debian man page for dlasorte

DLASORTE(l)						   LAPACK routine (version 1.5) 					       DLASORTE(l)

NAME
       DLASORTE - sort eigenpairs so that real eigenpairs are together and  complex are together

SYNOPSIS
       SUBROUTINE DLASORTE ( S, LDS, J, OUT, INFO )

	   INTEGER	   INFO, J, LDS

	   DOUBLE	   PRECISION OUT( J, * ), S( LDS, * )

PURPOSE
       DLASORTE sorts eigenpairs so that real eigenpairs are together and
	 complex are together.	This way one can employ 2x2 shifts easily
	 since every 2nd subdiagonal is guaranteed to be zero.
       This routine does no parallel work and makes no calls.

ARGUMENTS
       S       (local input/output) DOUBLE PRECISION array, dimension LDS
	       On  entry,  a  matrix  already  in Schur form.  On exit, the diagonal blocks of S have been rewritten to pair the eigenvalues.  The
	       resulting matrix is no longer similar to the input.

       LDS     (local input) INTEGER
	       On entry, the leading dimension of the local array S.  Unchanged on exit.

       J       (local input) INTEGER
	       On entry, the order of the matrix S.  Unchanged on exit.

       OUT     (local input/output) DOUBLE PRECISION array, dimension Jx2
	       This is the work buffer required by this routine.

       INFO    (local input) INTEGER
	       This is set if the input matrix had an odd number of real eigenvalues and things couldn't be paired or if the input  matrix  S  was
	       not originally in Schur form.  0 indicates successful completion.

	       Implemented by:	G. Henry, May 1, 1997

LAPACK version 1.5						    12 May 1997 						       DLASORTE(l)