lambert

eve::lambert = functor<lambert_t>

inlineconstexpr

Header file

#include <eve/module/special.hpp>

Callable Signatures

   namespace eve
   {
      // Regular overload
      constexpr auto lambert(floating_value auto x) ;                        noexcept; // 1
 
      // Lanes masking
      constexpr auto lambert[conditional_expr auto c](floating_value auto x) noexcept; // 2
      constexpr auto lambert[logical_value auto m](floating_value auto x)    noexcept; // 2
!   }

Parameters

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

Return value

1. A tuple of the two branch values of the Lambert function is returned with the following considerations:
   • The branches are not defined for input less than \(e^{-1}\) in that case the values returned are NaN.
   • If the inputs are positive, only one branch exist and the two returned values are equal.
2. The operation is performed conditionnaly.

External references

• Wikipedia: Lambert W function
• DLMF

Example

// revision 1
#include <eve/module/special.hpp>
#include <iostream>
 
int main()
{
  eve::wide wf = {-1.0, -0.367879441171441, 0.0, -0.2, 0.2, -0.0, 3.0, 100.0};
 
  std::cout << "-> lambert(wf)                = " << eve::lambert(wf) << "\n";
}