Function: msstar
Section: modular_symbols
C-Name: msstar
Prototype: GDG
Help: msstar(M,{H}): M being a full modular symbol space,
 as given by msinit, return the matrix of the * involution, induced by
 complex conjugation, acting on the (stable) subspace H (M if omitted).
Doc: $M$ being a full modular symbol space, as given by \kbd{msinit},
 return the matrix of the \kbd{*} involution, induced by complex conjugation,
 acting on the (stable) subspace $H$ ($M$ if omitted).
 \bprog
 ? M = msinit(11,2); \\ M_2(Gamma_0(11))
 ? w = msstar(M);
 ? w^2 == 1
 %3 = 1
 @eprog
