jacrs Subroutine

   subroutine jacrs(res_, ires, neq, t, c, cprime, rewt, savr, wk, h, cj, wp, iwp, ier, &
                    rpar, ipar)
   !! This routine interfaces to subroutines [[DRBDJA]] or [[DRBGJA]], depending on the flag
   !! `jbg=ipar(2)`, to generate and preprocess the block-diagonal Jacobian corresponding to
   !! the reaction term \(v\).
   !!
   !! * If `jbg==0`, we call [[DRBDJA]], with no block-grouping.
   !! * If `jbg==1`, we call [[DRBGJA]], and use block-grouping.
   !!
   !! Array `rpar`, containing the current \(v\) vector, is passed to [[DRBDJA]] and [[DRBGJA]]
   !! as argument `R0`, consistent with the loading of `rpar` in [[f]]. The procedure        name
   !! [[rates]] is passed as the name of the routine which computes the individual blocks of
   !! \(v\).
      external :: res_
      integer, intent(in) :: ires
      integer, intent(in) :: neq
      real(rk), intent(in) :: t
      real(rk), intent(in) :: c(*)
      real(rk), intent(in) :: cprime(*)
      real(rk), intent(in) :: rewt(*)
      real(rk), intent(in) :: savr(*)
      real(rk), intent(in) :: wk(*)
      real(rk), intent(in) :: h
      real(rk), intent(in) :: cj
      real(rk), intent(in) :: wp(*)
      integer, intent(in) :: iwp(*)
      integer, intent(in) :: ier
      real(rk), intent(in) :: rpar(*)
      integer, intent(in) :: ipar(*)

      integer :: jbg
      external :: drbdja, drbgja

      jbg = ipar(2)
      if (jbg == 0) then
         call drbdja(t, c, rpar, rates, wk, rewt, cj, wp, iwp, ier)
      else
         call drbgja(t, c, rpar, rates, wk, rewt, cj, wp, iwp, ier)
      end if

   end subroutine jacrs