diff_of_prod

auto eve::diff_of_prod = functor<diff_of_prod_t>

inlineconstexpr

Header file

#include <eve/module/core.hpp>

Callable Signatures

namespace eve
{
   // Regular overload
   constexpr auto diff_of_prod(floating_value auto x, floating_value auto y,
                               floating_value auto z, floating_value auto t)                          noexcept; // 1
 
   // Lanes masking
   constexpr auto diff_of_prod[conditional_expr auto c](floating_value auto x, floating_value auto y,
                                                        floating_value auto z, floating_value auto t) noexcept; // 2
 
   // Semantic exclusive options
   constexpr auto diff_of_prod[raw](floating_value auto x, floating_value auto y,
                                    floating_value auto z, floating_value auto t)                     noexcept; // 3
   constexpr auto diff_of_prod[pedantic](floating_value auto x, floating_value auto y,
                                         floating_value auto z, floating_value auto t)                noexcept; // 4
}

Parameters

• x, y, z, t: floating values.
• c: Conditional expression masking the operation.
• m: Logical value masking the operation.

Return value

1. The value of x*y-z*t, with better precision if correct fma is available, is returned.
2. The operation is performed conditionally.
3. computes a raw version of diff_of_prod, i.e. the naive formula (in fact fms(x, y, z*t))
4. computes a pedantic version of diff_of_prod ensuring better accuracy in any case.

Example

// revision 0
#include <eve/module/core.hpp>
#include <iostream>
 
int main()
{
  
  eve::wide wf0 = {3, 2, 1, 0};
  eve::wide wf1 = {4, 1, 2, 100};
  eve::wide wf2 = wf0+4*eve::eps(eve::as<float>());
  eve::wide wf3 = wf1-4*eve::eps(eve::as<float>());
  
  std::cout << "<- wf0                                              = " << wf0 << "\n";
  std::cout << "<- wf1                                              = " << wf1 << "\n";
  std::cout << "<- wf2                                              = " << wf2 << "\n";
  std::cout << "<- wf3                                              = " << wf3 << "\n";
  
  std::cout << "-> diff_of_prod(wf0, wf1, wf2, wf3)                 = " << eve::diff_of_prod(wf0, wf1, wf2, wf3) << "\n";
  std::cout << "-> diff_of_prod[ignore_last(2)](wf0, wf1, wf2, wf3) = " << eve::diff_of_prod[eve::ignore_last(2)](wf0, wf1, wf2, wf3) << "\n";
  std::cout << "-> diff_of_prod[raw](wf0, wf1, wf2, wf3)            = " << eve::diff_of_prod[eve::raw](wf0, wf1, wf2, wf3) << "\n";
  std::cout << "-> diff_of_prod[pedantic](wf0, wf1, wf2, wf3)       = " << eve::diff_of_prod[eve::pedantic](wf0, wf1, wf2, wf3) << "\n";
}