Clean up and move integral demo

Author: tonysyu

examples/pylab_examples/integral_demo.py

@@ -0,0 +1,39 @@
+"""
+Plot demonstrating the integral as the area under a curve.
+"""
+import numpy as np
+import matplotlib.pyplot as plt
+from matplotlib.patches import Polygon
+
+def func(x):
+    return (x-3)*(x-5)*(x-7)+85
+
+fig, ax = plt.subplots()
+
+a, b = 2, 9 # integral area
+x = np.linspace(0, 10)
+y = func(x)
+plt.plot(x, y, 'r', linewidth=2)
+
+# make the shaded region
+ix = np.linspace(a, b)
+iy = func(ix)
+verts = [(a,0)] + list(zip(ix,iy)) + [(b,0)]
+poly = Polygon(verts, facecolor='0.9', edgecolor='0.5')
+ax.add_patch(poly)
+
+plt.text(0.5 * (a + b), 30,
+         r"$\int_a^b f(x)\mathrm{d}x$", horizontalalignment='center',
+         fontsize=20)
+
+plt.axis([0,10, 0, 180])
+plt.figtext(0.9, 0.05, '$x$')
+plt.figtext(0.1, 0.9, '$y$')
+
+ax.spines['right'].set_visible(False)
+ax.spines['top'].set_visible(False)
+ax.set_xticks((a,b))
+ax.set_xticklabels(('$a$','$b$'))
+ax.set_yticks([])
+
+plt.show()

examples/showcase/integral_demo.py

@@ -91,6 +91,10 @@
     'subplot_demo.py',
     ]
 
+files['showcase'] = [
+    'integral_demo.py',
+    ]
+
 files['pylab'] = [
     'accented_text.py',
     'alignment_test.py',
@@ -175,7 +179,6 @@
     'image_nonuniform.py',
     'image_origin.py',
     'image_slices_viewer.py',
-    'integral_demo.py',
     'interp_demo.py',
     'invert_axes.py',
     'layer_images.py',