Integration Exercise 3

Imports



In [84]:

    
%matplotlib inline
import matplotlib.pyplot as plt
import numpy as np
from scipy import integrate
import math

2d polar integration

The 2d polar integral of a scalar function $f(r, \theta)$ is defined as:

$$ I(r_{max}) = \int_0^{r_{max}} \int_0^{2\pi} f(r, \theta) r d\theta $$

Write a function integrate_polar(f, rmax) that performs this integral numerically using scipy.integrate.dblquad.



In [142]:

    
def integrate_polar(f, rmax):
    """Integrate the function f(r, theta) over r=[0,rmax], theta=[0,2*np.pi]"""
    I, err = integrate.dblquad(lambda r,t: r*f(r,t), 0, 2*np.pi, lambda x: 0, lambda x: rmax)
    return I



In [143]:

    
integrate_polar(lambda r,t: 1, 1)









    Out[143]:





3.141592653589793



In [144]:

    
assert np.allclose(integrate_polar(lambda r,t: 1, 1.0), np.pi)
assert np.allclose(integrate_polar(lambda r, t: np.exp(-r)*(np.cos(t)**2), np.inf), np.pi)



In [25]: