rita 发表于 2007-5-23 08:41

关于polyeig这个函数

我在编程时需要用到polyeig这个函数,可是help中没有具体说明。有没有那位高手帮忙解释一下它的用法,我碰到的问题是,矩阵A0,A1.....Ap中有个零矩阵。我试验了一下,解出很多零解,可我的是特征值问题,不可能出现零解的,请高手帮帮忙吧

[ 本帖最后由 eight 于 2007-5-24 09:32 编辑 ]

huright 发表于 2007-5-23 08:46

polyeig
Polynomial eigenvalue problem

Syntax
= polyeig(A0,A1,...Ap)
e = polyeig(A0,A1,..,Ap)
= polyeig(A0,A1,..,AP)


Description
= polyeig(A0,A1,...Ap) solves the polynomial eigenvalue problem of degree p



where polynomial degree p is a non-negative integer, and A0,A1,...Ap are input matrices of order n. The output consists of a matrix X of size n-by-n*p whose columns are the eigenvectors, and a vector e of length n*p containing the eigenvalues.

If lambda is the jth eigenvalue in e, and x is the jth column of eigenvectors in X, then (A0 + lambda*A1 +... + lambda^p*Ap)*x is approximately 0.

e = polyeig(A0,A1,..,Ap) is a vector of length n*p whose elements are the eigenvalues of the polynomial eigenvalue problem.

= polyeig(A0,A1,..,AP) also returns a vector s of length p*n containing condition numbers for the eigenvalues. At least one of A0 and AP must be nonsingular. Large condition numbers imply that the problem is close to a problem with multiple eigenvalues.

Remarks
Based on the values of p and n, polyeig handles several special cases:

p = 0, or polyeig(A) is the standard eigenvalue problem: eig(A).

p = 1, or polyeig(A,B) is the generalized eigenvalue problem: eig(A,-B).

n = 1, or polyeig(a0,a1,...ap) for scalars a0, a1 ..., ap is the standard polynomial problem: roots().


If both A0 and Ap are singular the problem is potentially ill-posed. Theoretically, the solutions might not exist or might not be unique. Computationally, the computed solutions might be inaccurate. If one, but not both, of A0 and Ap is singular, the problem is well posed, but some of the eigenvalues might be zero or infinite.

rita 发表于 2007-5-23 08:49

谢谢你,就是因为help中没有我要的东西。能不能麻烦你用中文解释一下呀

huright 发表于 2007-5-23 09:13

呵呵
多项式特征值问题
应该能看个差不多吧

rita 发表于 2007-5-23 15:17

你帮忙试试吧。。有个为零怎么解呀

rita 发表于 2007-5-24 08:18

请高手帮忙看看吧,,程序进行不下去了
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