Known problems in MATLAB Answers

Walter Roberson on 18 Dec 2024 at 22:09

According to https://www.mathworks.com/matlabcentral/answers/2172128-ode45-not-able-to-solve-one-particular-ivp#comment_3319755 the file attachment problem has been fixed.

1 Reply

William Rose on 19 Dec 2024 at 13:37

data.txt

Thank you. Yes it is now working for me.

Walter Roberson on 16 Dec 2024 at 21:36

Previously wrong, repaired since then:

@doc is presenting messed up text until something is selected
Near the top of each Question is displayed a link of the most recent activity on the question. The link is normally clickable and takes you directly to the relevant contribution. But at the moment the link does not take you anywhere

1 Reply

Paul on 16 Dec 2024 at 22:10

Also previously wrong and repaired since then would be the issue with the mysterious variables in the initial workspace, which was shown to be repaired earlier today (16 Dec 2024).

Star Strider on 16 Dec 2024 at 20:16

With regard to:

Symbolic output is not displaying. The work-around is to disp(char(EXPRESSION))

I prefer:

pretty(EXPRESSION)

It preserves the formatting.

Paul on 16 Dec 2024 at 15:59

@Walter Roberson

Can/would you edit the top level post in this discussion to reflect all of the issues identified below and their current status?

Paul on 15 Dec 2024 at 18:22

I expect that every time I start to compose an answer or comment that the defaults (for everything) are active, and that when I click Run (or ctrl-enter) that the workspace "resets," i.e., as if I'm running everything in a fresh Matlab session, i.e., there is no memory between one Run, editing the code, and the next Run, and every Run starts with the defaults (and a clear workspace and a clear symbolic engine) in place.

However, I occasionally run into a problem on Answers where the Symbolic preferences (sympref) are NOT the default values when starting to compose an answer or when re-Run-ning the code. Usually, the problem is with the FloatingPointOutput being set to true, and I have force it to false with a call to sympref. A few minutes ago, I ran into the problem where the HeavisideAtOrigin did not start at the default value (1/2). As shown in the screen shot below, it starts at the non-default value of 1 and then only goes to the default value of 1/2 after I forcibly set the preference to the default. Needless to say, I was quite confused as to why I was getting unexpected results until I realized that I wasn't actually using default preferences. I guess the safest thing to do would be to always put sympref('default') before any symbolic code, as annoying as that may be.

Also, weirdly enough when I was playing around in the Answer shown below, I did once see the correct default value on the first call to sympref, but then hit ctrl-enter and got the result shown below.

1 Reply

Walter Roberson on 15 Dec 2024 at 19:06

I think I got FloatingPointOutput set once . My memory is fuzzy as to whether I ever got HeavisideAtOrigin to be anything other than 1/2. I haven't noticed any of the other preferences being mis-set.

In contrast, I have encounted i = [] several times.

DGM on 11 Dec 2024 (Edited on 11 Dec 2024)

inframe.png

I've been running into a new one today. Any file I try to attach for an example is made inaccessible by the uploading tool.

ls % why does it have a .html extension?
inframe.png.html
dir().bytes % it's an empty file
ans = 0
ans = 0
ans = 0
inpict = imread('inframe.png'); % obviously i can't use it
Error using imread>get_full_filename (line 633)
Unable to find file "inframe.png".

Error in imread (line 395)
        fullname = get_full_filename(filename);

Note that if you click on the attachment link, the actual PNG file is accessible -- just not programmatically.

Clayton Allen on 3 Dec 2024

I've also noticed some buggy behavior when trying to submit a question. Sometimes the main text entry form wont switch from disabled to enabled so you need to refresh or close the browser and navigate back to MATLAB Answers in order to input your question.

1 Reply

Rena Berman on 3 Dec 2024

(Answers Dev) Hi @Clayton Allen, could you try clearing your browser cache if that happens again? Thanks,

Rena

Paul on 2 Dec 2024

Mysterious variables are in the workspace at the initiation of an answer or comment. Also here in discussions. The empty i is particularly problematic.

Link to Answers thread

whos
  Name              Size            Bytes  Class             Attributes

  ans               1x1                 8  double                      
  cmd               1x1               294  string                      
  cmdout            1x33               66  char                        
  gdsCacheDir       1x14               28  char                        
  gdsCacheFlag      1x1                 8  double                      
  i                 0x0                 0  double                      
  managers          1x0                 0  cell                        
  managersMap       0x1                 8  containers.Map              
  mshDir            1x18               36  char                        
  prefDir           1x1               170  string                      
  status            1x1                 8  double                      

Walter Roberson on 25 Nov 2024

Using "@doc:" does not list audioDeviceReader or audioDeviceWriter

1 Reply

Walter Roberson on 13 Dec 2024

Earlier today, "@doc:size" did not list size() at all -- it listed lots of other things where "size" was a keyword in the help summary but omitted all of the various size functions.

DGM on 23 Nov 2024 (Edited on 23 Nov 2024)

I don't know how long it's been like this, but the popout search bar is completely broken in Firefox for me.

If I click on the search icon, the icon changes but nothing appears. I can type in the invisible search bar and the page overlay darkens and the related search dropdown shows up, but it's also obscured by the overlay. I don't know what the extra numbers are for. Maybe that's supposed to be the answers count icon and it's broken as well.

The only practical way to use the search atm is to open an invisible search bar, blindly keymash and hit enter to get to the search results page where a static search bar is available.

Walter Roberson on 21 Nov 2024

The @doc problem has been fixed in Answers (but at the moment has not been fixed in Discussions.)

1 Reply

Anusha Sridharan on 25 Nov 2024

This has now been resolved in Discussions as well. Thank you for reporting this!

Rena Berman on 21 Nov 2024

(Answers dev) @Paul thanks for reporting the latest activity link issue. I'll investigate that. The latest activity links from the search page are working.

Paul on 21 Nov 2024

Run is only repaired after clearing the browser cache (at least that what seems to do the trick based on direction from Rena Berman).

My problems with @doc are that the text is messed up until the top choice is selected, AND I can't see the full list of options for cases where the same command is supported by multiple products. The full list has some weird overlay look.

This discussion is good in the near term, but I think it would be better to have a page that's linked from Answers that lists all current issues affecting Answers functionality and provides a link to report new issues that may be observed. This page should be "followable" like other Answer threads so users can be notified of updates (new issues added, current issues resolved or status updated) if desired. As it stand now, whenever I see a problem on Answers (and I've suffered several over the last week or two) I have no way of knowing if the Answers devs even know about it, much less are working on a solution.

Walter Roberson on 20 Nov 2024

There was recently a performance degradation, slowing down bringing up Answers pages, or leading to messages about timeouts. This performance degradation has been repaired.

Walter Roberson on 20 Nov 2024

For a couple of days, the Run facility was broken. Run has been repaired today. You might need to refresh the page to get the changed version.

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