add script

(NOTE: this commit is backdated from 2017-12-26)

mandelbrot.py

@@ -0,0 +1,61 @@
+import numpy as np
+import matplotlib.pyplot as plt
+from multiprocessing.dummy import Pool as ThreadPool
+import os.path
+
+
+def f(x):
+    return 2 ** (1 - x)
+
+
+def mandelbrot(zoomlevel):
+    print(zoomlevel)
+    zoom = f(zoomlevel)
+    maxit = 30 + 10 * zoomlevel
+    xmin = center[0] - zoom
+    xmax = center[0] + zoom
+    ymin = center[1] - zoom
+    ymax = center[1] + zoom
+
+    loadfile = str(zoomlevel) + ".npy"
+    if os.path.isfile(loadfile):
+        divtime = np.load(loadfile)
+        return [zoomlevel, divtime, [xmin, xmax, ymin, ymax]]
+
+    """Returns an image of the Mandelbrot fractal of size (h,w)."""
+    y, x = np.ogrid[ymin:ymax:h * 1j, xmin:xmax:w * 1j]
+    c = x + y * 1j
+    z = c
+    divtime = maxit + np.zeros(z.shape, dtype=int)
+
+    for i in range(maxit):
+        z = z ** 2 + c
+        diverge = z * np.conj(z) > 2 ** 2  # who is diverging
+        div_now = diverge & (divtime == maxit)  # who is diverging now
+        divtime[div_now] = i  # note when
+        z[diverge] = 2  # avoid diverging too much
+        plt.close()
+    np.save(str(zoomlevel), divtime)
+    return [zoomlevel, divtime, [xmin, xmax, ymin, ymax]]
+
+
+h = w = 1024
+# center = [-0.73, -0.205]
+center = [-0.7768816266387022, -0.13675506794031342]
+
+pool = ThreadPool(3)
+
+results = pool.map(mandelbrot, range(17))
+pool.close()
+pool.join()
+
+for zl, dt, coordinates in results:
+    print("Bild:{nr}".format(nr=zl))
+    plt.imshow(dt, extent=coordinates)
+    plt.ticklabel_format(style='sci', scilimits=(0, 0))
+
+    # plt.axis("off")
+    plt.savefig("{img}.png".format(img=zl), dpi=350)
+
+# for zoomlevel in range(20):
+#     mandelbrot(zoomlevel)