endFx Function

    elemental function endFx(csf_i, sOrb) result(fx)
        ! flag function used in excitation tree generation to check if spatial
        ! orbital sOrb
        ! is 0,1 or 3. Probably possible to implement it on an efficient
        ! bit-rep level, todo
        type(CSF_Info_t), intent(in) :: csf_i
        integer, intent(in) :: sOrb
        real(dp) :: fx

        ! always one except d=2 at end
        if (csf_i%stepvector(sOrb) == 2) then
            fx = 0.0_dp
        else
            fx = 1.0_dp
        end if
    end function endFx