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dlaqr1.f(3) LAPACK dlaqr1.f(3)dlaqr1.fNAME-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.SYNOPSISFunction/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 =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.-si2AuthorGenerated automatically by Doxygen for LAPACK from the source code.Version 3.4.2Tue Sep 25 2012 dlaqr1.f(3)

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