pythonsympydifferentiation

Numerical value of differention in sympy in python

I can evaluate differential function in sympy python using g(x) = diff(f(x), x). My question is how do I evaluate numerical value of g(x)? for example at x = 2?

from sympy import *
f = diff(cos(x), x)
f(3.14)

This gives following error:

print(f(3.14))

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'Mul' object is not callable

Please help me out. Is there any other package?

Solution

  • You can try

    >>> from sympy import *
>>> x=Symbol('x')
>>> f = diff(cos(x), x)
>>> f
-sin(x)
>>> f.subs(x,3.14)
-0.00159265291648683
>>> f.subs(x,pi)
0
>>> f.subs(x,2)
-sin(2)
>>> f.subs(x,2).evalf()
-0.909297426825682
>>>