#include <stdio.h>
#include <stdlib.h>
typedef double R;
typedef struct{R* a; int m; int n;} mat; // a[m, n]
void mm(mat const a, mat const b, mat const c){
  if(!(b.n == c.m && a.m == b.m && a.n == c.n)) exit(printf("vit\n"));
  int i = a.m; while(i--){int j=a.n; while(j--){
  R s = 0; {int k=b.n; while(k--) s += b.a[i*b.n+k]*c.a[k*c.n+j];}
  a.a[i*a.n+j] = s;}}}
void pm(mat a, char * q){int i, j; printf("%s: %d by %d\n", q, a.m, a.n);
   for(i=0; i<a.m; ++i) {for(j=0; j<a.n; ++j) printf("%7.3f ", a.a[i*a.n+j]); printf("\n");}}

/*
int main(){R a[3][4], b[3][5], c[4][5];
   {int i=3; while(i--){int j=4; while(j--) a[i][j] = random()%53;}}
   {int i=4; while(i--){int j=5; while(j--) c[i][j] = random()%57;}}
   mat A = {(R*)a, 3, 4}, B = {(R*)b, 3, 5}, C = {(R*)c, 4, 5};
   mm(B, A, C); pm(A, "a"); pm(B, "b"); pm(C, "c");
   {int i=3; while(i--){int j=5; while(j--){
     R s=0; int k=4; while(k--) s += a[i][k]*c[k][j];
     if(s != b[i][j]) exit(printf("zonk b[%d][%d] = %8.2f s=%8.2f\n", i, j, b[i][j], s));}}}
   return 0;}
*/