Important: The polytools package has been deprecated. Use the superseding command PolynomialTools[IsSelfReciprocal] instead.

Determine whether a is a ``self-reciprocal'' polynomial in x. This property holds if and only if  for all , where .

If d is even and if the optional second argument p is specified, p is assigned the polynomial P of degree  such that .

Note that if d is odd, a being self-reciprocal implies a is divisible by . In this case, if p is specified then the result computed is for .