comparison armadillo-2.4.4/include/armadillo_bits/op_stddev_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_stddev
+//! @{
+
+
+//! \brief
+//! For each row or for each column, find the standard deviation.
+//! The result is stored in a dense matrix that has either one column or one row.
+//! The dimension for which the standard deviations are found is set via the stddev() function.
+template<typename T1>
+inline
+void
+op_stddev::apply(Mat<typename T1::pod_type>& out, const mtOp<typename T1::pod_type, T1, op_stddev>& in)
+  {
+  arma_extra_debug_sigprint();
+  
+  typedef typename T1::elem_type  in_eT;
+  typedef typename T1::pod_type  out_eT;
+  
+  const unwrap_check_mixed<T1> tmp(in.m, out);
+  const Mat<in_eT>&        X = tmp.M;
+  
+  const uword norm_type = in.aux_uword_a;
+  const uword dim       = in.aux_uword_b;
+  
+  arma_debug_check( (norm_type > 1), "stddev(): incorrect usage. norm_type must be 0 or 1");
+  arma_debug_check( (dim > 1),       "stddev(): incorrect usage. dim must be 0 or 1"      );
+  
+  const uword X_n_rows = X.n_rows;
+  const uword X_n_cols = X.n_cols;
+  
+  if(dim == 0)
+    {
+    arma_extra_debug_print("op_stddev::apply(), dim = 0");
+
+    arma_debug_check( (X_n_rows == 0), "stddev(): given object has zero rows" );
+    
+    out.set_size(1, X_n_cols);
+    
+    out_eT* out_mem = out.memptr();
+    
+    for(uword col=0; col<X_n_cols; ++col)
+      {
+      out_mem[col] = std::sqrt( op_var::direct_var( X.colptr(col), X_n_rows, norm_type ) );
+      }
+    }
+  else
+  if(dim == 1)
+    {
+    arma_extra_debug_print("op_stddev::apply(), dim = 1");
+    
+    arma_debug_check( (X_n_cols == 0), "stddev(): given object has zero columns" );
+
+    out.set_size(X_n_rows, 1);
+    
+    podarray<in_eT> tmp(X_n_cols);
+    
+    in_eT*  tmp_mem = tmp.memptr();
+    out_eT* out_mem = out.memptr();
+    
+    for(uword row=0; row<X_n_rows; ++row)
+      {
+      tmp.copy_row(X, row);
+      
+      out_mem[row] = std::sqrt( op_var::direct_var( tmp_mem, X_n_cols, norm_type) );
+      }
+    }
+  }
+
+
+
+//! @}
+