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, const typename arma_blas_type_only< typename T1::elem_type >::result *junk=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,
const typename arma_blas_type_only< typename T1::elem_type >::result *  junk = 0 
) [inline]

Definition at line 28 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().

00033   {
00034   arma_extra_debug_sigprint();
00035   
00036   typedef typename T1::elem_type eT;
00037   typedef typename T1::pod_type   T;
00038   
00039   const unwrap<T1>   tmp(X.get_ref());
00040   const Mat<eT>& A = tmp.M;
00041   
00042   Col<T> s;
00043   const bool status = auxlib::svd(s, A);
00044   
00045   if(status == true)
00046     {
00047     if(tol == T(0))
00048       {
00049       tol = (std::max)(A.n_rows, A.n_cols) * eop_aux::direct_eps(max(s));
00050       }
00051       
00052     // count non zero valued elements in s
00053     
00054     const T*  s_mem  = s.memptr();
00055     const u32 n_elem = s.n_elem;
00056           u32 count  = 0;
00057     
00058     for(u32 i=0; i<n_elem; ++i)
00059       {
00060       if(s_mem[i] > tol)
00061         {
00062         ++count;
00063         }
00064       }
00065     
00066     return count;
00067     }
00068   else
00069     {
00070     arma_print("rank(): singular value decomposition failed");
00071     return u32(0);
00072     }
00073    
00074   }