[子程序] 用雅可比法编了一个求特征向量的程序。显示外部符号wu'fa...

      program main
            implicit none
            double precision matrix(3,3),T(3,3),c,s,kexi,toll,eak
            integer i,j,m,n
            parameter (toll=0.000001)
            Matrix(1,1)=1
            matrix(1,2)=2
            matrix(2,1)=2
            matrix(1,3)=3
            matrix(3,1)=3
            matrix(2,2)=4
            matrix(2,3)=5
            matrix(3,2)=5
            matrix(3,3)=6
            Do i=1,3
                  Do j=1,3
                        T(i,j)=matrix(i,j)
                  end do
            end do
C
            Do i=1,100
                  call subroutine E_k(eak,T)
                  if (eak.gt.toll) then
                  call subroutine maxmatrix(m,n)
                  kexi=0.5*atan(2*T(m,n)/T(m,m)-T(n,n))
                  c=cos(kexi)
                  s=sin(kexi)
                  T(m,m)=c
                  T(n,n)=c
                  T(m,n)=s
                  T(m,n)=-s
                  end if
            end do
            write(*,*) T
            pause
      end program main
C
C
      subroutine E_k(eak)
            implicit none
            double precision a1,a2,a3,eak,T(3,3)
            a1=T(2,1)**2
            a2=T(3,1)**2
            a3=T(3,2)**2
            eak=a1+a2+a3
      end subroutine
C
      subroutine maxmatrix(m,n,T)
            implicit none
            double precision a,b,c,maxT,T(3,3)
            integer m,n
            a=T(2,1)
            b=T(3,1)
            c=T(3,2)
            if (a.ge.b) then
                  if (a.ge.c)then
                        maxT=a
                        m=2
                        n=1
                  else
                        maxT=c
                        m=3
                        n=2
                  end if
            else
                  if (b.ge.c)then
                        maxT=b
                        m=3
                        n=1
                  else
                        maxT=c
                        m=3
                        n=2
                  end if
            end if
      end subroutine