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annotate armadillo-2.4.4/include/armadillo_bits/fn_prod.hpp @ 0:8b6102e2a9b0

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Armadillo Library
author maxzanoni76 <max.zanoni@eecs.qmul.ac.uk>
date Wed, 11 Apr 2012 09:27:06 +0100
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rev   line source
max@0 1 // Copyright (C) 2009-2011 NICTA (www.nicta.com.au)
max@0 2 // Copyright (C) 2009-2011 Conrad Sanderson
max@0 3 //
max@0 4 // This file is part of the Armadillo C++ library.
max@0 5 // It is provided without any warranty of fitness
max@0 6 // for any purpose. You can redistribute this file
max@0 7 // and/or modify it under the terms of the GNU
max@0 8 // Lesser General Public License (LGPL) as published
max@0 9 // by the Free Software Foundation, either version 3
max@0 10 // of the License or (at your option) any later version.
max@0 11 // (see http://www.opensource.org/licenses for more info)
max@0 12
max@0 13
max@0 14 //! \addtogroup fn_prod
max@0 15 //! @{
max@0 16
max@0 17
max@0 18 //! \brief
max@0 19 //! Delayed product of elements of a matrix along a specified dimension (either rows or columns).
max@0 20 //! The result is stored in a dense matrix that has either one column or one row.
max@0 21 //! For dim = 0, find the sum of each column (i.e. traverse across rows)
max@0 22 //! For dim = 1, find the sum of each row (i.e. traverse across columns)
max@0 23 //! The default is dim = 0.
max@0 24 //! NOTE: this function works differently than in Matlab/Octave.
max@0 25
max@0 26 template<typename T1>
max@0 27 arma_inline
max@0 28 const Op<T1, op_prod>
max@0 29 prod(const Base<typename T1::elem_type,T1>& X, const uword dim = 0)
max@0 30 {
max@0 31 arma_extra_debug_sigprint();
max@0 32
max@0 33 return Op<T1, op_prod>(X.get_ref(), dim, 0);
max@0 34 }
max@0 35
max@0 36
max@0 37
max@0 38 //! \brief
max@0 39 //! Immediate 'product of all values' operation for a row vector
max@0 40 template<typename eT>
max@0 41 inline
max@0 42 arma_warn_unused
max@0 43 eT
max@0 44 prod(const Row<eT>& X)
max@0 45 {
max@0 46 arma_extra_debug_sigprint();
max@0 47
max@0 48 return arrayops::product(X.memptr(), X.n_elem);
max@0 49 }
max@0 50
max@0 51
max@0 52
max@0 53 //! \brief
max@0 54 //! Immediate 'product of all values' operation for a column vector
max@0 55 template<typename eT>
max@0 56 inline
max@0 57 arma_warn_unused
max@0 58 eT
max@0 59 prod(const Col<eT>& X)
max@0 60 {
max@0 61 arma_extra_debug_sigprint();
max@0 62
max@0 63 return arrayops::product(X.memptr(), X.n_elem);
max@0 64 }
max@0 65
max@0 66
max@0 67
max@0 68 //! \brief
max@0 69 //! Immediate 'product of all values' operation,
max@0 70 //! invoked, for example, by: prod(prod(A))
max@0 71
max@0 72 template<typename T1>
max@0 73 inline
max@0 74 typename T1::elem_type
max@0 75 prod(const Op<T1, op_prod>& in)
max@0 76 {
max@0 77 arma_extra_debug_sigprint();
max@0 78 arma_extra_debug_print("prod(): two consecutive prod() calls detected");
max@0 79
max@0 80 typedef typename T1::elem_type eT;
max@0 81
max@0 82 const unwrap<T1> tmp(in.m);
max@0 83 const Mat<eT>& X = tmp.M;
max@0 84
max@0 85 return arrayops::product( X.memptr(), X.n_elem );
max@0 86 }
max@0 87
max@0 88
max@0 89
max@0 90 template<typename T1>
max@0 91 inline
max@0 92 const Op<Op<T1, op_prod>, op_prod>
max@0 93 prod(const Op<T1, op_prod>& in, const uword dim)
max@0 94 {
max@0 95 arma_extra_debug_sigprint();
max@0 96
max@0 97 return Op<Op<T1, op_prod>, op_prod>(in, dim, 0);
max@0 98 }
max@0 99
max@0 100
max@0 101
max@0 102 //! product of all values of a subview_row
max@0 103 template<typename eT>
max@0 104 inline
max@0 105 arma_warn_unused
max@0 106 eT
max@0 107 prod(const subview_row<eT>& S)
max@0 108 {
max@0 109 arma_extra_debug_sigprint();
max@0 110
max@0 111 const Mat<eT>& X = S.m;
max@0 112
max@0 113 const uword n_elem = S.n_elem;
max@0 114 const uword row = S.aux_row1;
max@0 115 const uword start_col = S.aux_col1;
max@0 116 const uword end_col_plus_1 = start_col + S.n_cols;
max@0 117
max@0 118 eT val = eT(1);
max@0 119
max@0 120 if(n_elem > 0)
max@0 121 {
max@0 122 for(uword col=start_col; col<end_col_plus_1; ++col)
max@0 123 {
max@0 124 val *= X.at(row,col);
max@0 125 }
max@0 126 }
max@0 127
max@0 128 return val;
max@0 129 }
max@0 130
max@0 131
max@0 132
max@0 133 //! product of all values of a subview_col
max@0 134 template<typename eT>
max@0 135 inline
max@0 136 arma_warn_unused
max@0 137 eT
max@0 138 prod(const subview_col<eT>& S)
max@0 139 {
max@0 140 arma_extra_debug_sigprint();
max@0 141
max@0 142 return (S.n_elem > 0) ? arrayops::product( S.colptr(0), S.n_rows ) : eT(1);
max@0 143 }
max@0 144
max@0 145
max@0 146
max@0 147 //! product of all values of a diagview
max@0 148 template<typename eT>
max@0 149 arma_warn_unused
max@0 150 inline
max@0 151 eT
max@0 152 prod(const diagview<eT>& X)
max@0 153 {
max@0 154 arma_extra_debug_sigprint();
max@0 155
max@0 156 const uword X_n_elem = X.n_elem;
max@0 157
max@0 158 eT val = eT(1);
max@0 159
max@0 160 for(uword i=0; i<X_n_elem; ++i)
max@0 161 {
max@0 162 val *= X[i];
max@0 163 }
max@0 164
max@0 165 return val;
max@0 166 }
max@0 167
max@0 168
max@0 169
max@0 170 template<typename eT, typename T1>
max@0 171 inline
max@0 172 arma_warn_unused
max@0 173 eT
max@0 174 prod(const subview_elem1<eT,T1>& A)
max@0 175 {
max@0 176 arma_extra_debug_sigprint();
max@0 177
max@0 178 const Col<eT> X(A);
max@0 179
max@0 180 return prod(X);
max@0 181 }
max@0 182
max@0 183
max@0 184
max@0 185 //! @}