dec

eve::dec = functor<dec_t>

inlineconstexpr

Header file

#include <eve/module/core.hpp>

Callable Signatures

namespace eve
{
   // Regular overload
   constexpr auto dec(value auto x)                          noexcept; // 1
 
   // Lanes masking
   constexpr auto dec[conditional_expr auto c](value auto x) noexcept; // 2
   constexpr auto dec[logical_value auto m](value auto x)    noexcept; // 2
 
   // Semantic options
   constexpr auto dec[saturated](value auto x)               noexcept; // 3
   constexpr auto dec[lower](value auto x)                   noexcept; // 4
   constexpr auto dec[upper](value auto x)                   noexcept; // 5
   constexpr auto dec[lower][strict](value auto x)           noexcept; // 4
   constexpr auto dec[upper][strict](value auto x)           noexcept; // 5
   constexpr auto dec[mod = p](value auto x)                 noexcept; // 6

Parameters

• x: SIMD or scalar value.
• c: Conditional expression masking the operation.
• m: Logical value masking the operation.
• p: modulo p operation. p must be flint less than maxflint.

Return value

1. The value of x - 1 is returned.
2. The operation is performed conditionnaly.
3. The saturated decrementation of x. More specifically, for signed integral, dec[saturated](valmin(as<T>{})) returns eve:valmin(as<T>{})). This has no effect on floating types.
4. The decrement is computed in a 'round toward \(-\infty\) mode. The result is guaranted to be less or equal to the exact one (except for Nans). Combined with strict the option ensures generally faster computation, but strict inequality. This has no effect on integral types.
5. The decrement is computed in a 'round toward \(\infty\) mode. The result is guaranted to be greater or equal to the exact one (except for Nans).Combined with strict the option ensures generally faster computation, but strict inequality. This has no effect on integral types.
6. Computes the result in modular arithmetic. the parameter must be flint positive and less than the modulus. The modulus itself must be positive and less than maxflint. The result of the operation is unspecified if these conditions are not met.

Example

// revision 0
#include <eve/module/core.hpp>
#include <iostream>
#include <iomanip>
 
int main()
{
  auto sml = eve::smallestposval(eve::as(1.0));
  eve::wide wf0{sml, -sml, 1.0, -1.0, 2.0, -2.0, 3.0, -3.0};
  eve::wide wf1{0.0, 34.0, 0.0, 72.0, 4.0, 3.0, 2.0, 1.0};
  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 << "<- wf1                      = " << wf1 << "\n";
  std::cout << "<- wi0                      = " << wi0 << "\n";
  std::cout << "<- wu0                      = " << wu0 << "\n";
 
  std::cout << "-> dec(wf0)                 = " << eve::dec(wf0) << "\n";
  std::cout << "-> dec[ignore_last(2)](wf0) = " << eve::dec[eve::ignore_last(2)](wf0) << "\n";
  std::cout << "-> dec[wf0 != 0](wf0)       = " << eve::dec[wf0 != 0](wf0) << "\n";
  std::cout << "-> dec(wu0)                 = " << eve::dec(wu0) << "\n";
  std::cout << "-> dec[ignore_last(2)](wu0) = " << eve::dec[eve::ignore_last(2)](wu0) << "\n";
  std::cout << "-> dec[wu0 != 0](wu0)       = " << eve::dec[wu0 != 0](wu0) << "\n";
  std::cout << "-> dec[saturated](wu0)      = " << eve::dec[eve::saturated](wu0) << "\n";
  std::cout << "-> dec(wi0)                 = " << eve::dec(wi0) << "\n";
  std::cout << "-> dec[ignore_last(2)](wi0) = " << eve::dec[eve::ignore_last(2)](wi0) << "\n";
  std::cout << "-> dec[wi0 != 0](wi0)       = " << eve::dec[wi0 != 0](wi0) << "\n";
  std::cout << "-> dec[saturated](wi0)      = " << eve::dec[eve::saturated](wi0) << "\n";
  std::cout << std::setprecision(20) << "-> dec[lower](wf0)           = " << eve::dec[eve::lower](wf0) << "\n";
  std::cout << std::setprecision(20) << "-> dec[upper](wf0)           = " << eve::dec[eve::upper](wf0) << "\n";
  std::cout << std::setprecision(20) << "-> dec[lower][strict](wf0)   = " << eve::dec[eve::lower][eve::strict](wf0) << "\n";
  std::cout << std::setprecision(20) << "-> dec[upper][strict](wf0)   = " << eve::dec[eve::upper][eve::strict](wf0) << "\n";
  std::cout << std::setprecision(20) << "-> dec[mod = 97](wf1)        = " << eve::dec[eve::mod = 97](wf1) << "\n";
}