double_eig

NAME

double_eig

SYNOPSIS

Functions

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

Detailed Description

This is the group of double LAPACK TESTING EIG routines.

Function 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

Univ. of Colorado Denver

NAG Ltd.

Date:

December 2016

Author

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