Graphics Programs: Draw Circle using Polynomial Method

/**********************************************************
* Program : Simple Circle Drawing Algorithm
* Author : Vijay Kumar Verma (VJY) | MCA
* Website : vjysoftworx.com
* Date : 25-Jan-2014
***********************************************************/
#include ‹iostream.h›
#include ‹conio.h›
#include ‹graphics.h›
#include ‹math.h›
int main(){
  int dr=DETECT, md;
  initgraph(&dr,&md,"c:\\tc\\bgi");
  int h, k, r, x, y, xe,col;
  cout<<"Enter co-ordinate of center(h,k): ";
  cin>>h>>k;
  cout<<"Enter radius: ";
  cin>>r;
  cout<<"Enter Color code(0-15): ";
  cin>>col;
  x= 0;
  xe = (int)r/sqrt(2)+0.5;  //calculate the end point of x
  y = r;                     //add the value of r to y
  while(x <= xe){
   putpixel(x+h,y+k, col);
   putpixel(x+h,-y+k,col);
   putpixel(y+h,-x+k, col);
   putpixel(-y+h,-x+k, col);
   putpixel(-x+h,-y+k, col);
   putpixel(-x+h,y+k, col);
   putpixel(-y+h,x+k, col);
   putpixel(y+h,x+k, col);
   x++;
   y = (int)sqrt(r*r-x*x)+0.5;  //calculate the value of y
  }
 getch();
 closegraph();
 return 0;
}