LAPACK  3.5.0
LAPACK: Linear Algebra PACKage
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srot.f
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1 *> \brief \b SROT
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 SROT(N,SX,INCX,SY,INCY,C,S)
12 *
13 * .. Scalar Arguments ..
14 * REAL C,S
15 * INTEGER INCX,INCY,N
16 * ..
17 * .. Array Arguments ..
18 * REAL SX(*),SY(*)
19 * ..
20 *
21 *
22 *> \par Purpose:
23 * =============
24 *>
25 *> \verbatim
26 *>
27 *> 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 single_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 srot(N,SX,INCX,SY,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  REAL c,s
61  INTEGER incx,incy,n
62 * ..
63 * .. Array Arguments ..
64  REAL sx(*),sy(*)
65 * ..
66 *
67 * =====================================================================
68 *
69 * .. Local Scalars ..
70  REAL stemp
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  stemp = c*sx(i) + s*sy(i)
80  sy(i) = c*sy(i) - s*sx(i)
81  sx(i) = stemp
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  stemp = c*sx(ix) + s*sy(iy)
94  sy(iy) = c*sy(iy) - s*sx(ix)
95  sx(ix) = stemp
96  ix = ix + incx
97  iy = iy + incy
98  END DO
99  END IF
100  RETURN
101  END