21   function dfdt_vdp(t, dt, ib1, ibn, jb1, jbn, kb1, kbn, imax, jmax, kmax, n, f)
28     PetscReal, dimension(n, ib1:ibn, jb1:jbn, kb1:kbn), intent(inout) :: f
32     dfdt_vdp(1, :, :, :) = f(2, 1, 1, 1)
33     dfdt_vdp(2, :, :, :) = mu*(one - f(1, 1, 1, 1)**2)*f(2, 1, 1, 1) - f(1, 1, 1, 1)
46       function dfdt(t, dt, ib1, ibn, jb1, jbn, kb1, kbn, imax, jmax, kmax, n, f)
50         PetscReal, dimension(n, ib1:ibn, jb1:jbn, kb1:kbn), intent(inout) :: f
68   subroutine petsc_to_local(da, vec, array, f, dof, stw)  argument
74     PetscReal, intent(inout), dimension(:, 1 - stw:, 1 - stw:, 1 - stw:) :: f
78     call transform_petsc_us(array, f, stw)
80   subroutine transform_petsc_us(array, f, stw)  argument
84     PetscReal, intent(inout), dimension(:, 1 - stw:, 1 - stw:, 1 - stw:) :: f
85     f(:, :, :, :) = array(:, :, :, :)
87   subroutine local_to_petsc(da, vec, array, f, dof, stw)  argument
93     PetscReal, intent(inout), dimension(:, 1 - stw:, 1 - stw:, 1 - stw:)  :: f
95     call transform_us_petsc(array, f, stw)
98   subroutine transform_us_petsc(array, f, stw)  argument
102     PetscReal, intent(in), dimension(:, 1 - stw:, 1 - stw:, 1 - stw:)      :: f
103     array(:, :, :, :) = f(:, :, :, :)