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### Rounding Functions

    #include <boost/math/special_functions/round.hpp>

    template <class T>
    T round(const T& v);

    template <class T, class Policy>
    T round(const T& v, const Policy&);

    template <class T>
    int iround(const T& v);

    template <class T, class Policy>
    int iround(const T& v, const Policy&);

    template <class T>
    long lround(const T& v);

    template <class T, class Policy>
    long lround(const T& v, const Policy&);

    template <class T>
    long long llround(const T& v);

    template <class T, class Policy>
    long long llround(const T& v, const Policy&);

These functions return the closest integer to the argument v.

Halfway cases are rounded away from zero, regardless of the current rounding direction.

If the argument v is either non-finite or else outside the range of the result type, then returns the result of rounding_error: by default this throws an instance of `boost::math::rounding_error`.