Provided by: liblapack-doc-man_3.5.0-2ubuntu1_all
NAME
dlarz.f -
SYNOPSIS
Functions/Subroutines subroutine dlarz (SIDE, M, N, L, V, INCV, TAU, C, LDC, WORK) DLARZ applies an elementary reflector (as returned by stzrzf) to a general matrix.
Function/Subroutine Documentation
subroutine dlarz (characterSIDE, integerM, integerN, integerL, double precision, dimension( * )V, integerINCV, double precisionTAU, double precision, dimension( ldc, * )C, integerLDC, double precision, dimension( * )WORK) DLARZ applies an elementary reflector (as returned by stzrzf) to a general matrix. Purpose: DLARZ applies a real elementary reflector H to a real M-by-N matrix C, from either the left or the right. H is represented in the form H = I - tau * v * v**T where tau is a real scalar and v is a real vector. If tau = 0, then H is taken to be the unit matrix. H is a product of k elementary reflectors as returned by DTZRZF. Parameters: SIDE SIDE is CHARACTER*1 = 'L': form H * C = 'R': form C * H M M is INTEGER The number of rows of the matrix C. N N is INTEGER The number of columns of the matrix C. L L is INTEGER The number of entries of the vector V containing the meaningful part of the Householder vectors. If SIDE = 'L', M >= L >= 0, if SIDE = 'R', N >= L >= 0. V V is DOUBLE PRECISION array, dimension (1+(L-1)*abs(INCV)) The vector v in the representation of H as returned by DTZRZF. V is not used if TAU = 0. INCV INCV is INTEGER The increment between elements of v. INCV <> 0. TAU TAU is DOUBLE PRECISION The value tau in the representation of H. C C is DOUBLE PRECISION array, dimension (LDC,N) On entry, the M-by-N matrix C. On exit, C is overwritten by the matrix H * C if SIDE = 'L', or C * H if SIDE = 'R'. LDC LDC is INTEGER The leading dimension of the array C. LDC >= max(1,M). WORK WORK is DOUBLE PRECISION array, dimension (N) if SIDE = 'L' or (M) if SIDE = 'R' Author: Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Date: September 2012 Contributors: A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA Further Details: Definition at line 146 of file dlarz.f.
Author
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