[通用算法] 求取更快的運算方式

program ZWD_gamit                                                         
implicit none                                                             
                                                                          
  integer :: stat,stat2,stat3,stat4,yr,dayofyear,hr                       
  character :: filename_ztd*12,filename_zhd*12,filename_zwd*12            
  character :: c_time_all_ztd*12,c_time_all_zhd*12,c_zhd_mm*12            
  real*8 :: time_all_ztd,ztd_m,Tsr_deg,Ps_hpa,zhd_mm,ztd_mm,zwd_mm           
                                                                          
  open(11,file="list.txt")                                                
  close(11,status="delete")                                               
  open(22,file="list2.txt")                                               
  close(22,status="delete")                                               
  call system('for %f in (*_all.ztd) do echo %f >> list.txt')             
  call system('for %f in (*_all.zhd) do echo %f >> list2.txt')            
  open (11,file="list.txt")                                               
  open (22,file="list2.txt")                                              
                                                                          
  stat=0                                                                  
  stat2=0                                                                 
  do while (stat==0 .and. stat2==0)                                       
    read (11,"(a12)",iostat=stat) filename_ztd                            
    read (22,"(a12)",iostat=stat2) filename_zhd                           
    if (stat/=0 .and. stat2/=0) exit                                      
    open (33,file=filename_ztd)                                           
    open (44,file=filename_zhd)                                           
    filename_zwd=filename_ztd(1:8)//".zwd"                                
    open (55,file=filename_zwd)                                           
                                                                          
    stat3=0                                                               
    do while (stat3==0)                                                   
      read (33,50,iostat=stat3) c_time_all_ztd,ztd_m,yr,dayofyear,hr      
50    format (a12,4x,f6.1,3x,i4,3x,i3.3,3x,i2.2)                          
      if (stat3/=0) exit                                                  
      stat4=0                                                             
      do while (stat4==0)                                                 
        read (44,100,iostat=stat4) c_time_all_zhd,c_zhd_mm,Tsr_deg,Ps_hpa    
100     format (a12,3x,a12,3x,f6.1,3x,f6.1)                               
        if (stat4/=0) exit                                                
        if (c_time_all_ztd==c_time_all_zhd) then                          
          if( c_zhd_mm(1:1) /= "*") then                                  
            read (c_time_all_ztd,"(f12.7)") time_all_ztd                  
            read (c_zhd_mm,"(f12.7)") zhd_mm                              
            ztd_mm = ztd_m * 1D3                                          
            zwd_mm = ztd_mm - zhd_mm                                      
            write (55,150) time_all_ztd,zwd_mm,Tsr_deg,Ps_hpa,yr,dayofyear,hr
150         format (f12.7,3x,f12.7,3x,f6.1,3x,f6.1,3x,i4,3x,i3.3,3x,i2.2) 
            exit                                                          
          end if                                                          
        end if                                                            
      end do                                                              
      rewind(44)                                                          
    end do                                                                
    close(33)                                                             
    close(44)                                                             
    close(55)                                                             
  end do                                                                  
  close(11)                                                               
  close(22)                                                               
end program