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armadillo-code/include/armadillo_bits/fn_rank.hpp
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2021-03-05 11:31:14 +10:00

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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.
// ------------------------------------------------------------------------
//! \addtogroup fn_rank
//! @{
template<typename T1>
arma_warn_unused
inline
uword
rank
(
const Base<typename T1::elem_type,T1>& X,
typename T1::pod_type tol = 0.0,
const typename arma_blas_type_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;
Mat<eT> A(X.get_ref());
Col<T> s;
const bool status = auxlib::svd_dc(s, A);
if(status == false)
{
arma_stop_runtime_error("rank(): svd failed");
return uword(0);
}
const uword s_n_elem = s.n_elem;
const T* s_mem = s.memptr();
// set tolerance to default if it hasn't been specified
if( (tol == T(0)) && (s_n_elem > 0) )
{
tol = (std::max)(A.n_rows, A.n_cols) * s_mem[0] * std::numeric_limits<T>::epsilon();
}
uword count = 0;
for(uword i=0; i < s_n_elem; ++i) { count += (s_mem[i] > tol) ? uword(1) : uword(0); }
return count;
}
//! @}