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Cohérence Blas.

    1: *> \brief \b DROT
    2: *
    3: *  =========== DOCUMENTATION ===========
    4: *
    5: * Online html documentation available at 
    6: *            http://www.netlib.org/lapack/explore-html/ 
    7: *
    8: *  Definition:
    9: *  ===========
   10: *
   11: *       SUBROUTINE DROT(N,DX,INCX,DY,INCY,C,S)
   12: * 
   13: *       .. Scalar Arguments ..
   14: *       DOUBLE PRECISION C,S
   15: *       INTEGER INCX,INCY,N
   16: *       ..
   17: *       .. Array Arguments ..
   18: *       DOUBLE PRECISION DX(*),DY(*)
   19: *       ..
   20: *  
   21: *
   22: *> \par Purpose:
   23: *  =============
   24: *>
   25: *> \verbatim
   26: *>
   27: *>    DROT applies a plane rotation.
   28: *> \endverbatim
   29: *
   30: *  Authors:
   31: *  ========
   32: *
   33: *> \author Univ. of Tennessee 
   34: *> \author Univ. of California Berkeley 
   35: *> \author Univ. of Colorado Denver 
   36: *> \author NAG Ltd. 
   37: *
   38: *> \date November 2011
   39: *
   40: *> \ingroup double_blas_level1
   41: *
   42: *> \par Further Details:
   43: *  =====================
   44: *>
   45: *> \verbatim
   46: *>
   47: *>     jack dongarra, linpack, 3/11/78.
   48: *>     modified 12/3/93, array(1) declarations changed to array(*)
   49: *> \endverbatim
   50: *>
   51: *  =====================================================================
   52:       SUBROUTINE DROT(N,DX,INCX,DY,INCY,C,S)
   53: *
   54: *  -- Reference BLAS level1 routine (version 3.4.0) --
   55: *  -- Reference BLAS is a software package provided by Univ. of Tennessee,    --
   56: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
   57: *     November 2011
   58: *
   59: *     .. Scalar Arguments ..
   60:       DOUBLE PRECISION C,S
   61:       INTEGER INCX,INCY,N
   62: *     ..
   63: *     .. Array Arguments ..
   64:       DOUBLE PRECISION DX(*),DY(*)
   65: *     ..
   66: *
   67: *  =====================================================================
   68: *
   69: *     .. Local Scalars ..
   70:       DOUBLE PRECISION DTEMP
   71:       INTEGER I,IX,IY
   72: *     ..
   73:       IF (N.LE.0) RETURN
   74:       IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN
   75: *
   76: *       code for both increments equal to 1
   77: *
   78:          DO I = 1,N
   79:             DTEMP = C*DX(I) + S*DY(I)
   80:             DY(I) = C*DY(I) - S*DX(I)
   81:             DX(I) = DTEMP
   82:          END DO
   83:       ELSE
   84: *
   85: *       code for unequal increments or equal increments not equal
   86: *         to 1
   87: *
   88:          IX = 1
   89:          IY = 1
   90:          IF (INCX.LT.0) IX = (-N+1)*INCX + 1
   91:          IF (INCY.LT.0) IY = (-N+1)*INCY + 1
   92:          DO I = 1,N
   93:             DTEMP = C*DX(IX) + S*DY(IY)
   94:             DY(IY) = C*DY(IY) - S*DX(IX)
   95:             DX(IX) = DTEMP
   96:             IX = IX + INCX
   97:             IY = IY + INCY
   98:          END DO
   99:       END IF
  100:       RETURN
  101:       END