tutorial/FilteredRCBC.cc

This example shows how to use signals to control the number of elements from a random lattice sequence to be examined by a minimization algorithm, and thus ignore candidate lattices rejected by filters.

This example shows how to use signals to control the number of elements from a random lattice sequence to be examined by a minimization algorithm, and thus ignore candidate lattices rejected by filters.

// This file is part of LatNet Builder.
//
// Copyright (C) 2012-2021  The LatNet Builder author's, supervised by Pierre L'Ecuyer, Universite de Montreal.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#include "latbuilder/CoordUniformFigureOfMerit.h"
#include "latticetester/ProductWeights.h"
#include "latbuilder/Kernel/PAlpha.h"
#include "latbuilder/Kernel/PAlphaTilde.h"
#include "latbuilder/Accumulator.h"
#include "latbuilder/Storage.h"
 
#include "latbuilder/MeritFilterList.h"
#include "latbuilder/MeritFilter.h"
#include "latbuilder/Norm/Normalizer.h"
#include "latbuilder/Norm/PAlphaSL10.h"
#include "latbuilder/Functor/LowPass.h"
 
#include "latbuilder/MeritSeq/CoordUniformCBC.h"
#include "latbuilder/MeritSeq/CoordUniformInnerProd.h"
#include "latbuilder/GenSeq/GeneratingValues.h"
#include "latbuilder/GenSeq/Creator.h"
 
#include "latbuilder/Traversal.h"
#include "latbuilder/LFSR258.h"
#include "latbuilder/Functor/MinElement.h"
 
#include "latbuilder/TextStream.h"
 
#include "Path.h"
 
#include <iostream>
#include <limits>
 
using namespace LatBuilder;
using TextStream::operator<<;
 
template <typename T, typename... ARGS>
std::unique_ptr<T> unique(ARGS&&... args)
{ return std::unique_ptr<T>(new T(std::forward<ARGS>(args)...)); }

template <LatticeType LA, EmbeddingType ET>
class Observer {
public:
   typedef LatBuilder::LatDef<LA, ET> LatDef;
 
   Observer(int maxCount) { m_maxCount = maxCount; m_count = m_totalCount = 0; }
   void onStart() { m_count = m_totalCount = 0; }
   bool onElementVisited(const Real&) { ++m_totalCount; return ++m_count < m_maxCount; }
   void onReject(const LatDef&) { m_count--; }
   int count() const { return m_count; }
   int totalCount() const { return m_totalCount; }
private:
   int m_maxCount;
   int m_count;
   int m_totalCount;
};
 
 
template <LatticeType LA, EmbeddingType L, Compress C>
void test(const Storage<LA, L, C>& storage, Dimension dimension, int samples)
{
   auto weights = unique<LatticeTester::ProductWeights>();
   weights->setDefaultWeight(0.7);
 
   CoordUniformFigureOfMerit<Kernel::PAlpha> figure(std::move(weights), 2);
   std::cout << "figure of merit: " << figure << std::endl;
 
    /*
   // The P_{\alpha,PLR} figure of merit for polynomial lattices
   auto weights = unique<LatticeTester::ProductWeights>();
   weights->setDefaultWeight(0.7);
 
   CoordUniformFigureOfMerit<Kernel::PAlphaTilde> figure(std::move(weights), 2);
   std::cout << "figure of merit: " << figure << std::endl;
   */
 

   typedef GenSeq::GeneratingValues<LA, decltype(figure)::suggestedCompression(), Traversal::Random<LFSR258>> Coprime;
   auto genSeq  = GenSeq::Creator<Coprime>::create(storage.sizeParam());
   auto genSeq0 = GenSeq::Creator<Coprime>::create(SizeParam<LA,L>(LatticeTraits<LA>::TrivialModulus));

   auto cbc = MeritSeq::cbc<MeritSeq::CoordUniformInnerProd>(storage, figure);

   MeritFilterList<LA, L> filters;

   auto normalizer = unique<Norm::Normalizer<LA, L, Norm::PAlphaSL10>>(
         Norm::PAlphaSL10(figure.kernel().alpha(), figure.weights())
         );
   filters.add(std::move(normalizer));

   auto lowPass = unique<MeritFilter<LA, L>>(Functor::LowPass<Real>(1.0), "low-pass");
   filters.add(std::move(lowPass));
   std::cout << "filters: " << filters << std::endl;

   Functor::MinElement<Real> minElement;

   Observer<LA, L> obs(samples);
   minElement.onStart().connect(boost::bind(&Observer<LA, L>::onStart, &obs));
   minElement.onElementVisited().connect(boost::bind(&Observer<LA, L>::onElementVisited, &obs, _1));
   filters.template onReject<L>().connect(boost::bind(&Observer<LA, L>::onReject, &obs, _1));

   while (cbc.baseLat().dimension() < dimension) {
 
      Dimension baseDim = cbc.baseLat().dimension();
 
      std::cout << "CBC search for dimension: " << (baseDim + 1) << std::endl;
      std::cout << "base lattice: " << std::endl << cbc.baseLat();
      std::cout << "base merit value: " << cbc.baseMerit() << std::endl;

      auto meritSeq = cbc.meritSeq(baseDim == 0 ? genSeq0 : genSeq);

      auto filteredSeq = filters.apply(meritSeq);

      auto best = minElement(filteredSeq.begin(), filteredSeq.end(), 0);
      cbc.select(best.base());

      std::cout << "BEST LATTICE: " << std::endl << cbc.baseLat() << "Merit value: " << *best << std::endl;
      std::cout << obs.count() << " accepted / " << obs.totalCount() << " tried" << std::endl;;
 
      // use a different permutation for the next iteration
      genSeq.randomGenerator().jump();
   }
}
 
int main()
{
   SET_PATH_TO_LATNETBUILDER_FOR_EXAMPLES();
   Dimension dim = 3;
   int samples = 15;
   test(Storage<LatticeType::ORDINARY, EmbeddingType::UNILEVEL, Compress::SYMMETRIC>(257), dim, samples);
   /*
   test(Storage<LatticeType::POLYNOMIAL, EmbeddingType::UNILEVEL, Compress::NONE>(PolynomialFromInt(115)), dim, samples);
   */
   return 0;
}