initial skeleton with tests ran

SRC/dlarf1.f

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+*> \brief \b DLARF applies an elementary reflector to a general rectangular matrix.
+*
+*  =========== DOCUMENTATION ===========
+*
+* Online html documentation available at
+*            http://www.netlib.org/lapack/explore-html/
+*
+*> \htmlonly
+*> Download DLARF + dependencies
+*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlarf.f">
+*> [TGZ]</a>
+*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlarf.f">
+*> [ZIP]</a>
+*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlarf.f">
+*> [TXT]</a>
+*> \endhtmlonly
+*
+*  Definition:
+*  ===========
+*
+*       SUBROUTINE DLARF( SIDE, M, N, V, INCV, TAU, C, LDC, WORK )
+*
+*       .. Scalar Arguments ..
+*       CHARACTER          SIDE
+*       INTEGER            INCV, LDC, M, N
+*       DOUBLE PRECISION   TAU
+*       ..
+*       .. Array Arguments ..
+*       DOUBLE PRECISION   C( LDC, * ), V( * ), WORK( * )
+*       ..
+*
+*
+*> \par Purpose:
+*  =============
+*>
+*> \verbatim
+*>
+*> 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.
+*> \endverbatim
+*
+*  Arguments:
+*  ==========
+*
+*> \param[in] SIDE
+*> \verbatim
+*>          SIDE is CHARACTER*1
+*>          = 'L': form  H * C
+*>          = 'R': form  C * H
+*> \endverbatim
+*>
+*> \param[in] M
+*> \verbatim
+*>          M is INTEGER
+*>          The number of rows of the matrix C.
+*> \endverbatim
+*>
+*> \param[in] N
+*> \verbatim
+*>          N is INTEGER
+*>          The number of columns of the matrix C.
+*> \endverbatim
+*>
+*> \param[in] V
+*> \verbatim
+*>          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.
+*> \endverbatim
+*>
+*> \param[in] INCV
+*> \verbatim
+*>          INCV is INTEGER
+*>          The increment between elements of v. INCV <> 0.
+*> \endverbatim
+*>
+*> \param[in] TAU
+*> \verbatim
+*>          TAU is DOUBLE PRECISION
+*>          The value tau in the representation of H.
+*> \endverbatim
+*>
+*> \param[in,out] C
+*> \verbatim
+*>          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'.
+*> \endverbatim
+*>
+*> \param[in] LDC
+*> \verbatim
+*>          LDC is INTEGER
+*>          The leading dimension of the array C. LDC >= max(1,M).
+*> \endverbatim
+*>
+*> \param[out] WORK
+*> \verbatim
+*>          WORK is DOUBLE PRECISION array, dimension
+*>                         (N) if SIDE = 'L'
+*>                      or (M) if SIDE = 'R'
+*> \endverbatim
+*
+*  Authors:
+*  ========
+*
+*> \author Univ. of Tennessee
+*> \author Univ. of California Berkeley
+*> \author Univ. of Colorado Denver
+*> \author NAG Ltd.
+*
+*> \ingroup larf
+*
+*  =====================================================================
+      SUBROUTINE DLARF( SIDE, M, N, V, INCV, TAU, C, LDC, WORK )
+*
+*  -- LAPACK auxiliary routine --
+*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
+*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
+*
+*     .. Scalar Arguments ..
+      CHARACTER          SIDE
+      INTEGER            INCV, LDC, M, N
+      DOUBLE PRECISION   TAU
+*     ..
+*     .. Array Arguments ..
+      DOUBLE PRECISION   C( LDC, * ), V( * ), WORK( * )
+*     ..
+*
+*  =====================================================================
+*
+*     .. Parameters ..
+      DOUBLE PRECISION   ONE, ZERO
+      PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
+      INTEGER            IONE
+      PARAMETER          ( IONE = 1 )
+*     ..
+*     .. Local Scalars ..
+      LOGICAL            APPLYLEFT
+      INTEGER            I, LASTV, LASTC
+*     ..
+*     .. External Subroutines ..
+      EXTERNAL           DGEMV, DGER
+*     ..
+*     .. External Functions ..
+      LOGICAL            LSAME
+      INTEGER            ILADLR, ILADLC
+      EXTERNAL           LSAME, ILADLR, ILADLC
+*     ..
+*     .. Executable Statements ..
+*
+      APPLYLEFT = LSAME( SIDE, 'L' )
+      LASTV = 0
+      LASTC = 0
+      IF( TAU.NE.ZERO ) THEN
+!     Set up variables for scanning V.  LASTV begins pointing to the end
+!     of V.
+         IF( APPLYLEFT ) THEN
+            LASTV = M
+         ELSE
+            LASTV = N
+         END IF
+         IF( INCV.GT.0 ) THEN
+            I = 1 + (LASTV-1) * INCV
+         ELSE
+            I = 1
+         END IF
+!     Look for the last non-zero row in V.
+         DO WHILE( LASTV.GT.0 .AND. V( I ).EQ.ZERO )
+            LASTV = LASTV - 1
+            I = I - INCV
+         END DO
+         IF( APPLYLEFT ) THEN
+!     Scan for the last non-zero column in C(1:lastv,:).
+            LASTC = ILADLC(LASTV, N, C, LDC)
+         ELSE
+!     Scan for the last non-zero row in C(:,1:lastv).
+            LASTC = ILADLR(M, LASTV, C, LDC)
+         END IF
+      END IF
+!     Note that lastc.eq.0 renders the BLAS operations null; no special
+!     case is needed at this level.
+      IF( APPLYLEFT ) THEN
+*
+*        Form  H * C
+*
+         IF( LASTV.GT.0 ) THEN
+*
+*           w(1:lastc,1) := C(2:lastv,1:lastc)**T * v(2:lastv,1)
+*
+            CALL DGEMV( 'Transpose', LASTV, LASTC, ONE, C(2,1), LDC, 
+     $                  V(INCV), INCV, ZERO, WORK, 1 )
+*
+*           w(1:lastc,1) := w(1:lastc,1) + C(1,1:lastc)**T * v(1,1) 
+*                         = w(1:lastc,1) + C(1,1:lastc)**T
+*
+            CALL DAXPY(LASTC, ONE, C, LDC, WORK, 1)
+*
+*           C(1:lastv,1:lastc) := C(...) - v(1:lastv,1) * w(1:lastc,1)**T
+*
+            CALL DGER( LASTV, LASTC, -TAU, V, INCV, WORK, 1, C, LDC )
+         END IF
+      ELSE
+*
+*        Form  C * H
+*
+         IF( LASTV.GT.0 ) THEN
+*
+*           w(1:lastc,1) := C(1:lastc,1:lastv) * v(1:lastv,1)
+*
+            CALL DGEMV( 'No transpose', LASTC, LASTV, ONE, C, LDC,
+     $           V, INCV, ZERO, WORK, 1 )
+*
+*           C(1:lastc,1:lastv) := C(...) - w(1:lastc,1) * v(1:lastv,1)**T
+*
+            CALL DGER( LASTC, LASTV, -TAU, WORK, 1, V, INCV, C, LDC )
+         END IF
+      END IF
+      RETURN
+*
+*     End of DLARF
+*
+      END