ploteo

import numpy as np
import matplotlib.pyplot as plt

def function_or(a, b):
    return 0.5 * (a + b + abs(a - b))

x    = np.arange(0, 1, 0.001)
y    = np.arange(0, 1, 0.001)
X, Y = np.meshgrid(x, y)
Z    = function_or(X, Y)
im   = plt.imshow(Z, cmap=plt.cm.Spectral, extent=(0, 1, 0, 1), origin="lower")

plt.colorbar(im)
plt.title('$0.5 * (a + b + abs(a - b))$')
plt.show()