/*This is a simple program to read two vectors and compute their dot products */

#include<iostream>

using namespace std;

#define MAX_DIM 10

void readinvalues(double vector1[], double vector2[],int *dimensions)
{
  /*At the top, we just use vector1[] because C knows we want to use */
  /*a pointer to the whole array */
  int i;
  do
    {
      cout << "How many dimensions do the vectors have?" << endl;
      cin >> *dimensions;
      /* We used a pointer to dimensions because we want to be able to send back to the main loop how many dimensions our vector has */
    }
  while (*dimensions>MAX_DIM);
  for (i=0;i<*dimensions; i=i+1)
    {
      cout <<"Enter vector 1, element" << i << endl;
      cin >> vector1[i];
    }
  for (i=0;i<*dimensions; i=i+1)

    {
      cout <<"Enter vector 2, element" << i << endl;
      cin >> vector2[i];
    }

  return;
}

double dotproduct(double vector1[],double vector2[],int dimensions)
{
  int i;
  double dp;
  dp=0.0;
  for (i=0;i<dimensions;i=i+1)
    {
      dp=dp+vector1[i]*vector2[i];
      /*Here, we leave vector1[i] alone, rather than putting an  */
      /*asterisk before it, because we are not passing it to */
      /*another function. */
      cout << "i,vector1,vector2=" << " "<< i << " " << vector1[i] << " " << vector2[i] << endl;
    }
  return(dp);  
}

main()
{
  int dimensions;
  int i;
  double vector1[MAX_DIM];
  double vector2[MAX_DIM];
  double dp;
  readinvalues(vector1,vector2,&dimensions);
  dp=dotproduct(vector1,vector2,dimensions);
  cout << "The dot product is: " << dp <<endl;
}