eps

auto eve::eps = functor<eps_t>

inlineconstexpr

Defined in Header

#include <eve/module/core.hpp>

Callable Signatures

namespace eve
{
  template<eve::plain_value T> constexpr T eps(as<T> x) noexcept;
}

Parameters

• x : Type wrapper instance embedding the type of the constant.

Return value

The call eve::eps(as<T>()) returns elementwise, the smallest positive value x of the type such that 1+x != x.

• If T is an integral value the elements returned are equal to one.
• If T is a floating value the elements returned are equal to:
  • 2.220446049250313e-16 if the elements type is float.
  • 1.1920929e-07f if the elements type is double.

Example

#include <eve/module/core.hpp>
#include <eve/wide.hpp>
#include <iostream>
 
using wide_ft = eve::wide<float>;
using wide_dt = eve::wide<double>;
 
template<typename T>
consteval auto constexpr_eps() { return eve::eps(eve::as<T>{}); }
 
int main()
{
  wide_ft wxf;
  wide_dt wxi;
 
  std::cout << "---- simd" << '\n'
            << "-> eps(as<wide_ft>())  = " << eve::eps(eve::as<wide_ft>()) << '\n'
            << "-> eps(as<wide_dt>())  = " << eve::eps(eve::as<wide_dt>()) << '\n'
            << "-> eps(as(wxf))          = " << eve::eps(eve::as(wxf))     << '\n'
            << "-> eps(as(wxi))          = " << eve::eps(eve::as(wxi))     << '\n';
 
  float        xf;
  double       xd;
 
  std::cout << "---- scalar" << '\n'
            << "-> eps(as<float>())         = " << eve::eps(eve::as<float>()) << '\n'
            << "-> eps(as<double>())  = " << eve::eps(eve::as<double>()) << '\n'
            << "-> eps(as(xf))              = " << eve::eps(eve::as(xf)) << '\n'
            << "-> eps(as(xd))              = " << eve::eps(eve::as(xd)) << '\n';
 
  std::cout << "-> constexpr eps            = " << constexpr_eps<float>() << std::endl;
 
  return 0;
}