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ConstrainedOptPack_vector_change_stats.cpp
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41 
42 #include <limits>
43 
44 #include "ConstrainedOptPack_vector_change_stats.hpp"
45 #include "DenseLinAlgPack_DVectorClass.hpp"
46 #include "DenseLinAlgPack_AssertOp.hpp"
47 #include "Teuchos_ScalarTraits.hpp"
48 
49 void ConstrainedOptPack::vector_change_stats(
50  const DVectorSlice& x, const DVectorSlice& d
51  , value_type* max_term, size_type* max_k
52  , value_type* min_term, size_type* min_k
53  , value_type* av_term )
54 {
56  DenseLinAlgPack::VopV_assert_sizes( x.dim(), d.dim() );
57  const value_type
58  min_num = std::numeric_limits<value_type>::min(),
59  inf = std::numeric_limits<value_type>::max();
60  // Initialize statistics
61  *max_term = 0.0;
62  *max_k = 0;
63  *min_term = inf;
64  *min_k = 0;
65  *av_term = 0.0;
66  // Compute statistics
67  DVectorSlice::const_iterator
68  x_itr = x.begin(),
69  d_itr = d.begin();
70  for( size_type i = 1; x_itr != x.end(); ++i, ++d_itr, ++x_itr ) {
71  // Compute this ratio and make sure we are not dividing by zero.
72  // We only care about ratios less than 1.0 and also deal
73  // with the case that both x(i) and d(i) are zero (in which
74  // case the ratio should be zero since x(i) == x(i) + d(i)).
75  const value_type
76  term = ST::magnitude(*d_itr) / ( 1 + ST::magnitude(*x_itr) );
77  if( term > *max_term ) {
78  *max_term = term;
79  *max_k = i;
80  }
81  if( term < *min_term ) {
82  *min_term = term;
83  *min_k = i;
84  }
85  *av_term += term;
86  }
87  *av_term = *av_term / x.dim();
88 }
size_t size_type