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1 // Copyright (C) 2008-2011 NICTA (www.nicta.com.au)
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2 // Copyright (C) 2008-2011 Conrad Sanderson
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3 //
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4 // This file is part of the Armadillo C++ library.
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5 // It is provided without any warranty of fitness
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6 // for any purpose. You can redistribute this file
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7 // and/or modify it under the terms of the GNU
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8 // Lesser General Public License (LGPL) as published
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9 // by the Free Software Foundation, either version 3
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10 // of the License or (at your option) any later version.
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11 // (see http://www.opensource.org/licenses for more info)
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12
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13
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14 //! \addtogroup op_sum
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15 //! @{
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16
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17 //! \brief
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18 //! Immediate sum of elements of a matrix along a specified dimension (either rows or columns).
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19 //! The result is stored in a dense matrix that has either one column or one row.
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20 //! See the sum() function for more details.
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21 template<typename T1>
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22 inline
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23 void
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24 op_sum::apply(Mat<typename T1::elem_type>& out, const Op<T1,op_sum>& in)
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25 {
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26 arma_extra_debug_sigprint();
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27
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28 const uword dim = in.aux_uword_a;
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29 arma_debug_check( (dim > 1), "sum(): incorrect usage. dim must be 0 or 1");
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30
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31 typedef typename T1::elem_type eT;
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32
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33 const unwrap_check<T1> tmp(in.m, out);
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34 const Mat<eT>& X = tmp.M;
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35
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36 const uword X_n_rows = X.n_rows;
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37 const uword X_n_cols = X.n_cols;
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38
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39 if(dim == 0) // traverse across rows (i.e. find the sum in each column)
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40 {
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41 out.set_size(1, X_n_cols);
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42
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43 eT* out_mem = out.memptr();
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44
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45 for(uword col=0; col<X_n_cols; ++col)
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46 {
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47 out_mem[col] = arrayops::accumulate(X.colptr(col), X_n_rows);
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48 }
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49 }
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50 else // traverse across columns (i.e. find the sum in each row)
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51 {
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52 out.set_size(X_n_rows, 1);
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53
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54 eT* out_mem = out.memptr();
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55
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56 for(uword row=0; row<X_n_rows; ++row)
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57 {
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58 eT val = eT(0);
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59
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60 for(uword col=0; col<X_n_cols; ++col)
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61 {
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62 val += X.at(row,col);
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63 }
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64
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65 out_mem[row] = val;
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66 }
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67 }
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68 }
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69
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70
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71
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72 //! @}
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