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// Copyright 2008-2016 Conrad Sanderson (http://conradsanderson.id.au)
// Copyright 2008-2016 National ICT Australia (NICTA)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ------------------------------------------------------------------------
namespace newarp
{
template<typename eT>
inline
TridiagEigen<eT>::TridiagEigen()
: n(0)
, computed(false)
{
arma_extra_debug_sigprint();
}
template<typename eT>
inline
TridiagEigen<eT>::TridiagEigen(const Mat<eT>& mat_obj)
: n(mat_obj.n_rows)
, computed(false)
{
arma_extra_debug_sigprint();
compute(mat_obj);
}
template<typename eT>
inline
void
TridiagEigen<eT>::compute(const Mat<eT>& mat_obj)
{
arma_extra_debug_sigprint();
arma_debug_check( (mat_obj.is_square() == false), "newarp::TridiagEigen::compute(): matrix must be square" );
n = blas_int(mat_obj.n_rows);
main_diag = mat_obj.diag();
sub_diag = mat_obj.diag(-1);
evecs.set_size(n, n);
char compz = 'I';
blas_int lwork = blas_int(-1);
eT lwork_opt = eT(0);
blas_int liwork = blas_int(-1);
blas_int liwork_opt = blas_int(0);
blas_int info = blas_int(0);
// query for lwork and liwork
lapack::stedc(&compz, &n, main_diag.memptr(), sub_diag.memptr(), evecs.memptr(), &n, &lwork_opt, &lwork, &liwork_opt, &liwork, &info);
if(info == 0)
{
lwork = blas_int(lwork_opt);
liwork = liwork_opt;
}
else
{
lwork = 1 + 4 * n + n * n;
liwork = 3 + 5 * n;
}
info = blas_int(0);
podarray<eT> work(static_cast<uword>(lwork) );
podarray<blas_int> iwork(static_cast<uword>(liwork));
lapack::stedc(&compz, &n, main_diag.memptr(), sub_diag.memptr(), evecs.memptr(), &n, work.memptr(), &lwork, iwork.memptr(), &liwork, &info);
if(info < 0) { arma_stop_logic_error("lapack::stedc(): illegal value"); return; }
if(info > 0) { arma_stop_runtime_error("lapack::stedc(): failed to compute all eigenvalues"); return; }
computed = true;
}
template<typename eT>
inline
Col<eT>
TridiagEigen<eT>::eigenvalues()
{
arma_extra_debug_sigprint();
arma_debug_check( (computed == false), "newarp::TridiagEigen::eigenvalues(): need to call compute() first" );
// After calling compute(), main_diag will contain the eigenvalues.
return main_diag;
}
template<typename eT>
inline
Mat<eT>
TridiagEigen<eT>::eigenvectors()
{
arma_extra_debug_sigprint();
arma_debug_check( (computed == false), "newarp::TridiagEigen::eigenvectors(): need to call compute() first" );
return evecs;
}
} // namespace newarp
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