/******************************************************************************
   Lab Exercise #5 -- Implementation of support module
******************************************************************************/

using namespace std;

#include <iostream>
#include <cmath>

#include "lab05.support.h"

extern int InputStatus;

int InputStatus;

/*-----------------------------------------------------------------------------
   Name:  coefficients

   Purpose:  Accept the three coefficients of an equation from the user.
   Input:    The coefficients (A, B and C) of the equation
   Return:   The coefficients (as reference parameters)
             True if "end-of-file"; false otherwise (as the return expression)
-----------------------------------------------------------------------------*/

void coefficients( double & A, double & B, double & C )
{
  cout << "Please enter the coefficients for a quadratic equation" << endl;
  cout << "(enter A, B and C, or enter Ctrl-d to halt):" << endl;
  cin >> A >> B >> C;

  if (cin.eof())
  {
    InputStatus = 0;
  }
  else
  {
    InputStatus = 1;
  }
}

/*-----------------------------------------------------------------------------
   Name:  roots

   Purpose:  Compute the roots, given the coefficients of a quadratic equation.
   Receive:  The coefficients (A, B and C) of the equation
   Return:   The roots (as reference parameters)
             An error flag (as the return expression)
-----------------------------------------------------------------------------*/

int roots( double A, double B, double C, double & Root1, double & Root2 )
{
  int Flag;
  double Discriminant;

  if (A == 0.0)
  {
    Flag = 3;    // Not a quadratic equation
  }
  else
  {
    Discriminant = B*B-4.0*A*C;

    if (Discriminant < 0.0)
    {
      Flag = 2;    // Equation has complex roots
    }
    else if (Discriminant == 0.0)
    {
      Flag = 1;    // Equation has one real root

      Root1 = (-B)/(2.0*A);
    }
    else
    {
      Flag = 0;    // Equation has two real roots

      Root1 = (-B + sqrt( Discriminant ))/(2.0*A);
      Root2 = (-B - sqrt( Discriminant ))/(2.0*A);
    }
  }

  return Flag;
}