Multiplicação de Matrizes usando Threads em C

[Guest saulokada]

Eu tenho q faze um programa q faz multiplicação de matrizes so q usando threads... em C para linux...

vendo alguns sides do meu professor.. já fiz qse tudo...

so q no final...

o programa da

segment fault (core dumped)

o codigo segue abaixo:

#include <stdio.h>

#include <stdlib.h>

#include <math.h>

#include <pthread.h>

#define MAX_THRDS 4 //numero de processadores

#define max 1000 //tam. max. arquivo

float a[max][max], b[max][max], c[max][max];

int n,nprocs;

void readdata()

{

int i,j;

FILE *fpa,*fpb;

/* read matrix a */

fpa = fopen("a","r");

for (i=0; i < n; i++)

for (j=0; j < n; j++)

fscanf(fpa,"%f", &a[j]);

fclose(fpa);

/* read matrix b */

fpb = fopen("b","r");

for (i=0; i < n; i++)

for (j=0; j < n; j++)

fscanf(fpb,"%f", &b[j]);

fclose(fpb);

}

void printdata()

{

int i,j;

FILE *fpc;

/* write results */

fpc = fopen("thread_c","w");

for (i=0; i < n; i++)

for (j = 0; j < n; j++)

fprintf(fpc,"%f\n",c[j]);

fclose(fpc);

}

void matmul(int *num_thread) //funcao que multiplica..threads a chamam.

{

int i, j, k;

int iprocs, jprocs;

int my_id, i_id,j_id,ilb,iub,jlb,jub;

/* number of processors in i direction */

iprocs = (int) sqrt((double) nprocs);

/* number of processors in j direction */

jprocs = nprocs / iprocs;

my_id = *num_thread; //m_get_myid();

/* get processor ID in i and j dimensions */

i_id = my_id % iprocs;

j_id = my_id / iprocs;

/* find lower and upper bounds of i loop */

ilb = i_id * n / iprocs;

iub = (i_id + 1) * (n / iprocs);

/* find lower and upper bounds of j loop */

jlb = j_id * n / jprocs;

jub = (j_id + 1) * (n / jprocs);

for (i = ilb; i < iub; i++)

for (j = jlb; j < jub; j++) {

c[j] = 0.0;

for (k = 0 ; k < n; k++)

c[j] = c[j] + a[k] * b [k][j];

}

pthread_exit (NULL);

}

int main(int argc, char **argv)

{

pthread_t t[MAX_THRDS];

pthread_attr_t attr;

int param[MAX_THRDS];

int i;

void readdata(),matmul(),printdata();

//inicializacao das threads

pthread_attr_init(&attr);

pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);

pthread_attr_setscope(&attr,PTHREAD_SCOPE_SYSTEM);

/* get n and nprocs parameters */

if (argc != 3){

printf("usage: pth_matrix <size of matrices> <number of processors>\n");

exit(1);

}

n = atoi(argv[1]);

nprocs = atoi(argv[2]);

/* reads matrix a and b */

readdata();

/* create threads */

for (i=0; i < nprocs; i++){

param=i;

pthread_create(&t, &attr, (void *)matmul, &param);

}

/* wait termination of created threads */

for (i=0; i < nprocs; i++)

pthread_join(t, NULL);

/* outputs matrix c */

printdata();

return (0);

}

Se alguém puder me ajudar eu apreciaria muito!

abraços