Finalized lens work. Started initial unit tests.

examples/documentation/test_fractal.py

@@ -0,0 +1,57 @@
+import numpy as np
+from displayarray import display
+
+
+def mandel(height=240, width=320, itermax=255, y_min=-1.8, y_max=.6, x_min=-1.6, x_max=1.6):
+    """
+    Generate a view of the mandlebrot fractal
+
+    source: https://thesamovar.wordpress.com/2009/03/22/fast-fractals-with-python-and-numpy/
+
+    >>> img = mandel()
+    >>> center = (0, -1.78)
+    >>> length = 3.2
+    >>> d = display(img)
+    >>> while d:
+    ...   length*=.9
+    ...   y_min = center[1]-length/2.0
+    ...   y_max = center[1]+length/2.0
+    ...   x_min = center[0]-length/2.0
+    ...   x_max = center[0]+length/2.0
+    ...   img[...] = mandel(y_min=y_min, y_max=y_max, x_min=x_min, x_max=x_max)
+    """
+
+    ix, iy = np.mgrid[0:height, 0:width]
+    x = np.linspace(y_min, y_max, height)[ix]
+    y = np.linspace(x_min, x_max, width)[iy]
+    c = x + complex(0, 1) * y
+    del x, y
+    img = np.zeros_like(c, dtype=int)
+    c.shape = iy.shape = ix.shape = height * width
+    z = np.copy(c)
+    for i in range(itermax):
+        if not len(z):
+            break
+        z = z * z
+        z = z + c
+        rem = abs(z) > 4.0
+        img[ix[rem], iy[rem]] = i + 1
+        rem = ~rem
+        z = z[rem]
+        ix, iy = ix[rem], iy[rem]
+        c = c[rem]
+    return img / 255.0
+
+
+if __name__ == '__main__':
+    img = mandel()
+    center = (0, -.6)
+    length = 3.2
+    d = display(img)
+    while d:
+        length *= .9
+        y_min = center[1] - length / 2.0
+        y_max = center[1] + length / 2.0
+        x_min = center[0] - length / 2.0
+        x_max = center[0] + length / 2.0
+        img[...] = mandel(y_min=y_min, y_max=y_max, x_min=x_min, x_max=x_max)