Procedure from library finvar.lib (see finvar_lib).
Usage:
primary_char0(REY,M[,v]);
REY: a <matrix> representing the Reynolds operator, M: a 1x2 <matrix>
representing the Molien series, v: an optional <int>
Assume:
REY is the first return value of group_reynolds or reynolds_molien and
M the one of molien or the second one of reynolds_molien
Display:
information about the various stages of the programme if v does not
equal 0
Return:
primary invariants (type <matrix>) of the invariant ring
Theory:
Bases of homogeneous invariants are generated successively and those
are chosen as primary invariants that lower the dimension of the ideal
generated by the previously found invariants (see paper "Generating a
Noetherian Normalization of the Invariant Ring of a Finite Group" by
Decker, Heydtmann, Schreyer (1998)).