dlaqr1 (3)  Linux Man Pages
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 2by2 or 3by3 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 2by2 or 3by3 matrix H and specified shifts.
Purpose:

Given a 2by2 or 3by3 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.
HH is DOUBLE PRECISION array of dimension (LDH,N) The 2by2 or 3by3 matrix H in (*).
LDHLDH is integer The leading dimension of H as declared in the calling procedure. LDH.GE.N
SR1SR1 is DOUBLE PRECISION
SI1SI1 is DOUBLE PRECISION
SR2SR2 is DOUBLE PRECISION
SI2SI2 is DOUBLE PRECISION The shifts in (*).
VV 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.
Linux man pages generated by: SysTutorials
Linux Man Pages Copyright Respective Owners. Site Copyright © SysTutorials. All Rights Reserved.