# dlarf.f man page

dlarf.f

## Synopsis

### Functions/Subroutines

subroutine **dlarf** (SIDE, M, **N**, V, INCV, TAU, C, LDC, WORK)**DLARF** applies an elementary reflector to a general rectangular matrix.

## Function/Subroutine Documentation

### subroutine dlarf (character SIDE, integer M, integer N, double precision, dimension( * ) V, integer INCV, double precision TAU, double precision, dimension( ldc, * ) C, integer LDC, double precision, dimension( * ) WORK)

**DLARF** applies an elementary reflector to a general rectangular matrix.

**Purpose:**

DLARF applies a real elementary reflector H to a real m by n matrix C, from either the left or the right. H is represented in the form H = I - tau * v * v**T where tau is a real scalar and v is a real vector. If tau = 0, then H is taken to be the unit matrix.

**Parameters:***SIDE*SIDE is CHARACTER*1 = 'L': form H * C = 'R': form C * H

*M*M is INTEGER The number of rows of the matrix C.

*N*N is INTEGER The number of columns of the matrix C.

*V*V is DOUBLE PRECISION array, dimension (1 + (M-1)*abs(INCV)) if SIDE = 'L' or (1 + (N-1)*abs(INCV)) if SIDE = 'R' The vector v in the representation of H. V is not used if TAU = 0.

*INCV*INCV is INTEGER The increment between elements of v. INCV <> 0.

*TAU*TAU is DOUBLE PRECISION The value tau in the representation of H.

*C*C is DOUBLE PRECISION array, dimension (LDC,N) On entry, the m by n matrix C. On exit, C is overwritten by the matrix H * C if SIDE = 'L', or C * H if SIDE = 'R'.

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

*WORK*WORK is DOUBLE PRECISION array, dimension (N) if SIDE = 'L' or (M) if SIDE = 'R'

**Author:**Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**December 2016

Definition at line 126 of file dlarf.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

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

Tue Nov 14 2017 Version 3.8.0 LAPACK