chi

kyosu::chi = eve::functor<chi_t>

inlineconstexpr

Computes the gudermanian of the argument.

Header file

#include <kyosu/functions.hpp>

Callable Signatures

namespace kyosu
{
   constexpr auto chi(value auto z, auto belongs)                              noexcept;
}

Parameters

• z: Value to inspect.
• belongs: predicate function

Return value

Returns 1 in the type of z if belongs(x) evaluate to true else 0.

External references

• wikipedia: indicator function

Example

#include <kyosu/kyosu.hpp>
#include <eve/wide.hpp>
#include <iostream>
 
int main()
{
  eve::wide re = {2.0, -4.0, -10.0, 0.0};
  eve::wide im = {0.0, -1.0, 0.0, 5.0};
  auto c =  kyosu::complex(re, im);
  auto belongs =  [](auto v) {return kyosu::abs(v) > 8.0 || v == 2.0; };
 
  std::cout << " <- c                              = " << c << '\n';
  std::cout << " -> chi(c, belongs)                = " << kyosu::chi(c, belongs) << '\n';
  std::cout << " -> chi[real(c) > -2](c, belongs)  = " << kyosu::chi[kyosu::real(c) > -2](c, belongs) << '\n';
}