newton_method.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from __future__ import print_function

def f(x):
    return x**3 + 2*x**2 + 10*x - 20

def df(x):
    return 3*x**2 + 4*x + 10

def newton(init, tolerance=0.000001):
    x = init
    cnt = 0
    process = [(cnt, x)]

    while True:
        cnt += 1
        x1 = x - f(x) / df(x)
        process.append((cnt, x1))
        if (abs(x1 - x)) < tolerance:
            break
        else:
            x = x1
    return process

def main():
    print(newton(1.0))

if __name__ == '__main__':
    main()

大学の課題用スクリプト