value_comparison.h

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 *
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 *  Copyright (c) 2020,
 *  TU Dortmund - Institute of Control Theory and Systems Engineering.
 *  All rights reserved.
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 *  Authors: Christoph Rösmann
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#ifndef SRC_CORE_INCLUDE_CORBO_CORE_VALUE_COMPARISON_H_
#define SRC_CORE_INCLUDE_CORBO_CORE_VALUE_COMPARISON_H_

#include <algorithm>
#include <cmath>
#include <complex>

namespace corbo {

inline bool approx_equal_abs(double a, double b, double epsilon = 1e-6) { return std::abs(a - b) < epsilon; }

// The double/float comparison definitions can be found in "The art of computer programming by Knuth"

inline bool approx_equal(double a, double b, double epsilon = 1e-6) { return std::abs(a - b) <= std::max(std::abs(a), std::abs(b)) * epsilon; }

inline bool approx_equal(const std::complex<double>& a, const std::complex<double>& b, double epsilon = 1e-6)
{
    return approx_equal(a.real(), b.real(), epsilon) && approx_equal(a.imag(), b.imag(), epsilon);
}

inline bool essentially_equal(double a, double b, double epsilon = 1e-6) { return std::abs(a - b) <= std::min(std::abs(a), std::abs(b)) * epsilon; }

inline bool essentially_equal(const std::complex<double>& a, const std::complex<double>& b, double epsilon = 1e-6)
{
    return essentially_equal(a.real(), b.real(), epsilon) && essentially_equal(a.imag(), b.imag(), epsilon);
}

inline bool approx_zero(double val, double epsilon = 1e-10) { return std::abs(val) <= epsilon; }

inline bool definitely_greater_than(double a, double b, double epsilon = 1e-6) { return (a - b) > std::max(std::abs(a), std::abs(b)) * epsilon; }

inline bool definitely_less_than(double a, double b, double epsilon = 1e-6) { return (b - a) > std::min(std::abs(a), std::abs(b)) * epsilon; }

// almostEqual2sComplement(double A, double B, int maxUlps)
// {
//   assert(maxUlps > 0 && maxUlps < 4 * 1024 * 1024);
//   int64_t aLong = *reinterpret_cast<int64_t*>( &A );
//   if (aLong < 0) aLong = 0x8000000000000000 - aLong; int64_t bLong = *reinterpret_cast<int64_t*>( &B );
//   if (bLong < 0) bLong = 0x8000000000000000 - bLong; int64_t longDiff = (aLong - bLong) & 0x7FFFFFFFFFFFFFFF;
//   if (longDiff <= maxUlps) return true;
//   return false;
// }

}  // namespace corbo

#endif  // SRC_CORE_INCLUDE_CORBO_CORE_VALUE_COMPARISON_H_