Tetration fractal (Python 3)

tetration.py

#!/usr/bin/env python

import sys
import os
import math
import time
from PIL import Image

def tetration(l, t, w, h, sw, sh, mit):
    data = []
    for ky in range(sh):
        for kx in range(sw):
            x = l + w * kx / (sw - 1)
            y = t + h * ky / (sh - 1)
            for i in range(mit):
                try:
                    e = math.exp(-0.5 * math.pi * y)
                    p = math.pi * x * 0.5
                    x = e * math.cos(p)
                    y = e * math.sin(p)
                except:
                    break
                if math.hypot(x, y) > 1000000:
                    break
            data.append((i % 4 * 64, i % 8 * 32, i % 16 * 16))
    return data

def main(args):
    if len(args) < 6:
        print("Usage: %s imagefile left top width height [screen_width=512 screen_height=512 max_iters=256]" % os.path.basename(args[0]), file=sys.stderr)
        print("  Ex. %s tetration.png -1.5 0.0 0.75 0.75" % os.path.basename(args[0]), file=sys.stderr)
        sys.exit(1)

    imagefile = args[1]
    l, t, w, h = map(float, args[2:6])
    sw, sh, mit = 512, 512, 256
    if len(args) >= 7: sw = int(args[6])
    if len(args) >= 8: sh = int(args[7])
    if len(args) >= 9: mit = int(args[8])

    print("Range: (%f, %f) - (%f, %f)" % (l, t, l + w, t + h))
    print("Image: %d x %d" % (sw, sh))
    print("Max number of iterations: %d" % mit)

    start_time = time.time()
    data = tetration(l, t, w, h, sw, sh, mit)
    print("Time: %.2f" % (time.time() - start_time))

    im = Image.new("RGB", (sw, sh))
    for i, rgb in enumerate(data):
        im.putpixel((i % sw, i // sh), rgb)
    im.show()
    im.save(imagefile)

if __name__ == "__main__":
    main(sys.argv)