Serial Matrix Multiplication Some PVM Examples

```/*
Matrix Multiply

Originally:
From PVM: Parallel Virtual Machine
A Users' Guide and Tutorial for Networked Parallel Computing

Geist et al

Reduced to a serial program for comparison.

*/

#include <stdio.h>

void
InitBlock(float *a, float *b, float *c, int blk)
{
int len, ind;
int i,j;

len = blk*blk;
for (ind = 0; ind < len; ind++)
{ a[ind] = (float)(rand()%1000)/100.0; c[ind] = 0.0; }
for (i = 0; i < blk; i++) {
for (j = 0; j < blk; j++)
b[j*blk+i] = (i==j)? 1.0 : 0.0;
}
}

void
BlockMult(float* c, float* a, float* b, int blk)
{
int i,j,k;

for (i = 0; i < blk; i++)
for (j = 0; j < blk; j ++)
for (k = 0; k < blk; k++)
c[i*blk+j] += (a[i*blk+k] * b[k*blk+j]);
}

int
main(int argc, char* argv[])
{

float *a, *b, *c;

/* Compute the array dim from the same parameters. */
int sidesize;
if (argc == 3)
sidesize = atoi(argv[1]) * atoi(argv[2]);

else {
fprintf(stderr, "usage: mmult m blk\n");
exit(1);
}

/* allocate the memory for the arrays. */
a = (float*)malloc(sizeof(float)*sidesize*sidesize);
b = (float*)malloc(sizeof(float)*sidesize*sidesize);
c = (float*)malloc(sizeof(float)*sidesize*sidesize);
/* check for valid pointers */
if (!(a && b && c)) {
fprintf(stderr, "%s: out of memory!\n", argv[0]);
free(a); free(b); free(c);
exit(2);
}

/* initialize the arrays */
InitBlock(a, b, c, sidesize);

/* Multiply. */
BlockMult(c, a, b, sidesize);

/* check it */
int i;
for (i = 0 ; i < sidesize*sidesize; i++)
if (a[i] != c[i])
printf("Error a[%d] (%g) != c[%d] (%g) \n", i, a[i],i,c[i]);

printf("Done.\n");
free(a); free(b); free(c);
return 0;
}

```