How do I download Ubuntu using BitTorrent on Windows?

Question: I am trying to download and install Ubuntu. I was told that downloading a torrent was a good option, as it can deal with interrupted downloads very well.

Where should I go to download an Ubuntu torrent?
What programs should I use for this on Windows?
What is the bare minimum I need to know about BitTorrent for this use-case?
Answer: Canonical provides detailed instructions on how to use BitTorrent as well as how to obtain their official torrents for their ISO images here. Below is a brief summary on how to obtain a copy of those torrents to download.
Where should I go to download an Ubuntu torrent?
The torrent files needed for downloading an Ubuntu ISO are made available by Canonical as an alternative to downloading the entire ISO directly.

From the Ubuntu homepage, select the Download tab.
Next, scroll down to the bottom of the page and select the link:
Take a look at a full list of our previous versions and alternative downloads
On this page, you will see the links for the currently available Ubuntu torrents.

If you would prefer, you can select a local mirror that is geographically closer to your region to obtain the torrent.
Direct links to all ISO torrents:
These will open directly in your torrent client (uTorrent, Vuze, etc.)

Ubuntu 12.04.2 Precise Pangolin

Desktop

32-bit
64-bit

Alternate (text-based installer)

32-bit
64-bit

Server

32-bit
64-bit

Ubuntu 12.10 Quantal Quetzal

Desktop

32-bit
64-bit

Server

32-bit
64-bit

Ubuntu 13.04 Raring Ringtail

Desktop

32-bit
64-bit

Server

32-bit
64-bit

Source: http://www.ubuntu.com/download/desktop/alternative-downloads
See also: Previous AU Q&A
What programs should I use to download torrent files on Windows?

uTorrent
Vuze
BitTornado
BitComet

What is the bare minimum I need to know about BitTorrent for this use-case?
After installing your preferred BitTorrent client, all one needs to do is download the torrent file from the one of the direct links mentioned above. Your browser should ask you what you want to do with the file. Instead of saving it, have your browser open the file with your newly installed torrent client.
See also: A Beginner's Guide to BitTorrent
Answer: To download an official Ubuntu release via torrent visit http://www.ubuntu.com/download/desktop/alternative-downloads
The bare minimum you will need to know about bittorrent is that you will need an application which will start the download with a .torrent file. Then once the download has completed it will continue to share this file until the application exits.
utorrent has been the go-to application for a long time, however if you have the opera web browser installed already it will download a torrent natively.


It is normal for glass-ceramic cooktop to be hot?

Question: I just bought a stove with glass-ceramic cooktop and I'm frustrated because when I use one hot plate the whole cooktop is hot (even the metal corpus around it). Is this normal or the cooktop must be cold except working hot plate?
Comment: This is definitely not standard behavior. Something is weird here.
Comment: ...or maybe the cooktop is so stunningly good-looking? ;-) (HOT)
Comment: I use non-induction heating but I was thinking that the glass must remain cold (except working hot plate). Please give me more opinions if this is normal or not because I have no friends with ceramic stoves to ask (the all use gas cooking stoves).
Comment: @StevenSmith  I just checked this question on google pages in my country. People are saying that ceramic cooktop may behave like that (I mean, it may be ok that more than the under-pot plate is hot), but I my understanding of HSE matters (safety, for that matter) tells me that if corpus is hot, too, it may cause a risk of damage/incinerate shelves (depends on the temperature). You may want ot contact producer to explain this.
Comment: @MarekOleszczuk What made me tick was also the corpus. No appliance manufacturer is going to risk a user getting a burn and then suing them, not good for business.
Comment: how hot? do you have a temperature number to work with? we use a ceramic cooktop, and almost the entire thing gets warm, specially when the larger burners are used. not hot as in enough to burn, but definitely warmer than ambient.
Answer: No, it definitely sounds like there may be an issue with the contacts. If the cooktop is relatively new, contact the installer/manufacturer to decide if you have received a faulty product.


Customize style of a vector layer ol3

Question: I use a geojson file to build the layer added to a map. What I want is to customize style of the layer's polygons in order to have hatched polygons such as we can do that with mapserver symbols. Is it possible to do this with ol3? I tried to create an image and use it but it only works for point geometry. Thank you for your help.
Regards.
Answer: Fill patterns for polygons are not (yet) supported in OpenLayers 3, see also https://github.com/openlayers/ol3/issues/2208
Comment: Thank you very much, I m gonna find another way to style my polygons.
Answer: It is possible by now. The ol.style.Style object accepts a CanvasRenderingContext2D instance, where you can apply an image pattern to your polygons.
Example Code Snippet
var geojsonObject = 'someGeoJSON'
var source = new ol.source.Vector({
 features: (new ol.format.GeoJSON()).readFeatures(geojsonObject)
});

var layer = new ol.layer.Vector({
source: source
});

var cnv = document.createElement('canvas');
var ctx = cnv.getContext('2d');
var img = new Image();
img.src = 'https://mdn.mozillademos.org/files/222/Canvas_createpattern.png';
img.onload = function() {
  var pattern = ctx.createPattern(img, 'repeat');
  layer.setStyle(new ol.style.Style({
    fill: new ol.style.Fill({
      color: pattern
   })
 }));
};

A full example can be seen here: jsfiddle

Customize style of a vector layer ol3


What class should have ability to set a password (Repository, User, etc)?

Question: I'm using Entity Framework 4. I'm not really sure where the responsibility of setting a user's password should be. I thought about on the Repository like SetPassword(User user, string password). But it doesn't seem right.
The main problem is that it can't just be a simple property setter since I also return the salt that's generated.
Answer: You may want to create a module of some sort to handle password creation for the User class to call out to. This is more compliant with the Single Responsibility Principle (a class should have only 1 responsibility, sometimes read as "only 1 reason to change").
Since your passwords should be salted and hashed before they are persisted, that's definately out of the scope of what a User should be doing.
Then you could have a module separate of the User for authenticating the password using the same salt and hash method.
Comment: Would you recommend a `SetPassword(string password)` on the User that *calls* the "PasswordManager"?
Comment: That's precisely what I would do. Make an IPasswordManager and inject the dependency, though. Don't go new-ing up your own PasswordManager inside the User. You want to keep a loose coupling between the User and the PasswordManager.
Answer: You could introduce a Password class. The Password property on the User class should be of type Password, instead of string.
public class User
{
  public Password Password { get; set; }
}

public class Password
{
  private string value;
  private string salt;

  public Password(string value)
  {
    this.salt = "generated salt";
    this.value = value;
  }

  public string ToHashedString()
  {
    // Return the hashed password.
  }
}

The Password class could be responsible for generating the salt itself. You can also introduce a PasswordService that uses other dependencies to generate the salt and construct a Password instance.
Answer: It should not be in the Repository as it should only be for database access and not for  business logic. I think it should be in User class.
public class User
{
  IUserPasswordManager _userPasswordManager;

  public string SetPassword(string oldPassword, string newPassword)
  {
     //Set password and return salt
     return _userPasswordManager.SetPasswordForUser(this, oldPassword, newPAssword);

  }

}

Comment: Your answer is conflicting with what I've found: http://stackoverflow.com/questions/1307490/password-hashing-etc-in-service-layer-or-repository
Comment: Also consider to make roles explicit and Single Responsibility Principle and make separate type UserPasswordManager. Cos it is a little bit illogical for user to has method SetPassword, it is like saying "hey User, go and change your password" =) Instead of "hey PasswordManager please help me"


Stopping Heap Growth Related to a Core Data Managed Object

Question: I'm noticing some heap growth when I run instruments.  There are no leaks but there is some memory that is not clearing that looks to be caused by my use of core data.

From the stack trace it seems the growth happens when I save the managed object.
This is how I'm creating the managed object:
ScramblerGame *game = (ScramblerGame *)[NSEntityDescription insertNewObjectForEntityForName:@"ScramblerGame" inManagedObjectContext:self.context];
game.time = [NSNumber numberWithInt:self.time];
game.score = 0; //etc...

ScramblerGame is a managed object subclass created right from the data model with no modifications.
This is how I'm accessing and updating the managed object:
self.game.score = [NSNumber numberWithInt:[self.game.score intValue] + score];

self.game is a weak reference in another class to the managed object.
This is the method called at the end of a game that saves or deletes the data.  It is also the last of my methods called in the stack trace of the referenced image, which is leading to the heap growth.
-(void)saveAndHandleGameData:(BOOL)stillPlaying{
[[NSNotificationCenter defaultCenter] removeObserver:self name:NSManagedObjectContextObjectsDidChangeNotification object:nil];

//save the data to disk
self.game.inProgress = [NSNumber numberWithBool:stillPlaying];
SCAppDelegate *appDelegate = ((SCAppDelegate *)[[UIApplication sharedApplication] delegate]);
NSManagedObjectContext *context = appDelegate.managedObjectContext;

if([self.game.score intValue] == 0)
    [context deleteObject:self.game];
[context save:nil];
self.game = nil;

}

So am I doing anything wrong with core data that is causing this?  Any advice on how to stop the heap growth?
Answer: Everything looks OK. The minimal increase in memory can be regarded as normal and should be expected.


How to stop Mail.app in Lion creating an Archive folder for archiving in Gmail?

Question: Mail.app in Mac OS 10.7 added an Archive button. Unfortunately, when archiving a message in a Gmail account, instead of simply putting the message into All Mail folder, Mail.app creates a folder called Archive (in Gmail web interface this folder comes up as [Imap]/Archive) and puts the message there. Is there a way to tell Mail to put the archived messages into Gmail's All Mail instead?
Comment: I'm surprised there is no "Use this mailbox for Archive" feature like there is for Drafts/Junk/Sent/Trash.
Comment: I found out that a message that is moved to Archive folder will be archived for real in Gmail if I archive it again (in Archive folder).
Comment: I don't think it's a useful feature for Gmail IMAP. The mail in the inbox should already be in the All Mail folder so you're better off deleting it from the Inbox instead of archiving it.
Comment: The Mail.app which uses the Message.framework which contains the list of mailbox names that it uses does not specify an Archive mailbox name unlike the others.  strings /System/Library/Frameworks/Message.framework/Versions/Current/Message | grep MailboxName | sort seems to not show a notion of Archive, but there is a text called "Archive" which means that it is hard coded into the binary.
Answer: You could edit /Users/<username>/Library/Mail/V2/MailData/Accounts.plist setting ArchiveMailboxName to [Gmail]/All Mail then restart Mail. This seems to work for me.
Comment: this works great! just replace the "sj26" with your username
Comment: Yeah, this is perfect until a certain future version of OS X is released, then maybe Apple will fix the behavior. Please mark this as accepted.
Comment: Couldn't find this file in MacOS 12.6?
Answer: I created an AppleScript to move messages to [Gmail]/All Mail though and then created a service so I can run it from a keyboard shortcut. The AppleScript is here: http://gist.github.com/1134751 I'm not thrilled with it's performance though.
FastScripts (http://www.red-sweater.com/fastscripts/) could be be used to assign a keyboard shortcut to the script itself - without having to turn it into a service.
Answer: It seems that it's easier to turn off the "Move deleted message to Trash mailbox" in the Mailbox Behaviours tab of the Gmail account preferences and continue using the usual Delete button instead of the new Archive button. This way when you delete the message it is simply removed from Inbox, i.e. in Gmail terms "archived".
Comment: This isn't what the original poster (and myself) are looking for. Doing it your way means that no messages are deleted in normal operations. There's a number of messages that I DO want to delete, and others that I want to archive.
Comment: You sure? This answer comes from the original poster :p
Answer: I don't know how to change the button action.
However, it is possible to create a keyboard shortcut to Archive a message using the commercial plugin Mail Act-On. After watching a couple of the tutorials, I wrote an Act-On rule for every one of my accounts that archives ("moves") the message(s) to the correct [Gmail]/All Mail folder. You can map all of the rules to the same keystroke (I used Control-A) and tell each rule to stop when matched.
Answer: I went into Gmail on the browser, then settings -> labels.
Then unticked "Show in IMAP", back to inbox then closed browser.
I then gave it a moment and Quit mail and opened it again.
There was a huge sync, re-downloading all of Gmail messages again and the Archived folder is gone.


Microsoft Office Document Imaging with Windows CE 6.0

Question: Can I use the MODI library with Windows CE 6.0? Otherwise what kind of OCR can i use with Windows CE 6.0?
Answer: MODI is not supported on Windows CE. Nuance used to have a product called "Mobile OCR" that supported CE.  I don't see it on their web site any longer, though the OmniPage Capture SDK looks like it's the likely replacement.  Their site is unclear about platform support - they simply say "mobile" and "embedded" are supported, so you'd probably want to contact them and ask.


Rainbows on Titan?

Question: Could a methane rain on the moon Titan produce a rainbow under the right lighting conditions? If so, can the 'angle' of such a rainbow be predicted?
Comment: I found this link on the nasa website that discusses the possibility of rainbows on Titan: http://science.nasa.gov/science-news/science-at-nasa/2005/25feb_titan2/
Comment: @Paul  Thank you for the reference. It actually answers my question quite well, including the angle ( $49^\circ$ to $52^\circ$ degrees). It also mentions that a visible light rainbow would be very rare because of the haze but that an infrared rainbow would be possible.
Answer: No. The atmosphere of Titan is a thick brown haze. What light penetrates is diffuse, scattered in all directions. It would be like looking for a rainbow in a fog bank.
A rainbow requires direct sunlight coming from one direction.
Comment: Quote from the Wikipedia article on the atmosphere of Titan: "The Huygens probe was unable to detect the direction of the Sun during its descent, and although it was able to take images from the surface, the Huygens team likened the process to "taking pictures of an asphalt parking lot at dusk".
Answer: Extensing @Mmesser314 's pretty answer, it may be possible in its higher athmosphere. It depends on that does an altitude exist, where

the atmosphere is already enough rare to see the Sun (thus, sunlight is mainly unidirectional)
but, we aren't enough high to have small liquid methane drops in it.

Even if there is such an altitude, the rainbow wouldn't be visible from the surface (because even the Sun is not visible).

Rainbows on Titan?


Creating & handling large matrices in python?

Question: I need to create a large matrix of size 400,000*400,000 and do some transformation on it. I am not able to do it using python in my laptop due to memory constraints. What technologies I can use to achieve this?
Comment: Maybe [dask](https://dask.org/).
Comment: What transformation? Some operations don't require the entire matrix to be in memory, but rather you can load in columns/rows as needed and persist the rest to disk.
Comment: When you say 'not able to to it' do you mean you don't know how to technically implement it or do you run into errors/other issues?
Comment: I get  MemoryError: Unable to allocate 340. GiB for an array with shape (307180, 148485) and data type float64
Comment: I would have expected as much, I am not sure there are good solutions other than changing the data type to a lower precision (e.g. float32 or even lower if possible) or maybe using a sparse matrix if you're working with sparse data.
Comment: I am facing above error with a sparse matrix
Answer: I don't know if this is your job work or your personal project but cloud services can help you. Create a free account on Azure (you get 200$ worth free credit for 1 month) and the account is free for1 year.
You can run your project there using Azure Machine Learning/AutoML/Python SDK whatever you choose. Use the free 200$ credit in 1 month for any kind of large scale project which requires large computational power or large memory requirement. The link will give you an idea about the computational power and memory capacities on Azure.
Comment: So on Azure you can allocate a matrix of 340 GiB? Unlikely!
Comment: https://docs.microsoft.com/en-us/azure/virtual-machines/sizes-memory Yes you can. The Mv2 series offers upto 11.4Tb.
Answer: You can also buy some GPU's which will always help you to make up for the low memory allocation.
Cloud services will help as well but the variable costs are too high if your objective is to work on high dimension matrices
Comment: How does buying GPUs help in allocating a matrix of 340 GiB?
Answer: Are many of the entries in the matrix zero? In this case, you can often deal with large matrices without using large amounts of memory. Sparse matrix data structures exist and so do algorithms for doing arithmetic with them.
scipy includes support for sparse matrices.
https://docs.scipy.org/doc/scipy/reference/sparse.html
Answer: You can use Dask array, in which you can create essentially any size array and apply some transformation. What it basically does is load a chunk of the array that can be fit into memory process it and then save it. Check the following link :
[https://examples.dask.org/array.html][1]


Isn't this question too localized?

Question: Interview question: Why did you leave your previous role?

The title would make you believe that this is a generally useful question.

However, the content is very specific to one individual's situation.

Isn't this question too localized?
Answer: Not Quite Too Localized
Rarity made some edits to narrow it down a bit, which makes it a bit more readable. Reading it now, the situation is about a specific interview question, but it's something that a lot of people can probably relate to in a more general sense.
Additionally, some of us may have left jobs in the past in less than favorable circumstances. Therefore, it's quite possible that there is a large audience out there in the worldwide Internet that may benefit from the answers given to the question. After all, many of us have been asked a similar question in an interview before and many of us have probably had some bad employment experiences in our past.
However, I strongly suggest anyone who answers the question to try to generalize the information so that it would apply to anyone in this situation. The more broad and generalized the answer, the more likely it is to be helpful to others.
With that said, I think Jim's suggested edit could also be helpful to dispel further doubt as to whether or not the question is too localized.
Can a question be edited after it has answers?
I believe that 12 hours isn't too late to edit a question to make it fit the guidelines a bit better, despite answers. Anyone who answered will learn that the correct course of action is to seek clarification before answering, edit, vote to close, or flag, if a question doesn't meet guidelines.
Answers can't exist without questions, we've learned this from sites that have low questions per day. The way I see it, anyone who answers a question that should be closed is responsible for editing or deleting their answer if it no longer fits the question. I sort of see that as the cost of waiving one's responsibility to flag or vote to close. :)
I don't mean this to be harsh or disrespectful to anyone who answered, just that with the editable nature of our site, one has to understand that the goals are to make the content better, and that generally starts with the questions themselves.
Answer: As it's worded now, it is pretty localized. I think that it could be altered to be more general if it started with a modified version of the last line, perhaps something like

How can I explain leaving a company because of negative experiences/interactions/people without sounding bitter or trite?

and used a (much) briefer version of the rest of the question as an example.
However, I'm not sure if editing it to fit that would be too drastic (I think it might be a bit late here since there are several answers already). If we are going to close it as too localized, though, I think it would be best to go ahead and make such an improvement, biting the bullet as far as invalidating whatever answers it may.

Isn't this question too localized?


How to know base token from the pool

Question: here is quick question. From uniswap pool, which one is base token? token0 or token1?
Answer: Price in Uniswap pools is tracked in terms of token1/token0, so token1 is the numeraire token if that's what you're asking.
Comment: like when i flashloan from the pool, the loan must be repayed by base token. this is the reason i ask the question. so i must pay the loan in token1. Right?
Comment: @BirukDamte you can make a flash loan or a flash swap with Uni, but where does the name "base" comes from?
Comment: from youtube tutorial. Any way ur answer helped me. Thanks bro
Answer: There is no on-chain way to determine which token is a base token or which is a quote token if token0 and token1 are mapped to normal trading pairs.
The trading pair base-quote token order is a human-made concept for making natural reading easier. Thus, you need to have your own rules that determine which of the tokens is a quote token (determining quote is usually easier than determining base).
Here are some rules that can help you

First determine if a token is stablecoin. Have a hierarchy of stablecoins to determine a "better stablecoin for stable-stable pairs.

Then check for a native token. A quote token is usually ETH (WETH), MATIC (WMATIC), AVAX (WAVAX) or similar. All "large cap tokens", including BTC (WBTC) are good quote tokens.

If you still cannot determine then flip a coin. However, in this case, it's an exotic pair you probably do not want to trade in the first place.

How to know base token from the pool


Is there a way to find out a player's name using commands?

Question: I'm trying to make map where if you die, it says in the chat that the player in question has died. For example, if a guy named BlehBlehBleh died, it would say in the chat, "BlehBlehBleh has died!" or something like that.
P.S I think it has something to do with scoreboards.
Answer: Using selectors, you can easily say BlehBlehBleh died!
With the say command
/say @a[deaths=1] has died!
That will say any player with the score deaths = 1 has died. Then you would set his deaths to 0 to avoid a loop :) Also, detect IF a player has died first before doing the command.
So order of the commands:
scoreboard players test @a deaths 1
Then
say @a[deaths=1] has died!
scoreboard players set @a[deaths=1] deaths 0
So you would be right thinking its about scoreboards.
Edit: To store someones name in a scoreboard just make an objective then type this in
scoreboard players set @a objectiveName 0
That would make the score of every player set to 0. To add a deathcount just do
scoreboard objectives set deaths deathCount I believe


About Van der Waals (vdW) correction in VASP

Question: I would like to know when we need to apply Van der Waals (vdW) correction in our system. If I am dealing with 2d systems (monolayer or bilayer), then should I need to add IVDW (vdW (dispersion) correction) tag in the VASP input file. What is the role of vdW correction.
Also, I would like to know when we are applying SOC in the calculations, can we escape vdW correction at that time.
Comment: I gave my +1 long ago but have you figured this out now? Please update us! Are you still urgently or actively in need of an answer?
Answer: Van der Waals (vdW) correction is important in systems where non-local interactions between atoms or molecules play a significant role. It is particularly relevant for materials with layered structures, such as 2D systems (monolayers or bilayers), as these systems often exhibit weak interlayer interactions.
The vdW correction accounts for dispersion forces, which are long-range interactions arising from the fluctuating dipoles of atoms or molecules. These forces are not adequately captured by standard density functional theory (DFT) calculations. You might think that you will not include these forces in a monolayered system, however, weak interlayer interactions can still exist in monolayered systems due to the presence of vdW forces, specifically dispersion forces, that can arise from the fluctuations in electron density and induce temporary dipoles in adjacent atoms or molecules. These temporary dipoles can induce dipole-dipole interactions, resulting in weak attractive forces.
Regarding the inclusion of vdW correction when applying spin-orbit coupling (SOC). The vdW correction and SOC address different physical phenomena. The vdW correction accounts for long-range dispersion interactions, while SOC describes the interaction between the electron's spin and its motion. In most cases, both effects can coexist, and including both in your calculations provides a more comprehensive description of the system.


What does this small triangular symbol at the upper-left corner of a brush preset thumbnail mean?

Question:
I made a new triagular brush with Edit -> Define Brush Preset. In the Brushes panel, its thumbnail has a little triangle at the upper-left corner. The default round brush doesn't have one. What does it mean?
Answer: It means the brush is 16bits/channel, and when you made the brush you must have been in 16bits/channel mode. If you don't want 16bit brushes, click Image > Mode > 8 bits/channel before making the brush.
It's almost impossible to read the numbers, but there actually is a "16" in there.
Comment: Ah, of course! I found the 16 easy enough to read, but could only think of obviously incorrect things like 'it's the 16th preset/swatch'. ♂


I'm developing a Weebly app - why is the :jwt in the following entry in our manifest not being replaced?

Question: does anyone have any ideas why the :jwt in the following entry in our Weebly app manifest isn't being replaced?
"callback_url" : "https://www.mymobileapp.online/home/index?vendorId=Weebly&:jwt"
The incoming request I see is:
https://www.mymobileapp.online/home/index?vendorId=Weebly&:jwt?user_id=62581379&timestamp=1479434021&site_id=163706648712782041&hmac=...our_hmac...&version=1.0.0&callback_url=https%3A%2F%2Fwww.weebly.com%2Fapp-center%2Foauth%2Fauthorize
so, as you can see, the ':jwt' is still there, and Weebly is appending it's querystring operand and parameters after it.
I've read the "Configure the Manifest for OAuth" section on the page below, and as far as I can see I'm configuring the manifest correctly. What am I missing?
https://dev.weebly.com/configure-oauth.html
Answer: You may have figured this out, by now, but your callback_url should NOT have the  :jwt in it to begin with.. Problem solved ;)
If the user can manage the App/Settings, then you would use manage_app_url. And on the page of your website that you have set for the manage_app_url you would then listen for jwt. (then you can also use "oauth_final_destination" : "manage", if you want them to end up on your site after the install) See: https://dev.weebly.com/how-users-manage-your-app.html
**EDIT
See also: https://dev.weebly.com/sso-with-jwt.html
**
So for example, with PHP, on the manage_app_url page of your site you would do:
if (isset($_GET['jwt'])) {
   $app_client_id = "Your APP ID";
   $client_secret = "Your APP SECRET";
   $jtw = $_GET['jwt'];

   /**
   * You can add a leeway to account for when there is a clock skew times between
   * the signing and verifying servers. It is recommended that this leeway should not be bigger than a few minutes.
   * Source: http://self-issued.info/docs/draft-ietf-oauth-json-web-token.html#nbfDef
   */

   try {
     JWT::$leeway = 60; // $leeway in seconds
     $decoded = JWT::decode($jtw, $client_secret, array('HS256'));
     if (!empty($decoded)) {
         $decoded_array = (array) $decoded;
         // Continue with your websites code to verify the Weebly users info
     }
   }
} // END IF ISSET JWT

Answer: Although this response is correct, I think the original post was off as its the manage_app_url that uses the :jwt
I had the same issue, but discovered that it does not work when installing as a draft app, however, accessing the "manage app" link thru the app interface and it is correct. ie., the :jwt is replaced with the proper url.
Sop the issue is in the installing of a draft app, and not in the actual managing the app thru the front facing interface
Answer: Jeffery, you are absolutely correct sir. I am only adding this as an answer to expand upon yours with some additional security recommendations Weebly considers best practice.
The primary use cases when developers need to implement the JWT "JSON Web Token" are (see links in Jeffery's answer above for more details):

Providing user-contextualized data for Weebly Apps dependent upon configuration/setting parameters to be defined/stored/manipulated outside of Weebly (external services)
SSO (Single-Sign On) support

Two Ways the :jwt is included in the URL
Your Weebly App manifest.json file(s) may contain URLs that trigger Weebly to provide you a JWT:

manage_app_url
element.settings.config.external.url
Dashboard Card Link Components --> dashboard_cards.link || dashboard_cards.default[{{SOME_COMPONENT}}].link

Developers can define the position of the JWT in these URLs using one of two approaches:

IMPLICITLY DEFINED: Weebly automatically appends the JWT string to the developer-defined URL (and any appropriate operands such as & or ?)
EXPLICITLY DEFINED: Indicated by using :jwt at any valid location within the URL values you provide in your manifest.json file

Production Security Best Practices and Considerations
Using the decode method of the PHP library above is handy and quick during development, but when developers are ready to publish their Weebly Apps to the App Center, you will want to include the maximum security possible.

Request Scheme Invalidation: Verify the scheme of the inbound request is using https
Request Domain Invalidation: Verify the headers.host of the inbound request contains the valid weebly domain and .com TLD (since requests containing the JWT should only ever come from https://www.weebly.com
Auto-Reject Tokens with Mismatched Signature Types: Some JWT libraries do not auto-reject tokens if the signature type is mis-matched, which allows hackers to forge requests in these case read this document from Auth0 for more information
IP Address Max Requests per [TIMEFRAME]: To prevent brute-force hacking or DDOS attacks on these URLs, you may want to include functionality that automatically caches multiple requests within a specific timeframe. This should be a relatively high-value in a short-period of time, since humans can have request performance limitations in valid use-cases.

While the above content about security is not currently part of official Weebly documentation, I have submitted an issue to include it in the future.
Also, I saw that we recently moved content and did not include the 301 redirects for the URLs referenced in the original question or Jeffery's answer. We just fixed that so your links work properly.
I hope this helps and the information is valuable for you.


Gmail Draft emails do not sync properly between Apple Mail.app (on Mac) and iPad

Question: My Gmail drafts are not syncing properly between Apple's Mail.app (on the Mac) and the Mail app on the iPad. What is the proper way to set up drafts so that they sync properly?
Answer: First - you'll want to set up two draft messages. One on the iPad and check using a gmail web interface if it's really storing the drafts properly to gmail. The iOS uses exchange active sync, but that shouldn't matter to you - either the iPad is storing it to the server (as viewed through mobile safari or any other web interface to gmail) or it isn't.
Repeat for Mail.app on the OS X. Here, you have more control (and more opportunity to set it up improperly).
The main item that would cause issues is if mail thinks it's not supposed to store drafts on the server. See the Accounts preference for your gmail account.

From there, you'll have to use the help menu to look into how to manually synchronize or run the connection doctor to see if/why mail isn't able to store drafts as directed. The last resort would be to hit up the google support link provided at the bottom of the mail account pane. Hopefully, you can suss it out with these tips.
Comment: If you are using Exchange for Gmail on the iPad, drafts created on the iPad will not save to the server. If you use IMAP, they will.
Comment: Yes, but if my iPad's drafts are not being store on the server, how do I get it to do that??
Comment: Delete the account and set it up again? (check the outbox/drafts before deleting)


What is the highest possible frequency for an EM wave?

Question: What is the highest possible frequency, shortest wavelength, for an electromagnetic wave in free space, and what limits it? Is the answer different for EM waves in other materials or circumstances? How could waves of this frequency be generated and transmitted, again if that is possible?
Answer: String theory assumes that lorentz covariance is a perfect symmetry of our world. If that is true, it means a single photon is allowed to have an arbitrary energy, even greater than Planck length.
You need at least two photons that are not parallel to have a rest frame where something like a Planckian black hole might be generated that will absorb them. But single-photon states cannot be bounded in energy like this in a pure vacuum.
If the vacuum is not pure, presumably the ultra-planckian photon will react with background photons creating black holes in the rest frame and being absorbed by it.
Answer: It's theorized that the Planck length is the smallest meaningful unit of distance. A wave with that wavelength would have a frequency of $\approx 6.2\cdot 10^{34}\,\text{Hz}$. A gamma ray typically has a frequency of $>10^{19}\,\text{Hz}$. Since the energy of a photon is directly proportional to its frequency, this theoretical upper bound would require vastly more energetic processes than those we presently conceive of. The individual photons involved would each be carrying $41\,\text{joules}$, or $2.56\cdot 10^{20}\,\text{eV}$, of energy.
That's a lot of volts!
Comment: @lurscher: It's not a paradox, because the answer doesn't assume string theory is correct.
Comment: well, but there you got a nice paradox: since string theory assumes that lorentz covariance is a perfect symmetry of the world, a single photon could have any energy, even greater than Planck energy. You need at least two photons to have a rest frame where a plancking black hole will form
Comment: The Planck length isn't actually the smallest meaningful unit of distance - that's a widely held misconception. But it is theorized that there is some size below which any object collapses to a black hole, and that size is probably on the order of the Planck length.
Comment: I think you dropped a factor of c somewhere in your calculation.
Comment: How do you get 6.2e34 hz?  It's c/l, not 1/l.
Comment: I'm sure that if that's the bound, then it must be unreachable as asymptote. So, we'd need infinite energy to make such a photon.
Comment: Yup, c/l gives a frequency of about 1.85e+43 Hz with about 1.23e+9 J per photon! Quite a lot of energy there ; )
Answer: The highest measured frequencies of EM waves are Gamma-rays and are typically produced from the decay of atomic nuclei.  The most powerful sources of gamma-rays (and usually the sources with the shortest wavelength) are caused by astronomical events.  Recently there was a very strong gamma-ray burst from Cygnus-A, .  It is estimated that the gamma ray burst was the result of the black hole gobbling up something with three times the mass of the Earth.
There is no theoretical upper limit for the frequency of gamma-rays.  To make one bigger than what we've seen so far will require starting with a super-massive black hole and something much larger than the Earth.  Not quite reproducible in the laboratory.
Comment: You probably either meant [Cygnus A](http://en.wikipedia.org/wiki/Cygnus_A), the very distant radio galaxy, or [Sagittarius A*](http://en.wikipedia.org/wiki/Sagittarius_A*), the black hole at the center of our galaxy.
Comment: I suspect that there might be an upper limit where the wavelength of the photon approaches the [Planck length](http://en.wikipedia.org/wiki/Planck_length) (1.6162e-35 m). If my math is correct, this single photon would have an energy on the order of 12.3 GJ.
Comment: @ChrisWhite It's probably about [this](http://arxiv.org/abs/1305.2128). Also I believe that even if there is no perfect definition of gamma-ray bursts then this event was definitely not one of them.
Comment: our spectrum is only limited by the sensors we can build. Anything beyond that is not visible to us.
Answer: The theoretical maximum possible frequency threshold for small wavelength; it get's grainy in quantum scale, for electromagnetic radiation on Earth is the Planck frequency, which is approximately 1.85487×10^43 hertz. Which is the maximum conceivable inverse introduction of a EM wave from a source to it's successor or receiver in the maximum ideal threshold of time (Planck time) across a Planck unit of distance, this borders on 18 Trillion Quettahertz; Quetta being newly founded unit prefix...
Answer:
At what frequency does the wavelength = the height of the wave amplitude ?

At 7.7646 x 1020 Hz. The associated wavelength and amplitude is 3.861 x 10−13 m. The electron Compton wavelength is 2.426 × 10−12 m, which is 2π times this amplitude.

The wave height = the physical space the waveheight occupy in space, similar to the wavelength. My assumption is that the wave height of the basic electromagnetic wave is fixed.

Correct. Take a look at some pictures of the electromagnetic spectrum, note that the amplitude is the same regardless of frequency, and note that the dimensionality of action h can be expressed as momentum x distance. Also note that the reduced Planck's constant ħ is h divided by 2π.

It's important to note that an electromagnetic wave is an electromagnetic wave. Some people will tell you it's an electric wave and a magnetic wave which generate one another, and therefore no medium is required. That's not true. Check out the Wikipedia electromagnetic wave article and note this:
"Also, E and B far-fields in free space, which as wave solutions depend primarily on these two Maxwell equations, are in-phase with each other. This is guaranteed since the generic wave solution is first order in both space and time, and the curl operator on one side of these equations results in first-order spatial derivatives of the wave solution, while the time-derivative on the other side of the equations, which gives the other field".
What people call the electric wave is actually the spatial derivative of the electromagnetic wave, while the magnetic wave is actually the time derivative. They are merely two aspects of the same wave, not two different waves. And as Maxwell said, "light consists of transverse undulations in the same medium that is the cause of electric and magnetic phenomena". When an ocean wave travels through the sea, the sea waves. When a seismic wave travels through the ground, the ground waves. When a gravitational wave travels through space, space waves. See LIGO:
"Albert Einstein predicted the existence of gravitational waves in 1916 in his general theory of relativity. Einstein's mathematics showed that massive accelerating objects (such as neutron stars or black holes orbiting each other) would disrupt space-time in such a way that 'waves' of distorted space would radiate from the source (like the movement of waves away from a stone thrown into a pond)".
The same is true for an electromagnetic wave. When an electromagnetic wave travels through space, space waves.
from: John Duffield
Comment: Then space is the luminiferous aether?


Recursively and iteratively calculating integrals in Scheme

Question: I'm trying to create both recursive and iterative functions for integration in Scheme. So far, I haven't succeeded. How can I calculate integrals in Scheme?
Comment: what kind of integral? show us your code and describe the problem
Answer: What kind of integral are you trying to calculate, with what method? If it's helpful for you, in the book SICP, section 1.3.1 theres's an explanation on how to approximate integrals using a Scheme procedure. Also in the same book, in the exercise 1.29 it's explained how to calculate an integral using Simpson's Rule, which is a more accurate method of numerical integration - and there's a solution for that exercise in here.


How does current flow in this circuit, and why?

Question: I'm new to EE. I know this is a simple question, but I would like to know how the current flow in this circuit. My textbook says that the current does not pass through the capacitor, but I don't know why. Any help is appreciated, thanks!
Answer:
Figure 1. A classic capacitor diagram. Image source: Electronics Tutorials.
A capacitor consists of two conductive plates, foils or conductive materials, separated by an insulator or dielectric. No current (other than some leakage) can pass from one plate to the other when run inside the designed parameters.
The symbol for the capacitor represents the two plates with a gap between them. DC current can't flow. Current does flow to charge or discharge the capacitor when the voltage across the plates changes. That's why capacitors can "pass" alternating current and their apparent impedance (AC resistance) decreases with higher frequency. (Incidentally, the resistor symbol represents a wirewound resistor and the inductor symbol represents a coil of wire.)
Tip: when analysing a circuit like that you can think of capacitors as blocking DC and passing high frequency. Inductors, on the other hand, will pass DC but block high frequency.
The linked article is worth reading.
Answer:
My textbook says that the current does not pass through the capacitor, but I don't know why.

Capacitors act as open circuits to a DC source (which is what you have), so no current can pass through C1.  Since the capacitor doesn't pass current, R4 is not part of the circuit, and so current can only flow through R2->R3->R5.  You can then calculate that current value using V1 and Ohm's law.
Comment: When power is first applied, the capacitor will charge up to the voltage across R3.  When the power is removed, the capacitor will discharge through R3 and R4.
Comment: @PeterBennett True. But I think the answerer here was addressing only the OP's comment, "...my textbook says that the current does not pass through the capacitor..." That implies a steady-state perspective being demanded by the textbook. But your comment is also helpful in that the OP will soon need to step up to your point and understand it, too.
Comment: @jonk: I think I meant to put my comment under the original question - should pay more attention to where I post things!
Comment: @Peter Bennett, In such circuits with reactive elements it should be clear if the voltage source is open or short circuit after "the power is removed".


Is there a V speed for the point an aircraft starts an ascent at 0 angle of attack?

Question: Some aircraft with an angle of incidence or cambered airfoils are capable of climb without any angle of attack, Is there a V speed for the speed at which an aircraft starts a positive climb?
Comment: I'd like to point out that aircraft with an angle of incidence does not equate to zero angle of attack.  It means that the wing will have a positive angle of attack when the fuselage is aligned with the relative wind.  Regarding your question:  I will let the engineers answer, but yes, if a wing is capable of producing lift at zero angle of attack it will obviously start climbing once it attains a certain speed...  Are you asking how to calculate this?
Answer: No, there is no V-Speed associated with zero angle of attack, nor is climb associated with angle of attack. Since zero angle of attack does not directly translate to minimum drag for a production aircraft in operation, it is not a meaningful performance gate, which is what V-Speeds are designed to represent.
However, this is not to say that having a zero flow incidence against the fuselage is not desirable:

If the body-axis is aligned with the fuselage longitudinal axis, it would be desirable from a passenger comfort standpoint to fly at zero AOA during level cruise. We don't want to have an inclined martini glass for the whole duration of the flight.
Non-zero flow incidence against the fuselage does create drag. It would be desirable from a performance perspective to decrease any form of drag during cruise or climb.

This is achieved during aircraft design. The wing setting angle against the fuselage is tuned such that the average operational flow incidence angle against the fuselage is minimized.
Comment: My apologies, I'm confused, My question was for if there was a V-Speed Indicating the aircraft speed at where the lift force would be equal to weight at a zero angle of attack, such as a "Level flight" speed. (Of course, very dependent on the current weight of the aircraft such as fuel level and passengers aboard)
Comment: "Vtos" Is the minimum speed for climb with one engine operative, But what about in normal function? I was thinking vlof, but that does depend on angle of attack due to rotation on takeoff.
Comment: @James The question is, why do you want to lift off at zero AOA? What's special about zero AOA? If you have a tricycle, being able to rotate allows you to decrease the drag during ground roll, which increases field performance.
Comment: general aviation question for me honestly, What about a cruise/level flight where you want to be as level as possible without a change in pitch? ( I understand on my airplanes this requires a 1-2 degree nose up attitude )


Gnocchi install removes Keystone and another packages of OpenStack Queens on Ubuntu 16.04

Question: When the setup is going to install gnocchi-api and libapache2-mod-wsgi-py3, It tries to remove cinder-api keystone libapache2-mod-wsgi nova-placement-api openstack-dashboard packages from my openstack queens installation, I don't know what I have to do. Thanks for reading guys.
Answer: I faced a similar issue. Struggled with it a lot for days. Are you trying via pip install?
Anyway, I reinstalled keystone, openstack dashboard to get the system back to it original state. Once that is done, try installing gnocchi via apt install.
If you see gnocchi logs as it installs gnocchi, you will observe that it for some reason removes openstack dashboard, keystone and placement api, also. So, no service was running. That's when I reinstalled dashboard, keystone and placement api by following steps mentioned in stamdard openstack queens guide.
Comment: Hi Nishank. Can you give any more information about how and why the steps you suggested resolve the problem?
Comment: @Nishank edit the answer instead of adding it as a comment


Hide Search Bar and Tabs in Lightning

Question: I have a Visualforce tab, in which showHeader = false. In classic it is working fine. But when this Visualforce tab is getting clicked in lightning, the Visualforce page opens with the search bar and header tabs. How to hide these tabs and search bar?
Answer: Good question. From the documentation https://developer.salesforce.com/docs/atlas.en-us.pages.meta/pages/pages_compref_page.htm:

A Boolean value that specifies whether the Salesforce tab header is included in the page. If true, the tab header is displayed. If not specified, this value defaults to true.
  Note: In Lightning Experience and the Salesforce app the value of this attribute is overridden, and is always false.

HOWEVER: You can see that it is actually TRUE in Lightning Experience. As you will learn in the Trailhead module, that header cannot be removed in LEX.
For more information, try the Trailhead module Visualforce & Lightning Experience
https://trailhead.salesforce.com/en/content/learn/modules/lex_dev_visualforce

Hide Search Bar and Tabs in Lightning


No Apt found after installing 64-bit Ubuntu core 18.04 on Raspberry Pi 3B+

Question: I tried to install the 64 bits Ubuntu core onto my Raspberry Pi 3B+ this morning using Raspberry Pi Imager to burn the image to the microSD card. However, after booting and all the first time configuration, I can't run apt update because apt is not there. I checked the usr/bin on the current user and root already and there's no apt on both.
The steps that I did were:

run the Raspberry Pi Imager, choose the SD card, choose Ubuntu 64 bits 18.04 LTS version and hit write
insert the microSD card into Raspberry Pi and boot it up.

These are the tutorials that I followed on the raspberry pi official website:

https://www.raspberrypi.org/downloads/
https://ubuntu.com/tutorials/how-to-install-ubuntu-on-your-raspberry-pi#1-overview
https://ubuntu.com/download/raspberry-pi/thank-you?version=18.04&architecture=arm64+raspi

I have tried to reinstall using the Ubuntu raspberry pi from the Ubuntu website and burn manually without Raspberry Pi Imager and apt is still not there.
I tried with the answers in these questions to manually install apt to see if it can fix the issue: apt-get removed, how to reinstall it?.
However, I don't have wget or dpkg as well (I checked usr/bin).
Am I doing anything wrong? Do I need to install a specific version of Ubuntu manually or do I need to make any configuration?
p/s: I'm using a Windows PC to download and burn the image.
Answer: Ubuntu core 18.04 only has Snap for package management.


Upper critical dimension in field theory

Question: Is there field theory which describe a second-order phase transition without upper critical dimension? Mermin-Wagner says something about lower critical dimension but nothing about upper dimension.
Comment: You need a way to declare that two field theories in different dimensions are "the same". There are natural ways to do this for simple examples, but it is easy to make up a model where there is no upper critical dimension because you extrapolate wrong.
Comment: The upper critical dimension of field theories can be found with the help of a program, which also explains the mathematical background:
http://www.freewarefiles.com/Kanon_program_83832.html
Answer: The upper critical dimension is the dimension where the statistical field theory is well described by a mean field theory. It is also the dimension where the fluctuation theory turns into a free field theory. You can avoid having an upper critical dimension by tuning the kinetic terms properly:
Consider the Euclidean action:
$$S= \int |q|^{2n} |\phi|^2 + \lambda \phi^4 d^n x$$
This field theory never has an upper critical dimension. But this is because the dimensional extrapolation is wrong. For any fixed power of q, there is an upper critical dimension.
Comment: Does this action correspond to some physical model? It is not clear : "This field theory never has an upper critical dimension... there is an upper critical dimension"!
Comment: @PanAkry: Not really physical. The point of this example is that I continued the theory wrong into higher dimensions. The right continuation holds the power of q fixed (the exponent doesn't change with n), and this continuation _does_ have an upper critical d.
Comment: Why the downvote? It answers the question--- this is a silly mathematical continuation without upper critical dimension.


How do I change my monitor's gamma settings?

Question: How do I change my laptop monitor's gamma settings on Linux Mint 9 (preferably using a GUI interface)?
Answer: X11 can adjust gamma with the command xgamma, which should come standard with X11 on most Linux distros.  This works independent of what monitor you use.
The proprietary drivers for some graphics cards offer GUI gamma adjustments.
Comment: Do you know what driver I am using? inxi -G
Graphics:
Card Intel Mobile 945GM/GMS 943/940GML Express Integrated Graphics Controller
X.Org 1.7.6 Res: firstname.lastname@example.com
GLX Renderer Mesa DRI Intel 945GM GEM 20091221 2009Q4 x86/MMX/SSE2
GLX Version 1.4 Mesa 7.7.1
Comment: Thank you . Just looking at the man page for xgamma I found what I was looking for called xvidtune.


What should I do with Arduino starter kit?

Question: This is not actually a problem but I need your advice. I live in Greece and I want to start learning how to make things with Arduino. I can order the starter kit which costs 80 euros which is a good price, but with the shipping it's 100 euros (136 dollars). Should I save money to pay so much for this? I'm afraid that the starter kit does not provide enough for what I want to do and I will have to order more stuff. Just to have an idea how expensive they are (and not to mention the availability) 10 euros for few resistors are too much. What should I buy?
Comment: "does not provide enough for what I want to do" - what do you want to do?
Comment: TI's MSP430 was $4.30, there's some monster bargains to be had with STM32 Discovery boards too if you're not set on Arduino.
Answer: There many brands of Arduino starter kit, but most of them contains the basic parts such as: couple of leds, some resistors, diodes, and perhaps a servo engine or a 8-bit shifter.
The purpose of those kits is to put you on the right path as a beginner; They usually include a hard copy/PDF book with some circuits you can create with the parts they contain.
The real question is - do you want to make something specific? Or, do you just want to have a starting point. Usually the resistors and other parts supplied with those kits fits the circuits described in the attached book, so if that's your intention, you should be good to go.


WiFi networks appears be far away in spite of the router being close by

Question: I recently installed Ubuntu 14.04 and I'm facing a little inconvenience. The WiFi networks appears as if it is very far, when, in reality, the router is near the laptop.
In case of Windows (on the same laptop), it works good. Also works fine in case of a tablet.
For the time being, I am using a USB WiFi adapter to get access to the web.
My card is a Broadcom BCM43142
<code>Network controller: Broadcom Corporation BCM43142 802.11b/g/n (rev 01)
</code>
I hope somebody can give me a viable solution.
Comment: I've installed Elementary OS, wi-fi works preperly on this system, I don't know why
Answer: Here's a test. Take you laptop to a farther away location and see if the problem remains, say to the living room (if you're in your own room, for example), and see if you still show a weak signal. Weak metering in this case, does not always translate to weak signal.
If wifi performance remains good, then it may be just a meter scaling problem (my laptop rarely shows full-strength ever). Windows does not perform the metering, this is one of those proprietary driver issues that is solved by the manufacturer, they write the driver to please the customer, even when it reports loud and isn't . I always get 4 instead of the 5 bar reading, on my laptop.
If the wifi is working well, then the metering is just reading low, and there may be nothing wrong with it. I have found Ubuntu quirky that way. This is because they do very little in custom software for a given manufacturer. They tend to standardize. This is a good reason for some wifi to show loud, while others might show weak, or a little low (like on my laptop).
Hope that helps, have fun and good luck!
Comment: well when I take the laptop farther away, the problem gets worse, at the point there's no signal :(, look the locations:
The kitchen: good signal,
My room: poor signal,
Living room: signal is gone,
I'm thinking about to change the router's place
Comment: and this is using the USB wifi adapter, cause with the internal card i'm not able to discover all available wifi networks
Answer: OK, now we're getting somewhere.
1). Since the wifi equipment in/attached to your laptop doesn't change, the performance should not either.
SO the next thing we need to do is confirm performance, when on Windows. If you are using Ubuntu only, that now presents a nearly insurmountable problem.
If you are dual boot, I would recommend testing the wifi in Windows, and see if performance is roughly the same. Ignore the meter strength. The important thing is, does the wifi work about the same?
2). If the actual performance is about the same, then nothing is wrong. As you suggest, router performance varies from unit to unit. And the position of the router in the house has a direct effect on how well it covers the ground.
Remember, you are dealing with microwave frequencies, this means that while the companies that make routers say they  thing will work for several hundred yards; everything changes that performance. In microwave frequencies; metal, wood, and drywall stop radio waves. This means that the more stuff between your laptop and your router, the less signal you will get. We are talking about significant signal drop in many cases.
A lot has to do with how large your house is. Multiple floors make things complicated, because this changes the antenna dynamics. Some people have 3,000 sq.ft. homes. This is a very big house, for a router to reach everywhere. In larger homes, one router is sometimes not enough.
Centrally locating the router in the house will tend to feed the surrounding rooms more evenly. Sometimes a better router can expand the range. If you need to, don't be afraid to expand the wifi in your house with a 'range extender'. Many companies sell these and they're not drastically expensive.
And lastly, it is obvious that the built-in wifi is very poorly constructed. Most USB plug-in wifi units don't work as well as built-in units because the built-in unit can make use of the space to include a big internal antenna (some even place the antenna in the screen, which presents a very large loop to the router, and most of it is vertically polarized, the same as the antennas in most routers). The USB types only have the length of the unit as space for the antenna (a couple of inches).
Your situation means that either there is a problem with the wifi in the laptop or its internal antenna. You should not need a plug-in wifi unit. If your laptop is still in warranty, I'd insist on getting the wifi card and antenna replaced.
3). In general, my take on this is that it is not a Ubuntu Linux problem. I think we are dealing with a general wifi problem, and because the metering reads differently, the problem seems more pronounced than it is. But it does require attention, since you lose signal at points in the house. Since it does work, and the equipment is the same, you'll need to work on the wifi network as a whole (deal with the poor wifi in the laptop, and/or expand the wifi system in the house, with either a stronger router, or more routers [extenders]).
I hope you get this solved, wifi is the way to go with a laptop ! Have fun and good luck!
Comment: 1) In winddows the wifi works properly, there's good signal even in my room, and it shows many wifi networks.
It can be a problen with the wireless card, as you say, cause I have another old laptop, and works good talking about wireless, I'm thinking about to change the wireless cards between laptops, haha, thanks for your help.
Live free!!


Is it possible to access a GPU remotely (i.e., from another machine)?

Question: I want to access a GPU on a computer remotely, and share this GPU with different desktops. I envision this sort of access as being similar to using a VNC. Is it possible to do something like what I've just described, and if so, how would I go about doing it?
Comment: What do you mean by many computers sharing a single graphics card?  Only the "host computer" can directly issue OpenCL or CUDA kernels to a GPU, neither of these protocols are designed to run over networks.
Comment: I want to know is graphics card can shared with many computers or not by using gpu clouding? If yes, is that possible let each computer has independent desktop? Thank you~
Comment: I want to login to one server with different desktop and not sharing the same mouse cursor and could open different 3D apps.
Comment: sam, I couldn't understand your question. Based on Aron's edits and your comments, I've attempted to pose the question in a clearer manner. I also think that the question, as asked, is off-topic for this site because it is not apparent how it relates to scientific computing, and I feel that you might get a better answer at a site like SuperUser.SE, ServerFault.SE, or even possibly Stack Overflow. Please let me know if my edits preserve the intent of your question, and I will talk to mods on the other sites to see if it is a good candidate for migration.
Answer: VirtualGL/TurboVNC may help https://sourceforge.net/projects/virtualgl/. I haven't tried 3 VNC sessions at once but I think it should work. There are cloud solutions coming but are proprietory and you will have pay for them, it requires the hardware to handle sharing.
http://www.gputechconf.com/gtcnew/on-demand-gtc.php has some presentations on the tech.
Another thing that might help is rCUDA http://www.rcuda.net/
Comment: You say that you try 2 turbovnc client connect to one server. Is two client 'share the same desktop' or 'their mouse are different and could open different 3D apps that's what I want'?
Comment: VirtualGL allows you to access the GPU of an XServer through VNC. You run apps within the VNC session with vglrun . I know you can run multiple VNC sessions on the same node, I just don't know what happens when mutltiple sessions try to use vglrun at once. It should be easy to test (it is free), there are few configurations available, which may solve your problem http://virtualgl.svn.sourceforge.net/viewvc/virtualgl/vgl/tags/2.3.1/doc/index.html


Does Vital Strike apply when firing both barrels of a double-barreled firearm?

Question: Because a double-barreled musket, for example, can be used to make two attacks as a standard attack action, do both attacks realize the benefit of the feat Vital Strike?
Answer:
This musket has two parallel barrels; each barrel can be shot independently as separate attacks, or both can be fired at once as a standard action (the attack action).
If both barrels are fired at once, they must both target the same creature or object, and the gun becomes wildly inaccurate, taking a –4 penalty on each shot. Each barrel of a double-barreled musket uses either a bullet and a single dose of black powder or an alchemical cartridge as ammunition.

By the first quoted paragraph, both shots can be fired as an attack action. Hence, vital strike applies:

When you use the attack action, you can make one attack at your highest base attack bonus that deals additional damage. Roll the weapon's damage dice for the attack twice and add the results together before adding bonuses from Strength, weapon abilities (such as flaming), precision-based damage, and other damage bonuses. These extra weapon damage dice are not multiplied on a critical hit, but are added to the total.

But vital strike only allows one attack that deals additional damage.
Hence, the benefit of the vital strike only applies to one of the double-barreled attacks.

An alternative reading of vital strike is that it allows only one attack, and that only allowed attack is with bonuses. I don't see any way of deciding which interpretation is more correct.
To be more explicit, the different readings are:

When using the attack action, vital strike allows you to make one of the attacks you make (at highest BAB) to have additional damage.
When using the attack action and when making only a single attack, vital strike allows you to make that attack (at highest BAB) with extra damage.
Answer: Vital Strike was not written with double-barreled weapons (weapons that allow two attacks with a single attack action) in mind. Despite my best efforts to search the Paizo forums and FAQs, I did not find a clear developer clarification on how these things interact. As a result, the most basic answer to this question is that the ruling is up to your DM.
That said, let me take a stab at making a ruling:
By strict "rules as written", double-barreled weapons modify the attack action, causing it to fire two separate attacks. We can assume they are separate attacks because the wording references taking a penalty on "each shot".

If both barrels are fired at once, they must both target the same creature or object, and the gun becomes wildly inaccurate, taking a –4 penalty on each shot.

Vital Strike also modifies the attack action, making it explicitly clash with the double barrel rules. It refers to making "one attack at your highest BAB", which is clearly incompatible if the above rule regarding double barreled weapons is true. As a result, I would rule that you can use either modifier to the attack action separately, but not together.
Again, your DM's interpretation may vary.
Comment: Making an attack roll is different than making an attack.  The way the musket is worded, both attack rolls are part of the same attack action, so there's no reason Vital Strike couldn't be used with the two-bullet method.
Comment: If this is correct then you do the same with Palm Throw: When using little thrown weapons (darts, shuriken, and daggers; the DM may allow other weapons), a master thrower with this ability may throw two of each weapon with a single attack roll. Damage for each weapon is resolved separately, but the master thrower does not apply her Strength bonus to either damage roll. From Master Thrower from 3.5.
Answer: From the musket description:

each barrel can be shot independently as separate attacks, or both can be fired at once as a standard action (the attack action).

Vital Strike can definitely be used for both one shot and two because the musket description says it uses the attack action in both cases.
From Vital Strike:

add the results together before adding bonuses from Strength, weapon abilities (such as flaming), precision-based damage, and other damage bonuses.

Vital Strike is not precision damage, it is applied before precision damage as stated in the feat description.  Because it is not precision damage, Vital Strike applies to both bullets.


Can I create a worktree for an empty Git repo?

Question: I have an empty Git repository (i.e. it contains no commits yet). Is there a way to create a worktree using git worktree add command (with --no-checkout option) for this repo? I mean to instruct Git not to associate a newly created worktree with any HEAD yet.
Comment: Exactly. Just make a placeholder commit. ``git worktree add somepath $(git commit-tree -m placeholder `git mktree <&-`)`` and now you've got an empty worktree you can fill in later.
Comment: I don't think there's a way, because there's nothing (no commit-id, no tree-id, not tag, no branch) that this worktree could conceivably track. You could always create an empty commit to bootstrap your repository with and then start branching from there.
Comment: What would you expect that worktree to contain? There are no `tree` objects in your repository yet, so there's nothing to export.
Comment: I would expect a worktree to be blank, i.e. to have the same state as the main worktree has just after `git init`.
Comment: BTW, I'd generally suggest `</dev/null` over `<&-`; a nonexistent file descriptor often triggers outright errors where one pointing to a device (like `/dev/null`) that immediately EOFs is generally handled more gracefully.
Answer: In a completely empty repository, there can be no branches, because each branch name must identify one actual, existing commit.1  The main worktree, however, must be on some branch.  So Git has it on a non-existent branch, which Git calls both an unborn branch (in various messages and internal code) and an orphan branch (in flags like git checkout --orphan).
In theory, git worktree add could also allow --orphan, to put a new work-tree on an unborn branch.  It does not currently do so, however.  Should you wish to write new code for Git that allows it to do this, and send it to the Git maintenance folks, it might be a candidate for inclusion in a future Git release.  It's probably a good idea to include some sort of reasonably compelling use case.
Until then, you can't do this: you must make at least one initial commit (which then allows an infinite number of branch names to be created).
Edit: it seems --orphan might be in the next Git release (2.40, probably).  See VonC's comment.

1This constraint is somewhat arbitrary, but Git makes it anyway, so one must live with it (or rewrite Git).
Comment: [This patchset](https://firstname.lastname@example.com/) (Nov. 2022) seems related.
Comment: This is [now implemented](https://stackoverflow.com/a/76552472/6309, with Git 2.42 (Q3 2023).
Comment: I'm proud to announce that despite taking quite a bit of time, the aforementioned patchset has [finally graduated to master](https://firstname.lastname@example.com/) (commit [4dd0469328](https://github.com/git/git/commit/4dd046932835d14c449f04ee0f3885669cad60c5)) and should be in the next git release (2.42).

With this patchset, there is now a `--orphan` flag that you can use however for an empty repository it should just "do what you mean" when using the base `git worktree add` command.
Answer: git init
git checkout -b empty-commit-dont-touch
git commit --allow-empty --message=Init
git worktree add --detach ../empty-worktree

Now you have that empty-commit-dont-touch branch but at least the two
working directories are empty. That's the best I could do.


Can I put 6" recessed cans into 7" holes?

Question: I want to replace these 7" speaker holes with recessed lighting. Are there any issues with using 6" cans and have a 0,5" border opening? I'll be using the new-construction cans to nail to the wood instead of the remodel version so anchoring isn't a problem. Also will be using 8" trims. Would dust from the attic be a problem? Or something else an issue?
Comment: Have you found trim rings that will cover the gap?
Comment: Hi yes, there are trip rings that are 8" wide, so the gap will be covered.
Answer: No problem at all doing this. But I would come up with a way to fill in that gap you have. It will allow drafts and dust penetration. Personally, I'd square the opening in the ceiling, take a new piece of drywall the same size as the hole and put the hole for recessed can in it and then secure it to the existing ceiling drywall (used 1/8" plywood for securing the screws into), mud, texture, put the can in (new or old work), paint and then the trim.
Comment: I agree, but I'd endeavor to seal the gap without doing the drywall work. There are  plenty of options.
Comment: I have no dry wall experience lol. i'm thinking maybe buying very thin square ply wood and cutting a 6" hole and basically put it in between the can and opening.
Comment: That was my thought exactly. You'd probably have to split the plywood after cutting the hold so you can fit it through the drywall. I'm not sure what your insulation situation is, but you'll need to move that out of the way and use some construction adhesive or silicone to bond the plywood.

Can I put 6” recessed cans into 7” holes?


VBA Excel - IE GetElementByID not working - Runtime error 424 Object Required

Question: I'm having trouble getting Excel VBA (Office 2016) to control IE (version 11). I need to enter information into several fields in a form and click on a few radio buttons. I've identified the object IDs for all the fields I need to modify. My code is copied/modified from mature code that I wrote a few years ago to do similar things on another web site. Though it continues to work on the other website today, it isn't working here. Unfortunately, it is a proprietary website, so I can't share the link, but here is some of my code and a portion of the web page code:
Sample of my code:
Dim IE As Object, objShell As Object, objCollection As Object

' Take control of the webpage:

' Get the page url
URL = "---------"

' Find the correct instance of IE
marker = 0
Set objShell = CreateObject("Shell.Application")
IE_count = objShell.Windows.Count
For X = 0 To (IE_count - 1)
    On Error Resume Next
    my_title = objShell.Windows(X).Document.Title
    my_url = objShell.Windows(X).LocationURL
    If IsEmpty(my_url) Then
        my_url = objShell.Windows(X).Document.Location
    End If

    If my_url Like Left(URL, 45) & "*" Then 'compare to find if the desired web page is already open
        Set IE = objShell.Windows(X)
        marker = 1
        Exit For
    Else
    End If
Next
If marker = 0 Then
    MsgBox ("Webpage not found. Please login manually.")
    Exit Sub
End If
On Error GoTo -1
On Error GoTo 0
' Wait if necessary
Do Until (IE.ReadyState = 4 And Not IE.Busy)
    DoEvents
    Application.StatusBar = "Waiting for Internet Explorer."
Loop
Application.StatusBar = False

' Set objCollection object
Set objCollection = IE.Document.getElementByID("QSHAA5V0GH4LSAO2AI5R2M853SJ5AI")
' This is the actual ID of one of the fields I need to enter data into (see screenshot below)
' The above line gives the familiar "Runtime error 424 Object Required" error.

Screenshot of HTML code for webpage

Why would this work for one website and not another?
As an additional note: when I use
Set objCollection = IE.Document.getElementsByClassName("Class")
MsgBox objCollection.Length

it sometimes results in one or more objects being collected, but usually results in zero. Once I have the object I need in the collector I'm good, but I'm not there yet.
If you see a mistake I'm making, I would be very grateful to learn about it, as I'm very confused right now.
I have the following libraries included:
Visual Basic For Applications
Microsoft Excel 16.0 Object Library
OLE Automation
Microsoft Office 16.0 Object Library
Microsoft Forms 2.0 Object Library
Microsoft ActiveX Data Objects 6.1 Library
Microsoft Internet Controls
Microsoft HTML Object Library
***** Here is a (modified) screenshot of the webpage I am working with if that helps at all. *****

Looking at the screenshot, should I be looking for an object within an object? Do I need to find the parent object (the protruding form within the web page) before I can find the child object (field on the form)?
Comment: Looking at your limited code, if you don't match the URL, you will never create the IE object. If your IE object is not set, it will very likely throw that error. Can you put a breakpoint on that line and check if IE object is set and pointing to the wright IE session?
Comment: Good question. I checked using
    [ MsgBox URL & Chr(10) & my_url ]
and verified that the URLs match exactly.
Comment: ok, but is the IE object set as expected?
Comment: Also, I verified that IE is set to "Internet Explorer" (the correct session of it) after [ Set IE = objShell.Windows(X) ].
Comment: I added a modified screenshot of the webpage if that's helpful at all.
Answer: I found the answer! I should have posted just a little bit more of the web browser code in the picture above and someone else would have found it hours ago. Here it is with the extra code:
Larger screenshot of HTML code from webpage
The top-left corner of the screenshot shows the tagname "iframe" (which is new to me today). The objects I need are contained within this iframe object. Once I found this out, I found this discussion which helped me create this line of code:
Set objCollection = IE.Document.getElementsByTagName("iframe")(1).contentDocument.getElementsByTagName("input")

(The value of (1) is because I have two iframe objects and I am using the second one.)
Once I have this, it is just a matter of looking for the object with the correct ID in the collection!
I could dance for joy!


How come EDI can blow things up, but I can't?

Question: So both EDI and I have incinerate, and I'm currently running through the Rachni Quest line. When I tell EDI to incinerate a Gestation pod it burns in a glorious explosion. However, when I do it, sometimes, but not all the time, it just fizzles and doesn't do any damage. Why is it that EDI can always destroy gestation pods with her explosions, and mine just fizzle? And why is it that mine just fizzle some of the time and not all the top? Please, help me perform.
Comment: Have you selected the same level 4, 5, or 6 options for both EDI and your Shep?
Comment: @CaulynDarr I am 1 level above EDI (at 5) and we both have the same level 4 upgrade.
Comment: NPCs have absurdly perfect aim if you manually order them to cast a skill, player casted skills seem more spotty. Especially Charge, which sometimes just DOESN'T WORK ARG STUPID REYSHG RAEDFAS ASDF
Comment: I can think of few theories.  Powers for squad members work differently(there's precedent for this from the previous games in how weapon damage worked).  EDI has better aim than you.  Or in commanding EDI to attack with an incinerate, she also fires her weapon at the same target.
Answer: AI's powers attack with perfect precision. Meanwhile, your powers will curve and fly through the air. This causes them to sometimes work incorrectly on small sized enemies, because the projectile hits the ground in front of the enemy.
It seems to work better if you try to purposely put exaggerated curve up and over to the enemy, so that your power hits them on top.
My advice though is to just shoot the pods with they flamethower, there's like a million ammo throughout the level.
Comment: All this talk of flamethrowers and pods makes me think:
They mostly come out at night. Mostly.
Comment: I was using power because on the gestation pods it also kills the swarmers on the inside, so I don't have to waste more ammo. Though, having finished that part now, I agree, there was no reason to try and conserve ammo.


errors when building gcc-9.1.0 under cygwin

Question: I received this error:
>/usr/local/contrib/gcc-9.1.0/libbacktrace/pecoff.c: In function 'coff_add':
/usr/local/contrib/gcc-9.1.0/libbacktrace/pecoff.c:656:37: error: pointer of type 'void *' used in arithmetic [-Werror=pointer-arith]
  656 |       memcpy (&fhdr, fhdr_view.data + 4, sizeof fhdr);
      |                                     ^
/usr/local/contrib/gcc-9.1.0/libbacktrace/pecoff.c:690:22: error: pointer of type 'void *' used in arithmetic [-Werror=pointer-arith]
  690 |     (sects_view.data + fhdr.size_of_optional_header);
      |                      ^
/usr/local/contrib/gcc-9.1.0/libbacktrace/pecoff.c:730:45: error: pointer of type 'void *' used in arithmetic [-Werror=pointer-arith]
  730 |       str_size = coff_read4 (syms_view.data + syms_size);
      |                                             ^
cc1: all warnings being treated as errors
make[3]: *** [Makefile:1190: pecoff.lo] Error 1
make[3]: Leaving directory '/usr/local/contrib/gcc_build/x86_64-pc-cygwin/libbacktrace'
make[2]: *** [Makefile:973: all] Error 2
make[2]: Leaving directory '/usr/local/contrib/gcc_build/x86_64-pc-cygwin/libbacktrace'
make[1]: *** [Makefile:19155: all-target-libbacktrace] Error 2
make[1]: Leaving directory '/usr/local/contrib/gcc_build'
make: *** [Makefile:996: all] Error 2

when make was executing the following:
libtool: compile:  /usr/local/contrib/gcc_build/./gcc/xgcc -B/usr/local/contrib/gcc_build/./gcc/ -B/usr/local/x86_64-pc-cygwin/bin/ -B/usr/local/x86_64-pc-cygwin/lib/ -isystem /usr/local/x86_64-pc-cygwin/include -isystem /usr/local/x86_64-pc-cygwin/sys-include -DHAVE_CONFIG_H -I. -I/usr/local/contrib/gcc-9.1.0/libbacktrace -I /usr/local/contrib/gcc-9.1.0/libbacktrace/../include -I /usr/local/contrib/gcc-9.1.0/libbacktrace/../libgcc -I ../libgcc -funwind-tables -frandom-seed=pecoff.lo -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -Wmissing-format-attribute -Wcast-qual -Werror -g -O2 -pedantic -fomit-frame-pointer -m64 -mtune=sandybridge -march=sandybridge -c /usr/local/contrib/gcc-9.1.0/libbacktrace/pecoff.c -o pecoff.o

my make version is GNU Make 4.2.1 for x86_64-unknown-cygwin and my current GCC is 7.4.0
I typed the configure program inside the source as the following,
bash
/usr/local/contrib/gcc-9.1.0/configure --enable-static --disable-shared --with-mpfr-include=/usr/local/include/ --with-mpfr-lib=/usr/local/lib/ --with-mpc-include=/usr/local/include/ --with-mpc-lib=/usr/local/lib/ --with-gmp-include=/usr/local/include/ --with-gmp-lib=/usr/local/lib/ CC=gcc CFLAGS="-O2 -pedantic -fomit-frame-pointer -m64 -mtune=sandybridge -march=sandybridge"

for matter of compatibility with the other configurations I made for the dependencies mpfr, mpc and gmp all of which shared the same compiling options. --enable-static and --disable-shared is for the configuration to not look for shared libraries, choosing static ones instead, otherwise I run into errors building the dependencies, because gmp is built on static libraries
project on fossies website: gcc-9.1.0 source and the configure file: configuration step
After testing somethings I came to realize I need some more deffinitive ways to disable the pointer-arith error of the compiler. I am having issues with it because there are lots of rewrites of macros and variables on the Makefile and many candidates for change, which by the way I yet dont understand precisely the logic of their deffinitions. I tested changes at the lines it says it is giving errors, at the Makefile and on some variables like:
RECURSE_FLAGS_TO_PASS
TFLAGS
TARGET_FLAGS_TO_PASS
RECURSE_FLAGS_TO_PASS
and on terminal with BUILD_CONFIG and EXTRA_BUILD_FLAGS
trying to disable the warning, also I sometimes passed with CXX_FLAGS or CFLAGS, usually with CFLAGS, since the install documentation makes many refferences to it
I could get the make command to print:
[ -f stage_final ] || echo stage3 > stage_final
RECURSE_FLAGS_TO_PASS+=CFLAGS+=-W
TFLAGS+=CFLAGS+=-W
TARGET_FLAGS_TO_PASS+=CFLAGS+=-W
RECURSE_FLAGS_TO_PASS+=CFLAGS=-W

which I think may be some progress
Answer: using
AM_MAKEFLAGS+=CFLAGS+=-Wno-error=pointer-arith

solved the problem, AM_MAKEFLAGS macro is appended after the make command and Wno-error is used to tell that a particular error should be ignored, on my case since I should already use only GCC for my compilation the error presented is useless as its function is to avoid code that cant run on other compilers and that is pretty much all


Python - Best database for exponentially growing database?

Question: So I am making a Discord (social media) Bot in Python using discord.py-rewrite, and I need to save informations of lots of servers and users (such as how much money they have, what items thay have…). This can grow exponentially. My question was, what is the best database to use then (sqlite3, PostGreSQL/asyncpg, MySQL…)? I currently use sqlite3, but I heard it wasn't good enough for exponentially growing databases.
Answer: Based on your comment of only storing a few thousand rows, you should be fine with almost any database product. Most relational databases only start to have trouble when they're many orders of magnitude bigger, like TB's of data.
Keep in mind some free offerings, like SQL Server Express Edition do have size limits, but as you have outlined, you won't hit those. SQL Server Express Edition has a 10GB max data size, LINK: https://www.microsoft.com/en-us/sql-server/sql-server-2019-comparison#CP_StickyNav_1.
Found the limits on your chosen platform, https://www.sqlite.org/limits.html

Maximum Database Size

Every database consists of one or more "pages". Within a single database, every page is the same size, but different database can have page sizes that are powers of two between 512 and 65536, inclusive. The maximum size of a database file is 2147483646 pages. At the maximum page size of 65536 bytes, this translates into a maximum database size of approximately 1.4e+14 bytes (140 terabytes, or 128 tebibytes, or 140,000 gigabytes or 128,000 gibibytes).
This particular upper bound is untested since the developers do not have access to hardware capable of reaching this limit. However, tests do verify that SQLite behaves correctly and sanely when a database reaches the maximum file size of the underlying filesystem (which is usually much less than the maximum theoretical database size) and when a database is unable to grow due to disk space exhaustion.

You should be just fine in terms of size. The stuff about dynamic data typing is certainly interesting, and something you should be aware of.
Answer: You've got to define what best means for you.
The best database product is Oracle or SQL Server, depending on who you ask. These have licensing costs, and you're paying for features that are pretty awesome - if you use them.
If you can't name any features of Oracle or SQL Server that you think are worth paying for, then I'd recommend going with an unlicensed product, such as Postgres.


Is jdbc by itself compatible with mysql

Question: I'd like to know if jdbc by itself is compatible with mysql or do I have to intsall something extra? I was told it is not compatible and that I'd have to use a different database.
Answer: It does.
You have to use the correct mysql jdbc driver and that's it!
Some useful links:
Little old but still helpful:
Using JDBC with MySQL, Getting Started
Official reference:
Official JDBC Driver
JDBC reference
You have to look at your specific version.
MySQL belogs to Sun Microsystems now after all
Using MySQL from Java
Comment: Thanks for the thorough answer.
Answer: JDBC is a specification for Java/database interaction.  As a specification it's compatible with almost every DB.  However, you need a JDBC compliant driver written for your database.  Googling "jdbc driver {databasevendor}" should get you an the right track.

Is jdbc by itself compatible with mysql


Blender wont work and just stays white window

Question: I have been at this for hours and have not found a solution. Manually switched sound settings to 44100hz and then doesn't show that error but still opens and just stays all white window. I have checked my opengl and is on 4.4. I have tried older versions still same issue. I have copy and pasted opengl32 into the blender foundation folder. Tried -noaudio same issue. Im trying out Blender to learn animations and still have not been able to begin to learn. I hope it is not a sign that it is not something for me. Thank you so much for helping me.
Comment: Looks like it is not initializing properly. Do any other versions work? If so report it as a bug. Also, that is black not white :)
Comment: Possible duplicate (Search is your friend) https://blender.stackexchange.com/questions/77857/error-al-lib-updatedeviceparams-failed-to-set-44100hz-got-48000hz-instead-wh/77896
Comment: Does the program open after that warning? Does it continue hanging on without loading up the interface? Please clarify "still opens and just stays all white window". Maybe related https://blender.stackexchange.com/questions/61765/latest-version-of-blender-opens-with-blank-screen
Comment: I have also this message since I use USB headset, but Blender works properly. Only with different sound setting than default. I don't thing this is a problem. I thing the problem is what happen after - with no error message.
Answer: have you tried uninstalling Blender and removing all config files?
They're found in %appdata%\Roaming\Blender Foundation\Blender*version number*\config.
I had your same problem and solved it by uninstalling and removing that folder, then reinstalling. Let me know!


Topological entropy of semi-conjugated dynamical systems

Question: Let $(X,T)$ and $(Y,G)$ be topological dynamical systems. If $(Y,G)$ is a factor of $(X,T)$ it is well known and easy to proof that $h(G)\le h(T)$ , where $h$ denotes the topological entropy. If the systems are conjugated we have $h(T)=h(G)$. My question is under what (weaker) conditions we have $h(T)=h(G)$. I guess that this is true if the semi-conjugation is finite to one. Perhaps finite to one on a topological large set is enough, or?  Where do I find proofs of such results?
Answer: There is formula due to Rufus Bowen which can be stated as follows:
$$ h(T)\leq h(S) + \sup\left\{h\big(T,\pi^{-1}(y)\big) : y\in Y\right\},$$
where $\pi\colon X\to Y$ denotes the semi-conjugacy between $T$ and $G$, and $h(T,K)$ denotes the entropy of a non-necessary $T$-invariant set, as defined in the very same paper.


What does "numbers" mean in the picture?

Question: I can't figure out what the "new numbers" means in the picture. If this picture doesn't provide enough context to specify the meaning, please tell me possible answers.
Comment: Two double cheeseburgers used to be the *Number 2* for like 40 years. (*shakes angry old man fist*)
Answer: It is quite common in restaurants that every item on the menu has a number assigned to it that you can use to order. This can be done for multiple reasons:

The names of the meals may be hard to pronounce for the patrons (e.g. in my country, this is common in Asian restaurants),
The restaurant caters to tourists or is otherwise frequented by foreigners who may not speak the local language very well, or
The restaurant is operated by foreigners who may not speak the local language very well.

In all of these cases, the use of numbers instead of names of the meals makes it easier for patrons and servers to understand each other. Most people can speak and understand basic numbers in many languages but would not be able to correctly pronounce and/or understand the names of the meals.
If you go to such a restaurant often and you have a favorite meal that you always order, you might have memorized the number and might not look into the menu before ordering.
What this sign is saying is that the menu has changed and you should therefore check whether your favorite meal still has the same number as before.
Comment: The numbers are also used for performance reasons. Most fast food restaurants have their registers set up so that the numbered menu options can be entered in only one keypress (or at least, far fewer than for the same thing being entered otherwise), compared to needing potentially dozens for the same thing entered entirely by hand. They then make a point to have the numbered options be consistent with what gets ordered most frequently so that the average entry speed for an order on the register is as fast as possible.
Comment: Personally, I like to (redundantly) say both the number *and* the name of the meal, to maximize the chances of getting what I want (because numbers can be misunderstood as well, especially when ordering over the phone). Kind of like a built-in "checksum mechanism".
Comment: It's also quite likely that they put this sign up only *after* numerous complaints from people ordering their favorite dish by number and getting something else.  It does have a haphazard kind of "made in a hurry" sort of look to it, just being zip-tied to a post, rather than the more professionally mounted signage that fits into the décor.
Comment: In  the UK, ordering by number is stereotypically associated with Chinese takeaways, though numbers are printed on a wider range of menus. I've seen a mismatch between printed menus and the ones on the wall before, so it's always worth checking
Comment: Also, communicating number between patron/servers can be done by typing into a calculator/phone, as sometimes done when haggling in open markets.
Answer: Many fast-food outlets and restaurants give numbers as well as names to dishes and meals to make ordering easier. For example, using the menu below, if I wanted Beef with Green Pepper in Black Bean Sauce on Hot Stone Plate I could save everybody's time by just saying "A number 32 please". If it was a favourite dish of mine, I might memorise the number. Such a scheme is helpful if there is a potential language barrier, also if rapid service in important.
It seems that the restaurant which placed the sign had revised its menu, and, as well as adding new dishes, had changed the numbering scheme so that customers needed to check if their favourite dishes had new numbers.


Extruding without breaking edge loop

Question: I want to model a shape with only quads.
I created a circle shape and wanted to extrude some vertices away from the curve to form a keyhole.
I am able to create the shape, but all extruded vertices are not connected to the circle shape anymore and I can´t select the Edge loop via shift-alt-LMB.
I wanted to select the keyhole in an easy way to add a bevel.
Comment: Are you trying create an extra edge loop around the keyhole to reinforce it for sub-dividing later?
Comment: No. I wanted to extrude the rectangle shape of the keyhole parallel to the outline of the cube. Deleted a few Vertices and extruded parallel to the outline with E, G, Y. But now all newly extruded veritces are disconnected from the Edge loop which was not intended.
Answer: Here is how you make a keyhole with all vertices connected.
1) Create a circle (say 32 vertices)
Stay in Edit Mode
2) Create a plane (also with 32 vertices)
Both the circle and the plane are a part of one object now.
3) Select both loops and connect them with Edge->Bridge Edge Loops
4) Almost done. All inner vertices are now connected into one loop.
5) You can now model you keyhole.
Summary: Edge loops work. It's all quads.
Comment: Thats more or less how I created my keyhole. But instead of moving the lower 3 vertices I deleted them and extruded the rectangle shape of the keyhole out of the circle. With this all new vertices where disconnected from each other and not part of the edge loop anymore. How do you add Vertices which are part of the edge loop, or how would you select the inner shape without clicking on each of the edges?
Comment: @ThomasB Sure thing. - First, don't click on edges, but click on vertices when selecting the loop. Because you extruded your shape, there are corners, where the edge select mode will stop. - Second. If you really want to be able to select the loop in edge select mode, you need to rebuild your keyhole slightly, so that there are no corners in the loop. Compare closely my mesh with yours. My mesh doesn't have corners in the inner loop.

Extruding without breaking edge loop