SLANV2(3F)SLANV2(3F)NAME
SLANV2 - compute the Schur factorization of a real 2-by-2 nonsymmetric
matrix in standard form
SYNOPSIS
SUBROUTINE SLANV2( A, B, C, D, RT1R, RT1I, RT2R, RT2I, CS, SN )
REAL A, B, C, CS, D, RT1I, RT1R, RT2I, RT2R, SN
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.
ARGUMENTS
A (input/output) REAL
B (input/output) REAL C (input/output) REAL D
(input/output) REAL On entry, the elements of the input matrix.
On exit, they are overwritten by the elements of the standardised
Schur form.
RT1R (output) REAL
RT1I (output) REAL RT2R (output) REAL RT2I (output) REAL
The real and imaginary parts of the eigenvalues. If the
eigenvalues are both real, abs(RT1R) >= abs(RT2R); if the
eigenvalues are a complex conjugate pair, RT1I > 0.
CS (output) REAL
SN (output) REAL Parameters of the rotation matrix.
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