Mandelbrot set

function mandelbrot($real, $imaginary)
{
    $constant = new \stdClass();
    $constant->real = $real;
    $constant->imaginary = $imaginary;

    $z = new \stdClass();
    $z->real = 0;
    $z->imaginary = 0;

    for ($i = 0; $i < 4; $i++) {
        $z->real = $z->real * $z->real - $z->imaginary * $z->imaginary + $constant->real;
        $z->imaginary = 2 * $z->real * $z->imaginary + $constant->imaginary;
    }

    return ($z->real * $z->real + $z->imaginary * $z->imaginary) < 4;
}

for ($row = -100; $row < 100; $row++) {
    for ($column = -100; $column < 100; $column++) {
        echo mandelbrot($column / 100, $row / 100) ? '1'