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

Armadillo Library

+// Copyright (C) 2009-2011 NICTA (www.nicta.com.au)
+// Copyright (C) 2009-2011 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 op_prod
+//! @{
+
+//! \brief
+//! Immediate product of elements of a matrix along a specified dimension (either rows or columns).
+//! The result is stored in a dense matrix that has either one column or one row.
+//! See the prod() function for more details.
+template<typename T1>
+inline
+void
+op_prod::apply(Mat<typename T1::elem_type>& out, const Op<T1,op_prod>& in)
+  {
+  arma_extra_debug_sigprint();
+  
+  typedef typename T1::elem_type eT;
+  
+  const uword dim = in.aux_uword_a;
+  arma_debug_check( (dim > 1), "prod(): incorrect usage. dim must be 0 or 1");
+  
+  const unwrap_check<T1> tmp(in.m, out);
+  const Mat<eT>& X     = tmp.M;
+  
+  const uword X_n_rows = X.n_rows;
+  const uword X_n_cols = X.n_cols;
+    
+  if(dim == 0)  // traverse across rows (i.e. find the product in each column)
+    {
+    out.set_size(1, X_n_cols);
+    
+    eT* out_mem = out.memptr();
+    
+    for(uword col=0; col<X_n_cols; ++col)
+      {
+      out_mem[col] = arrayops::product(X.colptr(col), X_n_rows);
+      }
+    }
+  else  // traverse across columns (i.e. find the product in each row)
+    {
+    out.set_size(X_n_rows, 1);
+    
+    eT* out_mem = out.memptr();
+    
+    for(uword row=0; row<X_n_rows; ++row)
+      {
+      eT val = eT(1);
+      
+      for(uword col=0; col<X_n_cols; ++col)
+        {
+        val *= X.at(row,col);
+        }
+      
+      out_mem[row] = val;
+      }
+    }
+  }
+
+
+
+//! @}