fixed-point-iteration.py

#!/usr/bin/env python3

from sympy import lambdify
from itertools import count

function = lambdify("x", input("Enter a method to iterate with: "))
initial_value = float(input("Enter the initial value for the iteration: "))
target_diff = float(input("Enter the target value for the difference between iterations: "))

value = initial_value
for step in count():
    previous_value = value
    value = function(value)
    print(str(step).rjust(4), value)

    if abs(value - previous_value) <= target_diff:
        break