Access MATLAB function in own function via python

I want to access a MATLAB-function, that is used inside my own function via python. Therefore I use the python-package "matlab.engine". Including a MATLAB-function according to the documentation works fine. But supposing my MATLAB-function looks like this:

function y = test_function(input)
  y = isprime(input)
end

and I want to access it via the following python script:

import matlab.engine

eng = matlab.engine.start_matlab()
a = eng.test_function(37.0, nargout=0, async=False)
print(a)

Then I get the following error:

Undefined function 'isprime' for input arguments of type 'double'

Answer 1

[Helper]

Please make sure all the functions, "test_function" and "isprime" are in MATLAB search path or the current folder. The MATLAB engine we launched inside Python will have the default MATLAB search path. So if the function "isprime" is not in the search path or the current folder, then MATLAB cannot recognize it.