digamma

kyosu::digamma = eve::functor<digamma_t>

inlineconstexpr

Computes the Digamma function i.e. the logarithmic derivative of the \(\Gamma\) function.

Header file

#include <kyosu/functions.hpp>

Callable Signatures

namespace kyosu
{
  constexpr auto  digamma(auto z) noexcept;
}

Parameters

• z : value to process.

Return value

The value of the Digamma function: \(\frac{\Gamma'(z)}{\Gamma(z)}\) is returned.

External references

• Wikipedia: Digamma function

Example

#include <kyosu/kyosu.hpp>
#include <eve/wide.hpp>
#include <iostream>
 
int main()
{
 
 using wide_ft = eve::wide <float, eve::fixed<4>>;
  wide_ft ref1 = { 3.0f, 2.0f, 1.0f, 0.5f};
  wide_ft imf1 = { 2.0f , -1.0,  -5.0, 0.0};
  wide_ft ref2 = { 0.0, 1.0, 2.0, 3.0};
  auto zc = kyosu::complex_t<wide_ft>(ref1, imf1);
 
  std::cout
    << "---- simd" << std::endl
    << "<- zc               = " << zc << std::endl
    << "-> digamma(zc)      = " << kyosu::digamma(zc)<< std::endl
    << "-> digamma(ref2)    = " << kyosu::digamma(ref2) << std::endl;
 
  return 0;
}