sum_of_prod

eve::sum_of_prod = {}

inlineconstexpr

Computes the sum of products operation with better accuracy than the naive formula.

Defined in Header

#include <eve/module/core.hpp>

Callable Signatures

namespace eve
{
   template< eve::floating_value T
           , eve::floating_value U
           , eve::floating_value V
           , eve::floating_value W>
   T sum_of_prod(T x, U y, V z, W t ) noexcept;
}

Parameters

• x, y, z, t: floating value arguments.

Return value

The value of x*y+z*t, with better precision if correct fma is available, is returned.

Example

#include <eve/module/core.hpp>
#include <eve/wide.hpp>
#include <iostream>
#include <iomanip>
 
int main()
{
  using wf_t = eve::wide<float, eve::fixed<4>>;
  wf_t xf = {3, 2, 1, 0}, zf = {4, 1, 2, 100};
  wf_t tf = -(xf+4*eve::eps(eve::as<float>())), yf = zf-4*eve::eps(eve::as<float>());
 
  std::cout << "---- simd" << std::setprecision(8) << '\n'
            << " <- xf                           = " << xf << '\n'
            << " <- yf                           = " << yf << '\n'
            << " <- tf                           = " << tf << '\n'
            << " <- zf                           = " << zf << '\n'
            << " -> xf*yf+tf*zf                  = " << (xf*yf)+(tf*zf) << '\n'
            << " -> sum_of_prod(xf, yf, tf, zf)  = " << eve::sum_of_prod(xf, yf, tf, zf) << '\n';
 
  return 0;
}

Semantic Modifiers

• eve::raw

  The call eve::raw(eve::diff_of_prod)(x, y, z, t) computes a raw version of eve::sum_of_prod, i.e. the naive formula

• eve::pedantic

  The call eve::pedantic(eve::sum_of_prod)(x, y, z, t) computes a pedantic version of eve::sum_of_prod ensuring better accuracy in any case.

  Example

  #include <eve/module/core.hpp>
  #include <eve/wide.hpp>
  #include <iostream>
  #include <iomanip>
   
  int main()
  {
    using wf_t = eve::wide<float, eve::fixed<4>>;
    wf_t xf = {3, 2, 1, 0}, zf = {4, 1, 2, 100};
    wf_t tf = -(xf+4*eve::eps(eve::as<float>())), yf = zf-4*eve::eps(eve::as<float>());
   
    std::cout << "---- simd" << std::setprecision(8) << '\n'
              << " <- xf                           = " << xf << '\n'
              << " <- yf                           = " << yf << '\n'
              << " <- tf                           = " << tf << '\n'
              << " <- zf                           = " << zf << '\n'
              << " -> xf*yf+tf*zf                  = " << (xf*yf)+(tf*zf) << '\n'
              << " -> pedantic(sum_of_prod)(xf, yf, tf, zf) = " << eve::pedantic(eve::sum_of_prod)(xf, yf, tf, zf) << '\n';
   
    return 0;
  }