Fn_rank

Functions

template<typename T1 >
arma_warn_unused u32 rank (const Base< typename T1::elem_type, T1 > &X, typename T1::pod_type tol=0.0)

Function Documentation

template<typename T1 >
arma_warn_unused u32 rank ( const Base< typename T1::elem_type, T1 > &  X,
typename T1::pod_type  tol = 0.0 
) [inline]

Definition at line 27 of file fn_rank.hpp.

References arma_print(), eop_aux::direct_eps(), Base< elem_type, derived >::get_ref(), max(), Mat< eT >::memptr(), Mat< eT >::n_elem, and auxlib::svd().

00028   {
00029   arma_extra_debug_sigprint();
00030   
00031   typedef typename T1::elem_type eT;
00032   typedef typename T1::pod_type   T;
00033   
00034   const unwrap<T1>   tmp(X.get_ref());
00035   const Mat<eT>& A = tmp.M;
00036   
00037   Col<T> s;
00038   const bool status = auxlib::svd(s, A);
00039   
00040   if(status == true)
00041     {
00042     if(tol == T(0))
00043       {
00044       tol = (std::max)(A.n_rows, A.n_cols) * eop_aux::direct_eps(max(s));
00045       }
00046       
00047     // count non zero valued elements in s
00048     
00049     const T*  s_mem  = s.memptr();
00050     const u32 n_elem = s.n_elem;
00051           u32 count  = 0;
00052     
00053     for(u32 i=0; i<n_elem; ++i)
00054       {
00055       if(s_mem[i] > tol)
00056         {
00057         ++count;
00058         }
00059       }
00060     
00061     return count;
00062     }
00063   else
00064     {
00065     arma_print("rank(): singular value decomposition failed");
00066     return u32(0);
00067     }
00068    
00069   }