LAPACK  3.5.0
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dcopy.f
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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