PyEphem comes with a simple implementation of Newton’s Method, named newton.
>>> from ephem import newton
Given a continuous function and two x coordinates near which the function crosses zero, it returns the x coordinate of the actual zero crossing. For example, if asked to find the zero-crossing of the sin() function in the vicinity of the number three, it returns a quite good appoximation of π (“pi”):
>>> import math
>>> n = newton(math.sin, 3.0, 3.1)
>>> print n
3.14159265359