sufp

auto eve::sufp = functor<sufp_t>

inlineconstexpr

Header file

#include <eve/module/core.hpp>

Callable Signatures

namespace eve
{
   // Regular overload
   constexpr auto sufp(value auto x)                          noexcept; // 1
 
   // Lanes masking
   constexpr auto sufp[conditional_expr auto c](value auto x) noexcept; // 2
   constexpr auto sufp[logical_value auto m](value auto x)    noexcept; // 2
 
   // Semantic options
   constexpr auto sufp[kahan](value auto x)                   noexcept; // 1
   constexpr auto sufp[harrison](value auto x)                noexcept; // 3
}

Parameters

• x: value.
• c: Conditional expression masking the operation.
• m: Logical value masking the operation.

Return value

1. the signed unit value in the first place of the input. I.e. the greatest integer power of the base (2) less than or equal to |x| multiplied by the sign of x. (Kahan- definition)
   1. The operation is performed conditionnaly.
   2. The same value up to a factor 2, but with faster computation. (the result is times 2 is the input is not a power of 2).

Note

invalid entries return NaN

External references

• wikipedia
• HAL: On various ways to split a floating-point number

Example

// revision 0
#include <eve/module/core.hpp>
#include <iostream>
 
int main()
{
  eve::wide wf0{0.0, 1.0, 10.0, 100.0, -1.0e8, -2.0e5, -30.0, 10*eve::mindenormal(eve::as(-4.0))};
  eve::wide wi0{0, 1, 2, 3, -1, -2, -3, -4};
  eve::wide wu0{0u, 1u, 2u, 3u, 4u, 5u, 6u, 7u};
 
  std::cout << std::hexfloat << "<- wf0                          = " << wf0 << "\n";
  std::cout << "<- wi0                          = " << wi0 << "\n";
  std::cout << "<- wu0                          = " << wu0 << "\n";
 
  std::cout << "-> sufp(wf0)                 = " << eve::sufp(wf0) << "\n";
  std::cout << "-> sufp[kahan](wf0)          = " << eve::sufp[eve::kahan](wf0) << "\n";
  std::cout << "-> sufp[harrisson](wf0)      = " << eve::sufp[eve::harrisson](wf0) << "\n";
  std::cout << "-> sufp[ignore_last(2)](wf0) = " << eve::sufp[eve::ignore_last(2)](wf0) << "\n";
  std::cout << "-> sufp[wf0 != 1.0f](wf0)    = " << eve::sufp[wf0 != 1](wf0) << "\n";
  std::cout << "-> sufp(wu0)                 = " << eve::sufp(wu0) << "\n";
  std::cout << "-> sufp[ignore_last(2)](wu0) = " << eve::sufp[eve::ignore_last(2)](wu0) << "\n";
  std::cout << "-> sufp[wu0 != 2](wu0)       = " << eve::sufp[wu0 != 2](wu0) << "\n";
  std::cout << "-> sufp(wi0)                 = " << eve::sufp(wi0) << "\n";
  std::cout << "-> sufp[ignore_last(2)](wi0) = " << eve::sufp[eve::ignore_last(2)](wi0) << "\n";
  std::cout << "-> sufp[wi0 != 3](wi0)       = " << eve::sufp[wi0 != 3](wi0) << "\n";
}