MATLAB: Error when using openmp ‘collapse’ directive in matlab mex

collapsemexopenmp

Hi,
I am trying to optimize the code for matrix multiplication in a mex file with openmp. The code is given below.
void MatrixMultiply(double *in1,double *in2,double *out,int M, int N, int P)
{
/* Description: multiplies a MxN matrix with a NxP matrix */
int i,j,k;
omp_set_num_threads(2);
#pragma omp parallel for schedule(static) shared(in1,in2,out,M,N,P) private(i,j,k) 
   for (i= 0; i < M; i++) {
     for (j = 0; j < P; j++) {
         out[M*j + i] = 0;            
         for (k = 0; k < N; k++) {
             out[M*j + i] += in1[k*M + i]*in2[j*N + k]; 
         }
      }
   }
    return;
   }
However, when I change the directive to "#pragma omp parallel for collapse(3) schedule(static) shared(in1,in2,out,M,N,P) private(i,j,k) " I get an error – "error C3005: 'collapse' : unexpected token encountered on OpenMP 'parallel for' directive"
Any help in resolving this error would be appreciated.
Thanks!

Best Answer

Does your compiler support the collapse directive? What compiler are you using?
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