1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
|
SUBROUTINE DLAR2V( N, X, Y, Z, INCX, C, S, INCC )
*
* -- LAPACK auxiliary routine (version 2.0) --
* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
* Courant Institute, Argonne National Lab, and Rice University
* February 29, 1992
*
* .. Scalar Arguments ..
INTEGER INCC, INCX, N
* ..
* .. Array Arguments ..
DOUBLE PRECISION C( * ), S( * ), X( * ), Y( * ), Z( * )
* ..
*
* Purpose
* =======
*
* DLAR2V applies a vector of real plane rotations from both sides to
* a sequence of 2-by-2 real symmetric matrices, defined by the elements
* of the vectors x, y and z. For i = 1,2,...,n
*
* ( x(i) z(i) ) := ( c(i) s(i) ) ( x(i) z(i) ) ( c(i) -s(i) )
* ( z(i) y(i) ) ( -s(i) c(i) ) ( z(i) y(i) ) ( s(i) c(i) )
*
* Arguments
* =========
*
* N (input) INTEGER
* The number of plane rotations to be applied.
*
* X (input/output) DOUBLE PRECISION array,
* dimension (1+(N-1)*INCX)
* The vector x.
*
* Y (input/output) DOUBLE PRECISION array,
* dimension (1+(N-1)*INCX)
* The vector y.
*
* Z (input/output) DOUBLE PRECISION array,
* dimension (1+(N-1)*INCX)
* The vector z.
*
* INCX (input) INTEGER
* The increment between elements of X, Y and Z. INCX > 0.
*
* C (input) DOUBLE PRECISION array, dimension (1+(N-1)*INCC)
* The cosines of the plane rotations.
*
* S (input) DOUBLE PRECISION array, dimension (1+(N-1)*INCC)
* The sines of the plane rotations.
*
* INCC (input) INTEGER
* The increment between elements of C and S. INCC > 0.
*
* =====================================================================
*
* .. Local Scalars ..
INTEGER I, IC, IX
DOUBLE PRECISION CI, SI, T1, T2, T3, T4, T5, T6, XI, YI, ZI
* ..
* .. Executable Statements ..
*
IX = 1
IC = 1
DO 10 I = 1, N
XI = X( IX )
YI = Y( IX )
ZI = Z( IX )
CI = C( IC )
SI = S( IC )
T1 = SI*ZI
T2 = CI*ZI
T3 = T2 - SI*XI
T4 = T2 + SI*YI
T5 = CI*XI + T1
T6 = CI*YI - T1
X( IX ) = CI*T5 + SI*T4
Y( IX ) = CI*T6 - SI*T3
Z( IX ) = CI*T4 - SI*T5
IX = IX + INCX
IC = IC + INCC
10 CONTINUE
*
* End of DLAR2V
*
RETURN
END
|
