slanv2.f man page

slanv2.f —

Synopsis

Functions/Subroutines

subroutine slanv2 (A, B, C, D, RT1R, RT1I, RT2R, RT2I, CS, SN)
SLANV2 computes the Schur factorization of a real 2-by-2 nonsymmetric matrix in standard form.

Function/Subroutine Documentation

subroutine slanv2 (realA, realB, realC, realD, realRT1R, realRT1I, realRT2R, realRT2I, realCS, realSN)

SLANV2 computes the Schur factorization of a real 2-by-2 nonsymmetric matrix in standard form.

Purpose:

SLANV2 computes the Schur factorization of a real 2-by-2 nonsymmetric
matrix in standard form:

     [ A  B ] = [ CS -SN ] [ AA  BB ] [ CS  SN ]
     [ C  D ]   [ SN  CS ] [ CC  DD ] [-SN  CS ]

where either
1) CC = 0 so that AA and DD are real eigenvalues of the matrix, or
2) AA = DD and BB*CC < 0, so that AA + or - sqrt(BB*CC) are complex
conjugate eigenvalues.

Parameters:

A

A is REAL

B

B is REAL

C

C is REAL

D

D is REAL
On entry, the elements of the input matrix.
On exit, they are overwritten by the elements of the
standardised Schur form.

RT1R

RT1R is REAL

RT1I

RT1I is REAL

RT2R

RT2R is REAL

RT2I

RT2I is REAL
The real and imaginary parts of the eigenvalues. If the
eigenvalues are a complex conjugate pair, RT1I > 0.

CS

CS is REAL

SN

SN is REAL
Parameters of the rotation matrix.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Further Details:

Modified by V. Sima, Research Institute for Informatics, Bucharest,
Romania, to reduce the risk of cancellation errors,
when computing real eigenvalues, and to ensure, if possible, that
abs(RT1R) >= abs(RT2R).

Definition at line 128 of file slanv2.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

slanv2(3) is an alias of slanv2.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK