Provided by: liblapack-doc_3.3.1-1_all #### NAME

```       LAPACK-3  -  applies  a real elementary reflector H to a real M-by-N matrix C, from either
the left or the right

```

#### SYNOPSIS

```       SUBROUTINE SLARZ( SIDE, M, N, L, V, INCV, TAU, C, LDC, WORK )

CHARACTER     SIDE

INTEGER       INCV, L, LDC, M, N

REAL          TAU

REAL          C( LDC, * ), V( * ), WORK( * )

```

#### PURPOSE

```       SLARZ 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 STZRZF.

```

#### 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) REAL array, dimension (1+(L-1)*abs(INCV))
The vector v in the representation of H as returned by
STZRZF. V is not used if TAU = 0.

INCV    (input) INTEGER
The increment between elements of v. INCV <> 0.

TAU     (input) REAL
The value tau in the representation of H.

C       (input/output) REAL 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) REAL array, dimension
(N) if SIDE = 'L'
or (M) if SIDE = 'R'

```

#### FURTHERDETAILS

```        Based on contributions by
A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA

LAPACK routine (version 3.3.1)             April 2011                             SLARZ(3lapack)
```