# dlarfy.f - Man Page

## 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

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