Cannot find anonymous function

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Damien Watson
Damien Watson 2025-11-25
评论： dpb 2025-11-25，17:10
I have an anonymous function that pulls out data from a table for use in an arrayfun. This looks something like (I have not been able to reproduce this error with a minimal example):
arrayfun(@(x)(any(myTable{i, "Column"}.(string(x)))), myArray)
This works fine most of the time, but occasionally, it will get to this line and throw the following error
Error using indexing
Cannot find function "@(x)(any(myTable{i, "Column"}.(string(x))))" in "MyClass.m".
Error in MyClass>@(x)(any(myTable{i, "Column"}.(string(x)))) (line ...)
arrayfun(@(x)(any(myTable{i, "Column"}.(string(x)))), myArray)
Once this error occurs, any future attempt to run this code fails with the same error. I have tried "clear all" and reloading the project. I noticed that I can run the code if I F9 it while at a breakpoint at the arrayfun line. The only workaround I have found is to restart MATLAB. This is not ideal though, as this error can occur quite a while into the code, wasting significant time. Is this a bug in MATLAB or am I doing something wrong/is there a better workaround? I am using R2022a.
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Damien Watson
Damien Watson 2025-11-25，15:32
编辑：Damien Watson 2025-11-25，15:34
Ran in:
My minimal example does not exhibit this behaviour, and all the anonymous functions in the rest of the codebase do not act like this, but here is the minimal example:
myTable = table(struct("a", {true; true; false}, "b", {false; true; false}), VariableNames="Column");
myArray = ["a", "b"];
for i = 1:height(myTable)
f = @(x)(any(myTable{i, "Column"}.(string(x))));
disp(arrayfun(f, myArray))
end
1 0 1 1 0 0
The error does not have any more details other than the unrelated stack.
I forgot to mention in my original post, but I did find this stack overflow thread on this issue from over a decade ago, with a broken link back to mathworks' website: How can matlab be unable to find an anonymous function? - Stack Overflow.
dpb
dpb 2025-11-25，16:00
What if you passed the index as well as to the anonymous function? As is, it comes from the environment.
Code looks like it should work as is, but ...

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Damien Watson
Damien Watson 2025-11-25，16:32
After looking at some other issues, I found a bug report (https://uk.mathworks.com/support/bugreports/details/2804253) that confirms this behaviour when using clear all/classes, which explains why I was unable to recreate this issue when I wasn't clearing. The suggested fix is to upgrade to 2023b+ or to use a workaround by using named functions instead of anonymous functions.
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dpb
dpb 2025-11-25，17:10
" confirms this behaviour when using clear all/classes, ..."
clear all or clear classes is almost never required; and will reduce code efficiency. See the clear doc <Tips> on advice for specific conditions.

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