矩阵乘法优化

#include<stdio.h>
#include<omp.h>
#include<stdlib.h>
#include<math.h>

const int N = 500;

double a[500][500];
double b[500][500];
double c_0[500][500];
double c[500][500];

int main(){

//------------------------------------------// 
    FILE* f1;
    FILE* f2;
    FILE* out;
        
    f1 = fopen("data_a.txt", "r");
    f2 = fopen("data_b.txt", "r");
    out = fopen("data_c.txt", "w");
    
    for(int i=1;i<N;i++){
    
        for(int j=1;j<N;j++){
            fscanf(f1,"%lf",&a[i][j]);
            fscanf(f2,"%lf",&b[i][j]);
        }}
//--------------------------------------------------//    

    double t0,t1;
    double T0,T1;
    
    
//----------------------------------// 
    t0 = omp_get_wtime();
    //mul
    for(int i=1;i<N;i++)
        for(int j=1;j<N;j++)
            for(int k=1;k<N;k++)
                c_0[i][j] += a[i][k]*b[k][j];
    
    t1 = omp_get_wtime();
    
    T0 = (t1-t0)*1000;
    printf("优化前矩阵乘法耗时: %f ms\n", T0);
//---------------------------------------------------//    



    t0 = omp_get_wtime();
    
//---------------------// 
//--------------- c = a * b -------------------------//
    #pragma omp parallel for
    for(int i=1;i<N;i++)
        for(int j=1;j<N;j++)
            for(int k=1;k<N;k++)
                c[i][j] += a[i][k]*b[k][j];
    
//--------------------------------------------------//    

    t1 = omp_get_wtime();
    
    T1 = (t1-t0)*1000;
    printf("优化后矩阵乘法运行耗时: %f ms\n", T1);    

    printf("加速比为%f\n",T0/T1);

//-------------------------------------------// 
    for(int i=1;i<N;i++)
        for(int j=1;j<N;j++)
            fprintf(out,"%lf\n",c[i][j]);
//---------------------------------------------------//            
            
    fclose(f1);
    fclose(f2);
    fclose(out);            
}