83 lines
2.4 KiB
PHP
83 lines
2.4 KiB
PHP
set_time_limit(300);
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header("Content-Type: image/png");
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class Julia {
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static private $started = false;
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public static function start() {
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if (!self::$started) {
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self::$started = true;
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new self;
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}
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}
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const AXIS_REAL = 0;
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const AXIS_IMAGINARY = 1;
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const C = [-0.75, 0.1];
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const RADII = [1, 0.5];
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const CENTER = [0, 0];
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const MAX_ITERATIONS = 100;
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const TICK_SPACING = 0.001;
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private $maxDistance;
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private $imageResource;
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private $whiteColorResource;
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private $z0 = [];
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private function __construct() {
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$this->maxDistance = max($this->distance(self::C), 2);
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$this->imageResource = imagecreate(
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$this->coordinateToPixel(self::RADII[self::AXIS_REAL], self::AXIS_REAL),
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$this->coordinateToPixel(self::RADII[self::AXIS_IMAGINARY], self::AXIS_IMAGINARY)
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);
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imagecolorallocate($this->imageResource, 0, 0, 0);
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$this->whiteColorResource = imagecolorallocate($this->imageResource, 255, 255, 255);
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for ($x = self::CENTER[self::AXIS_REAL] - self::RADII[self::AXIS_REAL];
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$x <= self::CENTER[self::AXIS_REAL] + self::RADII[self::AXIS_REAL]; $x += self::TICK_SPACING) {
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$z0[self::AXIS_REAL] = $x;
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for ($y = self::CENTER[self::AXIS_IMAGINARY] - self::RADII[self::AXIS_IMAGINARY];
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$y <= self::CENTER[self::AXIS_IMAGINARY] + self::RADII[self::AXIS_IMAGINARY]; $y += self::TICK_SPACING) {
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$z0[self::AXIS_IMAGINARY] = $y;
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$iterations = 1;
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do {
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$z0 = $this->q($z0);
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$iterations++;
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} while($iterations < self::MAX_ITERATIONS && $this->distance($z0) <= $this->maxDistance);
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if ($iterations !== self::MAX_ITERATIONS) {
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imagesetpixel(
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$this->imageResource,
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$this->coordinateToPixel($x, self::AXIS_REAL),
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$this->coordinateToPixel($y, self::AXIS_IMAGINARY),
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$this->whiteColorResource
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);
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}
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$z0[self::AXIS_REAL] = $x;
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}
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}
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}
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public function __destruct() {
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imagepng($this->imageResource);
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imagedestroy($this->imageResource);
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}
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private function q($z) {
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return [ ($z[self::AXIS_REAL] ** 2) - ($z[self::AXIS_IMAGINARY] ** 2) + self::C[self::AXIS_REAL],
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(2 * $z[self::AXIS_REAL] * $z[self::AXIS_IMAGINARY]) + self::C[self::AXIS_IMAGINARY] ];
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}
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private function distance($z) {
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return sqrt( ($z[self::AXIS_REAL] ** 2) + ($z[self::AXIS_IMAGINARY] ** 2) );
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}
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private function coordinateToPixel($coordinate, $axis) {
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return ($coordinate + self::RADII[$axis]) * (self::TICK_SPACING ** -1);
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}
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}
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Julia::start();
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