#!/usr/bin/env python

# -*- coding:utf-8 -*-

# FileName: 002_integrate.py

#

# Description:

#

# Version: 1.0

# Created: 2018-06-13 09:26:33

# Last Modified: 2019-09-03 10:39:24

# Revision: none

# Compiler: gcc

#

# Author: zt ()

# Organization:

import numpy as np

from scipy.integrate import quad, dblquad

from scipy.special import jn

def f(x):

return x

x_lower = 0

x_upper = 1

val, abserr = quad(f, x_lower, x_upper)

print("integral value=", val, ",absolute error=", abserr)

def integrand(x, n):

return jn(n, x)

x_lower = 0

x_upper = 10

val, abserr = quad(integrand, x_lower, x_upper, args=(3, ))

print("integral value=", val, ",absolute error=", abserr)

val, abserr = quad(lambda x: np.exp(-x**2), -np.Inf, np.Inf)

print("integral value=", val, ",absolute error=", abserr)

analytical = np.sqrt(np.pi)

print("analytical=", analytical)

def integrand(x, y):

return np.exp(-x**2 - y**2)

x_lower = 0

x_upper = 10

y_lower = 0

y_upper = 10

val, abserr = dblquad(integrand, x_lower, x_upper, lambda x: y_lower,

lambda x: y_upper)

print("integral value=", val, ",absolute error=", abserr)