math.hpp

Go to the documentation of this file.

//
// Copyright 2014-2015 Ettus Research LLC
// Copyright 2018 Ettus Research, a National Instruments Company
//
// SPDX-License-Identifier: GPL-3.0-or-later
//

#ifndef INCLUDED_UHD_UTILS_MATH_HPP
#define INCLUDED_UHD_UTILS_MATH_HPP

#include <cmath>
#include <uhd/config.hpp>
#include <stdint.h>
#include <boost/numeric/conversion/bounds.hpp>

namespace uhd {

namespace math {

    static const float SINGLE_PRECISION_EPSILON = 1.19e-7f;
    static const double DOUBLE_PRECISION_EPSILON = 2.22e-16;

namespace fp_compare {

    template<typename float_t> class fp_compare_epsilon {
        public:
            UHD_INLINE fp_compare_epsilon(float_t value);
            UHD_INLINE fp_compare_epsilon(float_t value, float_t epsilon);
            UHD_INLINE fp_compare_epsilon(const fp_compare_epsilon<float_t>& copy);
            UHD_INLINE ~fp_compare_epsilon();
            UHD_INLINE void operator=(const fp_compare_epsilon& copy);

            float_t _value;
            float_t _epsilon;
    };

    /* A Note on Floating Point Equality with Epsilons
     *
     * There are obviously a lot of strategies for defining floating point
     * equality, and in the end it all comes down to the domain at hand. UHD's
     * floating-point-with-epsilon comparison algorithm is based on the method
     * presented in Knuth's "The Art of Computer Science" called "very close
     * with tolerance epsilon".
     *
     *      [(|u - v| / |u|) <= e] && [(|u - v| / |v|) <= e]
     *
     * UHD's modification to this algorithm is using the denominator's epsilon
     * value (since each float_t object has its own epsilon) for each
     * comparison.
     */

    template<typename float_t> UHD_INLINE
        bool operator==(fp_compare_epsilon<float_t> lhs, fp_compare_epsilon<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator!=(fp_compare_epsilon<float_t> lhs, fp_compare_epsilon<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator<(fp_compare_epsilon<float_t> lhs, fp_compare_epsilon<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator<=(fp_compare_epsilon<float_t> lhs, fp_compare_epsilon<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator>(fp_compare_epsilon<float_t> lhs, fp_compare_epsilon<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator>=(fp_compare_epsilon<float_t> lhs, fp_compare_epsilon<float_t> rhs);

    /* If these operators are used with floats, we rely on type promotion to
     * double. */
    template<typename float_t> UHD_INLINE
        bool operator==(fp_compare_epsilon<float_t> lhs, double rhs);
    template<typename float_t> UHD_INLINE
        bool operator!=(fp_compare_epsilon<float_t> lhs, double rhs);
    template<typename float_t> UHD_INLINE
        bool operator<(fp_compare_epsilon<float_t> lhs, double rhs);
    template<typename float_t> UHD_INLINE
        bool operator<=(fp_compare_epsilon<float_t> lhs, double rhs);
    template<typename float_t> UHD_INLINE
        bool operator>(fp_compare_epsilon<float_t> lhs, double rhs);
    template<typename float_t> UHD_INLINE
        bool operator>=(fp_compare_epsilon<float_t> lhs, double rhs);

    template<typename float_t> UHD_INLINE
        bool operator==(double lhs, fp_compare_epsilon<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator!=(double lhs, fp_compare_epsilon<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator<(double lhs, fp_compare_epsilon<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator<=(double lhs, fp_compare_epsilon<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator>(double lhs, fp_compare_epsilon<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator>=(double lhs, fp_compare_epsilon<float_t> rhs);

} // namespace fp_compare


    static const float SINGLE_PRECISION_DELTA = 1e-3f;
    static const double DOUBLE_PRECISION_DELTA = 1e-5;

    static const double FREQ_COMPARISON_DELTA_HZ = 0.1;


namespace fp_compare {

    template<typename float_t> class fp_compare_delta {
        public:
            UHD_INLINE fp_compare_delta(float_t value);
            UHD_INLINE fp_compare_delta(float_t value, float_t delta);
            UHD_INLINE fp_compare_delta(const fp_compare_delta<float_t>& copy);
            UHD_INLINE ~fp_compare_delta();
            UHD_INLINE void operator=(const fp_compare_delta& copy);

            float_t _value;
            float_t _delta;
    };

    template<typename float_t> UHD_INLINE
        bool operator==(fp_compare_delta<float_t> lhs, fp_compare_delta<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator!=(fp_compare_delta<float_t> lhs, fp_compare_delta<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator<(fp_compare_delta<float_t> lhs, fp_compare_delta<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator<=(fp_compare_delta<float_t> lhs, fp_compare_delta<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator>(fp_compare_delta<float_t> lhs, fp_compare_delta<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator>=(fp_compare_delta<float_t> lhs, fp_compare_delta<float_t> rhs);

    /* If these operators are used with floats, we rely on type promotion to
     * double. */
    template<typename float_t> UHD_INLINE
        bool operator==(fp_compare_delta<float_t> lhs, double rhs);
    template<typename float_t> UHD_INLINE
        bool operator!=(fp_compare_delta<float_t> lhs, double rhs);
    template<typename float_t> UHD_INLINE
        bool operator<(fp_compare_delta<float_t> lhs, double rhs);
    template<typename float_t> UHD_INLINE
        bool operator<=(fp_compare_delta<float_t> lhs, double rhs);
    template<typename float_t> UHD_INLINE
        bool operator>(fp_compare_delta<float_t> lhs, double rhs);
    template<typename float_t> UHD_INLINE
        bool operator>=(fp_compare_delta<float_t> lhs, double rhs);

    template<typename float_t> UHD_INLINE
        bool operator==(double lhs, fp_compare_delta<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator!=(double lhs, fp_compare_delta<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator<(double lhs, fp_compare_delta<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator<=(double lhs, fp_compare_delta<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator>(double lhs, fp_compare_delta<float_t> rhs);
    template<typename float_t> UHD_INLINE
        bool operator>=(double lhs, fp_compare_delta<float_t> rhs);

} // namespace fp_compare

    UHD_INLINE bool frequencies_are_equal(double lhs, double rhs) {
        return(fp_compare::fp_compare_delta<double>(lhs, FREQ_COMPARISON_DELTA_HZ)
                == fp_compare::fp_compare_delta<double>(rhs, FREQ_COMPARISON_DELTA_HZ));
    }

    template <typename float_t> UHD_INLINE
    float_t log2(float_t x)
    {
        // C++11 defines std::log2(), when that's universally supported
        // we can switch over.
        return std::log(x) / std::log(float_t(2));
    }


} // namespace math
} // namespace uhd

#include <uhd/utils/fp_compare_epsilon.ipp>
#include <uhd/utils/fp_compare_delta.ipp>

#endif /* INCLUDED_UHD_UTILS_MATH_HPP */