Dc_args module of gt4f90io provides subroutines for interpretation of command line arguments. By using dc_args, run time options and help message can be specified to user's program.
For example, a sample program using the dc_args module (diffusion_7.f90) is shown here, which are modified from diffusion_3.f90 in Fortran 90/95 general-purpose modules: (1) Type parameter specification. Statements with colored font (or bold font) are associated with the dc_message module.
!= Sample program for gt4_history/gt4f90io
!
! * 2007/06/27 M.Odaka
! * 2006/10/25 Y.Morikawa
! * 2003/08/21 M.Odaka
! * 2001/02/27 S.Takehiro
!
! Solving diffusion equation
! \[
! du/dt = \kappa d^2 u/dx^2
! \]
! for giving values of $u$ at $x=[0,1]$.
!
program diffusion_7
use gt4_history ! Access module (モジュール指定)
use dc_types, only : DP, STRING ! Access module (モジュール指定)
use dc_message, only: MessageNotify ! Access module (モジュール指定)
use dc_string, only : StoA, StoI ! Access module (モジュール指定)
use dc_args, only : ARGS, Open, Debug, Help, Strict, Close, Option
! Access module (モジュール指定)
integer, parameter :: nx=30 ! Grid number (グリッド数)
integer, parameter :: nt=200 ! Time step number (時間ステップ数)
integer, parameter :: ndisp=10 ! Output interval (出力間隔)
real(DP), parameter :: dx=1.0/(nx-1) ! Grid interval (グリッド間隔)
real(DP), parameter :: dt=0.0005 ! Time step (時間間隔)
real(DP), dimension(nx):: x=(/(dx*(i-1),i=1,nx)/) ! X coordinate (座標変数)
real(DP), dimension(nx):: temp ! Temperature (温度)
real(DP), parameter :: kappa=1.0 ! Diffusion coefficient (熱拡散係数)
type(ARGS) :: arg ! Command line argument (引数)
logical :: OPT_step ! logical parameter (引数用論理変数)
character(STRING) :: VAL_step ! Value of command line argument (引数の値)
call Open(arg) ! Initialize variable 'arg'
! (引数の初期化)
call Option(arg, StoA('-S', '--step'), OPT_step, VAL_step, &
& help="Specify time step (nt) [default value is 200]." )
! Set "-S/--step" option
! ("-S/--step" オプションの設定)
call Debug(arg) ! Set debug option
! (デバッグオプションの自動設定)
call Help(arg) ! Set help option
! ヘルプオプションの自動設定
call Strict(arg) ! Set exception handling
! (無効なオプション指定時に警告表示)
if (OPT_step) then
nt = StoI(VAL_step) ! Set "nt" specified by command line argument
! (引数の値を入力)
call MessageNotify( "M", "diffusion_7", &
& "Time step is %d", i=(/nt/) )
! Message dump
! (メッセージの出力)
end if
call Close(arg) ! Finalize variable 'arg'
! (引数の使用終了)
tinit = 0.0 ! 初期時刻設定
temp = exp(-((x-0.5)/0.1)**2) ! 初期値設定
call HistoryCreate( & ! ヒストリー作成
& file='diffusion_7.nc', title='Diffusion equation', &
& source='Sample program of gt4_history/gt4f90io', &
& institution='GFD_Dennou Club davis project', &
& dims=(/'x','t'/), dimsizes=(/nx,0/), &
& longnames=(/'X-coordinate','time '/), &
& units=(/'m','s'/), &
& origin=real(tinit), interval=real(ndisp*dt) )
call HistoryPut('x',x) ! 次元変数出力
call HistoryAddVariable( & ! 変数定義
& varname='temp', dims=(/'x','t'/), &
& longname='temperature', units='K', xtype='double')
call HistoryAddAttr('temp','gt_graph_tick_all',1)
call HistoryAddAttr('temp','gt_graph_contour_spacing',(/0.0,1.0,0.01/))
call HistoryAddAttr('temp','+gt_user_davis_kappa',kappa)
call HistoryPut('temp',temp) ! 変数出力
do it=1,nt
temp(2:nx-1) = temp(2:nx-1) & ! 時間積分
& + kappa*(temp(3:nx)-2*temp(2:nx-1)+temp(1:nx-2))/dx**2*dt
if ( mod(it,ndisp) == 0 ) then
call HistoryPut('temp',temp) ! 変数出力
endif
enddo
call HistoryClose
stop
end program diffusion_7
In this program, the time step number 'no' can be specified by command line argument. Execution in debug mode ( Fortran 90/95 general-purpose modules: (4) Debud support ), and help message can be also specified.
The time step number is specified as follows
$ ./a.out -S=<time step number>
or,
$ ./a.out --step=<time step number>
Debug option is specified as follows.
$ ./a.out -D
Debug messages are dumped to standard out.
Help message can be displayed as follows.
$ a.out -H
If the '-H' is given, following messages are displayed.
Options::
-S=VAL, --step=VAL
Specify time step (nt) [default value is 200].
-D=VAL, --debug=VAL
call dc_trace#SetDebug (display a lot of messages for debug).
VAL is unit number (default is standard output)
-h=VAL, -H=VAL, --help=VAL
display this help and exit. VAL is unit number (default is
standard output)Summary of dc_args module and its subroutines used in the sample program are as follows. In detail, please see gt4f90io reference manual.
