Transforming polynomial variable in Numpy

Question

I am trying to learn how to use Numpy. Consider I have the roots of a polynomial. I use coeff = np.polynomial.polynomial.polyfromroots(roots) to get the coefficients of the polynomial as an array. Then I use print np.poly1d(coeff) To print out the polynomial. Let that polynomial be

x^2 +3x + 2

Now how do I transform the variable such that

x is now 2/x

That is the equation becomes

(2/x)^2 + 6/x + 2

In scilab I can do this using the horner function. Is it possible in numpy?

Answer 1

In SymPy this would be simply:

from sympy.abc import x

f = x**2 + 3*x + 2
g = f.subs({x:2/x})

Resulting in:

print(g)
#2 + 6/x + 4/x**2