Physical meaning of the determinant .
What's an intuitive way to think about the determinant?
Maximum power transfer and Thevenin Overriding the final destination of the OAuth2.0 flow from a custom OAuth2.0 Auth provider Background:  I have created a custom Auth. Provider in Salesforce to reach out to an authorization server that isn't on the default list of Provider Types. I used  as a good starting point to extend the Auth.AuthProviderPluginClass. Once appropriately added to my org, it then became an option on the list of Provider Types. I was able to create an Auth. Provider using that new provider type and it works to initiate the OAuth2.0 flow. I am appropriately able to get the access token and refresh token from the authorization server.  The Problem:  As it currently stands, we will have users click on a button that will send them to the provided "OAuth-Only Initialization URL" link that was generated when I created the actual Auth. Provider record. The trick is that when the OAuth2.0 flow is completed, the user is redirected back to the Salesforce Setup Home page, and I don't see a good way in the documentation to override the final destination to be something else (like a success page or something).  Question:  Does anyone know of a way to override the final destination of the OAuth2.0 flow from a custom OAuth2.0 Auth provider?    UPDATE: I tried using the startUrl (and also tried retUrl for good measure) as query params, but doing so didn't change the behavior after the OAuth2.0 flow finished.  Meaning, both of the following URLs gave me the same final destination as not having any query params at all:  https://&lt;scratch org random url&gt;.my.salesforce.com/services/auth/oauth/MyCustomAuthProvider?retUrl=lightning%2Fpage%2Fhome   https://&lt;scratch org random url&gt;.my.salesforce.com/services/auth/oauth/MyCustomAuthProvider?startUrl=lightning%2Fpage%2Fhome     Another Update: This WORKED:  https:/&lt;scratch org random url&gt;.my.salesforce.com/services/auth/oauth/MyCustomAuthProvider?startURL=%2Flightning%2Fn%2FCustomPage   Apparently, it was important to add the leading /, (of course, url encoded to be %2F) and %2Flightning%2Fpage%2Fhome gets interpreted as the setup home and sends you there.    (Parallel posted to Salesforce Dev Forum: ) Are 7 hours enough time to leave the Brussels airport and go to the city center? Why does shell Command Substitution gobble up a trailing newline char? As per the following example, and as in  In bash, where has the trailing newline char gone?, I want to know "why" it happens    x="$(echo -ne "a\nb\n")" ; echo -n "$x" | xxd -p  # Output is: 610a62  # The trailing newline from the 'echo' command #   has been "deleted" by Command Substitution   I assume there must be some very significant reason for a shell action, namely Command Substitution, to actually delete some data from the command output it is substituting... but I can't get my head around this one, as it seems to be the antithesis of what it is supposed to do.. ie. to pass the output of a command back into the script process... Holding back one character seems weird to me, but I suppose there is a sensible reason for it...  I'm keen to find out what that reason is... For linear regression, we can check the diagnostic plots (residuals plots, Normal QQ plots, etc) to check if the assumptions of linear regression are violated.  For logistic regression, I am having trouble finding resources that explain how to diagnose the logistic regression model fit. Digging up some course notes for GLM, it simply states that checking the residuals is not helpful for performing diagnosis for a logistic regression fit.  Looking around the internet, there also seems to be various "diagnosis" procedures, such as checking the model deviance and performing chi-squared tests, but other sources state that this is inappropriate, and that you should perform a Hosmer-Lemeshow goodness of fit test. Then I find other sources that state that this test may be highly dependent on the actual groupings and cut-off values (may not be reliable).  So how should one diagnose the logistic regression fit? If I reboot Ubuntu, then I need to log on each site and into Google Chrome account. What is the reason?  My system is Ubuntu 16.04 and Google Chrome 53.0.2785.101 (64-bit). Regular expression to match balanced parentheses I've seen many science popularisation documentaries and read few books (obviously not being scientist myself). I am able to process and understand basic ideas behind most of these. However for general relativity there is this one illustration, which is being used over and over (image from Wikipedia):    I always thought that general relativity gives another way how you can describe gravity. However for this illustration to work, there needs to be another force, pulling the object down (referring to a direction in the attached image). If I put two non-moving objects in the image, what force will pull them together?  So where is my understanding incorrect? Or is general relativity not about explaining gravity and just describes how heavy objects bends spacetime (in that case the analogy is being used not correctly in my opinion)?    UPDATE Thank you for the answers and comments. Namely the XKCD comics is a spot on. I understand that the analogy with bent sheet of fabric pretty bad, but it seems that it can be fixed if you don't bent the fabric, but just distort the drawn grid.   Would you be so kind and answer the second part of the question as well - whether general relativity is explaining gravitational force. To me it seems that it is not (bending of spacetime simply can not affect two non-moving objects). However most of the time it is being presented that it does. If $\alpha$ is an algebraic element and $L \subset K$ are both field, does the polynomial ring $L[\alpha]$ is also a field?  I am trying to prove that the ring of fraction $L(\alpha)$ is equal to $L[\alpha]$. To do this, I use an exercise done in class : Let $K$ a field, $\alpha \in K$ and $L$ a subfield of $K$. Then $L(\alpha)$ is the smallest subfield of $K$ containing $L$ and $\alpha$.  Is anyone could help me? Can I see images and watch movies inside the terminal emulator Can't login with Google using Internet Accounts SPWeb.getFile(Url) exception : value does not fall within the expected range New to both Ruby and Rails but I'm book educated by now (which apparently means nothing, haha).  I've got two models, Event and User joined through a table EventUser  class User &lt; ActiveRecord::Base   has_many :event_users   has_many :events, :through =&gt; :event_users end  class EventUser &lt; ActiveRecord::Base   belongs_to :event   belongs_to :user    #For clarity's sake, EventUser also has a boolean column "active", among others end  class Event &lt; ActiveRecord::Base   has_many :event_users   has_many :users, :through =&gt; :event_users end   This project is a calendar, in which I have to keep track of people signing up and scratching their name out for a given event. I figure the many to many is a good approach, but I can't do something like this:  u = User.find :first active_events = u.events.find_by_active(true)   Because events don't actually HAVE that extra data, the EventUser model does.  And while I could do:  u = User.find :first active_events = [] u.event_users.find_by_active(true).do |eu|   active_events &lt;&lt; eu.event end   This seems to be contrary to "the rails way".  Can anyone enlighten me, this has been bugging me for a long time tonight (this morning)? I often find myself wanting to install something, but I'm unsure of what package it's in. This is a very common occurrence for me:  $ make html sphinx-build -b djangohtml -d _build/doctrees   . _build/html make: sphinx-build: Command not found make: *** [html] Error 127  $ sudo apt-get install sphinx E: Unable to locate package sphinx  $ sudo apt-get install sphinx-build E: Unable to locate package sphinx-build   googles  $ sudo apt-get install python-sphinx   Is there a better way? What are the dev-loop services that started on boot? Can I use a one-way ticket to come to the UK? Or do I need to show a return ticket to be able to get in? Doesn't the end of Looper create a time paradox? I guess this is more a question about the nature of time travel more than anything else.  At the end of the movie,      Joe shoots himself in a field and changes the course of history.   Does this create a paradox as it changes the history that led up to that point?      If his future self had never existed he'd never have gone on the mission he did and thus he never would have ended up in the field.   Once he did what he did, he could no longer have done it, and so theoretically, time and space should have just folded in on itself and popped out of existence.  Is there something I'm missing that would explain how the movie could have ended where it did without the events at the beginning to lead it there? Who was the colleague that Erik was going to contact for help? After S.H.I.E.L.D confiscates Jane's work in Thor, the researchers discuss what they'll do next.  Erik mentions two colleagues. The first is reasonably implied to be Bruce Banner, but who is the second colleague he mentions? Transcribed from the film:  Jane Who are these people? Erik I knew this scientist... a pioneer in gamma radiation. S.H.I.E.L.D showed up and... umm. He wasn't heard from again. Jane They're not going to do that to us. I'm going to get everything back. Erik mumbles Please. Let me contact one of my colleagues. He's had some dealings with these people before. I'll email him and maybe he can help. Darcy They took your laptop, too. Cleaning wax and pesticide from apple skin I love apples. I like to eat them with skin as it has plenty of fiber in the skin. But apples are famous for wax and pesticides on the skin which I don’t want to ingest. I have read many articles on the web and suggestions for removing the wax from the surface.   These suggestions include soaking in vinegar or hot water and other methods. They suggest that soaking apples in vinegar removes the wax that can be seen in the vinegar. I have done that, but never seen any residue of wax in the vinegar.   So I have set aside a new kitchen sink Scotch-Brite scrubber for this purpose and been scrubbing the apple skin under running water before eating. I think this method should remove most of the wax and pesticides. I would like to hear your input. How to derive variance-covariance matrix of coefficients in linear regression I am reading a book on linear regression and have some trouble understanding the variance-covariance matrix of $\mathbf{b}$:    The diagonal items are easy enough, but the off-diagonal ones are a bit more difficult, what puzzles me is that  $$ \sigma(b_0, b_1) = E(b_0 b_1) - E(b_0)E(b_1) = E(b_0 b_1) - \beta_0 \beta_1 $$  but there is no trace of $\beta_0$ and $\beta_1$ here.