github.com/gonum/lapack@v0.0.0-20181123203213-e4cdc5a0bff9/internal/testdata/netlib/dcopy.f (about)

     1  *> \brief \b DCOPY
     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 DCOPY(N,DX,INCX,DY,INCY)
    12  * 
    13  *       .. Scalar Arguments ..
    14  *       INTEGER INCX,INCY,N
    15  *       ..
    16  *       .. Array Arguments ..
    17  *       DOUBLE PRECISION DX(*),DY(*)
    18  *       ..
    19  *  
    20  *
    21  *> \par Purpose:
    22  *  =============
    23  *>
    24  *> \verbatim
    25  *>
    26  *>    DCOPY copies a vector, x, to a vector, y.
    27  *>    uses unrolled loops for increments equal to one.
    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 DCOPY(N,DX,INCX,DY,INCY)
    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        INTEGER INCX,INCY,N
    61  *     ..
    62  *     .. Array Arguments ..
    63        DOUBLE PRECISION DX(*),DY(*)
    64  *     ..
    65  *
    66  *  =====================================================================
    67  *
    68  *     .. Local Scalars ..
    69        INTEGER I,IX,IY,M,MP1
    70  *     ..
    71  *     .. Intrinsic Functions ..
    72        INTRINSIC MOD
    73  *     ..
    74        IF (N.LE.0) RETURN
    75        IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN
    76  *
    77  *        code for both increments equal to 1
    78  *
    79  *
    80  *        clean-up loop
    81  *
    82           M = MOD(N,7)
    83           IF (M.NE.0) THEN
    84              DO I = 1,M
    85                 DY(I) = DX(I)
    86              END DO
    87              IF (N.LT.7) RETURN
    88           END IF   
    89           MP1 = M + 1
    90           DO I = MP1,N,7
    91              DY(I) = DX(I)
    92              DY(I+1) = DX(I+1)
    93              DY(I+2) = DX(I+2)
    94              DY(I+3) = DX(I+3)
    95              DY(I+4) = DX(I+4)
    96              DY(I+5) = DX(I+5)
    97              DY(I+6) = DX(I+6)
    98           END DO
    99        ELSE      
   100  *
   101  *        code for unequal increments or equal increments
   102  *          not equal to 1
   103  *
   104           IX = 1
   105           IY = 1
   106           IF (INCX.LT.0) IX = (-N+1)*INCX + 1
   107           IF (INCY.LT.0) IY = (-N+1)*INCY + 1
   108           DO I = 1,N
   109              DY(IY) = DX(IX)
   110              IX = IX + INCX
   111              IY = IY + INCY
   112           END DO
   113        END IF
   114        RETURN
   115        END