Python - 数値積分（シンプソン則による定積分）！

#! /usr/local/bin/python3.6
"""
Definite integral by by simpson rule
"""
import math
import sys
import traceback


class DefiniteIntegralSimpson:
    M = 100  # Number of division

    def __init__(self):
        self.f = lambda x: math.sqrt(4 - x * x)

    def compute(self, a, b):
        """ Computation of infinite intagral

        :param float a
        :param float b
        """
        try:
            h = (b - a) / (2 * self.M)
            x, f_o, f_e = a, 0, 0
            for k in range(1, 2 * self.M - 1):
                x += h
                if k % 2 == 1:
                    f_o += self.f(x)
                else:
                    f_e += self.f(x)
            s  = self.f(a) + self.f(b)
            s += 4 * (f_o + self.f(b - h)) + 2 * f_e
            s *= h / 3.0
            print("  / {:f}".format(b))
            print("  |  f(x)dx = {:f} ".format(s))
            print("  / {:f}".format(a))
        except Exception as e:
            raise


if __name__ == '__main__':
    if len(sys.argv) < 3:
        print("USAGE: ./definite_integral_simpson.py A B")
        sys.exit(0)
    a, b = list(map(float, sys.argv[1:3]))
    if a == 0 and b == 0:
        sys.exit(0)

    try:
        obj = DefiniteIntegralSimpson()
        obj.compute(a, b)
    except Exception as e:
        traceback.print_exc()
        sys.exit(1)

$ chmod +x definite_integral_simpson.py

$ ./definite_integral_simpson.py -2 2
  / 2.000000
  |  f(x)dx = 6.282266
  / -2.000000