const Matrix /* or null */ *rawGBChangeOfBasis(Computation *C)
/* Yields the change of basis matrix from the Groebner basis to
the original generators, at least if n_rows_to_keep was set
when creating the GB computation. This matrix, after the
computation has run to completion, should satisfy:
(original matrix) = (GB matrix) * (change of basis matrix). */
{
try {
clear_emit_size();
GBComputation *G = C->cast_to_GBComputation();
if (G != 0)
return G->get_change();
ERROR("computation type unknown or not implemented");
return 0;
}
catch (exc::engine_error e) {
ERROR(e.what());
return NULL;
}
}
virtual const Matrix /* or null */ *get_change() { return G->get_change(); }