ceil

auto eve::ceil = functor<ceil_t>

inlineconstexpr

Defined in Header

#include <eve/module/core.hpp>

Callable Signatures

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

Return value

1. The smallest integer not less than x. The standard proposes 4 rounding modes namely: FE_TONEAREST, FE_DOWNWARD, FE_UPWARD, FE_TOWARDZERO. This function object implements the FE_UPWARD version.
2. The operation is performed conditionnaly.
3. almost allows a fuzzy interpretation of ceil associated to a scalar tolerance.
   • with an integral value tol: computes the ceil of the previous nth representable value in the x type.
   • with a floating value tol: computes the ceil 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 << "-> ceil(wf0)                 = " << eve::ceil(wf0) << "\n";
  std::cout << "-> ceil[ignore_last(2)](wf0) = " << eve::ceil[eve::ignore_last(2)](wf0) << "\n";
  std::cout << "-> ceil[wf0 != 0](wf0)       = " << eve::ceil[wf0 != 0](wf0) << "\n";
  std::cout << "-> ceil[almost](wf0)         = " << eve::ceil[eve::almost](wf0) << "\n";
  std::cout << "-> ceil(wu0)                 = " << eve::ceil(wu0) << "\n";
  std::cout << "-> ceil[ignore_last(2)](wu0) = " << eve::ceil[eve::ignore_last(2)](wu0) << "\n";
  std::cout << "-> ceil[wu0 != 0](wu0)       = " << eve::ceil[wu0 != 0](wu0) << "\n";
  std::cout << "-> ceil(wi0)                 = " << eve::ceil(wi0) << "\n";
  std::cout << "-> ceil[ignore_last(2)](wi0) = " << eve::ceil[eve::ignore_last(2)](wi0) << "\n";
  std::cout << "-> ceil[wi0 != 0](wi0)       = " << eve::ceil[wi0 != 0](wi0) << "\n";
}