#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <string.h>

#define M 20

// pour windows
//double get_time(){ return ((double) clock())/CLOCKS_PER_SEC;}

//pour linux
double get_time() {  
       struct timeval tv;  
       gettimeofday(&tv, (void *)0);  
       return (double) tv.tv_sec + tv.tv_usec*1e-6;
}


void remplir_matrice(double Mat[M][M]){
 int i,j;                       
 for(i=0;i<M;i++)  
   for(j=0;j<M;j++)
     {
        Mat[i][j]= (double)rand()/(double)RAND_MAX;
     }                                           
}

void afficher_matrice(double Mat[M][M]){ 
     int i, j;   
printf("\n===> matrice  <===\n");
for (i=0;i<M;i++)
    {
     for(j=0;j<M;j++)
          printf("%f", Mat[i][j]);
     printf("\n");
    }
                                           
}

double  calcul_prod_mat(double P[M][M],
                            double A[M][M],
                            double B[M][M], 
                            int nb_threads){
 int i, j, k;   
 double start,stop; 
 double cpu_time_used;  
 
 start = get_time();  
 
 for (i = 0; i < M; i++)
    for (j = 0; j<M; j++)
      {
        P[i][j] = 0;
        for (k = 0; k < M; k++)
         P[i][j] += A[i][k] * B[k][j];
     }
     
 stop=get_time();    
 cpu_time_used=stop-start;    
 return cpu_time_used;                                       
}


int main(int argc, char **argv){
    double A[M][M];
    double B[M][M];
    double P[M][M];      
    int nb;  
    double t=0.0; 
    
    srand(time(NULL)); 
    
    remplir_matrice(A);
    afficher_matrice(A);
    remplir_matrice(B); 
    afficher_matrice(A);
    
    system("Pause");
    
    printf("Nb.threads\tTps.\n");  
    for(nb=1;nb<=12;nb++){     
      t=calcul_prod_mat(P,A,B,nb);    
      printf("%d \t %f\n ",nb,t);  
    } 
    afficher_matrice(P);
    system("Pause");  
    return(EXIT_SUCCESS);
}