2.3 Comparision with Matrix Multiplication Execution Time, C (gcc)

Language: Layout:

#include <stdio.h>
#include <omp.h>
#include <stdlib.h>
#include <time.h>
#import <math.h>
int main(void)
{
 int r=1000;
 int c=1000;
 printf("%d %d \n",r,c);

// Taking Input for 2 arrays -
 int *arr1[r];
 int *arr2[r];
 for(int i=0;i<r;i++){
 arr1[i]=(int *)malloc(c*sizeof(int));
 }
 for(int i=0;i<r;i++){
 arr2[i]=(int *)malloc(c*sizeof(int));
 }
 for(int i=0;i<r;i++){
 for(int j=0;j<c;j++){
 arr1[i][j]=rand();
 }
 }
 for(int i=0;i<r;i++){
 for(int j=0;j<c;j++){
 arr2[i][j]=rand();
 }
 }
 printf("\nSequential Time: \n");
 int *arr3[r];
 for(int i=0;i<r;i++){
 arr3[i]=(int *)malloc(c*sizeof(int));
 }
 double start=omp_get_wtime();
 for (int i = 0; i < r; i++) {
 for (int j = 0; j < r; j++) {
 arr3[i][j] = 0;
 for (int k = 0; k < r; k++)
 arr3[i][j] += arr1[i][k]
 * arr2[k][j];
 }
 }
 double end=omp_get_wtime();
 printf("Execution Time : %f\n",end-start);
 // Starting parallel construct

printf("\nParallel Time: \n");
 int *arr4[r];
 for(int i=0;i<r;i++){
 arr4[i]=(int *)malloc(c*sizeof(int));
 }
 int i=0;
 int j=0;
 int k=0;
 double start1=omp_get_wtime();
 #pragma omp parallel for private(j,k)
 for (i = 0; i < r; i++) {
 for (j = 0; j < r; j++) {
 arr4[i][j] = 0;
 for (k = 0; k < r; k++)
 arr4[i][j] += arr1[i][k]
 * arr2[k][j];
 }
 }
 double end1=omp_get_wtime();
 printf("Execution Time : %f\n",end1-start1);

for(int i=0;i<r;i++){
 free(arr1[i]);
 free(arr2[i]);
 free(arr3[i]);
 free(arr4[i]);
 }
 return 0;
}

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Compilation time: 0.12 sec, absolute running time: 1.55 sec, cpu time: 2.98 sec, memory peak: 17 Mb, absolute service time: 1,87 sec