geommean

eve::geommean = functor<geommean_t>

inlineconstexpr

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 << "-> geommean(pf, qf)                = " << eve::geommean(pf, qf) << "\n";
  std::cout << "-> geommean(wt)                    = " << eve::geommean(wt) << "\n";
  std::cout << "-> geommean[ignore_last(2)](pf, qf)= " << eve::geommean[eve::ignore_last(2)](pf, qf) << "\n";
  std::cout << "-> geommean[pf >  0.0](pf, qf)     = " << eve::geommean[pf > 0.0](pf, qf) << "\n";
  std::cout << "-> geommean[pf >  0.0](pf, qf, rf) = " << eve::geommean(pf, qf, rf) << "\n";
  auto apf = eve::abs(pf);
  auto aqf = eve::abs(qf);
  auto arf = eve::abs(rf);
  std::cout << "-> geommean(apf, aqf, arf)            = " << eve::geommean(apf, aqf, arf) << "\n";
  std::cout << "-> geommean[kahan](apf, aqf, arf)     = " << eve::geommean[eve::kahan](apf, aqf, arf) << "\n";
  std::cout << "-> geommean[pedantic]](apf, aqf, arf) = " << eve::geommean[eve::pedantic](apf, aqf, arf) << "\n";
  auto tup = kumi::tuple{apf, aqf, arf};
  std::cout << "-> geommean[kahan](tup)         = " << eve::geommean[eve::kahan](tup) << "\n";
}

Header file

#include <eve/module/math.hpp>

Callable Signatures

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

Parameters

• x, ...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 geometric 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