debian man page for dlamsh

DLAMSH(l)					      LAPACK auxiliary routine (version 1.5)						 DLAMSH(l)

NAME
       DLAMSH - send multiple shifts through a small (single node) matrix to  see how consecutive small subdiagonal elements are modified by  sub-
       sequent shifts in an effort to maximize the number of bulges  that can be sent through

SYNOPSIS
       SUBROUTINE DLAMSH ( S, LDS, NBULGE, JBLK, H, LDH, N, ULP )

	   INTEGER	 LDS, NBULGE, JBLK, LDH, N

	   DOUBLE	 PRECISION ULP

	   DOUBLE	 PRECISION S(LDS,*), H(LDH,*)

PURPOSE
       DLAMSH sends multiple shifts through a small (single node) matrix to
	  see how consecutive small subdiagonal elements are modified by
	  subsequent shifts in an effort to maximize the number of bulges
	  that can be sent through.  DLAMSH should only be called when there are multiple shifts/bulges
	  (NBULGE > 1) and the first shift is starting in the middle of an
	  unreduced Hessenberg matrix because of two or more consecutive small
	  subdiagonal elements.

ARGUMENTS
       S       (local input/output) DOUBLE PRECISION array, (LDS,*)
	       On entry, the matrix of shifts.	Only the 2x2 diagonal of S is referenced.  It is assumed that S has JBLK double shifts	(size  2).
	       On exit, the data is rearranged in the best order for applying.

       LDS     (local input) INTEGER
	       On entry, the leading dimension of S.  Unchanged on exit.  1 < NBULGE <= JBLK <= LDS/2

       NBULGE  (local input/output) INTEGER
	       On  entry, the number of bulges to send through H ( >1 ).  NBULGE should be less than the maximum determined (JBLK).  1 < NBULGE <=
	       JBLK <= LDS/2 On exit, the maximum number of bulges that can be sent through.

       JBLK    (local input) INTEGER
	       On entry, the number of shifts determined for S.  Unchanged on exit.

       H       (local input/output) DOUBLE PRECISION array (LDH,N)
	       On entry, the local matrix to apply the shifts on.  H should be aligned so that the starting row  is  2.   On  exit,  the  data	is
	       destroyed.

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

       N       (local input) INTEGER
	       On  entry, the size of H.  If all the bulges are expected to go through, N should be at least 4*NBULGE+2.  Otherwise, NBULGE may be
	       reduced by this routine.

       ULP     (local input) DOUBLE PRECISION
	       On entry, machine precision Unchanged on exit.

	       Implemented by:	G. Henry, May 1, 1997

LAPACK version 1.5						    12 May 1997 							 DLAMSH(l)