/******************************************************************************
filename    array.c
author      Lucas Carpenter
DP email    lucas.c@digipen.edu
course      CS120
assignment  3
due date    11/1/2011

Brief Description:
does various operations on arrays, including reversal,  addition, dotting, and corssing.
******************************************************************************/

/******************************************************************************
function    reverse_array
author      Lucas Carpenter
DP email    lucas.c@digipen.edu
course      CS120
assignment  3
due date    11/1/2011

Brief Description:
reverses an array
******************************************************************************/

void reverse_array(int a[], int size)
{
  /*initialize variables*/
  int iter,
    begin,
    end,
    hold;
    /* begin is start of array, and end is... end*/
    begin = 0;
    end = (size - 1);

    /*perfrom element reversal (# of elements)/2 */
    for(iter = 0; iter < (size / 2); iter++)
    {
    /* hold left element value */
    hold = a[begin];
    /*assign left element the value of  right element */
    a[begin] = a[end];
    /* assign right element the former value of left element*/
    a[end] = hold;
    /* move towards the middle of the array */
    --end;
    ++begin;
    }

}

/******************************************************************************
function    add_arrays
author      Lucas Carpenter
DP email    lucas.c@digipen.edu
course      CS120
assignment  3
due date    11/1/2011

Brief Description:
adds the elements of two arrays
******************************************************************************/


void add_arrays(const int a[], const int b[], int c[], int size)
{
/* initialize variables */
  int i;
    /*perform once for each element */
  for (i = 0; i <= size; i++)
  {
  /* add each incrementing element from a and b, assign it to c  */
    c[i] = a[i] + b[i];
  }
}

/******************************************************************************
function    scalar_multiply
author      Lucas Carpenter
DP email    lucas.c@digipen.edu
course      CS120
assignment  3
due date    11/1/2011

Brief Description:
multiplies each element of an array by a scalar
******************************************************************************/

void scalar_multiply(int a[], int size, int multiplier)
{
/* initialize variables */
  int i;
  /* perform once for each element */
  for (i = 0; i <= size; i++)
  {
  /*multiply element by multipler */
    a[i] *= multiplier;
  }
}

/******************************************************************************
function    dot_product
author      Lucas Carpenter
DP email    lucas.c@digipen.edu
course      CS120
assignment  3
due date    11/1/2011

Brief Description:
dots two arrays
******************************************************************************/

int dot_product(const int a[], const int b[], int size)
{
/* initialize variables*/
  int result,
    i;
    i = 0;
    result = 0;
    /* perfrom once for each element */
    while(i < size)
    {
    /*take the sum total of each product */
    result += a[i] * b[i];
    ++i;
    }
  return result;
}

/******************************************************************************
function    cross_product
author      Lucas Carpenter
DP email    lucas.c@digipen.edu
course      CS120
assignment  3
due date    11/1/2011

Brief Description:
crosses two arrays
******************************************************************************/

void cross_product(const int a[], const int b[], int c[])
{
/* assign each cross to each c element */
  c[0] = a[1] * b[2] - a[2] * b[1];
  c[1] = a[2] * b[0] - a[0] * b[2];
  c[2] = a[0] * b[1] - a[1] * b[0];
}