fn_rank.hpp

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00001 // Copyright (C) 2009 NICTA
00002 // Copyright (C) 2009 Dimitrios Bouzas
00003 // 
00004 // Authors:
00005 // - Conrad Sanderson (conradsand at ieee dot org)
00006 // - Dimitrios Bouzas (dimitris dot mpouzas at gmail dot com)
00007 // 
00008 // This file is part of the Armadillo C++ library.
00009 // It is provided without any warranty of fitness
00010 // for any purpose. You can redistribute this file
00011 // and/or modify it under the terms of the GNU
00012 // Lesser General Public License (LGPL) as published
00013 // by the Free Software Foundation, either version 3
00014 // of the License or (at your option) any later version.
00015 // (see http://www.opensource.org/licenses for more info)
00016 
00017 
00018 //! \addtogroup fn_rank
00019 //! @{
00020 
00021 
00022 
00023 template<typename T1>
00024 inline
00025 u32
00026 rank(const Base<typename T1::elem_type,T1>& X, typename T1::pod_type tol = 0.0)
00027   {
00028   arma_extra_debug_sigprint();
00029   
00030   typedef typename T1::elem_type eT;
00031   typedef typename T1::pod_type   T;
00032   
00033   const unwrap<T1>   tmp(X.get_ref());
00034   const Mat<eT>& A = tmp.M;
00035   
00036   Col<T> s;
00037   const bool status = auxlib::svd(s, A);
00038   
00039   if(status == true)
00040     {
00041     if(tol == T(0))
00042       {
00043       tol = (std::max)(A.n_rows, A.n_cols) * op_eps::direct_eps(max(s));
00044       }
00045       
00046     // count non zero valued elements in s
00047     
00048     const T*  s_mem  = s.memptr();
00049     const u32 n_elem = s.n_elem;
00050           u32 count  = 0;
00051     
00052     for(u32 i=0; i<n_elem; ++i)
00053       {
00054       if(s_mem[i] > tol)
00055         {
00056         ++count;
00057         }
00058       }
00059     
00060     return count;
00061     }
00062   else
00063     {
00064     arma_print("rank(): singular value decomposition failed");
00065     return u32(0);
00066     }
00067    
00068   }
00069 
00070 
00071 
00072 //! @}