Navigation

Operators and Keywords

Function List:

C++ API

: [UR, SR] = ordschur (U, S, select)

Reorders the real Schur factorization (U,S) obtained with the schur function, so that selected eigenvalues appear in the upper left diagonal blocks of the quasi triangular Schur matrix.

The logical vector select specifies the selected eigenvalues as they appear along S’s diagonal.

For example, given the matrix A = [1, 2; 3, 4], and its Schur decomposition 

[U, S] = schur (A)

which returns 

U =

 -0.82456  -0.56577
  0.56577  -0.82456

S =

 -0.37228  -1.00000
  0.00000   5.37228

It is possible to reorder the decomposition so that the positive eigenvalue is in the upper left corner, by doing: 

[U, S] = ordschur (U, S, [0,1])

See also: schur.

Package: octave