I can't find helper function: transientBCHeatedBlock which is supposed to be in: matlab/R20​XXx/exampl​es/pde/mai​n

Trying to run example on Matlab site that includes:

model.EdgeBC(6)= ...

edgeBC(Temperature=@transientBCHeatedBlock);

[Steven Lord]

Can you confirm which release you're using and that you have Partial Differential Equations Toolbox installed? The ver function will include both these pieces of information.

Can you also show us the output of ls executed in that example's directory?

[John McGrath]

Hi Steven

Thanks for your response. I am using 2024a. I used ver and confirmed that I installed that toolbox. I don't understand your last question. Sorry

When try to run the code that I copied from the Matlab examples website I get the following in the Command Widow:

Undefined function 'solve' for input arguments of type 'struct'.

Error in untitled36 (line 28)

r= solve(model, tlist);

I think the problem is that I need to locate the help function that I was asking about and copy it into my code. I see the helper function as a subroutine that will be referenced when called on.

Answer 1

[Walter Roberson]

The first thing you need to do is go through Preferences -> Help and install help locally.

Once that is done, look for

try
ls(fullfile(matlabshared.supportpkg.getSupportPackageRoot, 'examples', 'pde', 'main', 'transientBCHeatedBlock.m'))
catch ME
    disp('not under support package root')
end

not under support package root

try
ls(fullfile(fileparts(docroot), 'examples', 'pde', 'main', 'transientBCHeatedBlock.m'))
catch ME
    disp('not under docroot')
end

not under docroot

If it is not under either place then there is trouble.

[John McGrath]

Hi Walter

I couldn't find it but thanks for your help.

john

[Walter Roberson]

See if

ls(fullfile(matlabshared.supportpkg.getSupportPackageRoot, 'examples', 'pde'))

exists at least.

This assumes that you went through Preferences -> Help to request that the help documents are loaded locally. And this also assumes that you have the PDE toolbox installed.

[John McGrath]

I pasted yoru suggestion into the Command Window and executed it. What came back was:

data examples.xml main

That seems promising but I don't know what to do next.

thanks for your help

[Walter Roberson]

Next see what shows up for

ls(fullfile(matlabshared.supportpkg.getSupportPackageRoot, 'examples', 'pde', 'main'))

[John McGrath]

Hi Walter,

The script file:

transientBCHeatedBlock.m

showed up in the files returned so that’s good.

I also noted this file that I would like to look at:

NoBoundaryConditionBetweenSubdomainsExample.mlx

Where can I find these?

Thanks

john

[Walter Roberson]

fullfile(matlabshared.supportpkg.getSupportPackageRoot, 'examples', 'pde', 'main', 'NoBoundaryConditionsBetweenSubdomainsExample.mlx')

Note that it is NoBoundaryConditionsBetweenSubdomainsExample.mlx

[John McGrath]

Hi Walter

Many thanks for your help. I apologize for being such a novice. I understood yoru answer ot mean that I could find the files of interest if I entered what you sent me into teh Command WIndow and ran it. When I did I got this repsonse:

ans = '/SupportPackages/examples/pde/main/NoBoundaryConditionsBetweenSubdomainsExample.mlx'

I don't know what to do.

john

[Walter Roberson]

Now

ls(fullfile(matlabshared.supportpkg.getSupportPackageRoot, 'examples', 'pde', 'main', 'NoBoundaryConditionsBetweenSubdomainsExample.mlx'))

Error using ls (line 47)
ls: cannot access '/SupportPackages/examples/pde/main/NoBoundaryConditionsBetweenSubdomainsExample.mlx': No such file or directory

to see if the file actually exists.

It is extremely unlikely that you happen to be using Linux and installed the files in /SupportPackages .

It is more likely that you are experimenting with using MATLAB Online. It is questionable whether MATLAB Online has the examples installed.

... I just checked using the Linux find utility. I confirm that MATLAB Online does not have the pde examples installed.