In many cases, it is necessary to dump message on standard output during program execution. However, well sophisticated WRITE and FORMAT statements are required for readable message. Moreover, when the message includes variables of not character literal constants, the conversion of type and concatenation are required, which are troublesome for programmers.
Dc_message module of gt4f90io provides subroutine for message dump. By using the dc_message module, readable message dump is realized in user's programs with ease.
For example, a sample program using the dc_message module (diffusion_4.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
!
! * 2007/06/25 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_4
use gt4_history ! Access module (モジュール指定)
use dc_types, only : DP ! Access module (モジュール指定)
use dc_message, only : MessageNotify ! 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)
real(DP) :: sigma ! Parameter (計算安定条件パラメタ)
tinit = 0.0 ! Set initial Time
! (初期時刻設定)
sigma = kappa*dt/dx**2.0d0
if ( sigma >= 0.5d0 ) then
call MessageNotify( "E", & ! Error message dump
& "diffusion_4", & ! (エラーメッセージ出力)
& "dt is too large: k*dt/(dx)^2 = %f", &
& d=(/sigma/) )
else if ( sigma >= 0.4d0 ) then
call MessageNotify( "W", & ! Warning message dump
& "diffusion_4", & ! (警告メッセージ出力)
& "dt is moderately large: k*dt/(dx)^2 = %f", &
& d=(/sigma/) )
else
call MessageNotify( "M", & ! Message dump
& "diffusion_4", & ! (メッセージ出力)
& "dt is sufficiently small: k*dt/(dx)^2 = %f", &
& d=(/sigma/) )
end if
temp = exp(-((x-0.5)/0.1)**2) ! Set initial value (初期値設定)
call HistoryCreate( & ! Create ouptpu file
& file='diffusion_4.nc', & ! (ヒストリー作成)
& 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) ! Output 'x' (次元変数出力)
call HistoryAddVariable( & ! Set output variable (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) ! Output 'temp' (変数出力)
do it=1,nt
temp(2:nx-1) = temp(2:nx-1) & ! Time integration (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) ! Output 'temp' (変数出力)
endif
enddo
call HistoryClose
stop
end program diffusion_4
Summary of dc_message module and its subroutines used in the sample program are as follows. In detail, please see gt4f90io reference manual.
