1 // SPDX-License-Identifier: Apache-2.0
2 //
3 // Copyright 2008-2016 Conrad Sanderson (http://conradsanderson.id.au)
4 // Copyright 2008-2016 National ICT Australia (NICTA)
5 //
6 // Licensed under the Apache License, Version 2.0 (the "License");
7 // you may not use this file except in compliance with the License.
8 // You may obtain a copy of the License at
9 // http://www.apache.org/licenses/LICENSE-2.0
10 //
11 // Unless required by applicable law or agreed to in writing, software
12 // distributed under the License is distributed on an "AS IS" BASIS,
13 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 // See the License for the specific language governing permissions and
15 // limitations under the License.
16 // ------------------------------------------------------------------------
17
18
19 namespace newarp
20 {
21
22
23 template<typename eT>
24 inline
TridiagEigen()25 TridiagEigen<eT>::TridiagEigen()
26 : n(0)
27 , computed(false)
28 {
29 arma_extra_debug_sigprint();
30 }
31
32
33
34 template<typename eT>
35 inline
TridiagEigen(const Mat<eT> & mat_obj)36 TridiagEigen<eT>::TridiagEigen(const Mat<eT>& mat_obj)
37 : n(mat_obj.n_rows)
38 , computed(false)
39 {
40 arma_extra_debug_sigprint();
41
42 compute(mat_obj);
43 }
44
45
46
47 template<typename eT>
48 inline
49 void
compute(const Mat<eT> & mat_obj)50 TridiagEigen<eT>::compute(const Mat<eT>& mat_obj)
51 {
52 arma_extra_debug_sigprint();
53
54 arma_debug_check( (mat_obj.is_square() == false), "newarp::TridiagEigen::compute(): matrix must be square" );
55
56 n = blas_int(mat_obj.n_rows);
57
58 main_diag = mat_obj.diag();
59 sub_diag = mat_obj.diag(-1);
60
61 evecs.set_size(n, n);
62
63 char compz = 'I';
64 blas_int lwork = blas_int(-1);
65 eT lwork_opt = eT(0);
66
67 blas_int liwork = blas_int(-1);
68 blas_int liwork_opt = blas_int(0);
69 blas_int info = blas_int(0);
70
71 // query for lwork and liwork
72 lapack::stedc(&compz, &n, main_diag.memptr(), sub_diag.memptr(), evecs.memptr(), &n, &lwork_opt, &lwork, &liwork_opt, &liwork, &info);
73
74 if(info == 0)
75 {
76 lwork = blas_int(lwork_opt);
77 liwork = liwork_opt;
78 }
79 else
80 {
81 lwork = 1 + 4 * n + n * n;
82 liwork = 3 + 5 * n;
83 }
84
85 info = blas_int(0);
86
87 podarray<eT> work(static_cast<uword>(lwork) );
88 podarray<blas_int> iwork(static_cast<uword>(liwork));
89
90 lapack::stedc(&compz, &n, main_diag.memptr(), sub_diag.memptr(), evecs.memptr(), &n, work.memptr(), &lwork, iwork.memptr(), &liwork, &info);
91
92 if(info < 0) { arma_stop_logic_error("lapack::stedc(): illegal value"); return; }
93
94 if(info > 0) { arma_stop_runtime_error("lapack::stedc(): failed to compute all eigenvalues"); return; }
95
96 computed = true;
97 }
98
99
100
101 template<typename eT>
102 inline
103 Col<eT>
eigenvalues()104 TridiagEigen<eT>::eigenvalues()
105 {
106 arma_extra_debug_sigprint();
107
108 arma_debug_check( (computed == false), "newarp::TridiagEigen::eigenvalues(): need to call compute() first" );
109
110 // After calling compute(), main_diag will contain the eigenvalues.
111 return main_diag;
112 }
113
114
115
116 template<typename eT>
117 inline
118 Mat<eT>
eigenvectors()119 TridiagEigen<eT>::eigenvectors()
120 {
121 arma_extra_debug_sigprint();
122
123 arma_debug_check( (computed == false), "newarp::TridiagEigen::eigenvectors(): need to call compute() first" );
124
125 return evecs;
126 }
127
128
129 } // namespace newarp
130