sub

auto eve::sub = functor<sub_t>

inlineconstexpr

Header file

#include <eve/module/core.hpp>

Callable Signatures

namespace eve
{
   // Regular overloads
   constexpr auto sub(value auto x, value auto ... xs)                          noexcept; // 1
   constexpr auto sub(kumi::non_empty_product_type auto const& tup)             noexcept; // 2
 
   // Lanes masking
   constexpr auto sub[conditional_expr auto c](/*any of the above overloads*/)  noexcept; // 3
   constexpr auto sub[logical_value auto m](/*any of the above overloads*/)     noexcept; // 3
 
   // Semantic options
   constexpr auto sub[saturated](/*any of the above overloads*/)                noexcept; // 4
   constexpr auto sub[lower](/*any of the above overloads*/)                    noexcept; // 5
   constexpr auto sub[upper](/*any of the above overloads*/)                    noexcept; // 6
   constexpr auto sub[widen](/*any of the above overloads*/)                    noexcept; // 7
   constexpr auto sub[right](/*any of the above overloads*/)                    noexcept; // 1
   constexpr auto sub[left](/*any of the above overloads*/)                     noexcept; // 8
}

Parameters

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

Return value

The value of the difference of its first argument with the sum of the others

1. Take care that for floating entries, the addition is not perfectly associative due to rounding errors. This call performs additions in reverse incoming order.
2. equivalent to the call on the elements of the tuple.
3. The operation is performed conditionnaly
4. The call sub[saturated](...) computes a saturated version of add. Take care that for signed integral entries this kind of a is highly order dependant. This call perform saturated additions in reverse incoming order. We do not advise to use it for more than 2 parameters.
5. The substraction is computed in a 'round toward \(-\infty\) mode. The result is guaranted to be less or equal to the exact one (except for Nans).
6. The substraction is computed in a 'round toward \(\infty\) mode. The result is guaranted to be greater or equal to the exact one (except for Nans).
7. The operation is computed in the double sized element type (if available). This decorator has no effect on double and 64 bits integrals.
8. sub[left](a, b) is semantically equivalent to sub(b, a)

Note

Although the infix notation with - is supported for two parameters, the - operator on standard scalar types is the original one and so can lead to automatic promotion.

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{1.0, 1.0, 2.0, 3.0, -1.0, -2.0, -3.0, -4.0};
  eve::wide wf1{sml, -sml, 1.0, -1.0, 2.0, -2.0, 3.0, -3.0};
  eve::wide wi0{0, 1, 2, 3, -1, -2, -3, -4};
  eve::wide wi1{0, -4, 1, -1, 2, -2, 3, -3};
  eve::wide wu0{0u, 1u, 2u, 3u, 4u, 5u, 6u, 7u};
  eve::wide wu1{7u, 6u, 5u, 4u, 3u, 2u, 1u, 0u};
 
  std::cout << "<- wf0                           = " << wf0 << "\n";
  std::cout << "<- wf1                           = " << wf1 << "\n";
  std::cout << "<- wi0                           = " << wi0 << "\n";
  std::cout << "<- wi1                           = " << wi1 << "\n";
  std::cout << "<- wu0                           = " << wu0 << "\n";
  std::cout << "<- wu1                           = " << wu1 << "\n";
 
  std::cout << "-> sub(wf0, wf1)                 = " << eve::sub(wf0, wf1) << "\n";
  std::cout << "-> sub[left](wf0, wf1)           = " << eve::sub[eve::left](wf0, wf1) << "\n";
  std::cout << "-> sub[ignore_last(2)](wf0, wf1) = " << eve::sub[eve::ignore_last(2)](wf0, wf1) << "\n";
  std::cout << "-> sub[wf0 != 0](wf0, wf1)       = " << eve::sub[wf0 != 0](wf0, wf1) << "\n";
  std::cout << "-> sub(wu0, wu1)                 = " << eve::sub(wu0, wu1) << "\n";
  std::cout << "-> sub(wi0, wi1)                 = " << eve::sub(wi0, wi1) << "\n";
 
  std::cout << std::setprecision(20) << "-> sub(wf0, wf1)          = " << eve::sub(wf0, wf1) << "\n";
  std::cout << std::setprecision(20) << "-> sub[lower](wf0, wf1)   = " << eve::sub[eve::lower](wf0, wf1) << "\n";
  std::cout << std::setprecision(20) << "-> sub[upper](wf0, wf1)   = " << eve::sub[eve::upper](wf0, wf1) << "\n";
 
  std::cout << "-> sub(wu0, wu1)                 = " << eve::sub(wu0, wu1) << "\n";
  std::cout << "-> sub[widen](wu0, wu1)          = " << eve::sub[eve::widen](wu0, wu1) << "\n";
  std::cout << "-> sub(wf0, wf1)                 = " << eve::sub(wf0, wf1) << "\n";
  std::cout << "-> sub[widen](wf0, wf1)          = " << eve::sub[eve::widen](wf0, wf1) << "\n";
}