THREADS

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <pthread.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/stat.h>

double *a,*b,*c;

int M;

void print_matrix(double *m)
{
    int i,j;
    for(i=0; i<M; i++)
    {
        for(j=0; j<M; j++)
        {
            printf("%g\t" ,*(m+M*i+j));
        }
        printf("\n");
    }
    printf("\n");
}

void calc_row(int *r)
{
    int row = *r;
    int j,k;

    for(j=0; j<M; j++)
    {
        *(c+row*M+j)=0;

        for(k=0; k<M; k++)
        {
            *(c+row*M+j)=*(c+row*M+j)+*(a+row*M+k)* *(b+k*M+j);
        }
    }
}

void generate_matrix(double *A)
{
    int i,j;
    for(i=0; i<M; i++)
    {
        for(j=0; j<M; j++)
        {
            *(A+i*M+j) = 1+rand()%100;
        }
    }
}

int main(int argc, char *argv[])
{
    srand(time(NULL));
    if(argc != 2)
    {
        printf("\nERROR\n");
        exit(0);
    }
    if(atoi(argv[1]) < 1 )
    {
        printf("\nERROR\n");
        exit(0);
    }
    clock_t t1,t2;
    int i;
    int args[2];
    M =args[1] = atoi(argv[1]);
    pthread_t pthread[M];
    a = (double *)malloc(M*M*sizeof(double));
    b = (double *)malloc(M*M*sizeof(double));
    c = (double *)malloc(M*M*sizeof(double));

    generate_matrix(a);
    generate_matrix(b);

    t1 = clock();

    int idx[M];

    for(i = 0 ; i < M ; ++i)
        idx[i] = i;
    for(i=0 ; i< M ; i++)
    {
        args[0] = i;
        if (pthread_create(&pthread[i], NULL, (void *) calc_row, (void *)&i /*&idx[i]*/) != 0)
        {
            fprintf(stderr, "pthread create thread error");
            exit(1);
        }
        (void)pthread_join(pthread[i], NULL);
    }


    t2= clock();
    print_matrix(a);
    print_matrix(b);
    print_matrix(c);


    printf("\n\ntime taken = %f\n\n",(double)(t2-t1)/(CLOCKS_PER_SEC / 1000.0));

    return 0;
}