anchor.diff:    !< Test implicit Adams-Moulton class of ODE solvers.
     !---------------------------------------------------------------------------------------------------------------------------------
     integer(I_P), intent(IN)      :: steps            !< Number of steps used: if negative all AB solvers are used.
  -  integer, parameter            :: am_steps=3       !< Adams-Moulton steps number.
  +  integer, parameter            :: am_steps=7       !< Adams-Moulton steps number.
     real(R_P), allocatable        :: solution(:,:)    !< Solution at each time step.
     integer(I_P)                  :: s                !< AM steps counter.
     integer(I_P)                  :: steps_range(1:2) !< Steps used.
  
positive.code:   !< Test explicit Adams-Bashforth class of ODE solvers.
    !---------------------------------------------------------------------------------------------------------------------------------
    integer(I_P), intent(IN)      :: steps            !< Number of steps used: if negative all AB solvers are used.
    integer, parameter            :: ab_steps=4       !< Adams-Bashforth steps number.
    real(R_P), allocatable        :: solution(:,:)    !< Solution at each time step.
    integer(I_P)                  :: s                !< AB steps counter.
    integer(I_P)                  :: steps_range(1:2) !< Steps used.
  
negative.code:   !< Test predictor-corrector Adams-Bashforth-Moulton class of ODE solvers.
    !---------------------------------------------------------------------------------------------------------------------------------
    integer(I_P), intent(IN)      :: steps            !< Number of steps used: if negative all AB solvers are used.
    integer, parameter            :: abm_steps=8      !< Adams-Bashforth-Moulton steps number.
    real(R_P), allocatable        :: solution(:,:)    !< Solution at each time step.
    integer(I_P)                  :: s                !< ABM steps counter.
    integer(I_P)                  :: steps_range(1:2) !< Steps used.
  