hypre_obj_SetupSolS Subroutine

    impure subroutine hypre_obj_SetupSolS(this)
      !> Setup the solution vector, and initialize it to zero
      implicit none
      class(hypre_obj), intent(inout) :: this                                  !! Hypre machinery
      ! Work variables
      real(wp), allocatable :: values(:)
      integer :: nval
      integer :: ierr

      ! Create empty vector
      call HYPRE_StructVectorCreate(this%comm,this%grid,this%sol,ierr)
      ! Indicate vector coefficients are ready to set
      call HYPRE_StructVectorInitialize(this%sol,ierr)

      ! Initial guess is the zero vector (maybe changed later)
      nval=(this%block%hi(3)-this%block%lo(3)+1) &
          *(this%block%hi(2)-this%block%lo(2)+1) &
          *(this%block%hi(1)-this%block%lo(1)+1)

      allocate(values(nval))
      values=0.0_wp

      call HYPRE_StructVectorSetBoxValues(this%sol,this%block%lo(1:this%dim), &
           this%block%hi(1:this%dim),values(1:nval),ierr)

      deallocate(values)

      ! Assemble for future use
      call HYPRE_StructVectorAssemble(this%sol,ierr)

      return
    end subroutine hypre_obj_SetupSolS