substit.f

二维热能方程的求解

c=======================================================================
      subroutine substit(mx,neqn,level,A,x)
c=======================================================================
      implicit none
      integer mx,neqn,level
      real*8 A(-mx:mx,neqn),x(neqn)

      integer j,k,kb

      if(level.ge.1) write(*,'("SUBSTIT: level=",i1)') level
      if(level.ge.2) print*,"bandwidth=",mx," neqn=",neqn
 
      do k=2,neqn
         kb   = min(k-1,mx)
         do j= 1, kb
            x(k) = x(k) - A(-j,k)*x(k-j)
         end do
      end do

      x(neqn) = x(neqn)/A(0,neqn)
      do k= neqn-1, 1, -1
         kb= min(neqn-k,mx)
         do j= 1,kb
            x(k) = x(k) - A(j,k)*x(k+j)
         end do
         x(k) = x(k)/A(0,k)
      end do  

      return
      end