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dlarfy.f(3) LAPACK dlarfy.f(3)

NAME

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

Univ. of Colorado Denver

NAG Ltd.

Date:

December 2016

Definition at line 110 of file dlarfy.f.

Author

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Tue Nov 14 2017 Version 3.8.0