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NAME
     dlarf - apply a real elementary reflector H to a real m by n
     matrix C, from either the left or the right

SYNOPSIS
     SUBROUTINE DLARF( SIDE, M, N, V, INCV, TAU, C, LDC, WORK )

     CHARACTER SIDE

     INTEGER INCV, LDC, M, N

     DOUBLE PRECISION TAU

     DOUBLE PRECISION C( LDC, * ), V( * ), WORK( * )



     #include <sunperf.h>

     void dlarf(char side, int m, int n,  double  *v,  int  incv,
               double tau, double *dc, int ldc) ;

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'

     where tau is a real scalar and v is a real vector.

     If tau = 0, then H is taken to be the unit matrix.


ARGUMENTS
     SIDE      (input) CHARACTER*1
               = 'L': form  H * C
               = 'R': form  C * H

     M         (input) INTEGER
               The number of rows of the matrix C.

     N         (input) INTEGER
               The number of columns of the matrix C.

     V         (input) 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      (input) INTEGER
               The increment between elements of v. INCV <> 0.

     TAU       (input) DOUBLE PRECISION
               The value tau in the representation of H.

     C         (input/output) 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       (input) INTEGER
               The leading dimension  of  the  array  C.  LDC  >=
               max(1,M).

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

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