libhoomd/utils/Variant.cc

   1 /*
   2 Highly Optimized Object-oriented Many-particle Dynamics -- Blue Edition
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  36 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS ``AS IS'' AND
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  41 IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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  49 // Maintainer: joaander
  50
  51 /*! \file Variant.cc
  52     \brief Defines Variant and related classes
  53 */
  54
  55 #ifdef WIN32
  56 #pragma warning( push )
  57 #pragma warning( disable : 4103 4244 )
  58 #endif
  59
  60 #include "Variant.h"
  61
  62 #include <iostream>
  63 #include <stdexcept>
  64 #include <boost/python.hpp>
  65 using namespace boost::python;
  66 using namespace std;
  67
  68 VariantLinear::VariantLinear()
  69     {
  70     // initialize m_a and m_b to the end
  71     m_a = m_values.end();
  72     m_b = m_values.end();
  73     }
  74
  75 /*! \param timestep Time step to set the value at
  76     \param val Value to set at \a timestep
  77
  78     If a point at \a timestep has already been set, this overwrites it.
  79 */
  80 void VariantLinear::setPoint(unsigned int timestep, double val)
  81     {
  82     m_values[timestep] = val;
  83     }
  84
  85 /*! \param timestep Timestep to get the value at
  86     \return Interpolated value
  87 */
  88 double VariantLinear::getValue(unsigned int timestep)
  89     {
  90     // first transform the timestep by the offset
  91     if (timestep < m_offset)
  92         timestep = 0;
  93     else
  94         timestep -= m_offset;
  95
  96     // handle the degenerate case that the variant is empty
  97     if (m_values.empty())
  98         {
  99         cerr << endl << "***Error! No points specified to VariantLinear" << endl << endl;
 100         throw runtime_error("Error getting variant value");
 101         }
 102
 103     // handle the degernate case that there is only one value in the variant
 104     if (m_values.size() == 1)
 105         return m_values.begin()->second;
 106
 107     // handle beginning case
 108     if (timestep < m_values.begin()->first)
 109         return m_values.begin()->second;
 110
 111     // handle end case
 112     map<unsigned int, double>::iterator last = m_values.end();
 113     --last;
 114     if (timestep >= last->first)
 115         return last->second;
 116
 117     // handle middle case
 118     // check to see if the cache is still correct
 119     bool cache_ok = m_a != m_values.end() && m_b != m_values.end() && timestep >= m_a->first && timestep < m_b->first;
 120     if (!cache_ok)
 121         {
 122         // reload the cached iterators
 123         m_a = m_values.upper_bound(timestep);
 124
 125         m_b = m_a;
 126         --m_a;
 127         assert(m_a != m_values.end());
 128         assert(m_b != m_values.end());
 129         }
 130
 131     // interpolate
 132     unsigned int ta = m_a->first;
 133     unsigned int tb = m_b->first;
 134     assert(tb > ta);
 135
 136     double va = m_a->second;
 137     double vb = m_b->second;
 138
 139     assert(timestep >= ta && timestep < tb);
 140     double f = double((timestep - ta)) / double((tb - ta));
 141     return (1.0 - f) * va + f * vb;
 142     }
 143
 144 void export_Variant()
 145     {
 146     class_<Variant, boost::shared_ptr<Variant> >("Variant", init< >())
 147     .def("getValue", &Variant::getValue)
 148     .def("setOffset", &Variant::setOffset);
 149
 150     class_<VariantConst, boost::shared_ptr<VariantConst>, bases<Variant> >("VariantConst", init< double >());
 151
 152     class_<VariantLinear, boost::shared_ptr<VariantLinear>, bases<Variant> >("VariantLinear", init< >())
 153     .def("setPoint", &VariantLinear::setPoint);
 154     }
 155
 156 #ifdef WIN32
 157 #pragma warning( pop )
 158 #endif