168 lines
3.5 KiB
C++
168 lines
3.5 KiB
C++
// SPDX-License-Identifier: Apache-2.0
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//
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// Copyright 2008-2016 Conrad Sanderson (http://conradsanderson.id.au)
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// Copyright 2008-2016 National ICT Australia (NICTA)
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// ------------------------------------------------------------------------
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//! \addtogroup op_cond
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//! @{
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template<typename T1>
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inline
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typename T1::pod_type
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op_cond::apply(const Base<typename T1::elem_type, T1>& X)
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{
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arma_debug_sigprint();
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typedef typename T1::elem_type eT;
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typedef typename T1::pod_type T;
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Mat<eT> A(X.get_ref());
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if(A.n_elem == 0) { return T(0); }
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if(is_op_diagmat<T1>::value || A.is_diagmat())
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{
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arma_debug_print("op_cond::apply(): diag optimisation");
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return op_cond::apply_diag(A);
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}
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if(sym_helper::is_approx_sym(A))
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{
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arma_debug_print("op_cond: symmetric/hermitian optimisation");
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return op_cond::apply_sym(A);
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}
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return op_cond::apply_gen(A);
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}
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template<typename eT>
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inline
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typename get_pod_type<eT>::result
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op_cond::apply_diag(const Mat<eT>& A)
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{
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arma_debug_sigprint();
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typedef typename get_pod_type<eT>::result T;
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const uword N = (std::min)(A.n_rows, A.n_cols);
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T abs_min = Datum<T>::inf;
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T abs_max = T(0);
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for(uword i=0; i < N; ++i)
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{
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const T abs_val = std::abs(A.at(i,i));
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if(arma_isnan(abs_val))
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{
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arma_warn(3, "cond(): failed");
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return Datum<T>::nan;
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}
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abs_min = (abs_val < abs_min) ? abs_val : abs_min;
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abs_max = (abs_val > abs_max) ? abs_val : abs_max;
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}
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if((abs_min == T(0)) || (abs_max == T(0))) { return Datum<T>::inf; }
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return T(abs_max / abs_min);
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}
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template<typename eT>
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inline
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typename get_pod_type<eT>::result
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op_cond::apply_sym(Mat<eT>& A)
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{
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arma_debug_sigprint();
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typedef typename get_pod_type<eT>::result T;
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Col<T> eigval;
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const bool status = auxlib::eig_sym(eigval, A);
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if(status == false)
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{
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arma_warn(3, "cond(): failed");
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return Datum<T>::nan;
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}
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if(eigval.n_elem == 0) { return T(0); }
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const T* eigval_mem = eigval.memptr();
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T abs_min = std::abs(eigval_mem[0]);
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T abs_max = abs_min;
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for(uword i=1; i < eigval.n_elem; ++i)
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{
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const T abs_val = std::abs(eigval_mem[i]);
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abs_min = (abs_val < abs_min) ? abs_val : abs_min;
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abs_max = (abs_val > abs_max) ? abs_val : abs_max;
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}
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if((abs_min == T(0)) || (abs_max == T(0))) { return Datum<T>::inf; }
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return T(abs_max / abs_min);
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}
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template<typename eT>
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inline
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typename get_pod_type<eT>::result
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op_cond::apply_gen(Mat<eT>& A)
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{
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arma_debug_sigprint();
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typedef typename get_pod_type<eT>::result T;
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Col<T> S;
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const bool status = auxlib::svd_dc(S, A);
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if(status == false)
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{
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arma_warn(3, "cond(): failed");
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return Datum<T>::nan;
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}
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if(S.n_elem == 0) { return T(0); }
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const T S_max = S[0];
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const T S_min = S[S.n_elem-1];
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if((S_max == T(0)) || (S_min == T(0))) { return Datum<T>::inf; }
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return T(S_max / S_min);
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}
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//! @}
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