dqli.f90

偏微分方程数值解输出离散解（详细内容见里面的说明）

      program Explicit_difference_scheme
      implicit none
      real,dimension(0:50,0:20)::v
      integer::m,n,i,j
      real::dx=0.05,dt,w
      print*,'input value dt'
      read*,dt
      w=dt/dx**2
      do m=0,10   !赋初值
         v(0,m)=0.1*m
	end do
	do m=11,20   !赋初值
	   v(0,m)=2.0-0.1*m
	end do
	do m=0,50     !赋边值
	   v(m,0)=0
         v(m,20)=0
	end do
	do m=0,49
	   do n=1,19
	      v(m+1,n)=v(m,n)+w*(v(m,n+1)-2.0*v(m,n)+v(m,n-1))
	   end do
	end do
	do
	  print*,'input time step i'
	  read*,i
	  if(i<0)exit
	  do j=0,20
	     open(unit=9,file="data.txt",position="rewind",form="formatted",action="write")
         write(unit=9,fmt="(f8.5,f9.4)")0.05*j,v(i,j)
	     write(*,"(f8.5,f9.4)")0.05*j,v(i,j)
	  end do
	end do
	end program Explicit_difference_scheme