is_negative

eve::is_negative = functor<is_negative_t>

inlineconstexpr

Header file

#include <eve/module/core.hpp>

Callable Signatures

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

Parameters

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

Return value

1. For signed types The call is_negative(x) returns true if and only if the bit of sign (most significant bit) is set. Of course the result on a NaN input is generally out of control.
2. The operation is performed conditionnaly.
3. with this option a NaN input always return false.

Note

this function coincides with is_ltz on integral real values, but for floating values T, is_negative(mzero<T>) is true and if n is a Nan the result depends of the bit of sign of n which can be out of control although not undefined.

Example

// revision 0
#include <eve/module/core.hpp>
#include <iostream>
 
int main()
{
  auto nan =  eve::nan(eve::as<double>());
  eve::wide wf0{0.0, 1.0, 2.0, 3.0, -1.0, -2.0, -nan, nan};
  eve::wide wi0{0, 1, 2, 3, -1, -2, -3, -4};
  eve::wide wu0{0u, 1u, 2u, 3u, 4u, 5u, 6u, 7u};
 
  std::cout << "<- wf0                              = " << wf0 << "\n";
  std::cout << "<- wi0                              = " << wi0 << "\n";
  std::cout << "<- wu0                              = " << wu0 << "\n";
 
  std::cout << "-> is_negative(wf0)                 = " << eve::is_negative(wf0) << "\n";
  std::cout << "-> is_negative[pedantic](wf0)       = " << eve::is_negative[eve::pedantic](wf0) << "\n";
  std::cout << "-> is_negative[ignore_last(2)](wf0) = " << eve::is_negative[eve::ignore_last(2)](wf0) << "\n";
  std::cout << "-> is_negative[wf0 != 0](wf0)       = " << eve::is_negative[wf0 != 0](wf0) << "\n";
  std::cout << "-> is_negative(wu0)                 = " << eve::is_negative(wu0) << "\n";
  std::cout << "-> is_negative[ignore_last(2)](wu0) = " << eve::is_negative[eve::ignore_last(2)](wu0) << "\n";
  std::cout << "-> is_negative[wu0 != 0](wu0)       = " << eve::is_negative[wu0 != 0](wu0) << "\n";
  std::cout << "-> is_negative(wi0)                 = " << eve::is_negative(wi0) << "\n";
  std::cout << "-> is_negative[ignore_last(2)](wi0) = " << eve::is_negative[eve::ignore_last(2)](wi0) << "\n";
  std::cout << "-> is_negative[wi0 != 0](wi0)       = " << eve::is_negative[wi0 != 0](wi0) << "\n";
}