dlarz (3) - Linux Man Pages
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.
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.
SIDE is CHARACTER*1 = 'L': form H * C = 'R': form C * H
M is INTEGER The number of rows of the matrix C.
N is INTEGER The number of columns of the matrix C.
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 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 is INTEGER The increment between elements of v. INCV <> 0.
TAU is DOUBLE PRECISION The value tau in the representation of H.
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 is INTEGER The leading dimension of the array C. LDC >= max(1,M).
WORK is DOUBLE PRECISION array, dimension (N) if SIDE = 'L' or (M) if SIDE = 'R'
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
- September 2012
- A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA
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