acospi

auto eve::acospi = functor<acospi_t>

inlineconstexpr

Header file

#include <eve/module/math.hpp>

Callable Signatures

namespace eve
{
   // Regular overloads
   constexpr auto acospi(floating_value auto x)                          noexcept; // 1
 
   // Semantic option
   constexpr auto acospi[raw](floating_value auto x)                     noexcept; // 2
 
   // Lanes masking
   constexpr auto acospi[conditional_expr auto c](floating_value auto x) noexcept; // 3
   constexpr auto acospi[logical_value auto m](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 arc cosine of the input in \(\pi\) multiples, in the range \([0 , 1]\). In particular:
   • If the element is \(1\), \(+0\) is returned.
   • If the element \(|x| > 1\), NaN is returned.
   • If the element is a Nan, NaN is returned.
2. Same as 1 but uses a faster implementation which can be slightly less accurate near x = 1
3. The operation is performed conditionnaly.

External references

• C++ standard reference: acos
• Wolfram MathWorld: Inverse Cosine
• DLMF: Error Functions
• Wikipedia: Arc cosinus

Example

// revision 1
#include <eve/module/math.hpp>
#include <iostream>
#include <iomanip>
 
int main()
{
  eve::wide wf = { 0.0f, 0.99f, -1.0f, -0.5f, -0.0f, 0.25f, 1.0f, -2.0f};
 
  std::cout << "<- wf = " << wf << "\n";
 
  std::cout << std::setprecision(10);
  std::cout << "-> acospi(wf)                = " << eve::acospi(wf) << "\n";
  std::cout << "-> acospi[raw](wf)           = " << eve::acospi[eve::raw](wf) << "\n";
  std::cout << "-> acospi[ignore_last(2)](wf)= " << eve::acospi[eve::ignore_last(2)](wf) << "\n";
  std::cout << "-> acospi[wf != -2.0f](wf)   = " << eve::acospi[wf != -2.0f](wf) << "\n";
}