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#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define N 1000
float A[N][N], B[N][N], C[N][N]; // declaring matrices of NxN size
int main ()
{
/* DECLARING VARIABLES */
int i, j, m; // indices for matrix multiplication
float t_1; // Execution time measures
clock_t c_1, c_2;
/* FILLING MATRICES WITH RANDOM NUMBERS */
srand ( time(NULL) );
for(i=0;i<N;i++) {
for(j=0;j<N;j++) {
A[i][j]= (rand()%10);
B[i][j]= (rand()%10);
}
}
/* MATRIX MULTIPLICATION */
printf("Max number of threads: %i \n",omp_get_max_threads());
#pragma omp parallel
printf("Number of threads: %i \n",omp_get_num_threads());
c_1=time(NULL);  // time measure: start mm
#pragma omp parallel for private(m,j)
// #pragma omp_set_num_threads(8)
for(i=0;i<N;i++) {
for(j=0;j<N;j++) {
C[i][j]=0.; // set initial value of resulting matrix C = 0
for(m=0;m<N;m++) {
C[i][j]=A[i][m]*B[m][j]+C[i][j];
}
//         printf("C: %f \n",C[i][j]);
}
}
/* TIME MEASURE + OUTPUT */
c_2=time(NULL);  // time measure: end mm
t_1 = (float)(c_2-c_1); // time elapsed for job row-wise
printf("Execution time: %f \n",t_1);
/* TERMINATE PROGRAM */
return 0;
}

prog.cpp: In function 'int main()':
prog.cpp:22:59: error: 'omp_get_max_threads' was not declared in this scope
 printf("Max number of threads: %i \n",omp_get_max_threads());
                                                           ^
prog.cpp:24:55: error: 'omp_get_num_threads' was not declared in this scope
 printf("Number of threads: %i \n",omp_get_num_threads());
                                                       ^

Standard output is empty