comparison armadillo-2.4.4/include/armadillo_bits/fn_prod.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 fn_prod
+//! @{
+
+
+//! \brief
+//! Delayed 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.
+//! For dim = 0, find the sum of each column (i.e. traverse across rows)
+//! For dim = 1, find the sum of each row (i.e. traverse across columns)
+//! The default is dim = 0.
+//! NOTE: this function works differently than in Matlab/Octave.
+
+template<typename T1>
+arma_inline
+const Op<T1, op_prod>
+prod(const Base<typename T1::elem_type,T1>& X, const uword dim = 0)
+  {
+  arma_extra_debug_sigprint();
+  
+  return Op<T1, op_prod>(X.get_ref(), dim, 0);
+  }
+
+
+
+//! \brief
+//! Immediate 'product of all values' operation for a row vector
+template<typename eT>
+inline
+arma_warn_unused
+eT
+prod(const Row<eT>& X)
+  {
+  arma_extra_debug_sigprint();
+  
+  return arrayops::product(X.memptr(), X.n_elem);
+  }
+
+
+
+//! \brief
+//! Immediate 'product of all values' operation for a column vector
+template<typename eT>
+inline
+arma_warn_unused
+eT
+prod(const Col<eT>& X)
+  {
+  arma_extra_debug_sigprint();
+  
+  return arrayops::product(X.memptr(), X.n_elem);
+  }
+
+
+
+//! \brief
+//! Immediate 'product of all values' operation,
+//! invoked, for example, by: prod(prod(A))
+
+template<typename T1>
+inline
+typename T1::elem_type
+prod(const Op<T1, op_prod>& in)
+  {
+  arma_extra_debug_sigprint();
+  arma_extra_debug_print("prod(): two consecutive prod() calls detected");
+  
+  typedef typename T1::elem_type eT;
+  
+  const unwrap<T1>   tmp(in.m);
+  const Mat<eT>& X = tmp.M;
+  
+  return arrayops::product( X.memptr(), X.n_elem );
+  }
+
+
+
+template<typename T1>
+inline
+const Op<Op<T1, op_prod>, op_prod>
+prod(const Op<T1, op_prod>& in, const uword dim)
+  {
+  arma_extra_debug_sigprint();
+  
+  return Op<Op<T1, op_prod>, op_prod>(in, dim, 0);
+  }
+
+
+
+//! product of all values of a subview_row
+template<typename eT>
+inline
+arma_warn_unused
+eT
+prod(const subview_row<eT>& S)
+  {
+  arma_extra_debug_sigprint();
+  
+  const Mat<eT>& X = S.m;
+  
+  const uword n_elem         = S.n_elem;
+  const uword row            = S.aux_row1;
+  const uword start_col      = S.aux_col1;
+  const uword end_col_plus_1 = start_col + S.n_cols;
+  
+  eT val = eT(1);
+  
+  if(n_elem > 0)
+    {
+    for(uword col=start_col; col<end_col_plus_1; ++col)
+      {
+      val *= X.at(row,col);
+      }
+    }
+  
+  return val;
+  }
+
+
+
+//! product of all values of a subview_col
+template<typename eT>
+inline
+arma_warn_unused
+eT
+prod(const subview_col<eT>& S)
+  {
+  arma_extra_debug_sigprint();
+  
+  return (S.n_elem > 0) ? arrayops::product( S.colptr(0), S.n_rows ) : eT(1);
+  }
+
+
+
+//! product of all values of a diagview
+template<typename eT>
+arma_warn_unused
+inline
+eT
+prod(const diagview<eT>& X)
+  {
+  arma_extra_debug_sigprint();
+  
+  const uword X_n_elem = X.n_elem;
+  
+  eT val = eT(1);
+  
+  for(uword i=0; i<X_n_elem; ++i)
+    {
+    val *= X[i];
+    }
+  
+  return val;
+  }
+
+
+
+template<typename eT, typename T1>
+inline
+arma_warn_unused
+eT
+prod(const subview_elem1<eT,T1>& A)
+  {
+  arma_extra_debug_sigprint();
+  
+  const Col<eT> X(A);
+  
+  return prod(X);
+  }
+
+
+
+//! @}