dlarz (l)  Linux Man Pages
dlarz: applies a real elementary reflector H to a real MbyN matrix C, from either the left or the right
NAME
DLARZ  applies a real elementary reflector H to a real MbyN matrix C, from either the left or the rightSYNOPSIS
 SUBROUTINE DLARZ(
 SIDE, M, N, L, V, INCV, TAU, C, LDC, WORK )
 CHARACTER SIDE
 INTEGER INCV, L, LDC, M, N
 DOUBLE PRECISION TAU
 DOUBLE PRECISION C( LDC, * ), V( * ), WORK( * )
PURPOSE
DLARZ applies a real elementary reflector H to a real MbyN matrix C, from either the left or the right. H is represented in the formH
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.
ARGUMENTS
 SIDE (input) CHARACTER*1

= aqLaq: form H * C
= aqRaq: form C * H  M (input) INTEGER
 The number of rows of the matrix C.
 N (input) INTEGER
 The number of columns of the matrix C.
 L (input) INTEGER
 The number of entries of the vector V containing the meaningful part of the Householder vectors. If SIDE = aqLaq, M >= L >= 0, if SIDE = aqRaq, N >= L >= 0.
 V (input) DOUBLE PRECISION array, dimension (1+(L1)*abs(INCV))
 The vector v in the representation of H as returned by DTZRZF. V is not used if TAU = 0.
 INCV (input) INTEGER
 The increment between elements of v. INCV <> 0.
 TAU (input) DOUBLE PRECISION
 The value tau in the representation of H.
 C (input/output) DOUBLE PRECISION array, dimension (LDC,N)
 On entry, the MbyN matrix C. On exit, C is overwritten by the matrix H * C if SIDE = aqLaq, or C * H if SIDE = aqRaq.
 LDC (input) INTEGER
 The leading dimension of the array C. LDC >= max(1,M).
 WORK (workspace) DOUBLE PRECISION array, dimension
 (N) if SIDE = aqLaq or (M) if SIDE = aqRaq
FURTHER DETAILS
Based on contributions by