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    1: *> \brief \b ZDOTU
    2: *
    3: *  =========== DOCUMENTATION ===========
    4: *
    5: * Online html documentation available at
    6: *            http://www.netlib.org/lapack/explore-html/
    7: *
    8: *  Definition:
    9: *  ===========
   10: *
   11: *       COMPLEX*16 FUNCTION ZDOTU(N,ZX,INCX,ZY,INCY)
   12: *
   13: *       .. Scalar Arguments ..
   14: *       INTEGER INCX,INCY,N
   15: *       ..
   16: *       .. Array Arguments ..
   17: *       COMPLEX*16 ZX(*),ZY(*)
   18: *       ..
   19: *
   20: *
   21: *> \par Purpose:
   22: *  =============
   23: *>
   24: *> \verbatim
   25: *>
   26: *> ZDOTU forms the dot product of two complex vectors
   27: *>      ZDOTU = X^T * Y
   28: *>
   29: *> \endverbatim
   30: *
   31: *  Arguments:
   32: *  ==========
   33: *
   34: *> \param[in] N
   35: *> \verbatim
   36: *>          N is INTEGER
   37: *>         number of elements in input vector(s)
   38: *> \endverbatim
   39: *>
   40: *> \param[in] ZX
   41: *> \verbatim
   42: *>          ZX is COMPLEX*16 array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
   43: *> \endverbatim
   44: *>
   45: *> \param[in] INCX
   46: *> \verbatim
   47: *>          INCX is INTEGER
   48: *>         storage spacing between elements of ZX
   49: *> \endverbatim
   50: *>
   51: *> \param[in] ZY
   52: *> \verbatim
   53: *>          ZY is COMPLEX*16 array, dimension ( 1 + ( N - 1 )*abs( INCY ) )
   54: *> \endverbatim
   55: *>
   56: *> \param[in] INCY
   57: *> \verbatim
   58: *>          INCY is INTEGER
   59: *>         storage spacing between elements of ZY
   60: *> \endverbatim
   61: *
   62: *  Authors:
   63: *  ========
   64: *
   65: *> \author Univ. of Tennessee
   66: *> \author Univ. of California Berkeley
   67: *> \author Univ. of Colorado Denver
   68: *> \author NAG Ltd.
   69: *
   70: *> \ingroup complex16_blas_level1
   71: *
   72: *> \par Further Details:
   73: *  =====================
   74: *>
   75: *> \verbatim
   76: *>
   77: *>     jack dongarra, 3/11/78.
   78: *>     modified 12/3/93, array(1) declarations changed to array(*)
   79: *> \endverbatim
   80: *>
   81: *  =====================================================================
   82:       COMPLEX*16 FUNCTION ZDOTU(N,ZX,INCX,ZY,INCY)
   83: *
   84: *  -- Reference BLAS level1 routine --
   85: *  -- Reference BLAS is a software package provided by Univ. of Tennessee,    --
   86: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
   87: *
   88: *     .. Scalar Arguments ..
   89:       INTEGER INCX,INCY,N
   90: *     ..
   91: *     .. Array Arguments ..
   92:       COMPLEX*16 ZX(*),ZY(*)
   93: *     ..
   94: *
   95: *  =====================================================================
   96: *
   97: *     .. Local Scalars ..
   98:       COMPLEX*16 ZTEMP
   99:       INTEGER I,IX,IY
  100: *     ..
  101:       ZTEMP = (0.0d0,0.0d0)
  102:       ZDOTU = (0.0d0,0.0d0)
  103:       IF (N.LE.0) RETURN
  104:       IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN
  105: *
  106: *        code for both increments equal to 1
  107: *
  108:          DO I = 1,N
  109:             ZTEMP = ZTEMP + ZX(I)*ZY(I)
  110:          END DO
  111:       ELSE
  112: *
  113: *        code for unequal increments or equal increments
  114: *          not equal to 1
  115: *
  116:          IX = 1
  117:          IY = 1
  118:          IF (INCX.LT.0) IX = (-N+1)*INCX + 1
  119:          IF (INCY.LT.0) IY = (-N+1)*INCY + 1
  120:          DO I = 1,N
  121:             ZTEMP = ZTEMP + ZX(IX)*ZY(IY)
  122:             IX = IX + INCX
  123:             IY = IY + INCY
  124:          END DO
  125:       END IF
  126:       ZDOTU = ZTEMP
  127:       RETURN
  128: *
  129: *     End of ZDOTU
  130: *
  131:       END