floor

eve::floor = functor<floor_t>

inlineconstexpr

Header file

#include <eve/module/core.hpp>

Callable Signatures

namespace eve
{
   // Regular overload
   constexpr auto floor(value auto x)                          noexcept; // 1
 
   // Lanes masking
   constexpr auto floor[conditional_expr auto c](value auto x) noexcept; // 2
   constexpr auto floor[logical_value auto m](value auto x)    noexcept; // 2
 
   // Semantic options
   constexpr auto floor[almost = tol](floating_value auto x)   noexcept; // 3
   constexpr auto floor[almost](floating_value auto x)         noexcept; // 4
}

Parameters

• x :value argument.
• c: Conditional expression masking the operation.
• m: Logical value masking the operation.
• tol scalar valued tolerance.

Return value

1. The largest integer not greater than `x`.
   The standard proposes 4 rounding modes namely: `FE_TONEAREST`, `FE_DOWNWARD`, `FE_UPWARD`,
   `FE_TOWARDZERO`. This function object implements the `FE_DOWNWARD` version.
2. [The operation is performed conditionnaly](@ref conditional).
3. `almost` allows a fuzzy interpretation of ceil associated to a scalar tolerance.
    - with an integral value `tol`: computes the floor of the next nth
      representable value in the `x` type.
    - with a floating  value `tol`: computes the floor with a tolerance `tol`
      using Hagerty's FL5 function.
4. with no tolerance value, the call is equivalent to `ceil[tolerance = 3*eps(as(x))(x)`

External references

• C++ standard reference
• Wikipedia
• Hagerty's FL5

Example

// revision 0
#include <eve/module/core.hpp>
#include <iostream>
 
int main()
{
  eve::wide wf0{0.0, 1.0, 2.0, 3.0, -1.0, -2.0, -3.0, -4.0};
  eve::wide wi0{0, 1, 2, 3, -1, -2, -3, -4};
  eve::wide wu0{0u, 1u, 2u, 3u, 4u, 5u, 6u, 7u};
 
  std::cout << "<- wf0                        = " << wf0 << "\n";
  std::cout << "<- wi0                        = " << wi0 << "\n";
  std::cout << "<- wu0                        = " << wu0 << "\n";
                                              
  std::cout << "-> floor(wf0)                 = " << eve::floor(wf0) << "\n";
  std::cout << "-> floor[ignore_last(2)](wf0) = " << eve::floor[eve::ignore_last(2)](wf0) << "\n";
  std::cout << "-> floor[wf0 != 0](wf0)       = " << eve::floor[wf0 != 0](wf0) << "\n";
  std::cout << "-> floor[almost](wf0)         = " << eve::floor[eve::almost](wf0) << "\n";
  std::cout << "-> floor(wu0)                 = " << eve::floor(wu0) << "\n";
  std::cout << "-> floor[ignore_last(2)](wu0) = " << eve::floor[eve::ignore_last(2)](wu0) << "\n";
  std::cout << "-> floor[wu0 != 0](wu0)       = " << eve::floor[wu0 != 0](wu0) << "\n";
  std::cout << "-> floor(wi0)                 = " << eve::floor(wi0) << "\n";
  std::cout << "-> floor[ignore_last(2)](wi0) = " << eve::floor[eve::ignore_last(2)](wi0) << "\n";
  std::cout << "-> floor[wi0 != 0](wi0)       = " << eve::floor[wi0 != 0](wi0) << "\n";
}