redhat man page for slanv2

SLANV2(l)								 )								 SLANV2(l)

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 con-
       jugate 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 eigenval-
	       ues are a complex conjugate pair, RT1I > 0.

       CS      (output) REAL
	       SN      (output) REAL Parameters of the rotation matrix.

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).

LAPACK version 3.0						   15 June 2000 							 SLANV2(l)