dgemm_omp.c
518caf62b093students-2020

dgemm_omp.c
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			#include <sys/time.h>
			#include <stdio.h>
			#include <omp.h>

			#define N 1000

			double second()
			{
			struct timeval tp;
			int i;
			i = gettimeofday(&tp,NULL);
			return ( (double) tp.tv_sec + (double) tp.tv_usec * 1.e-6 );
			}

			int main(){

			double ** A;
			double ** B;
			double ** C;
			int mysize, myrank;
			int chunk;
			int i,j,k;

			double t1,t2;

			A = (double*)malloc(Nsizeof(double*));
			B = (double*)malloc(Nsizeof(double*));
			C = (double*)malloc(Nsizeof(double*));

			for (i=0;i<N;i++){
			A[i]=(double)malloc(Nsizeof(double));
			B[i]=(double)malloc(Nsizeof(double));
			C[i]=(double)malloc(Nsizeof(double));
			}

			for (i=0;i<N;i++){
			for (j=0;j<N;j++){
			A[i][j] = 1.0;
			B[i][j] = 2.0;
			C[i][j] = 0.0;
			}
			}

			t1 = second();
			#pragma omp parallel shared(A,B,C) private(i,j,k,myrank)
			{
			myrank=omp_get_thread_num();
			mysize=omp_get_num_threads();
			chunk=(N/mysize);
			#pragma omp for schedule(runtime)
			for (i=0;i<N;i++){
			for (j=0;j<N;j++){
			for (k=0;k<N;k++){
			C[i][j]=C[i][j] + A[i][k]*B[k][j];
			}
			}
			}
			}
			t2 = second();

			printf("Time = %E [s], GF/s = %E \n",(t2-t1), (pow(N,3)/(t2-t1))/10E9 );

			}