テキストでマンデルブロー
#include <stdio.h>
#include <stdlib.h>
int check( float c_re, float c_im ) {
  int i;
  float re = c_re, im = c_im, norm;
  for( i = 0; i < 64 && ( norm = re*re-im*im ) < 4; i++ ) {
    im = 2*re*im+c_im;
    re = norm+c_re;
  }
  return i;
}
int main( int argc, char* argv[] ) {
  int x, y, c;
  for( y = 0; y < 22; y++ ) {
    for( x = 0; x < 79; x++ ) {
      c = check( (float)(x-50)/30, (float)(y-11)/10 );
      putchar( c == 64 ? ' ' : '@' + c%16 );
    }
    putchar( 'n' );
  }
  return 0;
}