pf_print_options Subroutine

  subroutine pf_print_options(pf, un_opt, show_mats_opt)
    type(pf_pfasst_t), intent(inout)           :: pf   
    integer,           intent(in   ), optional :: un_opt
    logical,           intent(in   ), optional :: show_mats_opt

    integer :: un = 6
    logical :: show_mats = .FALSE.
    integer :: l, i
    character(8)   :: date
    character(10)  :: time

    if (pf%rank /= 0) return
    if (present(un_opt)) un = un_opt
    write(un,*) '=================================================='
    write(un,*) 'PFASST Configuration'
    write(un,*) '--------------------'

    call date_and_time(date=date, time=time)
    write(un,*) 'date:        ', date
    write(un,*) 'time:        ', time

    write(un,*) 'double precision:   ', pfdp   ,'  bytes'
    write(un,*) 'quad precision:   ', pfqp   ,'  bytes'    

    write(un,*) 'nlevels:     ', pf%nlevels, '! number of pfasst levels'
    write(un,*) 'nprocs:      ', pf%comm%nproc, '! number of pfasst "time" processors'
    
    if (pf%comm%nproc == 1) then
       write(un,*) '            ', '             ', ' ! since 1 time proc is being used, this is a serial sdc run'
    else
       write(un,*) '            ', '             ', ' ! since >1 time procs are being used, this is a parallel pfasst run'
    end if
    write(un,*) 'niters:      ', pf%niters, '! maximum number of sdc/pfasst iterations'
    select case(pf%qtype)

    case (SDC_GAUSS_LEGENDRE)
       write(un,*) 'qtype:',pf%qtype, '! Gauss Legendre nodes are used'
    case (SDC_GAUSS_LOBATTO)
       write(un,*) 'qtype:',pf%qtype,'! Gauss Lobatto nodes are used'
    case (SDC_GAUSS_RADAU)
       write(un,*) 'qtype:',pf%qtype,'! Gauss Radua nodes are used'
    case (SDC_CLENSHAW_CURTIS)
       write(un,*) 'qtype:',pf%qtype,'! Clenshaw Curtis nodes are used'
    case (SDC_UNIFORM)
       write(un,*) 'qtype:', pf%qtype,'! Uniform  nodes are used'
    case default
       print *,'qtype = ',pf%qtype
       stop "ERROR: Invalid qtype"
    end select

    write(un,*) 'nnodes:      ', pf%levels(1:pf%nlevels)%nnodes, '! number of sdc nodes per level'
    
    write(un,*) 'mpibuflen:   ', pf%levels(1:pf%nlevels)%mpibuflen, '! size of data send between time steps'
    write(un,*) 'nsweeps:     ', pf%levels(1:pf%nlevels)%nsweeps, '! number of sdc sweeps performed per visit to each level'
    write(un,*) 'nsweeps_pred:     ', pf%levels(1:pf%nlevels)%nsweeps_pred, '! number of sdc sweeps in predictor'
    write(un,*) 'taui0:     ',   pf%taui0, '! cutoff for tau correction'
    write(un,*) 'abs_res_tol:', pf%abs_res_tol, '! absolute residual tolerance: '
    write(un,*) 'rel_res_tol:', pf%rel_res_tol, '! relative residual tolerance: '
    if (pf%use_Luq) then
       write(un,*) 'Implicit matrix is LU  '
    else
       write(un,*) 'Implicit matrix is backward Euler  '
    end if
    if (pf%Vcycle) then
       write(un,*) 'V-cycling is on'
    else
       write(un,*) 'V-cycling is off, fine level is pipelining'
    end if

    if (pf%rk_pred) then
       write(un,*) 'Runge-Kutta used for predictor'
    else
       
       if (pf%pipeline_pred) then
          write(un,*) 'Predictor pipelining is ON    '
       else
          write(un,*) 'Predictor pipelining is OFF    '
       end if
       if (pf%PFASST_pred) then
          write(un,*) 'PFASST Predictor style  '
       else
          write(un,*) 'Serial Predictor style  '
       end if
    endif

    if (pf%debug) write(un,*) 'Debug mode is on '

    write(un,*) ''

    if (present(show_mats_opt)) show_mats=show_mats_opt
    if (show_mats) then
       do l = 1, pf%nlevels
          print *, "Level", l
          print *, "-----------------"
          print *, "  nodes"
          print *, pf%levels(l)%nodes
          print *, "  Q"
          do i = 1, pf%levels(l)%nnodes-1
             print *, pf%levels(l)%sdcmats%qmat(i,:)
          end do
       end do
    end if
 


  end subroutine pf_print_options