LAPACK  3.10.0
LAPACK: Linear Algebra PACKage
cswap.f
Go to the documentation of this file.
1 *> \brief \b CSWAP
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 CSWAP(N,CX,INCX,CY,INCY)
12 *
13 * .. Scalar Arguments ..
14 * INTEGER INCX,INCY,N
15 * ..
16 * .. Array Arguments ..
17 * COMPLEX CX(*),CY(*)
18 * ..
19 *
20 *
21 *> \par Purpose:
22 * =============
23 *>
24 *> \verbatim
25 *>
26 *> CSWAP interchanges two vectors.
27 *> \endverbatim
28 *
29 * Arguments:
30 * ==========
31 *
32 *> \param[in] N
33 *> \verbatim
34 *> N is INTEGER
35 *> number of elements in input vector(s)
36 *> \endverbatim
37 *>
38 *> \param[in,out] CX
39 *> \verbatim
40 *> CX is COMPLEX array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
41 *> \endverbatim
42 *>
43 *> \param[in] INCX
44 *> \verbatim
45 *> INCX is INTEGER
46 *> storage spacing between elements of CX
47 *> \endverbatim
48 *>
49 *> \param[in,out] CY
50 *> \verbatim
51 *> CY is COMPLEX array, dimension ( 1 + ( N - 1 )*abs( INCY ) )
52 *> \endverbatim
53 *>
54 *> \param[in] INCY
55 *> \verbatim
56 *> INCY is INTEGER
57 *> storage spacing between elements of CY
58 *> \endverbatim
59 *
60 * Authors:
61 * ========
62 *
63 *> \author Univ. of Tennessee
64 *> \author Univ. of California Berkeley
65 *> \author Univ. of Colorado Denver
66 *> \author NAG Ltd.
67 *
68 *> \ingroup complex_blas_level1
69 *
70 *> \par Further Details:
71 * =====================
72 *>
73 *> \verbatim
74 *>
75 *> jack dongarra, linpack, 3/11/78.
76 *> modified 12/3/93, array(1) declarations changed to array(*)
77 *> \endverbatim
78 *>
79 * =====================================================================
80  SUBROUTINE cswap(N,CX,INCX,CY,INCY)
81 *
82 * -- Reference BLAS level1 routine --
83 * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
84 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
85 *
86 * .. Scalar Arguments ..
87  INTEGER INCX,INCY,N
88 * ..
89 * .. Array Arguments ..
90  COMPLEX CX(*),CY(*)
91 * ..
92 *
93 * =====================================================================
94 *
95 * .. Local Scalars ..
96  COMPLEX CTEMP
97  INTEGER I,IX,IY
98 * ..
99  IF (n.LE.0) RETURN
100  IF (incx.EQ.1 .AND. incy.EQ.1) THEN
101 *
102 * code for both increments equal to 1
103  DO i = 1,n
104  ctemp = cx(i)
105  cx(i) = cy(i)
106  cy(i) = ctemp
107  END DO
108  ELSE
109 *
110 * code for unequal increments or equal increments not equal
111 * to 1
112 *
113  ix = 1
114  iy = 1
115  IF (incx.LT.0) ix = (-n+1)*incx + 1
116  IF (incy.LT.0) iy = (-n+1)*incy + 1
117  DO i = 1,n
118  ctemp = cx(ix)
119  cx(ix) = cy(iy)
120  cy(iy) = ctemp
121  ix = ix + incx
122  iy = iy + incy
123  END DO
124  END IF
125  RETURN
126 *
127 * End of CSWAP
128 *
129  END
subroutine cswap(N, CX, INCX, CY, INCY)
CSWAP
Definition: cswap.f:81