two_sub

auto eve::two_sub = functor<two_sub_t>

inlineconstexpr

Header file

#include <eve/module/core.hpp>

Callable Signatures

namespace eve
{
   // Regular overload
   constexpr auto two_sub(floating_value auto x, floating_value auto y)            noexcept; //1
   constexpr auto two_sub[raw](floating_value auto x, floating_value auto y)       noexcept; //2
 
   // Semantic options
   constexpr auto two_sub[pedantic](floating_value auto x, floating_value auto y)  noexcept; //3
}

Parameters

• x, y: floating-point arguments.

Return value

Computes elementwise a pair of values [a, e] such that:

• a is x - y
• e is a value such that a \(\oplus\)e is equal to x \(\oplus\)(-y) where \(\oplus\) adds its two parameters with infinite precision.

1. Classical algorithm, always valid.
2. 'Fast' algorithm, valid only if |x| < |y|.
3. Handles overflow.

External references

• On the Computation of Correctly-Rounded Sums

Example

// revision 1
#include <eve/module/core.hpp>
#include <iostream>
#include <iomanip>
 
int main()
{
  eve::wide wf0 = {3.0f, 2.5f, -32.7f, 1.0f};
  eve::wide wf1 = {4.2f, 1.5f, -100.834f, eve::eps(eve::as<float>())/2};
 
  std::cout << "<- wf0               = " << wf0 << "\n";
  std::cout << "<- wf1               = " << wf1 << "\n";
  std::cout << std::setprecision(20);
  std::cout << "-> two_sub(wf0, wf1)      = " << eve::two_sub(wf0, wf1) << "\n";
  std::cout << "-> two_sub[raw](wf0, wf1) = " << eve::two_sub[eve::raw](wf0, wf1) << "\n";
}