harmmean

eve::harmmean = functor<harmmean_t>

inlineconstexpr

Header file

#include <eve/module/math.hpp>

Callable Signatures

namespace eve
{
   // Regular overloads
   constexpr auto harmmean(floating_value auto ... xs)                               noexcept; // 1
   constexpr auto harmmean(kumi::non_empty_product_type auto const& tup)             noexcept; // 2
 
   // Lanes masking
   constexpr auto harmmean[conditional_expr auto c](/*any of the above overloads*/)  noexcept; // 3
   constexpr auto harmmean[logical_value auto m](/*any of the above overloads*/)     noexcept; // 3
 
   // Semantic options
   constexpr auto harmmean[kahan](/*any of the above overloads*/)                    noexcept; // 4
}

Parameters

• xs: real arguments.
• tup: non empty tuple of arguments.
• c: Conditional expression masking the operation.
• m: Logical value masking the operation.

Return value

1. The harmonic mean of the inputs is returned
2. equivalent to the call on the elements of the tuple.
3. The operation is performed conditionnaly
4. uses kahan like compensated algorithm for better accuracy.

External references

• wikipedia Geometric mean

  Example

// revision 1
#include <eve/module/math.hpp>
#include <iostream>
 
int main()
{
  eve::wide pf = {3.0, -1.0, -3.0, 10.0};
  eve::wide qf = {4.0, 1.0, 1.0, 15.0};
  eve::wide rf = {-1.0, 2.0, 3.0, 1.5};
  kumi::tuple wt{pf, qf, rf};
 
  std::cout << "<- pf                              = " << pf << "\n";
  std::cout << "<- qf                              = " << qf << "\n";
  std::cout << "<- rf                              = " << rf << "\n";
  std::cout << "<- wt                              = " << wt << "\n";
 
  std::cout << "-> harmmean(pf, qf)                = " << eve::harmmean(pf, qf) << "\n";
  std::cout << "-> harmmean(wt)                    = " << eve::harmmean(wt) << "\n";
  std::cout << "-> harmmean[ignore_last(2)](pf, qf)= " << eve::harmmean[eve::ignore_last(2)](pf, qf) << "\n";
  std::cout << "-> harmmean[pf >  0.0](pf, qf)     = " << eve::harmmean[pf > 0.0](pf, qf) << "\n";
  std::cout << "-> harmmean[pf >  0.0](pf, qf, rf) = " << eve::harmmean(pf, qf, rf) << "\n";
  auto tup = kumi::tuple{pf, qf, rf};
  std::cout << "<- tup                             = " << tup  << "\n";
  std::cout << "-> harmmean[kahan](tup)            = " << eve::harmmean[eve::kahan](tup) << "\n";
}