/* matmul.c  100*100 matrix multiply */
#include <stdio.h>
#define N 100        /* SGI C89 will not use  const N = 100; below. YUK! */
int main()
{
  /* const N = 100; this should work, but doesn't on SGI */
  double a[N][N]; /* input matrix */
  double b[N][N]; /* input matrix */
  double c[N][N]; /* result matrix */
  int i,j,k;

  /* initialize */
  for(i=0; i<N; i++){    /* FYI in debugger, this is line 13 */
    for(j=0; j<N; j++){
      a[i][j] = (double)(i+j);
      b[i][j] = (double)(i-j);
    }
  }
  printf("starting multiply \n");

  for(i=0; i<N; i++){
    for(j=0; j<N; j++){
      c[i][j] = 0.0;
front:
      for(k=0; k<N; k++){  /* how many instructions are in this loop? */
        c[i][j] = c[i][j] + a[i][k]*b[k][j]; /* most time spent here! */
	                   /* this loop is executed one million times */
      }
back:;
    }
  }
  printf("a result %g \n", c[7][8]); /* prevent dead code elimination */
  return 0;
}