CODEWITHSUNDEEP
pythonpython-2.7numpysympy
MAS
MAS

Reputation: 4993

Integration in python

The code I have written to integrate is giving wrong results.I get the c_0,c_1,...c_4 to be zeros! What am I doing wrong? I am using simply 0.7.6 on a mac. 

from numpy import *
from matplotlib.pyplot import *
from sympy import *
x = Symbol('x')
f = 1.0*sin(np.pi * x)
phi_0 = 1.0
phi_1 = 1.0*x
phi_2 = 1./2*(3*x**2-1)
phi_3 = 1./2*(5*x**3-3*x)
phi_4 = 1./8*(35*x**4-30*x**2+3)
c_0 = integrate(f*phi_0, (x, -1.0, 1.0))
c_1 = integrate(f*phi_1, (x, -1.0, 1.0))
c_2 = integrate(f*phi_2, (x, -1.0, 1.0))
c_3 = integrate(f*phi_3, (x, -1.0, 1.0))
c_4 = integrate(f*phi_4, (x, -1.0, 1.0))
print c_0
print c_1
print c_2
print c_3
print c_4

Upvotes: 0

Views: 166

Answers (2)

dparadis28
dparadis28

Reputation: 101

I agree with smichr. Everything appears to be fine as long as your import numpy. You can also use scipy but that is dependent on your preferences and needs.

from scipy.integrate import quad

quad(lambda x: x**2, 0, 1)

Upvotes: 1

smichr
smichr

Reputation: 19093

Other than the need to import numpy as np, I don't see any problems in the most recent version (0.7.6). Some values are zero (as expected due to symmetry consideration) but others are not:

>>> print c_0
0
>>> print c_1
0.636619772367581
>>> print c_2
0
>>> print c_3
-0.330926260628403
>>> print c_4
0

Upvotes: 1

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