Simple autodiff

execute tests with pytest.

The autodiff operates on real numbers, represented by class Numtor. A few operations are implemented.

Usage:

import autodiff as ad 

a = ad.Numtor(1)
b = ad.Numtor(3)
r = a * b
r.backward()

print(a.grad, b.grad)

This snippet will calculate and evaluate the derivatives $\frac{dr}{da} = b = 3$ and $\frac{dr}{db} = a = 1$.