close_to_zero.h

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/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
 
#ifndef CXXUTILS_CLOSE_TO_ZERO_H
#define CXXUTILS_CLOSE_TO_ZERO_H
 
#include <limits>  //for epsilon
#include <cmath>   //for abs
#include <type_traits> //for std::is_integral_v etc
 
 
namespace CxxUtils {
  template <typename T>
  bool close_to_zero(T value, T eps = std::numeric_limits<T>::epsilon()) {
    if constexpr (std::is_integral_v<T>) {
      // For integers, only exact zero is invalid
      return value == 0;
    } else if constexpr (std::is_floating_point_v<T>) {
      return std::abs(value) < eps;
    } else {
      static_assert(std::is_arithmetic_v<T>, "close_to_zero: Only arithmetic types supported");
      return false;
    }
  }
}
 
#endif