I am getting the following error code when trying to evaluate a definite integral in Python.
AttributeError Traceback (most recent call last)
<ipython-input-7-2be8718c68ec> in <module>()
7 x, n = symbols('x n')
8
----> 9 f = (cos(n*x))*(x**2-pi**2)^2
10 integrate(f,(x,-n*pi,n*pi))
11
AttributeError: 'Mul' object has no attribute 'cos'
I have copied my input code below. Thanks for any help.
from pylab import *
from sympy import *
from numpy import *
init_printing(use_unicode=False, wrap_line=False, no_global=True)
x, n = symbols('x n')
f = (cos(n*x))*(x**2-pi**2)^2
integrate(f,(x,-n*pi,n*pi))
Your problem is with namespace clash, here
from sympy import *
from numpy import *
Since both numpy
and and sympy
have their own definition of cos
. The error is telling you that the Mul
object (which is n*x
) does not have a cosine method, since the interpreter is now confused between the sympy
and numpy
methods. Do this instead
import pylab as pl
import numpy as np
import sympy as sp
x, n = sp.symbols('x n')
f = (sp.cos(n*x))*(x**2-sp.pi**2)**2
sp.integrate(f,(x,-n*sp.pi,n*sp.pi))
Also note that I have changed ^
to **
as ^
is the Not
operator in sympy
. Here, I am assuming that you need the symbolic Pi
from sympy.core.numbers.Pi
and not the numeric one from numpy
. If you want the latter, then do this
f = (sp.cos(n*x))*(x**2-np.pi**2)**2
sp.integrate(f,(x,-n*np.pi,n*np.pi))