dlarzb (l) - Linux Manuals
dlarzb: applies a real block reflector H or its transpose H**T to a real distributed M-by-N C from the left or the right
Command to display dlarzb manual in Linux: $ man l dlarzb
NAME
DLARZB - applies a real block reflector H or its transpose H**T to a real distributed M-by-N C from the left or the right
SYNOPSIS
- SUBROUTINE DLARZB(
-
SIDE, TRANS, DIRECT, STOREV, M, N, K, L, V,
LDV, T, LDT, C, LDC, WORK, LDWORK )
-
CHARACTER
DIRECT, SIDE, STOREV, TRANS
-
INTEGER
K, L, LDC, LDT, LDV, LDWORK, M, N
-
DOUBLE
PRECISION C( LDC, * ), T( LDT, * ), V( LDV, * ),
WORK( LDWORK, * )
PURPOSE
DLARZB applies a real block reflector H or its transpose H**T to
a real distributed M-by-N C from the left or the right.
Currently, only STOREV = aqRaq and DIRECT = aqBaq are supported.
ARGUMENTS
- SIDE (input) CHARACTER*1
-
= aqLaq: apply H or Haq from the Left
= aqRaq: apply H or Haq from the Right
- TRANS (input) CHARACTER*1
-
= aqNaq: apply H (No transpose)
= aqCaq: apply Haq (Transpose)
- DIRECT (input) CHARACTER*1
-
Indicates how H is formed from a product of elementary
reflectors
= aqFaq: H = H(1) H(2) . . . H(k) (Forward, not supported yet)
= aqBaq: H = H(k) . . . H(2) H(1) (Backward)
- STOREV (input) CHARACTER*1
-
Indicates how the vectors which define the elementary
reflectors are stored:
= aqCaq: Columnwise (not supported yet)
= aqRaq: Rowwise
- M (input) INTEGER
-
The number of rows of the matrix C.
- N (input) INTEGER
-
The number of columns of the matrix C.
- K (input) INTEGER
-
The order of the matrix T (= the number of elementary
reflectors whose product defines the block reflector).
- L (input) INTEGER
-
The number of columns of the matrix V containing the
meaningful part of the Householder reflectors.
If SIDE = aqLaq, M >= L >= 0, if SIDE = aqRaq, N >= L >= 0.
- V (input) DOUBLE PRECISION array, dimension (LDV,NV).
-
If STOREV = aqCaq, NV = K; if STOREV = aqRaq, NV = L.
- LDV (input) INTEGER
-
The leading dimension of the array V.
If STOREV = aqCaq, LDV >= L; if STOREV = aqRaq, LDV >= K.
- T (input) DOUBLE PRECISION array, dimension (LDT,K)
-
The triangular K-by-K matrix T in the representation of the
block reflector.
- LDT (input) INTEGER
-
The leading dimension of the array T. LDT >= K.
- C (input/output) DOUBLE PRECISION array, dimension (LDC,N)
-
On entry, the M-by-N matrix C.
On exit, C is overwritten by H*C or Haq*C or C*H or C*Haq.
- LDC (input) INTEGER
-
The leading dimension of the array C. LDC >= max(1,M).
- WORK (workspace) DOUBLE PRECISION array, dimension (LDWORK,K)
-
- LDWORK (input) INTEGER
-
The leading dimension of the array WORK.
If SIDE = aqLaq, LDWORK >= max(1,N);
if SIDE = aqRaq, LDWORK >= max(1,M).
FURTHER DETAILS
Based on contributions by
A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA
Pages related to dlarzb
- dlarzb (3)
- dlarz (l) - applies a real elementary reflector H to a real M-by-N matrix C, from either the left or the right
- dlarzt (l) - forms the triangular factor T of a real block reflector H of order > n, which is defined as a product of k elementary reflectors
- dlar1v (l) - computes the (scaled) r-th column of the inverse of the sumbmatrix in rows B1 through BN of the tridiagonal matrix L D L^T - sigma I
- dlar2v (l) - applies a vector of real plane rotations from both sides to a sequence of 2-by-2 real symmetric matrices, defined by the elements of the vectors x, y and z
- dlarf (l) - applies a real elementary reflector H to a real m by n matrix C, from either the left or the right
- dlarfb (l) - applies a real block reflector H or its transpose Haq to a real m by n matrix C, from either the left or the right
- dlarfg (l) - generates a real elementary reflector H of order n, such that H * ( alpha ) = ( beta ), Haq * H = I
- dlarfp (l) - generates a real elementary reflector H of order n, such that H * ( alpha ) = ( beta ), Haq * H = I
- dlarft (l) - forms the triangular factor T of a real block reflector H of order n, which is defined as a product of k elementary reflectors