cospi

auto eve::cospi = functor<cospi_t>

inlineconstexpr

Header file

#include <eve/module/math.hpp>

Callable Signatures

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

Parameters

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

Return value

1. Returns the elementwise cosine of the input in \(\pi\) multiples. The call cospi(x) is semantically equivalent to \(\cos(\pi x)\). In particular:
   • If the element is \(\pm0\), \(1\) is returned.
   • If the element is \(\pm1/2\), \(0\) is returned.
   • If the element is \(\pm\infty\), Nan is returned.
   • If the element is a Nan, Nan is returned.
2. The operation is performed conditionnaly.
3. Assumes that the inputs elements belong to \([-1/4,1/4]\) and return NaN outside.

Example

// revision 1
#include <eve/module/math.hpp>
#include <iostream>
 
int main()
{
  eve::wide wf = {0.0, 0.25, 0.5, 2.0, -0.0, -0.25, -0.5, -2.0};
 
  std::cout << "<- wf                       = " << wf << "\n";
 
  std::cout << "-> cospi(wf)                = " << eve::cospi(wf) << "\n";
  std::cout << "-> cospi[ignore_last(2)](wf)= " << eve::cospi[eve::ignore_last(2)](wf) << "\n";
  std::cout << "-> cospi[wf > 0.0](wf)      = " << eve::cospi[wf > 0.0](wf) << "\n";
  std::cout << "-> cospi[quarter_circle](wf)= " << eve::cospi[eve::quarter_circle](wf) << "\n";
}