GroupWithMorphisms compute_image(const mod_t p, const MatrixQ& f,
const AbelianGroup& X, const AbelianGroup& Y)
{
MatrixQRefList to_X_dummy;
MatrixQList from_X = {MatrixQ::identity(f.width())};
GroupWithMorphisms K = compute_kernel(p, f, X, Y, to_X_dummy, ref(from_X));
MatrixQList to_X_2 = {MatrixQ::identity(X.rank())};
MatrixQList from_X_2 = {f,MatrixQ::identity(X.rank())};//hacky, since id:X->X doesn't vanish on K.
//but due to the implementation, the columns of this will contain
//representatives in X for the generators of img.
GroupWithMorphisms img =
compute_cokernel(p, K.maps_from[0], X, ref(to_X_2), ref(from_X_2));
return img;
}
