Fn_trace

Functions

template<typename T1 >
arma_warn_unused T1::elem_type trace (const Base< typename T1::elem_type, T1 > &X)
 Immediate trace (sum of diagonal elements) of a square dense matrix.
template<typename T1 >
arma_warn_unused T1::elem_type trace (const Op< T1, op_diagmat > &X)
template<typename T1 , typename T2 >
arma_warn_unused T1::elem_type trace (const Glue< T1, T2, glue_times > &X)
 speedup for trace(A*B), where the result of A*B is a square sized matrix

Function Documentation

template<typename T1 >
arma_warn_unused T1::elem_type trace ( const Base< typename T1::elem_type, T1 > &  X  )  [inline]

Immediate trace (sum of diagonal elements) of a square dense matrix.

Definition at line 26 of file fn_trace.hpp.

References Base< elem_type, derived >::get_ref().

00027   {
00028   arma_extra_debug_sigprint();
00029   
00030   typedef typename T1::elem_type eT;
00031   
00032   const Proxy<T1> A(X.get_ref());
00033 
00034   arma_debug_check( (A.n_rows != A.n_cols), "trace(): matrix must be square sized" );
00035   
00036   const u32 N   = A.n_rows;
00037         eT  val = eT(0);
00038   
00039   for(u32 i=0; i<N; ++i)
00040     {
00041     val += A.at(i,i);
00042     }
00043   
00044   return val;
00045   }

template<typename T1 >
arma_warn_unused T1::elem_type trace ( const Op< T1, op_diagmat > &  X  )  [inline]

Definition at line 53 of file fn_trace.hpp.

References Op< T1, op_type >::m, and diagmat_proxy< T1 >::n_elem.

00054   {
00055   arma_extra_debug_sigprint();
00056   
00057   typedef typename T1::elem_type eT;
00058   
00059   const diagmat_proxy<T1> A(X.m);
00060   
00061   const u32 N = A.n_elem;
00062   
00063   eT val = eT(0);
00064   
00065   for(u32 i=0; i<N; ++i)
00066     {
00067     val += A[i];
00068     }
00069   
00070   return val;
00071   }

template<typename T1 , typename T2 >
arma_warn_unused T1::elem_type trace ( const Glue< T1, T2, glue_times > &  X  )  [inline]

speedup for trace(A*B), where the result of A*B is a square sized matrix

Definition at line 79 of file fn_trace.hpp.

References Glue< T1, T2, glue_type >::A, Mat< eT >::at(), Glue< T1, T2, glue_type >::B, Mat< eT >::colptr(), unwrap< T1 >::M, Mat< eT >::n_cols, and Mat< eT >::n_rows.

00080   {
00081   arma_extra_debug_sigprint();
00082   
00083   typedef typename T1::elem_type eT;
00084   
00085   const unwrap<T1> tmp1(X.A);
00086   const unwrap<T2> tmp2(X.B);
00087   
00088   const Mat<eT>& A = tmp1.M;
00089   const Mat<eT>& B = tmp2.M;
00090   
00091   arma_debug_assert_mul_size(A, B, "matrix multiply");
00092   
00093   arma_debug_check( (A.n_rows != B.n_cols), "trace(): matrix must be square sized" );
00094   
00095   const u32 N1  = A.n_rows;
00096   const u32 N2  = A.n_cols;
00097         eT  val = eT(0);
00098   
00099   for(u32 i=0; i<N1; ++i)
00100     {
00101     const eT* B_colmem = B.colptr(i);
00102           eT  acc      = eT(0);
00103     
00104     for(u32 j=0; j<N2; ++j)
00105       {
00106       acc += A.at(i,j) * B_colmem[j];
00107       }
00108     
00109     val += acc;
00110     }
00111   
00112   return val;
00113   }