Provided by: liblapack-doc_3.8.0-2_all

#### NAME

```       double_eig

```

#### SYNOPSIS

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

```

#### DetailedDescription

```       This is the group of double LAPACK TESTING EIG routines.

```

#### FunctionDocumentation

```   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

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