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/*
* Mandelbrot example:
*
* $ ./duk mandel.js
* [...]
*/
function mandel() {
var w = 76, h = 28, iter = 100;
var i, j, k, c;
var x0, y0, xx, yy, xx2, yy2;
var line;
for (i = 0; i < h; i++) {
y0 = (i / h) * 2.5 - 1.25;
for (j = 0, line = []; j < w; j++) {
x0 = (j / w) * 3.0 - 2.0;
for (k = 0, xx = 0, yy = 0, c = '#'; k < iter; k++) {
/* z -> z^2 + c
* -> (xx+i*yy)^2 + (x0+i*y0)
* -> xx*xx+i*2*xx*yy-yy*yy + x0 + i*y0
* -> (xx*xx - yy*yy + x0) + i*(2*xx*yy + y0)
*/
xx2 = xx*xx; yy2 = yy*yy;
if (xx2 + yy2 < 4.0) {
yy = 2*xx*yy + y0;
xx = xx2 - yy2 + x0;
} else {
/* xx^2 + yy^2 >= 4.0 */
if (k < 3) { c = '.'; }
else if (k < 5) { c = ','; }
else if (k < 10) { c = '-'; }
else { c = '='; }
break;
}
}
line.push(c);
}
print(line.join(''));
}
}
try {
mandel();
} catch (e) {
print(e.stack || e);
}
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