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Hey I don't understand.. But it is perhaps the answer.

sage: R.<x> = LaurentPolynomialRing(ZZ,1); R
Univariate Laurent Polynomial Ring in x over Integer Ring
sage: f(x) = x^2 - 2*x^-2
sage: f.diff(x)
x |--> 2*x + 4/x^3

I hope it helps.


sage: R.<x> = LaurentPolynomialRing(ZZ,1); R
Univariate Laurent Polynomial Ring in x over Integer Ring
sage: f = x^2 - 2*x^-2
sage: ff = f; ff
x^2 - 2*x^-2
sage: f(x) = x^2 - 2*x^-2
sage: f
x |--> x^2 - 2/x^2
sage: diff(ff,x)
0
sage: ff
x^2 - 2*x^-2
sage: f.diff(x)
x |--> 2*x + 4/x^3
sage: diff?
sage: diff(ff)
0

The way of defining the "ff" is not good. Do we have to define a polynomial like this, in order to compute its derivative conveniently?

p(x) = x**2 + a1*x + a2

Thanks in advance!