/* dotpptr.c - pistetulo pointtereilla */
#include <stdio.h>
#define N 100
 
void read_vec(float *x, int n);
float dot_prod(float *x, float *y, int n);
 
main()
{
  float x[N], y[N];
  int n;
 
  printf("Vektorin alkioiden lukumaara: ");
  scanf("%d", &n);
  printf("anna x vektorin komponentit ");
  read_vec(x, n);
  printf("anna y vektorin komponentit ");
  read_vec(y, n);
  printf("Skalaaritulo = %7.2e\n", dot_prod(x, y, n));
}
 
void read_vec(float *x, int n)
{
  while ( (n--) > 0 ) {
    scanf("%f", x++);
  }
}
 
float dot_prod(float *x, float *y, int n)
{
  float sum = 0.0;
  while ( (n--) > 0 ) {
    sum += *(x++) * *(y++);
  }
  return (sum);
}