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armadillo-code/include/armadillo_bits/fn_svds.hpp
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2021-09-21 14:18:36 +10:00

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// SPDX-License-Identifier: Apache-2.0
//
// 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.
// ------------------------------------------------------------------------
//! \addtogroup fn_svds
//! @{
template<typename T1>
inline
bool
svds_helper
(
Mat<typename T1::elem_type>& U,
Col<typename T1::pod_type >& S,
Mat<typename T1::elem_type>& V,
const SpBase<typename T1::elem_type,T1>& X,
const uword k,
const typename T1::pod_type tol,
const bool calc_UV,
const typename arma_real_only<typename T1::elem_type>::result* junk = nullptr
)
{
arma_extra_debug_sigprint();
arma_ignore(junk);
typedef typename T1::elem_type eT;
typedef typename T1::pod_type T;
arma_debug_check
(
( ((void*)(&U) == (void*)(&S)) || (&U == &V) || ((void*)(&S) == (void*)(&V)) ),
"svds(): two or more output objects are the same object"
);
arma_debug_check( (tol < T(0)), "svds(): tol must be >= 0" );
const unwrap_spmat<T1> tmp(X.get_ref());
const SpMat<eT>& A = tmp.M;
const uword kk = (std::min)( (std::min)(A.n_rows, A.n_cols), k );
const T A_max = (A.n_nonzero > 0) ? T(max(abs(Col<eT>(const_cast<eT*>(A.values), A.n_nonzero, false)))) : T(0);
if(A_max == T(0))
{
// TODO: use reset instead ?
S.zeros(kk);
if(calc_UV)
{
U.eye(A.n_rows, kk);
V.eye(A.n_cols, kk);
}
}
else
{
SpMat<eT> C( (A.n_rows + A.n_cols), (A.n_rows + A.n_cols) );
SpMat<eT> B = A / A_max;
SpMat<eT> Bt = B.t();
C(0, A.n_rows, arma::size(B) ) = B;
C(A.n_rows, 0, arma::size(Bt)) = Bt;
Bt.reset();
B.reset();
Col<eT> eigval;
Mat<eT> eigvec;
eigs_opts opts;
opts.tol = (tol / Datum<T>::sqrt2);
const bool status = eigs_sym(eigval, eigvec, C, kk, "la", opts);
if(status == false)
{
U.soft_reset();
S.soft_reset();
V.soft_reset();
return false;
}
const T A_norm = max(eigval);
const T tol2 = tol / Datum<T>::sqrt2 * A_norm;
uvec indices = find(eigval > tol2);
if(indices.n_elem > kk)
{
indices = indices.subvec(0,kk-1);
}
else
if(indices.n_elem < kk)
{
const uvec indices2 = find(abs(eigval) <= tol2);
const uword N_extra = (std::min)( indices2.n_elem, (kk - indices.n_elem) );
if(N_extra > 0) { indices = join_cols(indices, indices2.subvec(0,N_extra-1)); }
}
const uvec sorted_indices = sort_index(eigval, "descend");
S = eigval.elem(sorted_indices); S *= A_max;
if(calc_UV)
{
uvec U_row_indices(A.n_rows, arma_nozeros_indicator()); for(uword i=0; i < A.n_rows; ++i) { U_row_indices[i] = i; }
uvec V_row_indices(A.n_cols, arma_nozeros_indicator()); for(uword i=0; i < A.n_cols; ++i) { V_row_indices[i] = i + A.n_rows; }
U = Datum<T>::sqrt2 * eigvec(U_row_indices, sorted_indices);
V = Datum<T>::sqrt2 * eigvec(V_row_indices, sorted_indices);
}
}
if(S.n_elem < k) { arma_debug_warn_level(1, "svds(): found fewer singular values than specified"); }
return true;
}
template<typename T1>
inline
bool
svds_helper
(
Mat<typename T1::elem_type>& U,
Col<typename T1::pod_type >& S,
Mat<typename T1::elem_type>& V,
const SpBase<typename T1::elem_type,T1>& X,
const uword k,
const typename T1::pod_type tol,
const bool calc_UV,
const typename arma_cx_only<typename T1::elem_type>::result* junk = nullptr
)
{
arma_extra_debug_sigprint();
arma_ignore(junk);
typedef typename T1::elem_type eT;
typedef typename T1::pod_type T;
if(arma_config::arpack == false)
{
arma_stop_logic_error("svds(): use of ARPACK must be enabled for decomposition of complex matrices");
return false;
}
arma_debug_check
(
( ((void*)(&U) == (void*)(&S)) || (&U == &V) || ((void*)(&S) == (void*)(&V)) ),
"svds(): two or more output objects are the same object"
);
arma_debug_check( (tol < T(0)), "svds(): tol must be >= 0" );
const unwrap_spmat<T1> tmp(X.get_ref());
const SpMat<eT>& A = tmp.M;
const uword kk = (std::min)( (std::min)(A.n_rows, A.n_cols), k );
const T A_max = (A.n_nonzero > 0) ? T(max(abs(Col<eT>(const_cast<eT*>(A.values), A.n_nonzero, false)))) : T(0);
if(A_max == T(0))
{
// TODO: use reset instead ?
S.zeros(kk);
if(calc_UV)
{
U.eye(A.n_rows, kk);
V.eye(A.n_cols, kk);
}
}
else
{
SpMat<eT> C( (A.n_rows + A.n_cols), (A.n_rows + A.n_cols) );
SpMat<eT> B = A / A_max;
SpMat<eT> Bt = B.t();
C(0, A.n_rows, arma::size(B) ) = B;
C(A.n_rows, 0, arma::size(Bt)) = Bt;
Bt.reset();
B.reset();
Col<eT> eigval_tmp;
Mat<eT> eigvec;
eigs_opts opts;
opts.tol = (tol / Datum<T>::sqrt2);
const bool status = eigs_gen(eigval_tmp, eigvec, C, kk, "lr", opts);
if(status == false)
{
U.soft_reset();
S.soft_reset();
V.soft_reset();
return false;
}
const Col<T> eigval = real(eigval_tmp);
const T A_norm = max(eigval);
const T tol2 = tol / Datum<T>::sqrt2 * A_norm;
uvec indices = find(eigval > tol2);
if(indices.n_elem > kk)
{
indices = indices.subvec(0,kk-1);
}
else
if(indices.n_elem < kk)
{
const uvec indices2 = find(abs(eigval) <= tol2);
const uword N_extra = (std::min)( indices2.n_elem, (kk - indices.n_elem) );
if(N_extra > 0) { indices = join_cols(indices, indices2.subvec(0,N_extra-1)); }
}
const uvec sorted_indices = sort_index(eigval, "descend");
S = eigval.elem(sorted_indices); S *= A_max;
if(calc_UV)
{
uvec U_row_indices(A.n_rows, arma_nozeros_indicator()); for(uword i=0; i < A.n_rows; ++i) { U_row_indices[i] = i; }
uvec V_row_indices(A.n_cols, arma_nozeros_indicator()); for(uword i=0; i < A.n_cols; ++i) { V_row_indices[i] = i + A.n_rows; }
U = Datum<T>::sqrt2 * eigvec(U_row_indices, sorted_indices);
V = Datum<T>::sqrt2 * eigvec(V_row_indices, sorted_indices);
}
}
if(S.n_elem < k) { arma_debug_warn_level(1, "svds(): found fewer singular values than specified"); }
return true;
}
//! find the k largest singular values and corresponding singular vectors of sparse matrix X
template<typename T1>
inline
bool
svds
(
Mat<typename T1::elem_type>& U,
Col<typename T1::pod_type >& S,
Mat<typename T1::elem_type>& V,
const SpBase<typename T1::elem_type,T1>& X,
const uword k,
const typename T1::pod_type tol = 0.0,
const typename arma_real_or_cx_only<typename T1::elem_type>::result* junk = nullptr
)
{
arma_extra_debug_sigprint();
arma_ignore(junk);
const bool status = svds_helper(U, S, V, X.get_ref(), k, tol, true);
if(status == false) { arma_debug_warn_level(3, "svds(): decomposition failed"); }
return status;
}
//! find the k largest singular values of sparse matrix X
template<typename T1>
inline
bool
svds
(
Col<typename T1::pod_type >& S,
const SpBase<typename T1::elem_type,T1>& X,
const uword k,
const typename T1::pod_type tol = 0.0,
const typename arma_real_or_cx_only<typename T1::elem_type>::result* junk = nullptr
)
{
arma_extra_debug_sigprint();
arma_ignore(junk);
Mat<typename T1::elem_type> U;
Mat<typename T1::elem_type> V;
const bool status = svds_helper(U, S, V, X.get_ref(), k, tol, false);
if(status == false) { arma_debug_warn_level(3, "svds(): decomposition failed"); }
return status;
}
//! find the k largest singular values of sparse matrix X
template<typename T1>
arma_warn_unused
inline
Col<typename T1::pod_type>
svds
(
const SpBase<typename T1::elem_type,T1>& X,
const uword k,
const typename T1::pod_type tol = 0.0,
const typename arma_real_or_cx_only<typename T1::elem_type>::result* junk = nullptr
)
{
arma_extra_debug_sigprint();
arma_ignore(junk);
Col<typename T1::pod_type> S;
Mat<typename T1::elem_type> U;
Mat<typename T1::elem_type> V;
const bool status = svds_helper(U, S, V, X.get_ref(), k, tol, false);
if(status == false) { arma_stop_runtime_error("svds(): decomposition failed"); }
return S;
}
//! @}