CODEWITHSUNDEEP
pythonsympy
Set
Set

Reputation: 934

Converting a function from sympy to numpy (attribute error)

import numpy as np
import sympy as sym
from numpy import sin
from sympy import symbols, diff

func = lambda x: sin(x)
x    = symbols('x')
print diff(func(x),x)

This works if I replace my function with a polynomial, or if I place the trig function directly into the diff operator. But in this format I get AttributeError: sin.

Basically I think python can't recognize func as just being a trig function which it knows how to symbolically integrate. I could just have sympy import sin and then things would work, but then I'm stuck with func referencing sin in the sympy namespace and there are future things I want to do with func which require that it be defined using sin in the numpy namespace.

Upvotes: 4

Views: 1503

Answers (2)

asmeurer
asmeurer

Reputation: 91490

You should build your expression up symbolically using SymPy functions, and then use lambdify to convert them into things that can be evaluated with NumPy.

Upvotes: 2

Mike Graham
Mike Graham

Reputation: 76683

This simply isn't how you use sympy. You can't use normal functions in conjunction with numpy--you need to build symbolic expressions using the stuff it provides.

To write code to get the derivative of sin(x), you would do

import sympy as sym
from sympy import sin, symbols, diff

x = symbols('x')
print diff(sin(x), x)

If you have some other particular case you're having trouble with, you'll have to show it. You can't mix sympy with non-sympy stuff in this way, so there isn't some general feedback that can be provided.

Upvotes: 0

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