[size=+3]ordqz

Reorder eigenvalues in QZ factorization

[size=+1]
Syntax

• [AAS,BBS,QS,ZS] = ordqz(AA,BB,Q,Z,select)
  [...] = ordqz(AA,BB,Q,Z,keyword)
  [...] = ordqz(AA,BB,Q,Z,clusters)
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  请问 其中的select 和clusters 该怎么去写啊，不是很懂？！

  [size=+1]
  Description
  

  [AAS,BBS,QS,ZS] = ordqz(AA,BB,Q,Z,select) reorders the QZ factorizations Q*A*Z = AA and Q*B*Z = BB produced by the qz function for a matrix pair (A,B). It returns the reordered pair(AAS,BBS) and the cumulative orthogonal transformations QS and ZS such that QS*A*ZS = AAS and QS*B*ZS = BBS. In this reordering, the selected cluster of eigenvalues appears in the leading (upper left) diagonal blocks of the quasitriangular pair (AAS,BBS), and the corresponding invariant subspace is spanned by the leading columns of ZS. The logical vector select specifies the selected cluster as E(select) where E = eig(AA,BB). Set Q = [] or Z = [] to get the incremental QS and ZS that transforms (AA,BB) into (AAS,BBS).

  [...] = ordqz(AA,BB,Q,Z,keyword) sets the selected cluster to include all eigenvalues in the region specified by keyword:

  
  

  keyword	Selected Region
  'lhp'	Left-half plane (real(E) < 0)
  'rhp'	Right-half plane (real(E) > 0)
  'udi'	Interior of unit disk (abs(E) < 1)
  'udo'	Exterior of unit disk (abs(E) > 1)

  
  

  [...] = ordqz(AA,BB,Q,Z,clusters) reorders multiple clusters at once. Given a vector clusters of cluster indices commensurate with E = eig(AA,BB), such that all eigenvalues with the sameclusters value form one cluster, ordqz sorts the specified clusters in descending order along the diagonal of (AAS,BBS). The cluster with highest index appears in the upper left corner.
  
  

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  请问 其中的select 和clusters 该怎么去写啊，不是很懂？！