Ratios.hpp

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#ifndef CPP_UTILITIES_DIMENSIONALANALYSIS_RATIO_HPP
#define CPP_UTILITIES_DIMENSIONALANALYSIS_RATIO_HPP
 
#include <utility>
#include <cstdint>
#include <cmath>
#include "../Common.h"
 
UTILITIES_NAMESPACE_BEGIN
 
namespace Dimensional {
inline std::pair<intmax_t, intmax_t> approximateRatio(long double value, int n)
{
    // Modulo operation for floating point
    auto mod = [](long double a, long double b) -> long double {
        while (a >= b) a -= b;
        return a;
    };
    // Greatest common divider for floating point
    auto gcd = [mod](long double x, long double y)
               -> std::pair<long double, long double> {
        long double a = x;
        long double b = y;
        long double c = mod(a, b);
        while (int(c) != 0)
        {
            a = b;
            b = c;
            c = mod(a, b);
        }
        return std::make_pair(x / b, y / b);
    };
    long double den = std::pow(static_cast<long double>(10), n);
    long double num = value * std::pow(static_cast<long double>(10), n);
    std::pair<long double, long double> pair = gcd(num, den);
    return std::make_pair(intmax_t(std::round(pair.first)),
                          intmax_t(std::round(pair.second)));
}
 
} // namespace dimensional
UTILITIES_NAMESPACE_END
 
#endif  // CPP_UTILITIES_DIMENSIONALANALYSIS_RATIO_HPP