Python求导数的方法

def func(coeff):  sum=''  for key in coeff:    sum=sum+'+'+str(key)+'*'+'x'+'**'+str(coeff[key])  return sum[1:]from sympy import *from sympy.core.sympify import SympifyErrorexpr = func({2:0,3:1,4:2,5:7})x = Symbol("x")sexpr = sympify(expr)print diff(sexpr, x)print diff(sexpr, x).subs('x',3)

(2+3*x+4*x**2+7*x**3.7).diff(x).subs({x:3}).evalf()