Returns a combined basis constructed from bases a
and b
as it occurs during a subspace expansion, something akin to a + b
.
Each sector of the new bases will have the size of the sum of the repective sectors in a
and b
respectively and the total dimension of the new bases is the sum of the total dimensions of the input bases. The function is asymmetric, combine_bases(a, b)
generates different IDs than combine_bases(b, a)
.
References syten::STensorImpl::SBasis::dir(), syten::STensorImpl::SBasis::get_ids(), and SYTEN_ASSERT_MSG.
Referenced by expand(), and zero_expand().