In the case of a constant polynomial (meaning degree 0 or length 1), the Graeffe Transform as implemented in #374 simply returned the input polynomial. That is incorrect; it should return the input polynomial squared.
This PR fixes that, and adapts the test code to cover non-monic polynomials.
In the case of a constant polynomial (meaning degree 0 or length 1), the Graeffe Transform as implemented in #374 simply returned the input polynomial. That is incorrect; it should return the input polynomial squared. This PR fixes that, and adapts the test code to cover non-monic polynomials.