# dlarfy.f man page

dlarfy.f

## Synopsis

### Functions/Subroutines

subroutine dlarfy (UPLO, N, V, INCV, TAU, C, LDC, WORK)
DLARFY

## Function/Subroutine Documentation

### subroutine dlarfy (character UPLO, integer N, double precision, dimension( * ) V, integer INCV, double precision TAU, double precision, dimension( ldc, * ) C, integer LDC, double precision, dimension( * ) WORK)

DLARFY

Purpose:

``` DLARFY applies an elementary reflector, or Householder matrix, H,
to an n x n symmetric matrix C, from both the left and the right.

H is represented in the form

H = I - tau * v * v'

where  tau  is a scalar and  v  is a vector.

If  tau  is  zero, then  H  is taken to be the unit matrix.```
Parameters:

UPLO

```          UPLO is CHARACTER*1
Specifies whether the upper or lower triangular part of the
symmetric matrix C is stored.
= 'U':  Upper triangle
= 'L':  Lower triangle```

N

```          N is INTEGER
The number of rows and columns of the matrix C.  N >= 0.```

V

```          V is DOUBLE PRECISION array, dimension
(1 + (N-1)*abs(INCV))
The vector v as described above.```

INCV

```          INCV is INTEGER
The increment between successive elements of v.  INCV must
not be zero.```

TAU

```          TAU is DOUBLE PRECISION
The value tau as described above.```

C

```          C is DOUBLE PRECISION array, dimension (LDC, N)
On entry, the matrix C.
On exit, C is overwritten by H * C * H'.```

LDC

```          LDC is INTEGER
The leading dimension of the array C.  LDC >= max( 1, N ).```

WORK

`          WORK is DOUBLE PRECISION array, dimension (N)`
Author:

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Date:

December 2016

Definition at line 110 of file dlarfy.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page dlarfy(3) is an alias of dlarfy.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK