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
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
|
SUBROUTINE MA02CD( N, KL, KU, A, LDA )
C
C SLICOT RELEASE 5.0.
C
C Copyright (c) 2002-2009 NICONET e.V.
C
C This program is free software: you can redistribute it and/or
C modify it under the terms of the GNU General Public License as
C published by the Free Software Foundation, either version 2 of
C the License, or (at your option) any later version.
C
C This program is distributed in the hope that it will be useful,
C but WITHOUT ANY WARRANTY; without even the implied warranty of
C MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
C GNU General Public License for more details.
C
C You should have received a copy of the GNU General Public License
C along with this program. If not, see
C <http://www.gnu.org/licenses/>.
C
C PURPOSE
C
C To compute the pertranspose of a central band of a square matrix.
C
C ARGUMENTS
C
C Input/Output Parameters
C
C N (input) INTEGER
C The order of the square matrix A. N >= 0.
C
C KL (input) INTEGER
C The number of subdiagonals of A to be pertransposed.
C 0 <= KL <= N-1.
C
C KU (input) INTEGER
C The number of superdiagonals of A to be pertransposed.
C 0 <= KU <= N-1.
C
C A (input/output) DOUBLE PRECISION array, dimension (LDA,N)
C On entry, the leading N-by-N part of this array must
C contain a square matrix whose central band formed from
C the KL subdiagonals, the main diagonal and the KU
C superdiagonals will be pertransposed.
C On exit, the leading N-by-N part of this array contains
C the matrix A with its central band (the KL subdiagonals,
C the main diagonal and the KU superdiagonals) pertransposed
C (that is the elements of each antidiagonal appear in
C reversed order). This is equivalent to forming P*B'*P,
C where B is the matrix formed from the central band of A
C and P is a permutation matrix with ones down the secondary
C diagonal.
C
C LDA INTEGER
C The leading dimension of the array A. LDA >= max(1,N).
C
C CONTRIBUTOR
C
C A. Varga, German Aerospace Center,
C DLR Oberpfaffenhofen, March 1998.
C Based on the RASP routine DMPTR.
C
C REVISIONS
C
C A. Varga, December 2001.
C V. Sima, March 2004.
C
C ******************************************************************
C
C .. Scalar Arguments ..
INTEGER KL, KU, LDA, N
C .. Array Arguments ..
DOUBLE PRECISION A(LDA,*)
C .. Local Scalars ..
INTEGER I, I1, LDA1
C .. External Subroutines ..
EXTERNAL DSWAP
C .. Intrinsic Functions ..
INTRINSIC MIN
C .. Executable Statements ..
C
C Quick return if possible.
C
IF( N.LE.1 )
$ RETURN
C
LDA1 = LDA + 1
C
C Pertranspose the KL subdiagonals.
C
DO 10 I = 1, MIN( KL, N-2 )
I1 = (N-I) / 2
IF( I1.GT.0 )
$ CALL DSWAP( I1, A(I+1,1), LDA1, A(N-I1+1,N-I1+1-I), -LDA1 )
10 CONTINUE
C
C Pertranspose the KU superdiagonals.
C
DO 20 I = 1, MIN( KU, N-2 )
I1 = (N-I) / 2
IF( I1.GT.0 )
$ CALL DSWAP( I1, A(1,I+1), LDA1, A(N-I1+1-I,N-I1+1), -LDA1 )
20 CONTINUE
C
C Pertranspose the diagonal.
C
I1 = N / 2
IF( I1.GT.0 )
$ CALL DSWAP( I1, A(1,1), LDA1, A(N-I1+1,N-I1+1), -LDA1 )
C
RETURN
C *** Last line of MA02CD ***
END
|
