PrintDegreePolynomial takes a Boolean value and is set to false by default. Its behaviour is identical to that of its use in the method secondaryInvariants. If it is set to true, then invariantRing will print a polynomial in the variable T giving information about the degrees of the secondary invariants it outputs. See secondaryInvariants(..., PrintDegreePolynomial => ...) for more information.
The example below computes a set of primary and secondary invariants for an action of the cyclic group of order 4 on QQ[x,y]. The optional argument PrintDegreePolynomial is set to true, so that invariantRing will print a polynomial before outputting the result. In the example, this polynomial tells us that there are 4 secondary invariants, with degrees 0,1,2 and 3.
i1 : L={sub(matrix{{0,-1},{1,0}},QQ)}; |
i2 : invariantRing(QQ[x,y],L,PrintDegreePolynomial=>true) 3 2 t - t - t + 1 4 2 3 o2 = ({x, y }, {1, y, y , y }) o2 : Sequence |