I am running code in MATLAB for soft demodulation, and I am using the file SisoDecode.c and SisoDecode.dll, but the program reports an error. I need a solution.

I am running code in MATLAB for soft demodulation, and I am using the file SisoDecode.c and SisoDecode.dll, but the program reports an error. I need a solution.

Answer 1

[Akanksha]

Hey Nguyen Hung,

The error you've reported : “Undefined function or variable 'SisoDecode'.” usually means MATLAB can't find the SisoDecode function.Most likely, it's written in a C file (SisoDecode.c) and needs to be compiled into a MEX file (like SisoDecode.dll on Windows) before MATLAB can use it.

Kindly try the following steps to fix it:

1. Compile the MEX file

Make sure SisoDecode.c is compiled. In MATLAB, just run:

mex SisoDecode.c 

Depending on yourOS, this will create: SisoDecode.mexw64 (for Windows), SisoDecode.mexa64(for Linux) or SisoDecode.mexmaci64(for macOS)

2. Add the MEX file to your MATLAB path

Make sure the compiled file is either in your current folder or added to MATLAB’s path. You can do that with:

addpath('path_to_mex_file_directory'); 

3. Check for any compilation issues

If the mex command fails, it could be due to:

• Missing libraries or dependencies
• Code that’s not compatible with your MATLAB version
• No compiler set up (you can run mex -setup to configure one)

4. Double-check the function definition

Make sure the SisoDecode function is properly defined in the .c file and that the way you're calling it in sim_sccc.m matches its input/output format.

Here are the official MathWorks documentation pages that you can refer for further queries :

https://www.mathworks.com/help/matlab/ref/mex.html

https://uk.mathworks.com/help/matlab/matlab_external/standalone-example.html

https://www.mathworks.com/help/matlab/call-mex-file-functions.html

Hope this helps!

[Nguyen Hung]

Thank you so much. I tried to run this code by Matlab 2009b and it worked.