KwekMehlhorn.cpp

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#include "storm/utility/KwekMehlhorn.h"
 
#include "storm/adapters/RationalNumberAdapter.h"
#include "storm/exceptions/PrecisionExceededException.h"
#include "storm/utility/constants.h"
 
namespace storm {
namespace utility {
namespace kwek_mehlhorn {
 
template<typename IntegerType>
std::pair<IntegerType, IntegerType> findRational(IntegerType const& alpha, IntegerType const& beta, IntegerType const& gamma, IntegerType const& delta) {
    std::pair<IntegerType, IntegerType> alphaDivBetaPair = storm::utility::divide(alpha, beta);
    std::pair<IntegerType, IntegerType> gammaDivDeltaPair = storm::utility::divide(gamma, delta);
 
    if (alphaDivBetaPair.first == gammaDivDeltaPair.first && !storm::utility::isZero(alphaDivBetaPair.second)) {
        std::pair<IntegerType, IntegerType> subresult = findRational(delta, gammaDivDeltaPair.second, beta, alphaDivBetaPair.second);
        std::pair<IntegerType, IntegerType> result(alphaDivBetaPair.first * subresult.first + subresult.second, subresult.first);
 
        return result;
    } else {
        std::pair<IntegerType, IntegerType> result(
            storm::utility::isZero(alphaDivBetaPair.second) ? alphaDivBetaPair.first : alphaDivBetaPair.first + storm::utility::one<IntegerType>(),
            storm::utility::one<IntegerType>());
        return result;
    }
}
 
template<typename RationalType, typename ImpreciseType>
std::pair<typename NumberTraits<RationalType>::IntegerType, typename NumberTraits<RationalType>::IntegerType> truncateToRational(ImpreciseType const& value,
                                                                                                                                 uint64_t precision) {
    typedef typename NumberTraits<RationalType>::IntegerType IntegerType;
 
    IntegerType powerOfTen = storm::utility::pow(storm::utility::convertNumber<IntegerType>(static_cast<uint64_t>(10)), precision);
    IntegerType truncated = storm::utility::trunc<RationalType>(value * powerOfTen);
    return std::make_pair(truncated, powerOfTen);
}
 
template<typename RationalType>
std::pair<typename NumberTraits<RationalType>::IntegerType, typename NumberTraits<RationalType>::IntegerType> truncateToRational(double const& value,
                                                                                                                                 uint64_t precision) {
    if (precision > std::numeric_limits<double>::max_digits10) {
        throw storm::exceptions::PrecisionExceededException() << "Exceeded precision of double, consider switching to rational numbers.";
    }
 
    double powerOfTen = std::pow(10, precision);
    auto truncated = storm::utility::trunc<double>(value * powerOfTen);
    return std::make_pair(storm::utility::convertNumber<typename NumberTraits<RationalType>::IntegerType>(truncated),
                          storm::utility::convertNumber<typename NumberTraits<RationalType>::IntegerType>(powerOfTen));
}
 
template<typename RationalType, typename ImpreciseType>
RationalType findRational(uint64_t precision, ImpreciseType const& value) {
    typedef typename NumberTraits<RationalType>::IntegerType IntegerType;
 
    std::pair<IntegerType, IntegerType> truncatedFraction = truncateToRational<RationalType>(value, precision);
    std::pair<IntegerType, IntegerType> result = findRational<IntegerType>(
        truncatedFraction.first, truncatedFraction.second, truncatedFraction.first + storm::utility::one<IntegerType>(), truncatedFraction.second);
 
    // Convert one of the arguments to a rational type to not get integer division.
    return storm::utility::convertNumber<RationalType>(result.first) / result.second;
}
 
template<typename RationalType, typename ImpreciseType>
RationalType sharpen(uint64_t precision, ImpreciseType const& value) {
    ImpreciseType integer = storm::utility::floor(value);
    ImpreciseType fraction = value - integer;
    auto rational = findRational<RationalType>(precision, fraction);
    return storm::utility::convertNumber<RationalType>(integer) + rational;
}
 
template<typename RationalType, typename ImpreciseType>
void sharpen(uint64_t precision, std::vector<ImpreciseType> const& input, std::vector<RationalType>& output) {
    for (uint64_t index = 0; index < input.size(); ++index) {
        output[index] = sharpen<RationalType, ImpreciseType>(precision, input[index]);
    }
}
 
template storm::RationalNumber sharpen(uint64_t precision, double const& input);
template storm::RationalNumber sharpen(uint64_t precision, storm::RationalNumber const& input);
 
template void sharpen(uint64_t precision, std::vector<double> const& input, std::vector<storm::RationalNumber>& output);
template void sharpen(uint64_t precision, std::vector<storm::RationalNumber> const& input, std::vector<storm::RationalNumber>& output);
 
}  // namespace kwek_mehlhorn
}  // namespace utility
}  // namespace storm