a, it will give count 1. If another sms also has content a, then count must be incremented to 1 i.e., 2. Below is my code:      package com.example.sms;      import java.util.ArrayList;      import android.app.Activity;     import android.database.Cursor;     import android.net.Uri;     import android.os.Bundle;     import android.widget.TextView;      public class Sms extends Activity {     int count=0;     int count1=0;        @Override       public void onCreate(Bundle savedInstanceState) {           super.onCreate(savedInstanceState);           setContentView(R.layout.activity_sms);           TextView view1 = (TextView)findViewById(R.id.textview1);           TextView view2 = (TextView)findViewById(R.id.textView2);           Uri uriSMSURI = Uri.parse("content://sms/inbox");           Cursor cur = getContentResolver().query(uriSMSURI, null, null, null,null);           String sms = "";           String data = null;           while (cur.moveToNext()) {               sms =cur.getString(12);                    if(sms=="a"){                       count=count+1;                       view1.setText("a"+count+")");                   }                    else if(sms=="b"){                       count1=count1+1;                       view2.setText("a("+count+")");                   }                   else{                       //view1.setText("no data");                   }               //data.add(cur.getString(12));              // view1.setText(cur.getString(12));           }            //view1.setText(sms);           //setContentView(view);       }     }

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


I am planning on buying a headset for my pc and its either going to be the Razer Kraken Pro or the Razer Kraken 7.1. The thing is that the 7.1 is a usb headset has some software for mic calibrations and sound quality which cannot be run under linux. My question is this, is there similar software in linux to calibrate the 7.1 headset or should I go for the analog Kraken Pro? Thanks in advance!

This question is targeted at mainstream or gamer-grade software-based audio/sound enhancements, found in highly integrated computing and entertainment systems like laptops, tablets and smartphones.  These are mostly marketed with fancy badges of known audio-releated brands on the product or packaging, while being mostly uncertain about the actual implementation or components used and poorly differentiated from the general audio capabilities of the system or device.     This question is not about actual hardware like speakers. If your headphones are not properly detected, your speakers are assigned wrong, work partially or not at all then your soundcard or chip is not properly detected and you should take a look at .   Some subwoofers on laptops require proper LFE remixing, which is currently disabled in PulseAudio.  This question is also not about enthusiast or recording-grade hardware like recording interfaces, amplifiers and DACs in a variety of formfactors. And this question is also not about audio encoding and playback of different audio formats like Dolby Digital, Dolby TrueHD and DTS. Most of these may be subject to patents and licensing, .   If you are just searching for an equalizer, please take a look at this question:     Simply speaking: Every feature where you would flip a switch or check a box in a fancy looking interface in Windows that makes the sound change from neutral to fancy.


After installing Ubuntu 14.04 guest on VirtualBox running on a Max OSX host, I am stuck with 640x480 screen resolution. Adding guest additions again doesn't help. Previous Ubuntu installations are fine with bigger resolution. The 'Detect Displays' button on the 'Display Settings' Settings screen is not reachable, because 640x480 is too small. I could not find a /etc/X11/xorg.conf file to configure manually.

Environment: Lenovo T530 running Windows 7.  Have installed Ubuntu 14.04 on a virtual machine using VM Virtual Box.  Have installed all the updates from both Virtual Box and Ubuntu.  Problem: While in Ubuntu's desktop and other Ubuntu initiated programs, the window is reduced to about 3x4 inches showing in the middle of the rest of my regular Virtual Box window.  I am seeing only the upper right hand of the screen output of what I would normally see.  Please help.   I've seen    But, none of these answers works in 14.04.


I'm using screen command after ssh to a public remote machine with Ubuntu 14.04 so that I could continue my sessions whenever I want. I've found that some admins are tracking my command history and they have access to my screen sessions too. I know that I can clear my bash history commands by removing .bash_history file in my home directory but couldn't find a way to clear my screen sessions' command history too.

I want to clear all previous commands from the history of my server. I used history -c and it seems all things are cleared but when I ssh to the server, all the commands are still there.  How can I clear them permanently?


I have a laptop with a mysterious pop up add that starts in a seperate tab. It opens some add site called "wonderlandads" which then redirects to other sites. (Links    )  I've scanned my laptop with avast and also kaspersky's rootkit detection program and they both haven't found anything. Even tried running Lavasoft's Adaware but no help.   After that I uninstalled and reinstalled chrome itself. Still no solution.  Internet explorer on the same laptop does not face this issue. I have manually set the dns server's to Google's 8.8.8.8 and 8.8.4.4. Also set the IPv6 DNS to google's servers.   I've checked the hosts file and there's no entries in there. Searched the registry but couldn't find any entry for "wonderlandads". I've disabled all extensions within Chrome.   If I open an incognito window within  chrome then there this spam tab does not get invoked.   Any other tips? The Laptop is running Windows 8. What else can I do to debug this?  Update:  It seems I've temporarily fixed the problem. No more popups. My approach was to kill seemingly redundant chrome threads via the process explorer. One of them must have been the offending one. The solution sustains on hibernation. Now will see if it sustains a chrome restart & then a laptop reboot (doubt it).

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


What I did:  I browned some beef cubes and put them in the slow-cooker. I then added some spices (a lot of spices), tomato juice, olive oil and vinegar.  For all kinds of reason, I waited a total of over 2 hours since placing the meat in the slow-cooker (mostly covered) before turning it on.   I then turned it on high. I plan on cooking the food for at least 7 hours.  Is it safe?  Thank you!

If I left food out of the refrigerator for some period of time, is it still safe? If I left it out too long, can I salvage it by cooking it more?


In earlier editions of D&D some powerful creatures had a percentage magic resistance which was checked before any saving throw (if applicable). If the percentage check was successful then the spell simply didn't work.  I'm trying to convert the Dragonlance Draconians to 5e, but they had 20% magic resistance (and per the source materials this prevented Raistlin's sleep spell working on them).  Simply giving them advantage on saving throws won't work on magical effects without saving throws such as sleep, and ignoring the magic resistance completely in the conversion will significantly weaken the main antagonists (apart from dragons) in the Dragonlance Campaign.

How do spell/magic resistance and spell/magic immunity work?  Per the PHB (p. 197) rules on damage resistance:     If a creature or an object has resistance to a damage type, damage of that type is halved against it.   So perhaps spell resistance halves damage from spells. Does spell resistance confer protection against non-damaging effects? Does it help with saving throws against charms or web, for example? What about spell immunity?  Per the MM (p. 8) rules on vulnerabilities, resistances and immunities:     Some creatures have vulnerability, resistance, or immunity to certain types of damage... If a creature is immune to a game effect that isn't considered damage or a condition, it has a special trait.   This is a bit sparse.  Aside from the PHB rules above on damage resistance, I can't find any reference to immunities or resistances in the indices of the DMG, PHB, or MM.  EDIT: Following up on Oblivious Sage's comment below: a number of entries in the MM aside from the Tarrasque have "magic resistance" as an ability, notably more powerful devils, demons, angels, etc. These are consistently of the "Advantage on saving throws versus spells and other magical effects."


I just installed Ubuntu 20.04 onto a HP Stream Mini desktop and am unable to get wifi to work.  I've researched and find a lot of references to issues with Broadcom drivers but nothing that seems to work.  Read through this thread () but the suggested solutions didn't work.  The device appears:   lsspci -knn | grep Net -A2  04:00.0 Network controller [0280]: Broadcom Inc. and subsidiaries BCM43142 802.11b/g/n [14e4:4365] (rev 01)     Subsystem: Hewlett-Packard Company BCM43142 802.11b/g/n [103c:804a]     Kernel modules: bcma, wl   But nothing in the network settings except the wired connection. It's probably something pretty stupid but I can't find it.

I'm having serious problems installing the Broadcom drivers for Ubuntu. It worked perfectly on my previous version, but now, it is impossible.   What are the steps to install Broadcom wireless drivers for a BCM43xx card?  I'm a user with no advance knowledge in Linux, so I would need clear explanations on how to make, compile, etc.    lspci -vnn | grep Network showed:   Broadcom Corporation BCM4322 802.11a/b/g/n Wireless LAN Controller [14e4:432b]      iwconfig showed:  lo        no wireless extensions. eth0      no wireless extensions.   NOTE: Answer below is updated every time new information is added and confirmed working.


I had an old laptop hard disk which was containing 5 drives created in Windows 7. When that laptop was got complaint I picked the hard disk and started using it as external hard disk. Now when I try to access the drives using Ubuntu, it shows the following error message for all the drives. What to do?

I replaced a buggy Windows Vista installation with Ubuntu. All works fine except that the main HD where I had all my files are now inaccessible. Here is the error message I get:   Error mounting: mount exited with exit code 13: ntfs_attr_pread_i: ntfs_pread failed: Input/output error Failed to read NTFS $Bitmap: Input/output error NTFS is either inconsistent, or there is a hardware fault, or it's a SoftRAID/FakeRAID hardware. In the first case run chkdsk /f on Windows then reboot into Windows twice. The usage of the /f parameter is very important! If the device is a SoftRAID/FakeRAID then first activate it and mount a different device under the /dev/mapper/ directory, (e.g. /dev/mapper/nvidia_eahaabcc1). Please see the 'dmraid' documentation for more details   Is it necessarily a hardware problem? If not, is there a way to repair the HD from Ubuntu?


I have to show that the following group $$ (G, * , e) $$ with its operation $*$, which is defined through $ g*g = e$  for every $g \in G $ is an abelian group. In order to do that one have only to show that the group is commutative. How can one prove it whereas the operation is defined always between an Element and itself? I reckon it is not so simple as it seems Thanks in advance for your help :)

Prove that if $g^2=e$ for all $g$ in $G$ then $G$ is Abelian.   This question is from group theory in Abstract Algebra and no matter how many times my lecturer teaches it for some reason I can't seem to crack it.   (Please note that $e$ in the question is the group's identity.)  Here's my attempt though...  First I understand Abelian means that if $g_1$ and $g_2$ are elements of a group $G$ then they are Abelian if $g_1g_2=g_2g_1$...  So, I begin by trying to play around with the elements of the group based on their definition...  $$(g_2g_1)^r=e$$  $$(g_2g_1g_2g_2^{-1})^r=e$$ $$(g_2g_1g_2g_2^{-1}g_2g_1g_2g_2^{-1}...g_2g_1g_2g_2^{-1})=e$$  I assume that the $g_2^{-1}$'s and the $g_2$'s cancel out so that we end up with something like,  $$g_2(g_1g_2)^rg_2^{-1}=e$$ $$g_2^{-1}g_2(g_1g_2)^r=g_2^{-1}g_2$$  Then ultimately...  $$g_1g_2=e$$  I figure this is the answer. But I'm not totally sure. I always feel like I do too much in the pursuit of an answer when there's a simpler way.  Reference: Fraleigh p. 49 Question 4.38 in A First Course in Abstract Algebra.


I would like to align some statements so that it's more pleasing to the eye. I have the following code, where the first version the two statements are not aligned. I use \phantom to force alignment but this introduces necessary space. It would be nice to place some text within a specified maximum width, but I don't know if this is possible with LaTeX. This is the MWE:  \documentclass{article}  \usepackage[noend]{algpseudocode} \usepackage{algorithm} \usepackage{algorithmicx}  \newcommand*\Let[2]{\State #1 $\gets$ #2}   \begin{document}  \begin{algorithm}[!h]   \caption{Integration } \begin{minipage}{\textwidth}  \begin{algorithmic}  \Let{$\mathbf k$} {$ \mathbf k + j  \mathbf w \left[ i \right] \mathbf B $}  \Let{$\mathbf r $} {$ \mathbf r - j   \mathbf w \left[ i \right]  \mathbf B$} \end{algorithmic} \end{minipage} \end{algorithm}  \begin{algorithm}[!h]   \caption{Integration } \begin{minipage}{\textwidth}  \begin{algorithmic}  \Let{$\phantom{\mathbf{r}}\mathbf k$} {$ \phantom{\mathbf{r}} \mathbf k \phantom{-}+ j  \mathbf w \left[ i \right] \mathbf B $}  \Let{$\phantom{\mathbf{k}}\mathbf r $} {$ \phantom{\mathbf{k}} \mathbf r \phantom{+}- j   \mathbf w \left[ i \right]  \mathbf B$} \end{algorithmic} \end{minipage} \end{algorithm}  \end{document}   which produces

I don't like how there is often a slight misalignment between assignment statements in an algorithmic environment. For example, the first version of the algorithm given below looks strange to me. I would like to be able to align the two statements, but the commented version in my example fails to even compile. I could always manually add some space to make things line up (see the last version below), but this is obviously not a good way to go about doing things for a number of reasons. Does anyone have a good way of making the assignment statements to line up?  \documentclass{article}     \usepackage{algorithm}     \usepackage{algorithmicx}     \usepackage{amsmath}  \begin{document}  \begin{algorithm}     \caption{Compute some stuff}     \begin{algorithmic}         \State \( x \gets 1 \)         \State \( m \gets 2 \)     \end{algorithmic} \end{algorithm}  %\begin{algorithm} %   \caption{Compute some stuff} %   \begin{algorithmic} %       \begin{align*} %           x & \gets 1 \\ %           m & \gets 2 %       \end{align*} %   \end{algorithmic} %\end{algorithm}  \begin{algorithm}     \caption{Compute some stuff}     \begin{algorithmic}         \State \( \hspace{3pt} x \gets 1 \)         \State \( m \gets 2 \)     \end{algorithmic} \end{algorithm}  \end{document}


This is related to my .  Suppose I have the polynomial $p(x) = x^2 - 2 \in \Bbb Q[x]$. This is irreducible over $\Bbb Q$ so we need to move up to the extension field $K/\Bbb Q = \Bbb Q(\sqrt{2})$. Now $p$ splits over $K$ into $(x - \sqrt{2})(x+\sqrt{2})$ and it can be shown that the Galois Group $\operatorname{Gal}(K/\Bbb Q) \cong \Bbb Z/2\Bbb Z$ since it contains only the identity automorphism and one involution that sends $\sqrt 2$ to its conjugate $-\sqrt 2$.   My question is this; what if I have a polynomial with ugly roots? Say, for instance,  $$p(x) = x^5 - x^3 - 2x^2 - 2x - 1$$  This was shown in my previous question to be irreducible over $\Bbb Q$ so the splitting field of $p$ is simply $\Bbb Q$ adjoin the roots of $p$. These roots are, however,   $$\alpha \approx 1.73469\ \ \ \beta \approx 0.79645e^{0.49411\pi i}\ \ \ \gamma \approx 0.9533e^{5.6494\pi i}$$  and the conjugates $\overline \beta, \overline \gamma$ (do we get the conjugates for free when we adjoin complex roots or do we explicitly have to adjoin them?).  Then the splitting field $F$ of $p$ is $\Bbb Q(\alpha, \beta, \gamma)$ and their conjugates (depending on the answer to the question just asked).  At this point I'm not sure where to go; I've been trying to list automorphisms that fix $\Bbb Q$, obviously the identity is included, it seems also that the autmorphisms  $$\varphi_1 : \begin{cases} \beta \to \overline \beta \\ \gamma \to \gamma \end{cases}\ \ \ \text{and}\ \ \ \varphi_2 : \begin{cases} \beta \to \beta\\ \gamma \to \overline \gamma \end{cases}$$  are in the galois group. Also, $\varphi_2 \circ \varphi_1 = \psi$ should be in the group and this sends both $\beta$ and $\gamma$ to their conjugates. Any composition of $\psi$ with either of the others I've listed gives the other. I'm stuck for finding more now though. Since conjugation is an involution automorphism these are self inverse.   I'm not sure where to go from here! Is what I've done thus far even correct or have I totally misunderstood the concepts I'm trying to understand here?

I've been learning about Galois theory recently on my own, and I've been trying to solve tests from my university. Even though I understand all the theorems, I  seem to be having some trouble with the technical stuff. A specific example would be how to find the Galois group of a given polynomial. I know some tricks, and I manage to solve some of those questions, but some not.  For example, one of the tests asks to find the Galois group of $x^{4}-4x+2$.  I can see that it is irreducible over $\mathbb Q$ (Eisenstein), but I have no clue as to how to find its Galois group over $\mathbb Q$. Can someone tell me how to do this? General techniques concerning this sort of problems are also welcome :).  Thanks!


I applied to a professional program that I had been striving for in my undergrad, at a top school, but I've since felt overwhelmed with how to pay for it and incurring so much debt. I think I should wait a year so get into a better place financially. I've become so anxious, thinking I've ruined my opportunity with this school if I don't go.  I am considering withdrawing my application, but I'm very worried about how it might hurt me in the future when I reapply. Or I may wait but need to decline if I am accepted, and reapply the following year. I feel like both will hurt my chances in the future. How will admissions consider me the second time?

I applied to a program that I had been striving for in my undergrad, at a top school, but I've since felt overwhelmed with the thought of going this year. I think I should have waited until I was absolutely sure I could handle grad school emotionally and financially. I am so anxious now, thinking I've ruined my opportunity with this school if I don't go.   I am seriously considering withdrawing my application, but I'm very worried about how it might hurt me in the future when I reapply.  Otherwise I may have to decline if I am accepted and reapply.


I've installed two programs (teamviewer and filezilla) so far that the resolution is just too small. How can I fix this? Picture below shows what I'm talking about.   Ubuntu 14.04 LTS on a Dell XPS 13.     My issue is only happening on certain programs -> teamviewer and filezilla so far. Everything else is the correct size. The post that was linked looks to be for a system wide issue for all programs.

How can I adapt Ubuntu to a high resolution display?  I have a display with 3200x1600px on only 11'' and everything looks really tiny.


I have created the field set as External Id and now I am changing the field to set as unique record identifier, I am not able to change, because Records exist already with duplicate values for that field.   So I want to query all the duplicate records. How do I perform a query to display the duplicate values for that particular field in test sandbox?   Then I will delete all the fields which contains duplicate External Ids, then I can change the field to Unique. Please anyone Guide me how to write a Query for Displaying the Duplicate Record Ids.

I have an external system that needs to update a record in my org. This system only knows the external id, but the problem is that this external id is not unique, e.g. multiple records might have the  external id. Now I am changing the record id to be unique, and I want to query the all records created with a duplicate record id.  How can I perform this query?


How can I remove a group that I created previously using :  groupName="machin"  root = QgsProject.instance().layerTreeRoot()  group = root.addGroup(groupName)

I am updating a plugin from QGIS 2 to 3.  I need to iterate through the groups (the names are dynamic) and remove them with their respective child layers.  I need to get a list of groups and then iterate through the groups and delete them.  The original code is as follows:  legend = self.iface.legendInterface() group_names = legend.groups() rev = self.groups[:] rev.reverse() ...     for i, group in enumerate(rev):         legend.removeGroup(group)   I replaced self.iface.legendInterface() with QgsProject.instance().layerTreeRoot() but group_names = legend.groups() fails with the message 'QgsLayerTree' object has no attribute 'groups'   What is the proper container of the groups and how do I access the collection; and, once found, how do I delete those groups?  A search for information on how to remove groups from a layer tree in QGIS 3 has proven fruitless.


Trying to understand the very basics of category theory... While trying to solve a simple exercise on the subject I suddenly realized that I don't even know what morphism equality is! (The exercise asked to prove that such-and-such morphism composition in such-and-such category is well-defined - but to prove this I had to prove that it is associative, which requires me to prove equality of the sort $f;(g;h)=(f;g);h$ - which gave raise to this question)  On the one hand, many proofs in category theory consist of diagrams of some sort where it is shown that $f;g=h;j$ because a square whose edges are morphisms $f:A\rightarrow B$, $g:B\rightarrow D$, $h:A\rightarrow C$ and $j:C\rightarrow D$ 'commutes':    So it would seem that two morphisms are equal iff they lead from the same source to the same destination?  On the other hand, this would mean that there may be at most one morphism in one direction between two given objects - but this seems not the case.  I looked at Wikipedia article but could not find morphism equality defined.  Sorry if this is an extremely basic question - but when are two morphisms equal?

I am learning basics of the category theory (CT).  I do understand that CT is a modern powerful framework to describe various branches of mathematics in a unified way.  I do admit that category's definition tells a lot about the whole thing and focuses on the most important properties, shadowing unnecessary details. However, the more I go forward, the more it feels like it should explicitly require a notion of morphisms equality (like it does with morphism composition). It feels so because equality or inequality of morphisms arises everywhere, since the very beginning: any commutative diagram eventually reduces to an equality of two different paths and many other things involve equality as well. Even composition is defined grounding upon an (implicit) equality!  I'll try to give an example of my concern. Consider $\mathbb{SET}$. Its objects are sets and morphisms are functions. Now, let's recall that functions are sets as well - to be more precise, a function $f : A \mapsto B$ is a subset of a $A \times B$ obeying certain properties, which I omit. Thus, one could argue that $f$ is both a morphism between objects $A, B \in Obj(\mathbb{SET})$ and an object defined as a set of pairs $\{ (a_1 \in A, b_1 \in B), ..., (a_n \in A, b_n \in B) \}$ and those are equal because both are essentially exactly the same thing.  I hope my concern is clear and I need some kind of "conceptual insight" from knowledgeable people to move forward. Please give me the right perspective.


My General relativity skills suck. I need a good paper that   does not start with equivalence principle and pages of elevator experiments derives principles mathematically, not by physical intuition explicitly shows how to compute things, again not via Penrose diagrams, in fact just for  completion no modern dualities or any such. Just dirty old GR does not make outlandish statements without proper(mathematical) justification Uses understandable English Is short ( 15>pages>35 ) and concise   :::::::::::::::::::  It should probably be an older paper with language closer to that of the intrinsic geometry school, may be closer to Tullio-Levi's absolute differential calculus, but with a slight modern improvement in the language.   It should have the spirit of Dirac, by this his sweet way of keeping it short and relevant, as in his General Relativity book, but not using his exact style.

Can someone suggest a textbook that treats general relativity from a rigorous mathematical perspective? Ideally, such a book would   Prove all theorems used. Use modern "mathematical notation" as opposed to "physics notation", especially with respect to linear algebra and differential geometry. Have examples that illustrate both computational and theoretical aspects. Have a range of exercises with varying degrees of difficulty, with answers.   An ideal text would read a lot more like a math book than a physics book and would demand few prerequisites in physics. Bottom line is that I would like a book that provides an axiomatic development of general relativity clearly and with mathematical precision works out the details of the theory.  Addendum (1): I did not intend to start a war over notation. As I said in one of the comments below, I think indicial notation together with the summation convention is very useful. The coordinate-free approach has its uses as well and I see no reason why the two can't peacefully coexist. What I meant by "mathematics notation" vs. "physics notation" is the following: Consider, as an example, one of the leading texts on smooth manifolds, John Lee's Introduction to Smooth Manifolds. I am very accustomed to this notation and it very similar to the notation used by Tu's Introduction to Manifolds, for instance, and other popular texts on differential geometry. On the other hand, take Frankel's Geometry of Physics. Now, this is a nice book but it is very difficult for me to follow it because 1) Lack of proofs and 2)the notation does not agree with other math texts that I'm accustomed to. Of course, there are commonalities but enough is different that I find it really annoying to try to translate between the two...  Addendum (2):  For the benefit of future readers, In addition to suggestions below, I have found another text that also closely-aligns with the criteria I stated above. It is, Spacetime: Foundations of General Relativity and Differential Geometry by Marcus Kriele. The author begins by discussing affine geometry, analysis on manifolds, multilinear algebra and other underpinnings and leads into general relativity at roughly the midpoint of the text. The notation is also fairly consistent with the books on differential geometry I mentioned above.


I have played Dungeons & Dragons 4th edition for a long time now, and I am sorry to see it go. I liked the complexity of it, where as 5e is really based on quickly getting through encounters.  Is it possible to play a completely solo D&D 4e game, on a budget? In the Red Box, in the player's book, there is a little bit of a solo game at the end, but I cannot find another solo adventure anywhere. I know there is , but I'd like to play it on the tabletop.

I've been wanting to start playing D&D for some time, and I was wondering how I could get started by myself with relative ease. I own the first two player handbooks, and a set of dice.


I getting a permission denied when trying to copy my cisco image to the switch and I thought the bold text may indicate something I was unaware of.

There are two directories shown by 'ls'.  Normally directories anywhere are blue on black background.  But the first one is blue on green and impossible to read.  Why is this?  How to make it blue on black, or at least something light on something dark?  This is on Ubuntu 12.04, using bash in Gnome Terminal.  In Konsole, the blue is slightly darker, and possible to read, though could be way better.


In French the word I'd use is mes connaissances. But this word also (and mainly) means the things I know, and then the traduction I find is: my knowledges.  Is this double meaning exists in English and what should I say to talk about people I know and who know me without being my friends?  Edit (an example of context):     This software is very popular, if you have any problem with it just ask to your connaissances, I think that somebody could help you.

He's a friend of mine   The message is clear. He's my friend. He wishes all good for me and helps me whenever I need one.      He's an enemy of mine   The message is clear again. He's my enemy. He wishes all bad for me and never helps me whenever I need!     He's ...... of mine!   The message is clear. He's neither friend nor enemy. He's in between. At times, he may help me but then I cannot always rely on him. He's not a friend of mine.   Other times, he does really bad to me but maybe, there was no any other go for him. He's not an enemy of mine! :)


I have read al lot of the pgrouting, but i still not quite sure if it can do what i want.  I have 20 stop points and i have 1 starting point and 1 finish point.  I want to calculate the shortest path between starting point, all 20 stop point and finish point.  Its something like delivering packects, so from starting point to point x then point y and last finish point,  Maybe iets possible with a dijkstra algorimte ?

I am using postgreSQL, postGIS and pgrouting. Now I am really confused on how am I going to find the shortest path between multiple points.   I know how to find it between two points through dijkstra but I am confused how to accomplish the same result with more than two points.   I have done some research and found this:    But still I did not understand if its the right way and how to install it.


If $X$ is a generator subset of $\Bbb{Q}$ then for $x\in X$,   $X\setminus\{x\}$ also generates $\Bbb{Q}$.   Clearly if I can express $x$ as a combination of the remaining generators we are done. After struggling for an hour I took a different approach: tried to show that if $\langle X\setminus\{x\}\rangle\not=\Bbb{Q}$, $\langle X\setminus\{x\}\rangle$ is a maximal subgroup of $\Bbb{Q}$. That is, if $G\leq\Bbb{Q}$ and $\langle X\setminus\{x\}\rangle\subset G$, then $G=\Bbb{Q}$. For this purpose it is enough to show that $x\in G$. But I doubt that this is true. Any ideas?

In a comment to Arturo Magidin's answer to , Jack Schmidt says that the additive group of the rationals has no minimal generating set.     Why does $(\mathbb{Q},+)$ have no minimal generating set?


What Options are there to activate Windows XP nowadays?  The "regular" methods provided with XP (phone and online) don't work anymore. The phone number is not valid for activation anymore (I tried the German one) and the online activation does not work either (in a quick test within a DMZ other protocols like ICMP or HTTP worked fine when I accessed an internet server).    The latest question/answer I could find here on superuser is this one:  which doesn't provide an answer to my question. In addition the question asks only if it can be done in general not how (neither does the existing answer say how), and about other problems (dual boot), so I decided to post the question again as specific question just about the activation process.  The solutions can be a workaround (disabling the activation check), but for security reasons, it shouldn't contain a binary download. Preferably it also shouldn't require a network/internet connection. Although there is no way around using WinXP, I want to minimize security risks.  EDIT1: Since quite a few people asked, please note why (in my opinion) this question is not a duplicate of , please see my explanation above. I made a thorough explanation in meta .  EDIT2: it was suggested to call MS support and/or sales unfortunately they do not help with WinXP anymore.  EDIT3: please be aware that running an outdated OS without security updates poses security risks explained  as  points out correctly. Therefore, if possible you should change/upgrade the OS of your device. However in some cases it's not an option to change to a different OS, e.g. because certain drivers/HW/SW is only compatible with Win XP.  EDIT4:  note, the activation process comes after entering a installation/serial key (e.g. from the licence sticker)

I will need to keep an OEM version of XP on one machine to run a number of expensive older programs. I propose to leave that machine unconnected to the Internet so security support is not a problem. The question still remains though, if I need to do a clean re-install of that XP can I re-activate it after April 2014?  Also I need to build a new machine and dual boot another OEM copy of XP Professional (from a discarded machine) with Windows 8.1.  Does anyone see any problems in doing that?


Whenever I try to use a search cursor from arcpy in pycharm, I get this unresolved reference error. I should note that it was working fine earlier in the night, I have no idea what happened.     I've tried everything in this Q&A already:     Other arcpy functions seem to work fine. I've also tried restarting computer and reinstalling pycharm. I can use the search cursor when I use IDLE.

How would I setup  to recognize import arcpy?   I'd like to use PyCharm to develop and debug geoprocessing tool.


I am a statistical newbie. I recently started doing some text analysis in my text columns to find if a usage of specific word is causing my score to be high or low score. Previously I was finding the correlation then I came to know correlation does not tell you what variables affect other variables.  Q1: Is it possible to determine causality? and if yes what are the tools that I can use to do that? Im working in R and azure, so is there any tool I can use?

In his 1984 paper , Paul Holland raised one of the most fundamental questions in statistics:     What can a statistical model say about   causation?   This led to his motto:     NO CAUSATION WITHOUT MANIPULATION   which emphasized the importance of restrictions around experiments that consider causation.  Andrew Gelman makes :     "To find out what happens when you change something, it is necessary to change it."...There are things you learn from perturbing a system that you'll never find out from any amount of passive observation.   His ideas are summarized in .  What considerations should be made when making a causal inference from a statistical model?


This is my first project on threading but i'm lost..  The problem is: I want to make a second counter, where every prime number turn color.   Thread thread1; private void Form1_Load(object sender, EventArgs e) {     thread1 = new Thread(new ThreadStart(voidPrime)); }  int sec=0;  void voidPrime() {      sec+= 1;     label1.Text = sec.ToString();     if (isprime(int.Parse(label1.Text)))     {         label1.ForeColor = Color.RED;     }     else      {         label1.ForeColor = Color.Black;     } }  private void PLAY_Click(object sender, EventArgs e) {     thread1.Start();      while (thread1.IsAlive)     {         Thread.Sleep(1000);     } }   When I start and press the PLAY button, throws me      Cross-thread operation not valid: Control 'label2' accessed from a thread other than the thread it was created on.

Which is the simplest way to update a Label from another Thread?   I have a Form running on thread1, and from that I'm starting another thread (thread2).  While thread2 is processing some files I would like to update a Label on the Form with the current status of thread2's work.   How could I do that?


I have 3 servers (server1, server2 and server3) with Apache and SCP (and/or FTP server). These servers are behind a router. I have another server with a public IP used as a proxy for Apache. So, if I'm trying to access website1 (hosted on server1) my requests are proxied to server1. The same for website2 and website3.... Now, I would like to do the same thing for FTP or SCP. Is this possible? e.g.: If I install an FTP server on server1, server2 and server3, can I proxy my requests based on the hostname? ftp.website1 to the ftp server on server1 and so on.... I can also use SCP, there is no difference, and I have full access to proxy and 3 servers.

I've grown quite fond of HTTP reverse proxies in our development environment and found the DNS based virtual host reverse proxy quite useful. Having only one port (and the standard one) open on the firewall makes it much easier for management.  I'd like to find something similar to do SSH connections but haven't had much luck. I'd prefer not to simply use SSH tunneling since that requires opening port ranges other than the standard. Is there anything out there that can do this?  Could HAProxy do this?


I would like to proof that: $$z = |z|\big(\cos(\phi) + i \sin(\phi)\big)$$ of course the second part can be shown using Euler's formula. That's why I would like to prove that: $$z = |z|e^{i \phi}$$ I can use only the series definition of exp and some basic properties like $e^{a+b} = e^ae^b$. I think it must be quite trivial but I really don't know how to do it properly.    I think that my problem is a bit different to the one in the suggested  post. I do know how to prove that $e^{i\phi} = \cos \phi + i\sin \phi$ but I do not know how to prove that  $$\forall_{z \in \mathbb{C}} z = |z|\exp(ix)$$ for some $x \in \mathbb{R}$.

Euler’s formula states that $e^{i  x} = \cos(x) + i \sin(x)$.  I can see from the MacLaurin Expansion that this is indeed true; however, I don’t intuitively understand how raising $e$ to the power of $ix$ produces rotation.  Can anyone give me an intuitive understanding?


I understand that there is a lot of similar questions, but I can't grasp on when to use a one tailed or two tailed test when reading a example such as the one below:  We suspect that test driven development is better than writing tests afterwards, i.e. results in fewer faults in the system we are looking at. Is this a one tailed or a two tailed situation? How do these two differ?  I understand that two tailed can test both if the mean is greater or less than X and that one tail only test if its less or greater than X and not both. So is one tail testing the best one?

For example, how would you decide between which tailed test to do in the following experiment:  Ethanol dilutions were made with different proportions and Daphnias were submerged in them to collect their heart rates. The Daphnias were also submerged into beakers with different temperatures.  My null hypothesis was that the Daphnia will not be affected by the changing variables and if they are, it is due to a purely kinesis response (caused by chance).   My alternative hypothesis was that Ethanol would decrease the heart rates of the Daphnias as the dilution concentrations increase. I assumed this because Ethanol is a respiratory and nervous system depressant that acts as an anesthetic and potentially leads to death after an overdose. I also assumed that the Daphnias' heart rates would fall and become steadier in lower temperatures because they usually inhabit cooler, freshwater habitats.


I have a point shapefile that has a 'rank' attribute with numbers between 0-100. I need to calculate the sum of this value for points within a 10km circular moving window anywhere within my area of interest. The result would be a raster, where each pixel represents the sum value of the ranks taken from all point features within a 10km radius. In ArcGIS Desktop, I could do this using the Point Statistics tool. Is there a way of doing this in QGIS?

the point represents rates like 10%, etc. (this was also pretty clear from 2 years ago) -- been trying to do this for 2 yrs...  the points dont represent numbers of events since they are rates ()    but the points have geo ids so they are attached to location, not distance (whatever distance is to imply) -- update: it represents z-value but we're just dealing with rates


i made a registration and login form where the user can add a profile pic. When they login they are redirected to dashboard.php. There i want to show them their name and profile pic but only for the active user.   At this moment, this is my code:     <?php session_start(); require_once 'header.php'; /*Veradneren + aanpassing navigatie.php*/ $current = 'dashboard.php'; require_once 'navigatie.php'; function getImage() {     require "connectie.php";     $user = $_SESSION["username"];     try {         $stmt = $db->prepare("SELECT * FROM gebruiker WHERE username = $user");         $stmt ->bindParam("username",$user);         $stmt->execute();         $results = $stmt->fetchAll();             return $results;     }      catch (PDOException $e) {         $message = $e;     } } ?>
     <?php echo $message;?>

<?php echo "Welkom, " . $_SESSION["username"];?>
             <?php                 $results = getImage();                 foreach ($results as $row){                     echo "                         ";                 } ?>

  <?php require_once 'footer.php'; ?>    Database structure:   The pictures are uploaded in the folder uploads

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


Is it possible for the impact count to go down on a SE site?  I have a fairly active profile on . The people reached count from my various posts touched ~1.4m around a month ago. But today I happen to notice that the count has gone down to ~1.3m.  I have always observed this number going up. The uptick was prominently visible when the number was in hundreds and thousands.  Is it ever possible for this number to go down? If yes, what possibly causes this? I don't remember deleting any of my posts in a long while (last 3-4 months).  Has some recent change in SE engine caused this (corrected) count?

I posted this  a few weeks ago. The photo I posted shows that I had impacted 25k people. Now it says this:   I only impacted 1k people, 24k less than what my impact was a few weeks ago! I am sure that 24k people didn't delete their accounts within a few weeks and this is probably a bug. What happened to my impact score?


This question is Problem 13(b) in Spivak's Calculus. As stated, I haven't come up with a way to prove the irrationality of $\sqrt6 - \sqrt2 - \sqrt3$ (or, in general, the sum of any three irrational square roots). It is straightforward to prove that the sum of any two square roots (e.g. $\sqrt2 + \sqrt3$) is irrational. One can assume it is rational, square it, then find that it is irrational and prove by contradiction. I have tried to square $\sqrt6 - \sqrt2 - \sqrt3$ twice but still can't find any contradiction. Could anyone please give me an example of how to solve this type of question? Thanks so much!!!

Prove that $\sqrt{6}-\sqrt{2}-\sqrt{3}$ is irrational   My attempt:-     Suppose $\sqrt{6}-\sqrt{2}-\sqrt{3}$ is rational, then for some $x\in\mathbb{Q}$ we have $$\sqrt{6}-\sqrt{2}-\sqrt{3}=x$$ Rewriting this equation as $$\sqrt{6}-x=\sqrt{2}+\sqrt{3}$$ and now squaring this we get $$ 6-2x\sqrt{6}+x^2=5+2\sqrt{6}$$. This implies that $$\sqrt{6}=\frac{x^2-1}{2+2x}$$ but this is absurd as RHS of the above equation is rational but we know that $\sqrt6$ is irrational. Therefore , $\sqrt{6}-\sqrt{2}-\sqrt{3}$ is irrational. Does this look good? Have I written it properly? Is there any other proof besides this..like one using geometry? Thank you.


I run Ubuntu 20.04 LTS with the GNOME desktop. Within the last few days the top bar was suddenly smooshed (see image below). I am not sure how it happened and it occurs on all monitors. How do I fix it?  Notes:  I have an NVIDIA GPU This is not an issue anywhere else on the desktop, just the top bar

So I was configuring VS code on my Notebook when suddenly I noticed that my interface font got really small on my desktop, terminal and files. I use Gnome Tweaks Tool to increase my scaling factor to 1,15 , but, even though it was active, the font stayed tiny. The solution I found was moving my scaling factor, which instantly fixed my font issue, however, every time I restart my Notebook the font gets tiny again and I have to repeat the process. I tried reseting my font configuration using this command, but had no success. gsettings reset org.gnome.desktop.interface text-scaling-factor  I also tried using the command dconf reset -f /  Finally, I tried using dconf-editor, but still had no success altering the font rendering DPI or changing the scaling factor. All of the steps I mentioned fixed my fonts temporarily, but the issue still persists when I restart my Notebook I am out of ideas and even considered getting a fresh Ubuntu install by now... My video card: NVIDIA GeForce GTX 1050 GPU


According to WolframAlpha, this evaluates to $2^{-t} (-t + 2^{t + 1} - 2)$.

How can I evaluate $$\sum_{n=1}^\infty\frac{2n}{3^{n+1}}$$? I know the answer thanks to , but I'm more concerned with how I can derive that answer. It cites tests to prove that it is convergent, but my class has never learned these before. So I feel that there must be a simpler method.  In general, how can I evaluate $$\sum_{n=0}^\infty (n+1)x^n?$$


I would like to install your OS into my laptop (gaming x64bits ) that currently uses Windows 8.1 Pro And I would like to know if this will remove Windows or have both OS and if this will keep any of my files/programs Windows Office,Games and Docs/Images  Thank You for your time.

I'm absolutely new to Linux. I would like to know how to install Ubuntu alongside the pre-installed Windows 8+ OS.  Should I do it with Wubi, or through the Live USB/DVD?  What steps do I need to take to correctly install Ubuntu?


It is well-known that $\sum_{n=0}^\infty x^n=1/(1-x)$. However, it seems difficult to find $\sum_{n=0}^\infty x^{n^2}$. A natural problem is study its behavior around $1$. A problem states that $$\lim_{x\to 1}\sqrt{1-x}\sum_{n=0}^\infty x^{n^2}=\sqrt{\pi}/2.$$  How can we prove this? Abel summation formula? Any others? I have no idea.

I need some suggestions, hints for the limit when $a \to 1^{-}$ of $$\sqrt{\,1 - a\,}\,\sum_{n = 0}^{\infty}a^{n^{2}}.$$


In many cases 'make me' 'get me' 'has me' doing something mean 'to force'. What is the difference between them in this meaning? Is there any sense to use one or the other?

What's the difference between:        Have someone do something     Make someone do something   Get someone do something.      To have someone do something means to cause someone to do something. To make someone do something means to force someone to do something. To get someone do something means to persuade someone or trick someone to do something.  This is what the dictionary says but I saw they're sometimes interchangeably used, so dictionary definitions are not enough.


Let $(a_n)$ be a sequence of real numbers. Prove that   $$\limsup_{n\to \infty}\frac{a_n}{n}\leq \limsup_{n\to\infty}\,  (a_{n}-a_{n-1}). $$   If the sequence $(a_n)$ converges, then this is immediate: both sides are $0$. If it is not convergent, how should I approach this problem?

This is a question from the book Methods of Real Analysis by R. R. Goldberg.     If $(s_n)$ is a sequence of real numbers and if $$\sigma_n=\frac{s_1+s_2+\cdots+s_n}{n}$$ then prove that: $\operatorname{{lim sup}}\sigma_n \leq \operatorname{lim sup} s_n$.   I don't have any idea how to start working on this problem. Please help. Thanks.


When i wrote this question in SuperUser there was not any information and solution about Wanna Cry attack in SuperUser. So this is not a duplicate question and has special information and useful solutions for you about Wanna Cryattack.    How to protect my Windows (Client|Server) from the popular Wanna Cry (Wanna Crypt)? What to do if my system is affected to WannaCry? How to remove it? How Wanna Cry work?

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


I was following the instructions on the  for winehq installation. When I executed   sudo apt-add-repository 'deb https://dl.winehq.org/wine-builds/ubuntu/ xenial main'   a blank line appeared with no response and it brought me back to the input line. I thought maybe it worked and then I executed sudo apt update and it said   Malformed entry 6 in list file /etc/apt/sources.list (component).    Can anyone help?   deb-src https://archive.Ubuntu.com/Ubuntu   xenial-security main restricted universe multiverse   Also if I may add I am running a chroot

I have unistalled and reinstalled the Ubuntu Software Center as per info I found in a similar thread and I got the same response about line 91 or something like that.  I just tried to upload a screen shot but since I'm new it won't allow me to.  I also can not figure out how to cut and paste anything so I have to hand type what the error screen says, both when I attempt to open the software center and nothing happens, when I try to enter commands into the terminal to uninstall, reinstall, whatever I get the same following:  COULD NOT INTITIALIZE THE PACKAGE INFORMATION An unresolvable problem occured while initializing the package information Please report t:his bug against the 'update-manager' package and include the following error message: 'E: Malformed line 91 in source list/etc/apt/sources.list (dist parse)  E: The list of sources could not be read.,  E: The package list of status file could not be parsed or opened.   How do I report bugs?  What can be done about this.  I have searched and everything everyone says to do leads me back to the same line error message.  So, I don't know how to get to line 91 in the source list; to tell you what it says. Sorry, I'm really new to this. That is what I need is to find out how to get there and fix what it says. I would really like to NOT have to re partition my hard drive and start from scratch, so I'm really looking forward to getting this problem solved. I need to be able to install new software.


Sometimes I'd like to discuss some ideas related to a question without including them in the comments. For (1) it gets too long and (2) often the discussion is quite specific and probably isn't relevant to others who come across the question.  Having the automatic "move to chat" feature when comments get too long is a great idea, but I think SO users should be able to pre-empt this and start a chat for a question, and maybe an answer too, manually.  For others who then come across this chat through another means than the question it'd be nice for them to know the context of the chat. I'd like to have an automatic explicit link between the chat and question created in such cases.

When comments get too chatty the move-to-chat feature asks if you'd like to move it out. But this often happens after the fact and thus doesn't prevent it.   I propose that:   Move-to-chat be provided as a button along side so that a user who knows their question or conversation may become drawn out may elect to preempt and take the conversation "off-line"


We have documents that describe all HTML tags. We have documents that describe all CSS properties. However, I have failed to find a document that would exhaustively declare which CSS properties influence rendering of which HTML tags. Does such document exist? For example, is there a document that states that rendering of hr tag depends on the value of the margin-top CSS property?

I'm looking for a source/spec that can tell me what CSS properties can applied to which HTML elements.  For instance, the css property; "overflow".  I know I can apply this to div, p, textarea but what other elements can I apply this too?  Is there a spec somewhere I can reference?


Using Firebase database to display the data in a RecyclerView. The app crashes when they run this line of code   itemGroup.setHeaderTitle(groupSnapShot.child("headerTitle").getValue(true).toString());   I get this Error:     java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference   private void getFirebaseData(){     dialog.show();     myData.addListenerForSingleValueEvent(new ValueEventListener() {         @Override         public void onDataChange(@NonNull DataSnapshot dataSnapshot) {             List<ItemGroup> itemGroups = new ArrayList<>();             for(DataSnapshot groupSnapShot:dataSnapshot.getChildren())             {                 ItemGroup itemGroup = new ItemGroup();      itemGroup.setHeaderTitle(groupSnapShot.child("headerTitle").getValue(true).String());    GenericTypeIndicator<ArrayList<ItemData>> genericTypeIndicator = new GenericTypeIndicator<ArrayList<ItemData>>(){};     itemGroup.setListItem(groupSnapShot.child("listItem").getValue (genericTypeIndicator));    itemGroups.add(itemGroup);              }             iFirebaseLoadListener.onFirebaseLoadSuccess(itemGroups);         }          @Override         public void onCancelled(@NonNull DatabaseError databaseError) {   iFirebaseLoadListener.onFirebaseLoadFailed(databaseError.getMessage());          }     });  }   when i comment out that line of code, i get this E/RecyclerView: No adapter attached; skipping layout from my logcat... Im not sure if this affects the RecyclerView adapter...

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


I am wondering how it is possible to change mm/yyyy to mm.yyyy in biblatex. Are these used correctly? alldates=terse labeldate=year  if I say labeldate = year, wouldn't that usually lead to omitting the month? Or did I get that wrong. Is terse the right option if I want a date like mm.yyyy? (I have been checking the documentation but not really sure about the / . replacement! Sorry!  MWE:  \documentclass[   12pt,   a4paper,   headings=standardclasses,   listof=totoc,   numbers=noenddot ]{scrartcl}  \usepackage[left=2.50cm, right=2.50cm, top=2.50cm, bottom=2.00cm, footskip=1cm]{geometry} \usepackage[onehalfspacing]{setspace} \usepackage[main=ngerman, english]{babel} \usepackage[babel, german=quotes]{csquotes} \usepackage[ngerman]{isodate} \usepackage[ngerman]{datetime} %---------------------------------------------------------------------------- %   BIB %---------------------------------------------------------------------------- \usepackage[   backend=biber,   style=ext-authoryear,   sorting=nyvt,   datamodel=customstyles,   maxnames=25,   innamebeforetitle=true,   usetranslator=true,   alldates=terse,   labeldate=year,   dashed=false,   doi=false,   isbn=false ]{biblatex} \addbibresource{\jobname.bib} \usepackage[hidelinks, pdfencoding=auto]{hyperref}  \DeclareDelimFormat[bib]{nametitledelim}{\addcolon\space}  % editor in parentheses \DeclareDelimFormat{editortypedelim}{\addspace}  \DeclareFieldFormat{editortype}{\mkbibparens{#1}} \DeclareDelimAlias{translatortypedelim}{editortypedelim} \DeclareFieldAlias{translatortype}{editortype}  \DeclareFieldFormat   [article,inbook,incollection,inproceedings,patent,online]   {title}{#1\isdot} %-------------------------------------------------------------------- %   MAIN %-------------------------------------------------------------------- \begin{filecontents}{\jobname.bib} @report{Chafe.1974, author = {Chafe, Wallace L.},   title = {An Approach to Verbalization and Translation by Machine. Final Report},   month = {10},  year = {1974},   institution = {{California University, Berkely}},   address = {New York}   } \end{filecontents}  \begin{document} \parencite{Chafe.1974}  \clearpage \printbibheading[heading=bibintoc,title={Literaturverzeichnis}] \printbibliography \end{document}

So this might be a bit specific of a question, but I need BibLaTeX to output dates in the long DMY format - dd.mm.yyyy that is.  BibLaTeX documentation states that one can achieve dd/mm/yyyy by using the date = terse setting.  However, I'd like to have the date separator to be a dot instead of a slash. I didn't find any easy way to do this while browsing through the documentation.  Here's an MWE (and its output) on what I'm working on, roughly. I have been modifying the style = chem-rsc package to fit my needs (or rather my Uni's requirements), but I've omitted those changes here for they are irrevelent in this case.  \documentclass[a4paper,12pt,british]{article}  \usepackage[T1]{fontenc}  \usepackage[utf8]{inputenc} \usepackage[labelfont=bf]{caption} \usepackage[british]{babel} \usepackage{filecontents} \usepackage{csquotes}  \usepackage[backend=biber,     style     = chem-rsc,     autocite  = superscript,     autopunct = true,     sorting   = none,     sortcites = true,     eventdate = terse,     datezeros = true,]{biblatex}  \begin{filecontents}{viitteet.bib} @inproceedings{othusitse2015,     author      = {Nhlanhla Othusitse and Edison Muzenda},     title       = {Predictive Models of Leaching Processes: A Critical Review},     booktitle   = {7th Int. Conf. on Latest Trends in Engineering \& Technology},     location    = {Irene, Pretoria, South Africa},     eventdate   = {2015-11-26/2015-11-27},     pages       = {136--141}, } \end{filecontents}  \addbibresource{viitteet.bib}  \begin{document}  \section{Section}  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.\supercite{othusitse2015}  \printbibliography  \end{document}     EDIT:  I tried tinkering with something like this...  \DefineBibliographyExtras{british}{%     \renewrobustcmd*{\bibdatesep}{\adperiod} }   ... but to no avail.


Recently, I've found myself writing sentences which are statements, but which conclude with a question, either in parentheses or as a quotation, and being unable to decide quite how to punctuate.  For example:  She said, "Are you coming home?" -- versus -- She said, "Are you coming home"?  ... and:  He looks unhappy (but isn't he rich?)  -- versus --  He looks unhappy (but isn't he rich?).  Also, is this affected by whether on not one is using British Punctuation (cf. the Oxford Comma) or American Punctuation?

I know that when brackets enclose part of a sentence, the full stop goes outside.     I tripped over this morning. I was distracted by a plane (which turned out to be Superman).   If it's a full sentence, the full stop goes inside.     I tripped over. (I was distracted by a plane that turned out to be Superman.)   What happens when there's a question mark and only part of the sentence is a question?     I tripped over this morning. I was distracted by a plane (or was it Superman?)      (or was it Superman?).      (or was it Superman)?   What happens to the full stop that belongs to the rest of the sentence, and why?


I use set -e in scripts quite often, but sometimes, it's ok for a script to fail in some of it's commands. I tried checking if set -e was ON, but couldn't find a way to do it - there's no option (that I know of) in set that will provide the current value. Also tried this: set | grep errexit (errexit is the option name for -e) and set | grep "-e", no luck there. I would like to check if the errexit option is set, so I could temporarily disable it in some of my library functions that I built over time (using set +e and re-applying set -e if needed). Something like: if [ errexit is set ]; then    ERR_EXIT=1    set +e fi ... run some code that may fail ... if [ "${ERR_EXIT}" = 1 ]; then     set -e fi

I'm writing a shell function that will be called from many different places and I want to ignore all errors occurring inside the function disabling the (possibly enabled) set -e shell option, executing set +e.  The problem is that I don't know if that option was set or not, so I don't know if it's really needed to disable it, and more important, if I need to set it again at the end.  So, how do I know if it is set or not? Is there any way to ignore errors of all commands inside a shell function ignoring the -e shell option if is set?


Suppose we have applied a voltage to a transformer with an open secondary, we will get a certain flux in the core and a certain voltage at the secondary depending upon the turns ratio. Now, suppose we connect resistance to the secondary and therefore current will start to flow through it and a reflected current will flow in the transformer's primary winding. But the magnitude of flux remains the same with or without the load. So my question is: What exactly changes when we connect a load to the transformer, which results in power transfer from primary to secondary? In short, which magnetic parameter is responsible for power transfer between primary and secondary? As far I understand, change in flux induces a voltage but does not carry any power, and change in flux remains the same with or without the load.

I'm trying to get my head wrapped around transformer operation and in the process regretting the times I snoozed in my Electromagnetics class as a EE student back when I was a lad :)  I'm looking for an intuitive understanding, but not just an analogous one. I'd like it to be grounded in the actual physics of what's happening. I've found several excellent sources on the web, but they all seem to skirt this question.  I've come across a few interesting hints and am now tantalizingly close, I think, but still yearning :)  Fact 1: Although varying sinusoidally, the "peak-to-peak" flux, so to speak, in a transformer's core is essentially constant (for a given voltage applied to the primary), regardless of the load.  My intuitive hypothesis was that variation in the "strength" of the flux was what transferred the energy from the primary to the secondary, but this fact would seem to contradict that theory. I had thought that the primary makes a bunch of flux based on the current flowing through it and the secondary sucks it up to make current of its own. No dice, it seems.  Then of course there's the fact that the formula for flux involves only voltage, time (frequency), and turns :)  Fact 2: The current in the primary is (approximately) 90 degrees out of phase with the voltage at no load, and approximately aligned in phase at full load.  This fact seems very promising and also curiously satisfying. It would imply that the Volt-Amps (VA) of the primary is constant and only the power factor changes as the current load on the secondary increases.  But I still don't get how the energy is actually being transferred. It seems vaguely like the flux is just there as an energy conductor or something and some other phenomenon is actually doing the energy transfer bit.  Can someone see what I'm missing and explain what's actually happening in there?


There are a lot of question similar to it but I want to give a good reason to do this.  I did this question:   The answer was not exactly good, but the problem is the information that I put in it. Maybe, I will sell the project and if the people that will buy it search my name and find it, I can have a problem and lost money. Even if he search it without my name, I will have the same problem.  Maybe I don't sell anything, but now this information have a good value to me. :) So, how can I force to delete it because I don't want to show this information anymore!   It was online for 4 month, so I thing this time pay the answer. Maybe I accept to restore it in one year.  So how can I force to delete my own question?  Ps. I flag the question but it not solve the problem!

The Creative Commons FAQ      Third, if the licensor does not like how the material has been modified or used, CC licenses require that the licensee remove the attribution information upon request [...]  in 4.0, this also applies to the unmodified work.   How do I remove / dissociate my name from a post, in accordance with this clause?  Also, what are the effects of having my post dissociated from my account?  Finally, how will dissociation requests be handled for posts licensed under earlier versions of the license, which do not require dissociation upon request in all cases?


we're two students working on a seminar paper (topic: Marketing in the Age of Big Data) where we have to conduct a cluster analysis by using nearest neighbour clustering. unfortunately, we cannot differentiate between nearest neighbour clustering and K-nearest neighbours. At first of all we thought that it is the same just called different. After we've read many papers where it is said that KNN is a supervised machine learning algorithm, while our professor said that the nearest neighbour is an unsupervised algorithm we recognised that there must be a difference. There are a lot of different declarations on the internet, why we are confused now.  Hopefully, someone can help us to solve the understanding problems.  Many thanks in advance and many greetings

I know that k-means is unsupervised and is used for clustering etc and that k-NN is supervised. But I wanted to know concrete differences between the two?


For example, if I had the list:  list_a = [5, 2, 30, 6, 17]   The lists I want to obtain relate to the len(list_b), for example:  list_b = [40, 90]   So the lists I need to create are:  [5, 2] [2, 30] [30, 6] [6, 17]   How can I slice or use a loop to do this?

I have a list of arbitrary length, and I need to split it up into equal size chunks and operate on it. There are some obvious ways to do this, like keeping a counter and two lists, and when the second list fills up, add it to the first list and empty the second list for the next round of data, but this is potentially extremely expensive.  I was wondering if anyone had a good solution to this for lists of any length, e.g. using generators.  I was looking for something useful in itertools but I couldn't find anything obviously useful. Might've missed it, though.  Related question:


Let $p: E\to B$ be a covering map; let $B$ connected. Show that if $p^{-1}(b_0)$ has $k$ elements for some $b_0 \in B$, then $p^{-1}(b)$ has $k$ elements for every $b \in B$.   I know that $E$ has a unique slice because $B$ is connected, but I don't know what to do next.    For the sake of providing some context, this is Section 53, Exercise 3 of Munkres' Topology.

In "Knots and Primes: An Introduction to Arithmetic Topology", the author uses the following proposition   Let $h: Y \to X$ be a covering. For any path $\gamma : [0,1] \to X$ and any $y \in h^{-1}(x) (x = \gamma(0))$, there exists a unique lift $\hat{\gamma} : [0,1] \to Y$ of $\gamma$ with $\hat{\gamma}(0) = y$. Furthermore, for any homotopy $\gamma_t (t \in [0,1])$ of $\gamma$ with $\gamma_t = \gamma(0)$ and $\gamma_t(1) = \gamma(1)$, there exists a unique lift of $\hat{\gamma_t}$ such that $\hat{\gamma_t}$ is the homotopy of $\hat{\gamma}$ with $\hat{\gamma_t}(0) = \hat{\gamma}(0)$ and $\hat{\gamma_t}(1) = \hat{\gamma}(1)$.  The author then follows with; "In the following, we assume that any covering space is connected. By the preceding proposition, the cardinality of the fiber $h^{-1}(x)$ is independent of $x \in X$."   I am not sure why this results is true. This is my attempt at explaining it to myself. Take two different $x_1, x_2$ and their fibers $h^{-1}(x_1), h^{-1}(x_2)$ such that $y_1 \in h^{-1}(x_1)$ and $y_2 \in h^{-1}(x_2)$. Take two paths $\gamma_1, \gamma_2$ such that $\gamma_1(0) = x_1$ and $\gamma_2(0) = x_2$. Then we get two lifts $\hat{\gamma_1}, \hat{\gamma_2}$ with $\hat{\gamma_1}(0) = y_1$ and $\hat{\gamma_2}(0) = y_2$. Now, since our covering space is connected we can continuously deform $\hat{\gamma_1}$ into $\hat{\gamma_2}$ and conclude that every elements in $h^{-1}(x_1)$ is also in $h^{-1}(x_2)$ and vice versa. I feel that this is wrong but cannot figure out the right way to see this. Any help would be appreciated.