Why is the code replacement triggered for the Matrix Inverse block but not the inv() function in a MATLAB function block?

I am generating code for a model with a MATLAB Function block. In the MATLAB Function block, I call the inv() function.

I expect the code generated for the inv() function by embedded coder to be replaced by the function "matrix_inv_2x2_double" (a function specified in the rtwdemo_crlmatops demo). However this does not happen. On the other hand, the matrix inverse block is indeed replaced by this function. 

Is there a way to get the inv() function in the MATLAB Function block replaced by "matrix_inv_2x2_double"?

Answer 1

[MathWorks Support Team]

Unfortunately, "inv" cannot be replaced when used in a MATLAB Function block, since this is a limitation with replacing functions in MATLAB code: 

1. Please run the below command in the MATLAB R2018b command window to get the release specific documentation

   web(fullfile(docroot, 'ecoder/ug/code-you-can-replace-from-simulink-models.html'))

2. Please run the below command in the MATLAB R2018b command window to get the release specific documentation

   web(fullfile(docroot, 'ecoder/ug/code-you-can-replace-from-matlab-code.html'))

The former contains "inv" as an operator that can be replaced, but the latter does not. Thus, the Code Replacement Library does not support the inv() function. There is a workaround to this however: the "inv" operation was wrapped inside an additional MATLAB Function "myInvWrapper". A code replacement for that was then specified, using the following workflow:

Please run the below command in the MATLAB R2018b command window to get the release specific documentation

web(fullfile(docroot, 'ecoder/ug/replace-matlab-functions-specified-in-matlabfunction-blocks-sc.html'))

Please follow the below link to search for the required information regarding the current release:

https://www.mathworks.com/help/