MATLAB Answers

ERROR: Wavelet + MATLAB Coder

6 views (last 30 days)
Nycholas Maia
Nycholas Maia on 1 May 2018
Commented: Nycholas Maia on 23 May 2018
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);
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?


Sign in to comment.

Answers (1)

Arnab De
Arnab De on 9 May 2018
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
Nycholas Maia on 9 May 2018
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
Arnab De on 22 May 2018
Ah! My bad. Can you please post the codegen command you are using? According to the doc (, signal should be double vector.
Nycholas Maia
Nycholas Maia on 23 May 2018
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?

Sign in to comment.

Sign in to answer this question.