invariantRing G, R^G
The following example defines an action of a twodimensional torus on a fourdimensional vector space with a basis of weight vectors whose weights are the columns of the input matrix.




The algebra generators for the ring of invariants are computed upon initialization by the method invariants.
Alternatively, we can use the following shortcut to construct a ring of invariants.

The object invariantRing is a method function with options.