1 SUBROUTINE DLAR2V( N, X, Y, Z, INCX, C, S, INCC )
2 *
3 * -- LAPACK auxiliary routine (version 3.2) --
4 * -- LAPACK is a software package provided by Univ. of Tennessee, --
5 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
6 * November 2006
7 *
8 * .. Scalar Arguments ..
9 INTEGER INCC, INCX, N
10 * ..
11 * .. Array Arguments ..
12 DOUBLE PRECISION C( * ), S( * ), X( * ), Y( * ), Z( * )
13 * ..
14 *
15 * Purpose
16 * =======
17 *
18 * DLAR2V applies a vector of real plane rotations from both sides to
19 * a sequence of 2-by-2 real symmetric matrices, defined by the elements
20 * of the vectors x, y and z. For i = 1,2,...,n
21 *
22 * ( x(i) z(i) ) := ( c(i) s(i) ) ( x(i) z(i) ) ( c(i) -s(i) )
23 * ( z(i) y(i) ) ( -s(i) c(i) ) ( z(i) y(i) ) ( s(i) c(i) )
24 *
25 * Arguments
26 * =========
27 *
28 * N (input) INTEGER
29 * The number of plane rotations to be applied.
30 *
31 * X (input/output) DOUBLE PRECISION array,
32 * dimension (1+(N-1)*INCX)
33 * The vector x.
34 *
35 * Y (input/output) DOUBLE PRECISION array,
36 * dimension (1+(N-1)*INCX)
37 * The vector y.
38 *
39 * Z (input/output) DOUBLE PRECISION array,
40 * dimension (1+(N-1)*INCX)
41 * The vector z.
42 *
43 * INCX (input) INTEGER
44 * The increment between elements of X, Y and Z. INCX > 0.
45 *
46 * C (input) DOUBLE PRECISION array, dimension (1+(N-1)*INCC)
47 * The cosines of the plane rotations.
48 *
49 * S (input) DOUBLE PRECISION array, dimension (1+(N-1)*INCC)
50 * The sines of the plane rotations.
51 *
52 * INCC (input) INTEGER
53 * The increment between elements of C and S. INCC > 0.
54 *
55 * =====================================================================
56 *
57 * .. Local Scalars ..
58 INTEGER I, IC, IX
59 DOUBLE PRECISION CI, SI, T1, T2, T3, T4, T5, T6, XI, YI, ZI
60 * ..
61 * .. Executable Statements ..
62 *
63 IX = 1
64 IC = 1
65 DO 10 I = 1, N
66 XI = X( IX )
67 YI = Y( IX )
68 ZI = Z( IX )
69 CI = C( IC )
70 SI = S( IC )
71 T1 = SI*ZI
72 T2 = CI*ZI
73 T3 = T2 - SI*XI
74 T4 = T2 + SI*YI
75 T5 = CI*XI + T1
76 T6 = CI*YI - T1
77 X( IX ) = CI*T5 + SI*T4
78 Y( IX ) = CI*T6 - SI*T3
79 Z( IX ) = CI*T4 - SI*T5
80 IX = IX + INCX
81 IC = IC + INCC
82 10 CONTINUE
83 *
84 * End of DLAR2V
85 *
86 RETURN
87 END
2 *
3 * -- LAPACK auxiliary routine (version 3.2) --
4 * -- LAPACK is a software package provided by Univ. of Tennessee, --
5 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
6 * November 2006
7 *
8 * .. Scalar Arguments ..
9 INTEGER INCC, INCX, N
10 * ..
11 * .. Array Arguments ..
12 DOUBLE PRECISION C( * ), S( * ), X( * ), Y( * ), Z( * )
13 * ..
14 *
15 * Purpose
16 * =======
17 *
18 * DLAR2V applies a vector of real plane rotations from both sides to
19 * a sequence of 2-by-2 real symmetric matrices, defined by the elements
20 * of the vectors x, y and z. For i = 1,2,...,n
21 *
22 * ( x(i) z(i) ) := ( c(i) s(i) ) ( x(i) z(i) ) ( c(i) -s(i) )
23 * ( z(i) y(i) ) ( -s(i) c(i) ) ( z(i) y(i) ) ( s(i) c(i) )
24 *
25 * Arguments
26 * =========
27 *
28 * N (input) INTEGER
29 * The number of plane rotations to be applied.
30 *
31 * X (input/output) DOUBLE PRECISION array,
32 * dimension (1+(N-1)*INCX)
33 * The vector x.
34 *
35 * Y (input/output) DOUBLE PRECISION array,
36 * dimension (1+(N-1)*INCX)
37 * The vector y.
38 *
39 * Z (input/output) DOUBLE PRECISION array,
40 * dimension (1+(N-1)*INCX)
41 * The vector z.
42 *
43 * INCX (input) INTEGER
44 * The increment between elements of X, Y and Z. INCX > 0.
45 *
46 * C (input) DOUBLE PRECISION array, dimension (1+(N-1)*INCC)
47 * The cosines of the plane rotations.
48 *
49 * S (input) DOUBLE PRECISION array, dimension (1+(N-1)*INCC)
50 * The sines of the plane rotations.
51 *
52 * INCC (input) INTEGER
53 * The increment between elements of C and S. INCC > 0.
54 *
55 * =====================================================================
56 *
57 * .. Local Scalars ..
58 INTEGER I, IC, IX
59 DOUBLE PRECISION CI, SI, T1, T2, T3, T4, T5, T6, XI, YI, ZI
60 * ..
61 * .. Executable Statements ..
62 *
63 IX = 1
64 IC = 1
65 DO 10 I = 1, N
66 XI = X( IX )
67 YI = Y( IX )
68 ZI = Z( IX )
69 CI = C( IC )
70 SI = S( IC )
71 T1 = SI*ZI
72 T2 = CI*ZI
73 T3 = T2 - SI*XI
74 T4 = T2 + SI*YI
75 T5 = CI*XI + T1
76 T6 = CI*YI - T1
77 X( IX ) = CI*T5 + SI*T4
78 Y( IX ) = CI*T6 - SI*T3
79 Z( IX ) = CI*T4 - SI*T5
80 IX = IX + INCX
81 IC = IC + INCC
82 10 CONTINUE
83 *
84 * End of DLAR2V
85 *
86 RETURN
87 END