mandelbrot_bellard.cjs
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mandelbrot_bellard.cjs
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	/* Mandelbrot display on a color terminal
	(c) 2025 Fabrice Bellard
	MIT license
	*/
	function mandelbrot(center_x, center_y, scale, w, h, max_it) {
	var x1, y1, y2, i, x, y, cx, cy, fx, fy, i, t, c, s, c0;
	var colors = [14, 15, 7, 8, 0, 4, 12, 5, 13, 1, 9, 3, 11, 10, 2, 6];
	fx = (scale * 0.5) / Math.min(w, h);
	fy = fx * 2;
	for (y1 = 0; y1 < h; y1++) {
	s = '';
	for (x1 = 0; x1 < w; x1++) {
	for (y2 = 0; y2 < 2; y2++) {
	cx = (x1 - w * 0.5) * fx + center_x;
	cy = (y1 + y2 * 0.5 - h * 0.5) * fy + center_y;
	x = 0;
	y = 0;
	for (i = 0; i < max_it && x * x + y * y < 4; i++) {
	t = x * x - y * y + cx;
	y = 2 * x * y + cy;
	x = t;
	}
	if (i >= max_it) {
	c = 0;
	} else {
	c = colors[i % colors.length];
	}
	if (y2 == 0) c0 = c;
	}
	s += '\x1b[' + (c0 >= 8 ? 82 + c0 : 30 + c0) + ';' + (c >= 8 ? 92 + c : 40 + c) + 'm\u2580';
	}
	s += '\x1b[0m'; /* reset the colors */
	console.log(s);
	}
	}

	mandelbrot(-0.75, 0.0, 2.0, 80, 25, 50);