/* ===========================================================
 * RectangleRule_Prec: Precision-driven Rect Rule
 * =========================================================== */

#include <iostream.h>


float RectangleRule_Prec(float f(float), float a, float b, float EPS)
{
  /* ------------------------------
     "Local" Variables
     ------------------------------ */
   int N;
   float V1, V2;		// Successive estimates

   extern float RectangleRule(float(float), float, float, int);

   N = 1;
   V1 = RectangleRule(f, a, b, N);
   cout << "Approximation = " << V1 << "\n";

   N = 2*N;
   V2 = RectangleRule(f, a, b, N);
   cout << "Approximation = " << V2 << "\n";

   while ( fabs((V2 - V1)) > EPS )
   {
      V1 = V2;
      N = 2*N;
      V2 = RectangleRule(f, a, b, N);
      cout << "Approximation = " << V2 
	   << "     |V2-V1| = " << fabs((V2 - V1)) << "\n";
   }

   return(V2);
}