Why is help() malfunctioning

Matlab seems to know that the help command is there, at least as far as which() is concerned

>> which -all help
C:\Program Files\MATLAB\R2019a\toolbox\matlab\helptools\help.m

And yet, I get this,

>> help help

help not found.

Use the Help browser search field to search the documentation, or
type "help help" for help command options, such as help for methods.

Any idea why this is happening?

[Matt J]

What happens with doc help ?

[Catalytic]

doc help seems to work and so does help doc

>> help doc
doc - Reference page in Help browser

    This MATLAB function opens the Help browser.

    doc
    doc name

    See also help, web

    Reference page for doc

[per isakson]

On my R2018b

>> help help
   help Display help text in Command Window.
      help NAME displays the help for the functionality specified by NAME,
      such as a function, operator symbol, method, class, or toolbox.
      NAME can include a partial path.
      .... in total 43 lines          

and type help displays the function in Command Window.

That doesn't help you and I have no idea.

[Matt J]

So help was discontinued after R2018b. Interesting...

[Catalytic]

Upgraded to R2019b and the problem has disappeared. I'm glad they decided to bring help back in 2019b. I sorely missed it.

Answer 1

[Matt J]

I ran into this problem later. The problem turned out to be that Mathworks help.m file uses a command called strip(). This function was being shadowed by my own strip.m file that was higher in the path. Generally speaking, you need to be sure that help.m and its dependencies are higher on the path than any user-defined mfiles.

[John D'Errico]

In general, that is ALWAYS true. But better, never define a function with the same name as an existing function name in MATLAB. If you do so, then expect arbitrarily random things to break.

[Matt J]

That doesn't help if your function predates the Mathworks' version, unfortunately... IMHO, functions as critical as help() and doc() should be implemented as a built-in, not as an mfile.

Answer 2

[Steven Lord]

The output you posted for help doc doesn't match the help text I see when I run that command. Did you post exactly what you see or did you paraphrase?

In release R2019a, what is the last line of your help.m file? In my installation it is a blank line, line 67. The copyright line (line 41) states 1984-2019. Can you confirm that you see the same?

In my installation, doc.m has 209 lines with line 209 being a blank line. The last function in doc.m is displayFile. The copyright line (line 45) reads 1984-2013. Can you confirm that you see the same?

I'm wondering if you accidentally copied versions of help.m file (and maybe doc.m) from an older release of MATLAB.

[Catalytic]

Thank you, Steven. Nothing I posted was paraphrased and regarding everything you have described about help.m and doc.m, I see the same.