ERROR: Wavelet + MATLAB Coder

I'm trying to convert my function called myFunc to C. The 'signal' input argument is a vector (1000, 1) that contains only uint16 numbers.

function [out] = myFunc(signal)
    [c,l] = wavedec(signal, 8, 'db8');
    [out] = detcoef(c,l, 4);
end

When I tried to convert this MATLAB function to a C function, I got a error inside the: wavedec.m - Line 29

This assignment writes a 'double' value into a 'single' type. Code generation does not support changing types through assignment. Check preceding assignments or input type specifications for type mismatches.

Line 29:

c = zeros(0,1);

When I put my mouse over the 'c' variable on the error window, MATLAB shows me that this 'c' variable is single type and 'zeros(0, 1)' return a double type.

Could you please help me to convert this function to a C file?

Answer 1

[Arnab De]

There must be other assignments to the variable 'c' where the assigned value is single. If you want 'c' to be single, change the line 29 to

c = zeros(0,1,'single');

[Nycholas Maia]

Yes, I think that you are right, but my question in about the change a original/official internal MATLAB file.

This error above is not inside my script, but is in inside the: wavedec.m - Line 29

I'm afraid to change something in this file, and another scripts stop running.

May be the MATLAB developers team should look it, right?

[Arnab De]

Ah! My bad. Can you please post the codegen command you are using? According to the doc (https://www.mathworks.com/help/wavelet/ref/wavedec.html), signal should be double vector.

[Nycholas Maia]

Yes, the signal input argument is already double.

I'm not using codegen by command window. I'm using MATLAB Coder app (GUI), so I don't have the codegen command.

Do you have any idea?