file not found in current directory

This sounds very similar to other entries in this forum and elsewhere e.g.

https://au.mathworks.com/matlabcentral/answers/353198-why-can-t-matlab-access-a-file-that-is-in-its-current-directory

https://au.mathworks.com/matlabcentral/answers/113517-m-files-cannot-run

https://stackoverflow.com/questions/7251612/why-cant-matlab-see-my-function

But a little different, and those answers don't help me. When I got this message the first time, I realised I had forgotten to copy a file across from a neighbouring folder. (I would hardlink if windows allowed that on network drives, or softlink if matlab could follow windows' softlinks... but I digress.) Even after copying the file, I still get the file not found message. Weirdly, 'edit my_function.m' works!

>> my_function
'my_function' is not found in the current folder or on
the MATLAB path, but exists in:
    H:\path\to\nearby_folder

Change the MATLAB current folder or add its folder to the MATLAB
path.

>> exist('my_function')

ans =

       0

>> which -all my_function.m
'my_function.m' not found.
>> edit my_function.m
>> ls

.                                      
..                                     
picture.png  
figure.pdf               
my_function.m                
my_script.m

[Image Analyst]

What was the current directory when you were doing all of this?

Did you at any time, between these commands, change the current directory from the start to "H:\path\to\nearby_folder", or any other folder or were you in the original folder the whole time?

[craq]

The file in question has been copied into the current working directory. You can see this because it comes up when I run 'ls'. I didn't change the current directory at any time.

[Image Analyst]

I ask because I think the post you made has been altered. For example, I doubt that you really have a folder called "H:\path\to\nearby_folder" -- maybe you do have a folder with that exact name, but it seems like a strange folder name to have so that's why I think some things were altered and not a clean unmodified copy and paste from your command window. Again, what is the current folder?

[craq]

Yes, I altered the folder name and file names for privacy. But the function m-file is in the cwd, so the path shouldn't really matter. It is not in matlabroot.

Answer 1

[Cam Salzberger]

Hello Chris,

By default, MATLAB will cache functions and files for faster finding and executing of them. Generally files newly added to folders will be found properly, but sometimes it needs to be told to rehash before it will detect the new file. That it finds the file with edit and ls likely has more to do with those commands using a different system for finding files than the execution engine.

If rehash doesn't do it for you, try rehash toolboxcache just to be sure. Restarting MATLAB is something of the nuclear option here, but should work in almost all cases.

-Cam

[craq]

I went with a restart, so unfortunately I can't test whether rehash would've worked. I can confirm that restarting works ;-) and the rest sounds logical, so I've accepted your answer.

[craq]

I just had this happen again. This time I tried your suggestions. Nothing changed when I ran rehash. rehash toolboxcache fixed it.

[Cam Salzberger]

Thanks for the update. The toolboxcache should only matter if the folder you're changing the files is within the MATLAB installation or local preferences directory. If you are changing files outside of that, and you are seeing rehash by itself failing to affect it reproducibly and consistently, please contact tech support with the reproduction steps.

[craq]

The first time was outside the matlab installation and outside the preferences directory. The second time I didn't record the directory I was in. It has only happened twice so far, so it's hard to talk about "reproducibility". If it happens again and I notice anything, I will contact tech support.