/* Show approximation in floating-point operations
   Emad Arasteh
   October 10, 2019
*/

#include <stdio.h>

int main() {

  float r = 1.2;
  float R = 4.7;
  float pi = 3.14159, eps = 0.0001;
  float x = 0, y = 0, diff = 0;

  x = pi * R * R - pi * r * r;

  y = pi * (R * R - r * r);

  diff = x - y;

  if (x == y) {
    printf("x and y are equal! \n");
  }

  if (x != y) {
    printf("x and y are not equal! \n");
  }

  /* abs(diff) < eps */
  if (diff < eps && diff > -eps) {
    printf("x and y are approximately equal! \n");
  }

  /* abs(diff) > eps  */
  if (!(diff < eps && diff > -eps)) {
    printf("x and y are not approximately equal! \n");
  }

  printf("The value of x is %f \n", x);
  printf("The value of y is %f \n", y);

  return 0;
}