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man pages->IRIX man pages -> complib/dlarf (3)
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### Contents

```
DLARF(3F)							     DLARF(3F)

```

### NAME[Toc][Back]

```     DLARF - applie a real elementary reflector	H to a real m by n matrix C,
from either the left or the right
```

### SYNOPSIS[Toc][Back]

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

CHARACTER     SIDE

INTEGER       INCV, LDC, M, N

DOUBLE	       PRECISION TAU

DOUBLE	       PRECISION C( LDC, * ), V( * ), WORK( * )
```

### PURPOSE[Toc][Back]

```     DLARF 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'

where tau is a real scalar	and v is a real	vector.

If	tau = 0, then H	is taken to be the unit	matrix.

```

### ARGUMENTS[Toc][Back]

```     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.

V	     (input) DOUBLE PRECISION array, dimension
(1	+ (M-1)*abs(INCV)) if SIDE = 'L' or (1 + (N-1)*abs(INCV)) if
SIDE = 'R'	The vector v in	the representation of H. 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 m by	n matrix C.  On	exit, C	is overwritten by the
matrix H *	C if SIDE = 'L', or C *	H if SIDE = 'R'.

Page 1

DLARF(3F)							     DLARF(3F)

LDC     (input) INTEGER
The leading dimension of the array	C. LDC >= max(1,M).

WORK    (workspace) DOUBLE	PRECISION array, dimension
(N) if SIDE = 'L' or (M) if SIDE =	'R'
DLARF(3F)							     DLARF(3F)

```

### NAME[Toc][Back]

```     DLARF - applie a real elementary reflector	H to a real m by n matrix C,
from either the left or the right
```

### SYNOPSIS[Toc][Back]

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

CHARACTER     SIDE

INTEGER       INCV, LDC, M, N

DOUBLE	       PRECISION TAU

DOUBLE	       PRECISION C( LDC, * ), V( * ), WORK( * )
```

### PURPOSE[Toc][Back]

```     DLARF 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'

where tau is a real scalar	and v is a real	vector.

If	tau = 0, then H	is taken to be the unit	matrix.

```

### ARGUMENTS[Toc][Back]

```     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.

V	     (input) DOUBLE PRECISION array, dimension
(1	+ (M-1)*abs(INCV)) if SIDE = 'L' or (1 + (N-1)*abs(INCV)) if
SIDE = 'R'	The vector v in	the representation of H. 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 m by	n matrix C.  On	exit, C	is overwritten by the
matrix H *	C if SIDE = 'L', or C *	H if SIDE = 'R'.

Page 1

DLARF(3F)							     DLARF(3F)

LDC     (input) INTEGER
The leading dimension of the array	C. LDC >= max(1,M).

WORK    (workspace) DOUBLE	PRECISION array, dimension
(N) if SIDE = 'L' or (M) if SIDE =	'R'

PPPPaaaaggggeeee 2222```
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