Chris@49: // Copyright (C) 2009-2011 NICTA (www.nicta.com.au)
Chris@49: // Copyright (C) 2009-2011 Conrad Sanderson
Chris@49: // 
Chris@49: // This Source Code Form is subject to the terms of the Mozilla Public
Chris@49: // License, v. 2.0. If a copy of the MPL was not distributed with this
Chris@49: // file, You can obtain one at http://mozilla.org/MPL/2.0/.
Chris@49: 
Chris@49: 
Chris@49: //! \addtogroup op_stddev
Chris@49: //! @{
Chris@49: 
Chris@49: 
Chris@49: //! \brief
Chris@49: //! For each row or for each column, find the standard deviation.
Chris@49: //! The result is stored in a dense matrix that has either one column or one row.
Chris@49: //! The dimension for which the standard deviations are found is set via the stddev() function.
Chris@49: template<typename T1>
Chris@49: inline
Chris@49: void
Chris@49: op_stddev::apply(Mat<typename T1::pod_type>& out, const mtOp<typename T1::pod_type, T1, op_stddev>& in)
Chris@49:   {
Chris@49:   arma_extra_debug_sigprint();
Chris@49:   
Chris@49:   typedef typename T1::elem_type  in_eT;
Chris@49:   typedef typename T1::pod_type  out_eT;
Chris@49:   
Chris@49:   const unwrap_check_mixed<T1> tmp(in.m, out);
Chris@49:   const Mat<in_eT>&        X = tmp.M;
Chris@49:   
Chris@49:   const uword norm_type = in.aux_uword_a;
Chris@49:   const uword dim       = in.aux_uword_b;
Chris@49:   
Chris@49:   arma_debug_check( (norm_type > 1), "stddev(): incorrect usage. norm_type must be 0 or 1");
Chris@49:   arma_debug_check( (dim > 1),       "stddev(): incorrect usage. dim must be 0 or 1"      );
Chris@49:   
Chris@49:   const uword X_n_rows = X.n_rows;
Chris@49:   const uword X_n_cols = X.n_cols;
Chris@49:   
Chris@49:   if(dim == 0)
Chris@49:     {
Chris@49:     arma_extra_debug_print("op_stddev::apply(), dim = 0");
Chris@49: 
Chris@49:     arma_debug_check( (X_n_rows == 0), "stddev(): given object has zero rows" );
Chris@49:     
Chris@49:     out.set_size(1, X_n_cols);
Chris@49:     
Chris@49:     out_eT* out_mem = out.memptr();
Chris@49:     
Chris@49:     for(uword col=0; col<X_n_cols; ++col)
Chris@49:       {
Chris@49:       out_mem[col] = std::sqrt( op_var::direct_var( X.colptr(col), X_n_rows, norm_type ) );
Chris@49:       }
Chris@49:     }
Chris@49:   else
Chris@49:   if(dim == 1)
Chris@49:     {
Chris@49:     arma_extra_debug_print("op_stddev::apply(), dim = 1");
Chris@49:     
Chris@49:     arma_debug_check( (X_n_cols == 0), "stddev(): given object has zero columns" );
Chris@49: 
Chris@49:     out.set_size(X_n_rows, 1);
Chris@49:     
Chris@49:     podarray<in_eT> dat(X_n_cols);
Chris@49:     
Chris@49:     in_eT*  dat_mem = dat.memptr();
Chris@49:     out_eT* out_mem = out.memptr();
Chris@49:     
Chris@49:     for(uword row=0; row<X_n_rows; ++row)
Chris@49:       {
Chris@49:       dat.copy_row(X, row);
Chris@49:       
Chris@49:       out_mem[row] = std::sqrt( op_var::direct_var( dat_mem, X_n_cols, norm_type) );
Chris@49:       }
Chris@49:     }
Chris@49:   }
Chris@49: 
Chris@49: 
Chris@49: 
Chris@49: //! @}
Chris@49: