[python-arrayfire] 160/250: Example: Adding fractal example

[Ghislain Vaillant]

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ghisvail-guest pushed a commit to branch debian/master
in repository python-arrayfire.

commit e182b22fc9df9abf448757678accd8d6b16c96f6
Author: Pavan Yalamanchili <pavan at arrayfire.com>
Date:   Wed Dec 9 15:10:37 2015 -0500

    Example: Adding fractal example
---
 examples/graphics/fractal.py | 74 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)

diff --git a/examples/graphics/fractal.py b/examples/graphics/fractal.py
new file mode 100644
index 0000000..eed8fea
--- /dev/null
+++ b/examples/graphics/fractal.py
@@ -0,0 +1,74 @@
+#!/usr/bin/python
+
+#######################################################
+# Copyright (c) 2015, ArrayFire
+# All rights reserved.
+#
+# This file is distributed under 3-clause BSD license.
+# The complete license agreement can be obtained at:
+# http://arrayfire.com/licenses/BSD-3-Clause
+########################################################
+
+import arrayfire as af
+import sys
+from math import sqrt
+
+width = 400
+height = 400
+
+def complex_grid(w, h, zoom, center):
+    x = (af.iota(d0 = 1, d1 = h, tile_dims = (w, 1)) - h/2) / zoom + center[0]
+    y = (af.iota(d0 = w, d1 = 1, tile_dims = (1, h)) - w/2) / zoom + center[1]
+    return af.cplx(x, y)
+
+def mandelbrot(data, it, maxval):
+    C = data
+    Z = data
+    mag = af.constant(0, *C.dims())
+
+    for ii in range(1, 1 + it):
+        # Doing the calculation
+        Z = Z * Z + C
+
+        # Get indices where abs(Z) crosses maxval
+        cond = af.cast((af.abs(Z) > maxval), af.Dtype.f32)
+        mag = af.maxof(mag, cond * ii)
+
+        C = C * (1 - cond)
+        Z = Z * (1 - cond)
+
+        af.eval(C)
+        af.eval(Z)
+
+    return mag / maxval
+
+def normalize(a):
+    mx = af.max(a)
+    mn = af.min(a)
+    return (a - mn)/(mx - mn)
+
+if __name__ == "__main__":
+    if (len(sys.argv) > 1):
+        af.set_device(int(sys.argv[1]))
+
+    af.info()
+
+    print("ArrayFire Fractal Demo\n")
+
+    win = af.Window(width, height, "Fractal Demo")
+    win.set_colormap(af.COLORMAP.SPECTRUM)
+
+    center = (-0.75, 0.1)
+
+    for i in range(10, 400):
+        zoom = i * i
+        if not (i % 10):
+            print("Iteration: %d zoom: %d" % (i, zoom))
+
+        c = complex_grid(width, height, zoom, center)
+        it = sqrt(2*sqrt(abs(1-sqrt(5*zoom))))*100
+
+        if (win.close()): break
+        mag = mandelbrot(c, int(it), 1000)
+
+        win.image(normalize(mag))

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