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