Question

求三对称矩阵特征值 用二分法来解的matlab程序 ，有些高校有上数值线性代数的

Answer 1

%对称三对角矩阵特征值的二分法
program ex0001 integer n
real x1,x2,x,f1,f2,fx,eps
real,allocatable::d(,e(
write(*,*) "Please enter n:" read(*,*) n
allocate(d(n),e(n-1)) eps=1.0E-6 fx=1.0 do j=1,n d(j)=-2 end do do j=1,n-1 e(j)=1 end do
!write(*,*) "Please enter array d and e:" !read(*,*) d,e a1=d(1)-e(1) a2=d(1)-2*e(1) a3=d(1)+e(1) a4=d(1)+2*e(2) y1=min(a1,a2)

- 2 -
y2=max(a4,a3) y=(y2-y1)/n x1=y1 x2=y1+y
write(*,*)"矩阵的特征值为:" do m=1,n temp=x2
10 if(abs(fx)>eps) then x=(x1+x2)/2
f1=MValue(x1,n,d,e) f2=MValue(x2,n,d,e) fx=MValue(x,n,d,e)
if (fx*f1>0) then x1=x else x2=x end if
go to 10 end if
print*,"--------------------" write(*,*) x x1=temp x2=temp+y z=(x1+x2)/2
fx=MValue(z,n,d,e) end do
print*,"--------------------"
contains
real function mValue(x,n,d,e) Integer n,i real x
real d(n),e(n-1),s(n) S(1)=x-d(1)
S(2)=(x-d(1))*(x-d(2))-e(1)**2

- 3 -
Do i=3,n
S(i)=(x-d(i))*s(i-1)-e(i-1)**2*s(i-2) End do
mValue=s(n) return
End function mValue
end

这是程序，没排版的，自己排吧，绝对能用