How can I update to Ubuntu 21.04?
I am currently using 19.04 and I got "No new release found for 19.10"
I have read the explanation for this in several textbooks, but I am struggling to understand it via Archimedes' principle. If someone can clarify with a diagram or something so I can understand or a clear equation explanation that would be great. Convert String to Integer in QGIS tables What’s the difference between "Array()" and "[]" while declaring a JavaScript array? Explanation of Spikes in training loss vs. iterations with Adam Optimizer I am training a neural network using i) SGD and ii) Adam Optimizer. When using normal SGD, I get a smooth training loss vs. iteration curve as seen below (the red one). However, when I used the Adam Optimizer, the training loss curve has some spikes. What's the explanation of these spikes?   Model Details:  14 input nodes -> 2 hidden layers (100 -> 40 units) -> 4 output units  I am using default parameters for Adam beta_1 = 0.9, beta_2 = 0.999, epsilon = 1e-8 and a batch_size = 32.  i) With SGD  ii) With Adam I want to  GRANT SELECT     ON ALL TABLES     TO foo;   But postgres tells me I have a syntax error at "TO". It expects a GRANT like:  GRANT SELECT     ON ALL TABLES     IN SCHEMA public     TO foo;   We have a handful of tables that have been sharded such that public, shard123, and shard124 all have a table my_table, and public.my_table is the parent of both shard123.my_table and shard124.my_table. I've GRANTed SELECT to foo for public schema, but foo doesn't have permission for any of the shard schemas.  I've also done:  ALTER DEFAULT PRIVILEGES     FOR ROLE dba     GRANT SELECT     ON TABLES     TO foo;   ...which should automatically grant for any new tables and schemas made from now on.  There are 1000 &lt; n &lt; 10000 shards/schemas, so GRANTing separately for each shard/schema is impractical.  How can I GRANT to a role for all existing tables across all existing schemas (all shards)?  Or even better, can I GRANT for all schemas LIKE 'shard%'? Real numbers equipped with the metric $ d (x,y) = | \arctan(x) - \arctan(y)| $ is an incomplete metric space I have to show that the real numbers equipped with the metric $ d (x,y) = | \arctan(x) - \arctan(y)| $ is an incomplete metric space.  Certainly, I have to search for a Cauchy sequence of real numbers with respect to given metric that must not be convergent. But I am unable to figure out that.  Can anybody help me with this.   Thanks for helping me. How to edit / how to format box overlapping with footer when scrolling down Java Generics: List, List, List Can someone explained, as detailed as possible, the differences between the following types?  List List&lt;Object&gt; List&lt;?&gt;   Let me make this more specific. When would I want to use  // 1  public void CanYouGiveMeAnAnswer(List l) { }  // 2 public void CanYouGiveMeAnAnswer(List&lt;Object&gt; l) { }  // 3 public void CanYouGiveMeAnAnswer(List&lt;?&gt; l) { } Access server by host name? I have a mixed network with mostly Windows machines, a Mac, and a few Linux boxes.  There is no DNS or WINS server, and adding one is outside of my control.  If I put a clean install of 10.04 desktop on a computer, then all other machines on the network can get to that machine by hostname just fine.    However, if I put 10.04 server on the same computer, then the other machines can only get to it by IP address.  The hostname does not resolve.  What do I need to do on the server so that all the other machines on the network can get to it? This is a "catch-all" question designed to serve as an answer for all questions about choosing web hosting.  Pro Webmasters no longer accepts new questions about how to choose hosting.  All future questions pertaining to finding web hosting should be closed as a duplicate of this question. For more information about this policy please see .    How to find web hosting that meets my requirements?  What we're looking for in answers to this question are the basics about web hosting:   What is web hosting? What is the difference between shared, VPS, and dedicated hosting? How does a content delivery network relate to web hosting? Anything else you feel is helpful in finding a web host.   What we do not want is:   Endorsements or recommendations for specific web hosts We do not want your experience or other subjective information (just the facts please) Use of 'prototype' vs. 'this' in JavaScript? I am a permanent resident (U.S) and I'm crossing the border into Mexico and taking a flight to Mexico city. The passport from my home nation is expired and I'm trying to avoid the last minute 500 mile+ trip to the nearest embassy. My question is, can I get on the plane with my green card or state license? or my expired passport and birth certificate? also, can i get the FMM/tourist card with my drivers license? all the official information says i need a valid passport, but other travelers have had different experiences, does it just depend on the officer? I already purchased my flight! Google Maps Location History is showing an incorrect location I have a major problem that I hope someone can help with. On my Google Maps feature under my Location History it shows a location that I was never at at any point, but when my wife happened to see that location she doesn't believe me that the GPS could be wrong and pinpoint that location if I was never there.  I was first wondering myself how could that could be possible if I was never there or my phone was never at that location that was 35 miles away from me and second is there any way I could prove the GPS being wrong? Can I contact Google Maps and can they give an official printout of that certain day and every location I was? I really need to prove my honesty to her and hope there is a way. n tasks assigned to n computers, what is the EX value of a computer getting 5 or more tasks? Say a central server assigns each of n tasks uniformly and independently at random to n computers connected to it on a network. Say a computer is ‘overloaded’ if it receives 5 or more tasks.  Q: Calculate the expected number of overloaded computers.  I thought of doing [1 - Pr(a computer is not overloaded)] but that leads me to a complicated expression of: $$1 - PR(NotOver) = 1 - \sum_{i=0}^4  \left( \frac{1}{n} \right)^{i} { \left( \frac{n-1}{n} \right)}^{n-i}$$ multiplying this by n would(hopefully) give the Expected value. But the answer seems not very elegant atall, is there something I'm missing or an easier way to tackle this? Thanks! How to Send Html Emails in Google Spreadsheet Here's an example of a Google Docs Spreadsheet script that sends emails using Google spreadsheets. I want the email Sent in HTML not plain text. Can someone help me out?  function sendEmails() {   var sheet = SpreadsheetApp.getActiveSheet();   var startRow = 2;  // First row of data to process   var numRows = 2;   // Number of rows to process   // Fetch the range of cells A2:B3   var dataRange = sheet.getRange(startRow, 1, numRows, 2)   // Fetch values for each row in the Range.   var data = dataRange.getValues();   for (i in data) {     var row = data[i];     var emailAddress = row[0];  // First column     var message = row[1];       // Second column     var subject = "Sending emails from a Spreadsheet";     MailApp.sendEmail(emailAddress, subject, message);   } } I hope I'm right in thinking this is the site where you post general computer-related problems...  A problem I have when playing games (since you won't be pressing multiple keys simultaneously anytime else), is that when I press up/left and then another key, it fails to 'register' as if that last key is never pressed. This doesn't happen when I'm pressing any other two arrow keys, e.g. down/left or up/right. The weird thing is that when I'm playing with WASD instead of the arrow keys, i still have this problem! Meaning W+A+another button doesn't work.  If anyone knows what I should, I'd appreciate the help. (My reflexes are fast and I can always circumvent this problem, but it's quite annoying and shouldn't exist to begin with!) What does $\rightarrow$ mean in $p \rightarrow q$ I was looking at an exercise where it asked the following:  $$\begin{array}{ccc} p&amp;q&amp;p\rightarrow q \\ T&amp;T&amp;T \\ &amp;\ldots \end{array}$$  So, for the third column, I just put $T$ which was correct but I didn't understand what $\rightarrow$ meant. I have seen $\implies$ but I haven't the arrow. Are they the same thing?  Thanks a bunch! Finding empty directories recursively What is the term for taking it out on someone even though you will be harmed by this too? When you are so mad at someone that you make a bad decision, even though you will be harmed by it as well, in order to harm that person; is there a good term for this?   For example burning $100 because he owns $20 of it. Version tags reloaded I'm getting sick of version numbers in tag names (aka version tags). Look,      I just want them all to be just . They are all about JSF. I browse and answer questions about JSF. I don't want to browse in all those different tags. I don't want gold badges for both  and . I can't hammer a duplicate  question because I don't have a gold badge for that. Across years I observed that a version tag is usually only picked by the asker when a &quot;relatively new&quot; or &quot;relatively old&quot; version is being treated in the question. When the &quot;currently mainstream&quot; version is being treated,  or when the asker is &quot;more proficient&quot; in the language, then askers often just pick the versionless . While moving in time, this may cause confusion by future readers when the version isn't explicitly specified anywhere in the question. I try to maintain them by adding/removing the version tag depending on its relevance, and by adding the versionless tag when it's absent. It only feels a neverending story. I'm sure other tag caretakers also have mixed feelings on this. I propose to normalize the version from the tag name:  Ban version numbers in tag names in the model (not in the UI). Add an optional single-choice version field to the Tag entity in the model. Users with edit privileges (no suggested edits please) must be able to change versions. Users with gold tagbadges must be able to add and edit versions. I'd imagine the version edit thing to be reachable via that tag info popover (when you hover the tag). Tags themselves however should look exactly the same, the version just separated with e.g. a hyphen from the tag name.  When in place, migration of existing version tags should be piece of cake. There's apparently already a script in place which recognizes version tags, it could be reused to re-match current tags and extract the version from it into the new version field. The alternative would be to automatically add the versionless tag when a version tag is being used. But this is IMO only tag pollution.  I'm posting this on meta.se instead of meta.so because version numbers aren't only on SO a problem, but on basically all HW/SW related sites.