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dlaqr1.f(3)				      LAPACK				      dlaqr1.f(3)

NAME
       dlaqr1.f -

SYNOPSIS
   Functions/Subroutines
       subroutine dlaqr1 (N, H, LDH, SR1, SI1, SR2, SI2, V)
	   DLAQR1 sets a scalar multiple of the first column of the product of 2-by-2 or 3-by-3
	   matrix H and specified shifts.

Function/Subroutine Documentation
   subroutine dlaqr1 (integerN, double precision, dimension( ldh, * )H, integerLDH, double
       precisionSR1, double precisionSI1, double precisionSR2, double precisionSI2, double
       precision, dimension( * )V)
       DLAQR1 sets a scalar multiple of the first column of the product of 2-by-2 or 3-by-3
       matrix H and specified shifts.

       Purpose:

		 Given a 2-by-2 or 3-by-3 matrix H, DLAQR1 sets v to a
		 scalar multiple of the first column of the product

		 (*)  K = (H - (sr1 + i*si1)*I)*(H - (sr2 + i*si2)*I)

		 scaling to avoid overflows and most underflows. It
		 is assumed that either

			 1) sr1 = sr2 and si1 = -si2
		     or
			 2) si1 = si2 = 0.

		 This is useful for starting double implicit shift bulges
		 in the QR algorithm.

       Parameters:
	   N

		     N is integer
			 Order of the matrix H. N must be either 2 or 3.

	   H

		     H is DOUBLE PRECISION array of dimension (LDH,N)
			 The 2-by-2 or 3-by-3 matrix H in (*).

	   LDH

		     LDH is integer
			 The leading dimension of H as declared in
			 the calling procedure.  LDH.GE.N

	   SR1

		     SR1 is DOUBLE PRECISION

	   SI1

		     SI1 is DOUBLE PRECISION

	   SR2

		     SR2 is DOUBLE PRECISION

	   SI2

		     SI2 is DOUBLE PRECISION
			 The shifts in (*).

	   V

		     V is DOUBLE PRECISION array of dimension N
			 A scalar multiple of the first column of the
			 matrix K in (*).

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   September 2012

       Contributors:
	   Karen Braman and Ralph Byers, Department of Mathematics, University of Kansas, USA

       Definition at line 122 of file dlaqr1.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2				 Tue Sep 25 2012			      dlaqr1.f(3)
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