comparison armadillo-2.4.4/include/armadillo_bits/fn_trace.hpp @ 0:8b6102e2a9b0

Armadillo Library

+// Copyright (C) 2008-2010 NICTA (www.nicta.com.au)
+// Copyright (C) 2008-2010 Conrad Sanderson
+// 
+// This file is part of the Armadillo C++ library.
+// It is provided without any warranty of fitness
+// for any purpose. You can redistribute this file
+// and/or modify it under the terms of the GNU
+// Lesser General Public License (LGPL) as published
+// by the Free Software Foundation, either version 3
+// of the License or (at your option) any later version.
+// (see http://www.opensource.org/licenses for more info)
+
+
+//! \addtogroup fn_trace
+//! @{
+
+
+//! Immediate trace (sum of diagonal elements) of a square dense matrix
+template<typename T1>
+inline
+arma_warn_unused
+typename T1::elem_type
+trace(const Base<typename T1::elem_type,T1>& X)
+  {
+  arma_extra_debug_sigprint();
+  
+  typedef typename T1::elem_type eT;
+  
+  const Proxy<T1> A(X.get_ref());
+
+  arma_debug_check( (A.get_n_rows() != A.get_n_cols()), "trace(): matrix must be square sized" );
+  
+  const uword N   = A.get_n_rows();
+        eT  val = eT(0);
+  
+  for(uword i=0; i<N; ++i)
+    {
+    val += A.at(i,i);
+    }
+  
+  return val;
+  }
+
+
+
+template<typename T1>
+inline
+arma_warn_unused
+typename T1::elem_type
+trace(const Op<T1, op_diagmat>& X)
+  {
+  arma_extra_debug_sigprint();
+  
+  typedef typename T1::elem_type eT;
+  
+  const diagmat_proxy<T1> A(X.m);
+  
+  const uword N = A.n_elem;
+  
+  eT val = eT(0);
+  
+  for(uword i=0; i<N; ++i)
+    {
+    val += A[i];
+    }
+  
+  return val;
+  }
+
+
+//! speedup for trace(A*B), where the result of A*B is a square sized matrix
+template<typename T1, typename T2>
+inline
+arma_warn_unused
+typename T1::elem_type
+trace(const Glue<T1, T2, glue_times>& X)
+  {
+  arma_extra_debug_sigprint();
+  
+  typedef typename T1::elem_type eT;
+  
+  const unwrap<T1> tmp1(X.A);
+  const unwrap<T2> tmp2(X.B);
+  
+  const Mat<eT>& A = tmp1.M;
+  const Mat<eT>& B = tmp2.M;
+  
+  arma_debug_assert_mul_size(A, B, "matrix multiply");
+  
+  arma_debug_check( (A.n_rows != B.n_cols), "trace(): matrix must be square sized" );
+  
+  const uword N1  = A.n_rows;
+  const uword N2  = A.n_cols;
+        eT  val = eT(0);
+  
+  for(uword i=0; i<N1; ++i)
+    {
+    const eT* B_colmem = B.colptr(i);
+          eT  acc      = eT(0);
+    
+    for(uword j=0; j<N2; ++j)
+      {
+      acc += A.at(i,j) * B_colmem[j];
+      }
+    
+    val += acc;
+    }
+  
+  return val;
+  }
+
+
+
+//! @}