check_dist_fn Subroutine

  subroutine check_dist_fn(report_unit)
    use nonlinear_terms, only: nonlin
    use kt_grids, only: is_box
    use species, only: spec, nspec, has_electron_species
    use warning_helpers, only: not_exactly_equal, is_not_zero
    implicit none
    integer, intent(in) :: report_unit
    integer :: is 

    if (not_exactly_equal(driftknob, 1.)) then
       write (report_unit, *) 
       write (report_unit, fmt="('################# WARNING #######################')")
       write (report_unit, fmt="('You selected driftknob = ',e11.4,' in dist_fn_knobs.')") driftknob
       write (report_unit, fmt="('THIS IS EITHER AN ERROR, or you are DELIBERATELY SCALING THE DRIFTS.')") 
       write (report_unit, fmt="('The normal choice is driftknob = 1.')")
       write (report_unit, fmt="('################# WARNING #######################')")
       write (report_unit, *) 
    end if

    if (not_exactly_equal(tpdriftknob, 1.)) then
       write (report_unit, *) 
       write (report_unit, fmt="('################# WARNING #######################')")
       write (report_unit, fmt="('You selected tpdriftknob = ',e11.4,' in dist_fn_knobs.')") tpdriftknob
       write (report_unit, fmt="('THIS IS EITHER AN ERROR, or you are DELIBERATELY SCALING THE TRAPPED PARTICLE DRIFTS (either via driftknob or via tpdriftknob).')") 
       write (report_unit, fmt="('The normal choice is tpdriftknob = 1.')")
       write (report_unit, fmt="('################# WARNING #######################')")
       write (report_unit, *) 
    end if

    if (not_exactly_equal(vparknob, 1.)) then
       write (report_unit, *)
       write (report_unit, fmt="('################# WARNING #######################')")
       write (report_unit, fmt="('You selected vparknob = ',e11.4,' in dist_fn_knobs.')") vparknob
       write (report_unit, fmt="('THIS IS EITHER AN ERROR, or you are DELIBERATELY SCALING THE PARALLEL VELOCITY.')")
       write (report_unit, fmt="('The normal choice is vparknob = 1.')")
       write (report_unit, fmt="('################# WARNING #######################')")
       write (report_unit, *)
    end if

    select case (boundary_option_switch)
    case (boundary_option_linked)
       write (report_unit, *) 
       if (.not. is_box) then
          write (report_unit, *) 
          write (report_unit, fmt="('################# WARNING #######################')")
          write (report_unit, fmt="('Linked boundary conditions require a box for a simulation domain.')")
          write (report_unit, fmt="('THIS IS PROBABLY AN ERROR.')") 
          write (report_unit, fmt="('################# WARNING #######################')")
          write (report_unit, *) 
       else
          write (report_unit, *) 
          write (report_unit, fmt="('Linked (twist and shift) boundary conditions will be used.')")
          write (report_unit, *) 
          if (esv) then 
             write (report_unit, fmt="('################# WARNING #######################')")
             write (report_unit, fmt="('Single valued antot arrays will be enforced.')")
             write (report_unit, fmt="('This can significantly increase the cost of the run.')")
             write (report_unit, fmt="('################# WARNING #######################')")
             write (report_unit, *) 
          endif
       end if
    case (boundary_option_self_periodic)
       write (report_unit, *) 
       write (report_unit, fmt="('Periodic boundary conditions will be used.')")
       write (report_unit, fmt="('(No twist and shift.)')")
       write (report_unit, *) 
    case default
       write (report_unit, *) 
       write (report_unit, fmt="('Outgoing boundary conditions will be used.')")
    end select

    write (report_unit, fmt="('Parallel bc for passing particles at ends of the domain is:')")
    if (nonad_zero) then
       write (report_unit, fmt="(T20,'g_wesson = g_krt = 0')")
       write (report_unit, fmt="('ie NO incoming particles in the nonadiabatic piece of delta(f)')") 
    else
       write (report_unit, fmt="(T20,'g_gs2 = 0')")
       write (report_unit, fmt="('NB this ONLY gives NO incoming particles in the nonadiabatic piece of delta(f)')")
       write (report_unit, fmt="(T20,'if phi and bpar are zero at the ends of the domain')") 
    endif
    write (report_unit, *) 

    if (.not. has_electron_species(spec)) then
       select case (adiabatic_option_switch)
       case (adiabatic_option_default)
          write (report_unit, *) 
          write (report_unit, fmt="('The adiabatic electron response is of the form:')")
          write (report_unit, *) 
          write (report_unit, fmt="('             ne = Phi')")
          write (report_unit, *) 
          write (report_unit, fmt="('This is appropriate for an ETG simulation,')") 
          write (report_unit, fmt="('where the role of ions and electrons in GS2 is switched.')")
          write (report_unit, *) 

       case (adiabatic_option_fieldlineavg)
          write (report_unit, *) 
          write (report_unit, fmt="('The adiabatic electron response is of the form:')")
          write (report_unit, *) 
          write (report_unit, fmt="('             ne = Phi - <Phi>')")
          write (report_unit, *) 
          write (report_unit, fmt="('The angle brackets denote a proper field line average.')") 
          write (report_unit, fmt="('This is appropriate for an ITG simulation.')") 
          write (report_unit, *) 

       case (adiabatic_option_yavg)
          write (report_unit, *) 
          write (report_unit, fmt="('################# WARNING #######################')")
          write (report_unit, fmt="('The adiabatic electron response is of the form:')")
          write (report_unit, *) 
          write (report_unit, fmt="('             ne = Phi - <Phi>_y')")
          write (report_unit, *) 
          write (report_unit, fmt="('The angle brackets denote an average over y only.')") 
          write (report_unit, fmt="('THIS IS PROBABLY AN ERROR.')") 
          write (report_unit, fmt="('Perhaps you want field-line-average-term for adiabatic_option.')") 
          write (report_unit, fmt="('################# WARNING #######################')")
          write (report_unit, *) 
       end select
    end if

    if (is_not_zero(poisfac)) then
       write (report_unit, *) 
       write (report_unit, fmt="('Quasineutrality is not enforced.  The ratio (lambda_Debye/rho)**2 = ',e11.4)") poisfac
       write (report_unit, *) 
    end if

    if (mult_imp .and. nonlin) then
       write (report_unit, *) 
       write (report_unit, fmt="('################# WARNING #######################')")
       write (report_unit, fmt="('For nonlinear runs, all species must use the same values of fexpr and bakdif')")
       write (report_unit, fmt="('in the dist_fn_species_knobs_x namelists.')")
       write (report_unit, fmt="('THIS IS AN ERROR AND MULT_IMP WILL BE SET FALSE.')")
       write (report_unit, fmt="('################# WARNING #######################')")
       write (report_unit, *) 
    end if

    if (def_parity .and. nonlin) then
       write (report_unit, *) 
       write (report_unit, fmt="('################# WARNING #######################')")
       write (report_unit, fmt="('Choosing a definite parity for a nonlinear run has never been tested.')")
       write (report_unit, fmt="('THIS IS PROBABLY AN ERROR.')") 
       write (report_unit, fmt="('################# WARNING #######################')")
       write (report_unit, *) 
    end if

    if (def_parity) then
       if (even) then
          write (report_unit, fmt="('Only eigenmodes of even parity will be included.')")
       else
          write (report_unit, fmt="('Only eigenmodes of odd parity will be included.')")
       end if
    end if

    write (report_unit, *) 
    write (report_unit, fmt="('------------------------------------------------------------')")
    write (report_unit, *) 
    write (report_unit, fmt="('The ExB parameter is ',f7.4)") g_exb
    if (abs(g_exb) > epsilon(0.0)) then
       write (report_unit, fmt="('Perp shear terms will be multiplied by factor',f7.4)") g_exbfac
       write (report_unit, fmt="('Parallel shear term will be multiplied by factor',f7.4)") omprimfac
    endif

    write (report_unit, *) 
    write (report_unit, fmt="('------------------------------------------------------------')")
    write (report_unit, *) 

    select case (source_option_switch)

    case (source_option_full)
       write (report_unit, *) 
       write (report_unit, fmt="('The standard GK equation will be solved.')")
       write (report_unit, *) 

    case(source_option_phiext_full)
       write (report_unit, *) 
       write (report_unit, fmt="('The standard GK equation will be solved,')")
       write (report_unit, fmt="('with an additional source proportional to Phi*F_0')")
       write (report_unit, fmt="('Together with phi_ext = -1., this is the usual way to &
            & calculate the Rosenbluth-Hinton response.')")
       write (report_unit, *)

    case (source_option_homogeneous)
       write (report_unit, *)
       write (report_unit, fmt="('################# WARNING #######################')")
       write (report_unit, fmt="('The homogeneous GK equation will be solved.')")
       write (report_unit, fmt="('The calculated response matrices and resulting')")
       write (report_unit, fmt="('potentials will not be accurate.')")
       write (report_unit, fmt="('################# WARNING #######################')")
       write (report_unit, *)
    end select

    ! 
    ! implicitness parameters
    !
    do is = 1, nspec
       write (report_unit, fmt="('Species ',i2,' has fexpr = ', e11.4)") is, fexp(is)
    end do
  end subroutine check_dist_fn