redhat man page for dlanv2

DLANV2(l)								 )								 DLANV2(l)

NAME
       DLANV2 - compute the Schur factorization of a real 2-by-2 nonsymmetric matrix in standard form

SYNOPSIS
       SUBROUTINE DLANV2( A, B, C, D, RT1R, RT1I, RT2R, RT2I, CS, SN )

	   DOUBLE	  PRECISION A, B, C, CS, D, RT1I, RT1R, RT2I, RT2R, SN

PURPOSE
       DLANV2 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) DOUBLE PRECISION
	       B       (input/output) DOUBLE PRECISION C       (input/output) DOUBLE PRECISION D       (input/output) DOUBLE PRECISION	On  entry,
	       the elements of the input matrix.  On exit, they are overwritten by the elements of the standardised Schur form.

       RT1R    (output) DOUBLE PRECISION
	       RT1I	(output) DOUBLE PRECISION RT2R	  (output) DOUBLE PRECISION RT2I    (output) DOUBLE PRECISION The real and imaginary parts
	       of the eigenvalues. If the eigenvalues are a complex conjugate pair, RT1I > 0.

       CS      (output) DOUBLE PRECISION
	       SN      (output) DOUBLE PRECISION 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 							 DLANV2(l)