"help" does not work

I noticed this in R2025B. "help <myfunction>" just displays two blank lines, not the comments on top of <myfunction.m>. This m-file is in a directory at the beginning of my path.

Answer 1

[Matt J]

Possibly help.m is calling a function which you have shadowed. You will probably have to use dbstep to track this, or the equivalent Matlab Editor button:

[Ravi]

Thanks. When I type "wihch help" I get

C:\Program Files\MATLAB\R2025b\toolbox\matlab\helptools\help.m

seems like the legitimate one. Is it not the right one?

[Torsten]

Same for

which help -all

/MATLAB/toolbox/matlab/helptools/help.m

?

[Matt J]

seems like the legitimate one. Is it not the right one?

It's the right one, but it is not what I was talking about. You have to open help.m and step through the code inside it line by line, until you see it call a function you recognize as one of your own personal mfiles.

It may also be helpful to test help() after activating the debugger with,

>>dbstop if caught error

from the command line.

Do you have the same problem when you use doc()?

[Matt J]

Another, perhaps easier thing to try is restoredefaultpath, which will set the path back to its default state. Do this and see if help() works normally.

[Ravi]

Thanks for all your suggestions. Nothing works!

• There is no error when using "help"
• It works fine with all functions except those I have defined myself.
• restoredefaultpath does nothing.
• "doc <myfunction>" takes forever to return to a prompt. It opens a browser window with blank lines.
• "doc <matlabfunction>" opens the help for that function in a browser window.

[Steven Lord]

Please attach one such myfunction.m file with which you see this behavior. It's possible, given that you said "It works fine with all functions except those I have defined myself.", that there's something about the way you defined your help text in those files that causes help to display just blank lines.

Please attach the file rather than quoting it here, in case there's some non-printable characters (that appear as blanks / spaces) introduced by say writing the code in Microsoft Word and having it formatted by that program.

[Ravi]

Here you are. I just created this in the MATLAB editor just to make sure it is a text file.It is in the current directory and I can run it. But "help" returns nothing.

[Torsten]

Do you get the same output as below if you type

dbtype 'C:\Program Files\MATLAB\R2025b\toolbox\matlab\helptools\help.m'

for the first five lines of "help.m" on your computer ?

dbtype '/MATLAB/toolbox/matlab/helptools/help.m' 1:5

1     function [out, docTopic] = help(varargin)
2         % Help is helpful!
3         cleanup.cache = matlab.lang.internal.introspective.cache.enable; %#ok<STRNU>
4     
5         process = matlab.internal.help.helpProcess(nargout, nargin, varargin);

[Ravi]

Yes I got the same output as you. .

Of course, I had to change the path from your example. I typed:

dbtype 'C:\Program Files\MATLAB\R2025b\toolbox\matlab\helptools\help.m' 1:5.

[Steven Lord]

dbtype 1:10 myfunction.m

1     function [out] = myfunction(in)
2     %
3     %[out] = myfunction(in)
4     %
5     % This is to test out help 
6     %
7     %
8     
9     out = in;
10    

help myfunction

 
 [out] = myfunction(in)
 
  This is to test out help

To confirm, this is not the behavior you see on your machine for those two commands? Can you run that on your machine and copy and paste the output into a comment here?

[Torsten]

And if you save the file "myfunction.m" as "myfunction.m" in your working directory and type

help myfunction.m

 
 [out] = myfunction(in)
 
  This is to test out help

blank lines are displayed - in contrast to what you get here ? Then either there is a second file "help.m" on your MATLAB path or the "help.m" under C:\Program Files\MATLAB\R2025b\toolbox\matlab\helptools\help.m is corrupted.

[Ravi]

>> dbtype 1:10 myfunction.m

1 function [out] = myfunction(in)

2 %[out] = myfunction(in)

3 %

4 % This is to test out help

5 %

6 %

7

8 out = in;

9

[Ravi]

I removed the top comment line

[Ravi]

>> help myfunction.m

>>

[Ravi]

>> which help

C:\Program Files\MATLAB\R2025b\toolbox\matlab\helptools\help.m

[Ravi]

>> dbtype help

1 function [out, docTopic] = help(varargin)

2 % Help is helpful!

3 cleanup.cache = matlab.lang.internal.introspective.cache.enable; %#ok<STRNU>

4

5 process = matlab.internal.help.helpProcess(nargout, nargin, varargin);

6 if isnumeric(process.inputTopic)

7 process.inputTopic = inputname(process.inputTopic);

8 end

9

10 try %#ok<TRYNC>

11 % no need to tell customers about internal errors

12

13 process.callerContext = matlab.lang.internal.introspective.IntrospectiveContext.caller;

14

15 process.getHelpText;

16

17 process.prepareHelpForDisplay;

18 end

19

20 if nargout > 0

21 out = process.helpStr;

22 if nargout > 1

23 docTopic = process.docLinks.referencePage;

24 if isempty(docTopic)

25 docTopic = process.docLinks.productName;

26 end

27 end

28 end

29 end

30

31 % Copyright 1984-2023 The MathWorks, Inc.

[Ravi]

>> help help

help - Help for functions in Command Window

This MATLAB function displays the help text for the functionality

specified by name, such as a function, method, class, toolbox, variable,

or namespace.

Syntax

help name

help

Input Arguments

name - Functionality name

character vector | string scalar

Examples

Display Function and Overloaded Method Help

Display Namespace, Class, and Method Help

Display Variable Help

Display Help for Functions in Folder

See also doc, lookfor, more, what, which, whos

Introduced in MATLAB before R2006a

Documentation for help

Other uses of help

Folders named help

[Torsten]

What if you copy the function "help.m" from C:\ProgramFiles\MATLAB\R2025b\toolbox\matlab\helptools\ to your working directory and then execute

help("myfunction.m") 

 
 [out] = myfunction(in)
 
  This is to test out help

? If this doesn't work, I think you will have to reinstall MATLAB R2025b.

If this doesn't work either, contact MATLAB Technical Support:

https://uk.mathworks.com/support/contact_us.html

[Ravi]

That did not help either! I guess I will try and reinstall MALAB! What a pain!

[Torsten]

You checked whether the system requirements for MATLAB R2025b are fulfilled for your computer ?

https://uk.mathworks.com/support/requirements/matlab-system-requirements.html

[Ravi]

As I suspected. I wasted time reinstalling it and it still has the same problem! Yes, the computer supports these requirements. Thanks for your help.

Oh well, maybe somebody from Mathworks can help. I have another computer on which I will install it and see if it has the same problem. Obviously it worked fine for you, so maybe there is something peculiar about this specific computer!

[Ravi]

I have reached out to Tech Support. Let's see if they can help.

[Torsten]

If they are successful finding the cause of the problem, please report their solution here to help other MATLAB users with the same problem.