Julia Set

   TODO

  ___________________________________________________________________
 | Julia Set for -0.34 - 0.63i       :.                              |
 |                                ..':. ..                           |
 |                                '':.:'''      ..       ..          |
 |                                 :':::.. ''  ::.    .. :.'         |
 |                                  '::::. :: :::. .   :.'': .       |
 |                              ......':::.::.:: ...::.:::.::.. .    |
 |                              :::::::::':'.':.::::::::':.::''::..  |
 |                   .             '::::'':':::':'':::'  ::''  '     |
 |                   ':.       .   .. ..::'::':::.   '   :'          |
 |                 . :: :'     ::..::::::: ::: ':::..     '          |
 |                   :'::::   '.:::::::::'.::::'  ''                 |
 |                    .:::::' ':::::::::. ''::::'.                   |
 |                  :. '::::'.::::::::::.  '::':.'                   |
 |          . .   '':::. ::: ::::::::'::'    .::::                   |
 |         :':.  ... ':::.:':::''  '  '        ''.                   |
 |        ..::  .::::::...':.::::::.:                                |
 |   :::...' '.::::::::'.: .:.:'::::'':                              |
 |    '' :. : .:''':' :::'::':::.   ' '                              |
 |         '::'': '' '::: ::'':::::                                  |
 |          ::       ':.  '' '':::.:                                 |
 |         ' '       '        ::.:.'.'                               |
 |                              ::'                                  |
 |                              '                                    |
 |___________________________________________________________________|

                                      Code

   The following code is a simple [1]C program that renders given Julia set
   into terminal (for demonstrative purposes, it isn't efficient or do any
   [2]antialiasing).

 #include <stdio.h>

 #define ROWS 30
 #define COLS 70
 #define SET_X -0.36 // Julia set parameter
 #define SET_Y -0.62 // Julia set parameter
 #define FROM_X -1.5
 #define FROM_Y 1.0
 #define STEP (3.0 / ((double) COLS))

 unsigned int julia(double x, double y)
 {
   double cx = x, cy = y, tmp;

   for (int i = 0; i < 1000; ++i)
   {
     tmp = cx * cx - cy * cy + SET_X;
     cy = 2 * cx * cy + SET_Y;
     cx = tmp;

     if (cx * cx + cy * cy > 10000000000)
       return 0;
   }

   return 1;
 }

 int main(void)
 {
   double cx, cy = FROM_Y;

   for (int y = 0; y < ROWS; ++y)
   {
     cx = FROM_X;

     for (int x = 0; x < COLS; ++x)
     {
       unsigned int point =
         julia(cx,cy) + (julia(cx,cy + STEP) * 2);  

       putchar(point == 3 ? ':' : (point == 2 ? '\'' :
         (point == 1 ? '.' : ' ')));

       cx += STEP;
     }

     putchar('\n');

     cy -= 2 * STEP;
   }

   return 0;
 }

Links:
1. c.md
2. antialiasing.md