NAME
ZLARZ - applies a complex elementary reflector H to a complex M-by-N matrix C, from either the left or the right
SYNOPSIS
- SUBROUTINE ZLARZ(
-
SIDE, M, N, L, V, INCV, TAU, C, LDC, WORK )
- CHARACTER
-
SIDE
- INTEGER
-
INCV, L, LDC, M, N
- COMPLEX*16
-
TAU
- COMPLEX*16
-
C( LDC, * ), V( * ), WORK( * )
PURPOSE
ZLARZ applies a complex elementary reflector H to a complex M-by-N matrix C, from either the left or the right. H is represented in the form
H = I - tau * v * v'
where tau is a complex scalar and v is a complex vector.
If tau = 0, then H is taken to be the unit matrix.
To apply H' (the conjugate transpose of H), supply conjg(tau) instead tau.
H is a product of k elementary reflectors as returned by ZTZRZF.
ARGUMENTS
- SIDE (input) CHARACTER*1
-
= 'L': form H * C
= 'R': 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 = 'L', M >= L >= 0, if SIDE = 'R', N >= L >= 0.
- V (input) COMPLEX*16 array, dimension (1+(L-1)*abs(INCV))
-
The vector v in the representation of H as returned by ZTZRZF. V is not used if TAU = 0.
- INCV (input) INTEGER
-
The increment between elements of v. INCV <> 0.
- TAU (input) COMPLEX*16
-
The value tau in the representation of H.
- C (input/output) COMPLEX*16 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 (input) INTEGER
-
The leading dimension of the array C. LDC >= max(1,M).
- WORK (workspace) COMPLEX*16 array, dimension
-
(N) if SIDE = 'L' or (M) if SIDE = 'R'
FURTHER DETAILS
Based on contributions by
A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA