log2

auto kyosu::log2 = eve::functor<log2_t>

inlineconstexpr

Computes the principal branch of the base 2 logarithm of the argument.

Header file

#include <kyosu/functions.hpp>

Callable Signatures

namespace kyosu
{
   //  regular call
   template<kyosu::concepts::cayley_dickson_like T> constexpr complexify_t<T> log2(T z)              noexcept; //1
   template<kyosu::concepts::cayley_dickson_like T> constexpr complexify_t<T> log2(T z eve::value k) noexcept; //2
 
   // semantic modifyers
   template<concepts::real T> constexpr T log2[real_only](T z)                                       noexcept; //1
}

Parameters

• z: Value to process.

Return value

1. a real typed input z is treated as if complex(z) was entered, unless the option real_only is used in which case the parameter must be a floating_value, the result will the same as to an eve::log2 call implying a Nan result if the input is not greater than zero.
2. returns log(z)/log_2(as(z)).
3. with two parameters return the nth branch of the function.

External references

• Wikipedia: Binary Logarithm

Example

#include <eve/wide.hpp>
#include <iostream>
#include <kyosu/kyosu.hpp>
 
int main()
{
  using kyosu::complex_t;
  using kyosu::log2;
  using kyosu::quaternion_t;
  using e_t = float;
  using c_t = kyosu::complex_t<float>;
  using q_t = kyosu::quaternion_t<float>;
  using we_t = eve::wide<e_t, eve::fixed<2>>;
  using wc_t = eve::wide<c_t, eve::fixed<2>>;
  using wq_t = eve::wide<q_t, eve::fixed<2>>;
 
  std::cout << "Real:        \n";
  e_t e(2.9f);
  we_t we = we_t(e);
  std::cout << e << " -> " << log2(e) << "\n";
  std::cout << we << " -> " << log2(we) << "\n";
  std::cout << log2(c_t(e)) << "\n";
  std::cout << log2(q_t(e)) << "\n";
  std::cout << log2(wc_t(e)) << "\n";
  std::cout << log2(wq_t(e)) << "\n";
 
  std::cout << "Complex:     \n";
  c_t c(3.5f, -2.9f);
  wc_t wc = wc_t(c);
  std::cout << c << " -> " << log2(c) << "\n";
  std::cout << wc << " -> " << log2(wc) << "\n";
  std::cout << log2(q_t(c)) << "\n";
  std::cout << log2(wq_t(c)) << "\n";
 
  std::cout << "Quaternion:  \n";
  q_t q(3.5f, -2.9f, 2.1f, 3.2f);
  wq_t wq = wq_t(q);
  std::cout << q << " -> " << log2(q) << "\n";
  std::cout << wq << " -> " << log2(wq) << "\n";
 
  return 0;
}