How to convert Matlab code(Decimate Function) to C code?

Hi everyone,

I'm trying to convert Decimate function to C code using MATLAB coder. But generation failed with the error, "All inputs must be constant" for cheby1 function in decimate.m file. The part of code is as shown:

function odata = decimate (idata, r, nfilt, option) %#codegen

...

...

[b,a] = cheby1(nfilt, rip, .8/r);

while all (b==0) || (abs(filtmag_db(b,a,.8/r)+rip)>1e-6)

nfilt = nfilt - 1;

if nfilt == 0

break

end

[b,a] = cheby1(nfilt, rip, .8/r); %The error line

end

...

...

I call the decimate function to a main math file in my project. I read the information about cheby1 function (https://www.mathworks.com/help/signal/ref/cheby1.html) and I understand why error occured because of the statement :"All inputs must be constants. Expressions or variables are allowed if their values do not change"

I think when the variable -nfilt- changes, dimensions of arrays(b,a) changes. So we can not use that arrays (changing dinamically their dimension) in C code.

How can I modify this code? Could you help me please?

I specify b= zeros(50,1) and a = zeros(50,1) before. But it is not working.

Is there anyone have an idea to modify?

Adem