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ConstrainedOptPack_vector_change_stats.cpp
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00041 
00042 #include <limits>
00043 
00044 #include "ConstrainedOptPack_vector_change_stats.hpp"
00045 #include "DenseLinAlgPack_DVectorClass.hpp"
00046 #include "DenseLinAlgPack_AssertOp.hpp"
00047 #include "Teuchos_ScalarTraits.hpp"
00048 
00049 void ConstrainedOptPack::vector_change_stats(
00050     const DVectorSlice& x, const DVectorSlice& d
00051   , value_type* max_term, size_type* max_k
00052   , value_type* min_term, size_type* min_k
00053   , value_type* av_term )
00054 {
00055   typedef Teuchos::ScalarTraits<value_type> ST;
00056   DenseLinAlgPack::VopV_assert_sizes( x.dim(), d.dim() );
00057   const value_type
00058     min_num   = std::numeric_limits<value_type>::min(),
00059     inf     = std::numeric_limits<value_type>::max();
00060   // Initialize statistics
00061   *max_term = 0.0;
00062   *max_k    = 0;
00063   *min_term = inf;
00064   *min_k    = 0;
00065   *av_term  = 0.0;
00066   // Compute statistics
00067   DVectorSlice::const_iterator
00068     x_itr = x.begin(),
00069     d_itr = d.begin();
00070   for( size_type i = 1; x_itr != x.end(); ++i, ++d_itr, ++x_itr ) {
00071     // Compute this ratio and make sure we are not dividing by zero.
00072     // We only care about ratios less than 1.0 and also deal
00073     // with the case that both x(i) and d(i) are zero (in which
00074     // case the ratio should be zero since x(i) == x(i) + d(i)).
00075     const value_type
00076       term = ST::magnitude(*d_itr) / ( 1 + ST::magnitude(*x_itr) );
00077     if( term > *max_term ) {
00078       *max_term = term;
00079       *max_k    = i;
00080     }
00081     if( term < *min_term ) {
00082       *min_term = term;
00083       *min_k    = i;
00084     }
00085     *av_term += term;
00086   }
00087   *av_term = *av_term / x.dim();
00088 }
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