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Annotation of rpl/lapack/lapack/dla_wwaddw.f, revision 1.15

1.8       bertrand    1: *> \brief \b DLA_WWADDW adds a vector into a doubled-single vector.
1.5       bertrand    2: *
                      3: *  =========== DOCUMENTATION ===========
                      4: *
1.12      bertrand    5: * Online html documentation available at
                      6: *            http://www.netlib.org/lapack/explore-html/
1.5       bertrand    7: *
                      8: *> \htmlonly
1.12      bertrand    9: *> Download DLA_WWADDW + dependencies
                     10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dla_wwaddw.f">
                     11: *> [TGZ]</a>
                     12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dla_wwaddw.f">
                     13: *> [ZIP]</a>
                     14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dla_wwaddw.f">
1.5       bertrand   15: *> [TXT]</a>
1.12      bertrand   16: *> \endhtmlonly
1.5       bertrand   17: *
                     18: *  Definition:
                     19: *  ===========
                     20: *
                     21: *       SUBROUTINE DLA_WWADDW( N, X, Y, W )
1.12      bertrand   22: *
1.5       bertrand   23: *       .. Scalar Arguments ..
                     24: *       INTEGER            N
                     25: *       ..
                     26: *       .. Array Arguments ..
                     27: *       DOUBLE PRECISION   X( * ), Y( * ), W( * )
                     28: *       ..
1.12      bertrand   29: *
1.5       bertrand   30: *
                     31: *> \par Purpose:
                     32: *  =============
                     33: *>
                     34: *> \verbatim
                     35: *>
                     36: *>    DLA_WWADDW adds a vector W into a doubled-single vector (X, Y).
                     37: *>
                     38: *>    This works for all extant IBM's hex and binary floating point
1.15    ! bertrand   39: *>    arithmetic, but not for decimal.
1.5       bertrand   40: *> \endverbatim
                     41: *
                     42: *  Arguments:
                     43: *  ==========
                     44: *
                     45: *> \param[in] N
                     46: *> \verbatim
                     47: *>          N is INTEGER
                     48: *>            The length of vectors X, Y, and W.
                     49: *> \endverbatim
                     50: *>
                     51: *> \param[in,out] X
                     52: *> \verbatim
                     53: *>          X is DOUBLE PRECISION array, dimension (N)
                     54: *>            The first part of the doubled-single accumulation vector.
                     55: *> \endverbatim
                     56: *>
                     57: *> \param[in,out] Y
                     58: *> \verbatim
                     59: *>          Y is DOUBLE PRECISION array, dimension (N)
                     60: *>            The second part of the doubled-single accumulation vector.
                     61: *> \endverbatim
                     62: *>
                     63: *> \param[in] W
                     64: *> \verbatim
                     65: *>          W is DOUBLE PRECISION array, dimension (N)
                     66: *>            The vector to be added.
                     67: *> \endverbatim
                     68: *
                     69: *  Authors:
                     70: *  ========
                     71: *
1.12      bertrand   72: *> \author Univ. of Tennessee
                     73: *> \author Univ. of California Berkeley
                     74: *> \author Univ. of Colorado Denver
                     75: *> \author NAG Ltd.
1.5       bertrand   76: *
1.12      bertrand   77: *> \date December 2016
1.5       bertrand   78: *
                     79: *> \ingroup doubleOTHERcomputational
                     80: *
                     81: *  =====================================================================
1.1       bertrand   82:       SUBROUTINE DLA_WWADDW( N, X, Y, W )
                     83: *
1.12      bertrand   84: *  -- LAPACK computational routine (version 3.7.0) --
1.5       bertrand   85: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
                     86: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.12      bertrand   87: *     December 2016
1.1       bertrand   88: *
                     89: *     .. Scalar Arguments ..
                     90:       INTEGER            N
                     91: *     ..
                     92: *     .. Array Arguments ..
                     93:       DOUBLE PRECISION   X( * ), Y( * ), W( * )
                     94: *     ..
                     95: *
                     96: *  =====================================================================
                     97: *
                     98: *     .. Local Scalars ..
                     99:       DOUBLE PRECISION   S
                    100:       INTEGER            I
                    101: *     ..
                    102: *     .. Executable Statements ..
                    103: *
                    104:       DO 10 I = 1, N
                    105:         S = X(I) + W(I)
                    106:         S = (S + S) - S
                    107:         Y(I) = ((X(I) - S) + W(I)) + Y(I)
                    108:         X(I) = S
                    109:  10   CONTINUE
                    110:       RETURN
                    111:       END