Inserting C Code in Simulink block

Hello;

I'm trying to learn how to insert C code in the user defined blocks of simulink, but I didn't have success.

I made this code in Code Composer Studio:

#include <stdio.h>
#include <math.h>
double y;
double u;

int main(void)
{
  y=u*2;
    return(y);
}

And I made this simple diagram

With this code in the matlab coder:

function y = callingmultiplicador(u)
%#codegen
y = 0.0;
y = coder.ceval('multiplicador',u);

But When i try to run, i obtain this error:

Warning c2_untitled.c: 180  missing prototype for multiplicador 
Warning c2_untitled.c: 180  Missing prototype for 'multiplicador' 
0 errors, 2 warnings 
c2_untitled.obj .text: undefined reference to 'multiplicador' 
    "C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\bin\lcc64.exe" -dll -noregistrylookup  -c -Zp8 -DLCC_WIN64 -DMATLAB_MEX_FILE -DMX_COMPAT_32 -nodeclspec  -I"C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\include64"  -I"C:\Program Files\MATLAB\R2016a\extern\include"  -I"C:\Program Files\MATLAB\R2016a\simulink\include"  -I"C:\Program Files\MATLAB\R2016a\simulink\include\sf_runtime"  -I"C:\Program Files\MATLAB\R2016a\stateflow\c\mex\include"  -I"C:\Program Files\MATLAB\R2016a\rtw\c\src"  -I"C:\Users\Alberto\Desktop\slprj\_sfprj\untitled\_self\sfun\src"  -I"C:\Users\Alberto\Desktop"  "untitled_sfun.c" 
    "C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\bin\lcc64.exe" -dll -noregistrylookup  -c -Zp8 -DLCC_WIN64 -DMATLAB_MEX_FILE -DMX_COMPAT_32 -nodeclspec  -I"C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\include64"  -I"C:\Program Files\MATLAB\R2016a\extern\include"  -I"C:\Program Files\MATLAB\R2016a\simulink\include"  -I"C:\Program Files\MATLAB\R2016a\simulink\include\sf_runtime"  -I"C:\Program Files\MATLAB\R2016a\stateflow\c\mex\include"  -I"C:\Program Files\MATLAB\R2016a\rtw\c\src"  -I"C:\Users\Alberto\Desktop\slprj\_sfprj\untitled\_self\sfun\src"  -I"C:\Users\Alberto\Desktop"  "c2_untitled.c" 
    "C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\bin\lcc64.exe" -dll -noregistrylookup  -c -Zp8 -DLCC_WIN64 -DMATLAB_MEX_FILE -DMX_COMPAT_32 -nodeclspec  -I"C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\include64"  -I"C:\Program Files\MATLAB\R2016a\extern\include"  -I"C:\Program Files\MATLAB\R2016a\simulink\include"  -I"C:\Program Files\MATLAB\R2016a\simulink\include\sf_runtime"  -I"C:\Program Files\MATLAB\R2016a\stateflow\c\mex\include"  -I"C:\Program Files\MATLAB\R2016a\rtw\c\src"  -I"C:\Users\Alberto\Desktop\slprj\_sfprj\untitled\_self\sfun\src"  -I"C:\Users\Alberto\Desktop"  "untitled_sfun_registry.c" 
    "C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\bin\lcc64.exe" -dll -noregistrylookup  -c -Zp8 -DLCC_WIN64 -DMATLAB_MEX_FILE -DMX_COMPAT_32 -nodeclspec  -I"C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\include64"  -I"C:\Program Files\MATLAB\R2016a\extern\include"  -I"C:\Program Files\MATLAB\R2016a\simulink\include"  -I"C:\Program Files\MATLAB\R2016a\simulink\include\sf_runtime"  -I"C:\Program Files\MATLAB\R2016a\stateflow\c\mex\include"  -I"C:\Program Files\MATLAB\R2016a\rtw\c\src"  -I"C:\Users\Alberto\Desktop\slprj\_sfprj\untitled\_self\sfun\src"  -I"C:\Users\Alberto\Desktop"  "C:\Users\Alberto\Desktop\multiplicador.c" 
    "C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\bin\lcc64.exe" -dll -noregistrylookup  -c -Zp8 -DLCC_WIN64 -DMATLAB_MEX_FILE -DMX_COMPAT_32 -nodeclspec  -I"C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\include64"  -I"C:\Program Files\MATLAB\R2016a\extern\include"  -I"C:\Program Files\MATLAB\R2016a\simulink\include"  -I"C:\Program Files\MATLAB\R2016a\simulink\include\sf_runtime"  -I"C:\Program Files\MATLAB\R2016a\stateflow\c\mex\include"  -I"C:\Program Files\MATLAB\R2016a\rtw\c\src"  -I"C:\Users\Alberto\Desktop\slprj\_sfprj\untitled\_self\sfun\src"  -I"C:\Users\Alberto\Desktop"  "C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\mex\lccstub.c" 
    "C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\bin\lcclnk64.exe" -s -dll -L"C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\lib64" -entry LibMain -map sfun.map  -o untitled_sfun.mexw64 @untitled_sfun.lmko 
C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\bin\lccmake.exe: Error code 1 
C:\Program Files\MATLAB\R2016a\sys\lcc64\lcc64\bin\lccmake.exe: 'untitled_sfun.mexw64' removed.
Component: Make | Category: Make error
Unable to create mex function 'untitled_sfun.mexw64' required for simulation.

Can you help to understand the problem???

Thanks

Regards

Answer 1

[Rick Rosson]

   double multiplicador(double u) {
        return 2.0*u;
   }

[Alberto Prudhomme]

Thanks that works, but now I try another test but I have a rare error, but I will open another question for it. Thanks again.