"help" does not work
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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.
回答（1 个）
Matt J
2025-11-4，19:46
24 个评论
Ravi
2025-11-4，20:13
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?
Matt J
2025-11-4，20:51
编辑：Matt J
2025-11-4，20:52
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
2025-11-4，22:50
编辑：Matt J
2025-11-4，22:50
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
2025-11-5，14:43
编辑：Ravi
2025-11-5，14:45
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
2025-11-5，15:40
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
2025-11-5，15:47
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
2025-11-5，19:42
编辑：Torsten
2025-11-5，19:43
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);
Steven Lord
2025-11-5，20:13
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
2025-11-5，20:16
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
2025-11-5，20:35
>> 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
2025-11-5，20:37
>> 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
2025-11-5，20:40
>> 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
character vector | string scalar
Examples
Introduced in MATLAB before R2006a
Torsten
2025-11-5，21:07
编辑：Torsten
2025-11-5，21:24
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:
Torsten
2025-11-5，21:35
You checked whether the system requirements for MATLAB R2025b are fulfilled for your computer ?
Ravi
2025-11-5，22:00
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
2025-11-7，13:12
They haven't been able to find anything yet. The one thing they asked me to do was to run
>>ver -support
I got this: "Java Version: Java is not enabled" as one of the responses. I wonder if that is a problem? Also, as a test, I installed MATLAB on a completely different computer. A DELL instead of an HP. I got the same issue, i.e., "help" not working for myfunction.
Let's see if Mathworks can get to the bottom of this...
By the way, "doc myfunction" does not show anything. At least when I click on "View code for myfunction.m" I see the function text, which means it is pointing to the right function.
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