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CentOS 7.0 - man page for dlaqr1.f (centos section 3)

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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