mul

auto eve::mul = functor<mul_t>

inlineconstexpr

Header file

#include <eve/module/core.hpp>

Callable Signatures

namespace eve
{
   // Regular overloads
   constexpr auto mul(value auto x, value auto ... xs)                          noexcept; // 1
   constexpr auto mul(eve::non_empty_product_type auto const& tup)             noexcept; // 2
 
   // Lanes masking
   constexpr auto mul[conditional_expr auto c](/*any of the above overloads*/)  noexcept; // 3
   constexpr auto mul[logical_value auto m](/*any of the above overloads*/)     noexcept; // 3
 
   // Semantic options
   constexpr auto mul[saturated](/*any of the above overloads*/)                noexcept; // 4
   constexpr auto mul[lower](/*any of the above overloads*/)                    noexcept; // 5
   constexpr auto mul[upper](/*any of the above overloads*/)                    noexcept; // 6
   constexpr auto mul[lower][strict](/*any of the above overloads*/)            noexcept; // 5
   constexpr auto mul[upper][strict](/*any of the above overloads*/)            noexcept; // 6
   constexpr auto mul[widen](/*any of the above overloads*/)                    noexcept; // 7
   constexpr auto mul[mod = p](/*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 product of the arguments is returned.

1. Take care that for floating entries, the multiplication is not perfectly associative due to rounding errors. This call performs multiplications in reverse incoming order.
2. equivalent to the call on the elements of the tuple.
3. The operation is performed conditionnaly
4. The call mul[saturated](...) computes a saturated version of mul. Take care that for signed integral entries this kind of multiplication is not associative at all. This call perform saturated multiplications in reverse incoming order.
5. The product 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.
6. The product 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.
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. compute the result in modular arithmetic. the parameters must be flint positive and less than the modulus. The modulus itself must be less than maxflint.

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 <eve/module/math.hpp>
#include <iostream>
#include <iomanip>
 
 
int main()
{
  eve::wide wf0{0.0, 1.0, 2.0, 3.0, -1.0, -2.0, -3.0, -4.0};
  eve::wide wf1{0.0, -4.0, 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 << "-> mul(wf0, wf1)                 = " << eve::mul(wf0, wf1) << "\n";
  std::cout << "-> mul[ignore_last(2)](wf0, wf1) = " << eve::mul[eve::ignore_last(2)](wf0, wf1) << "\n";
  std::cout << "-> mul[wf0 != 0](wf0, wf1)       = " << eve::mul[wf0 != 0](wf0, wf1) << "\n";
  std::cout << "-> mul(wu0, wu1)                 = " << eve::mul(wu0, wu1) << "\n";
  std::cout << "-> mul(wi0, wi1)                 = " << eve::mul(wi0, wi1) << "\n";
 
  std::cout << "-> mul(wu0, wu1)                 = " << eve::mul(wu0, wu1) << "\n";
  std::cout << "-> mul[widen](wu0, wu1)          = " << eve::mul[eve::widen](wu0, wu1) << "\n";
  std::cout << "-> mul(wf0, wf1)                 = " << eve::mul(wf0, wf1) << "\n";
  std::cout << "-> mul[widen](wf0, wf1)          = " << eve::mul[eve::widen](wf0, wf1) << "\n";
  std::cout << std::setprecision(15);
  auto pi = eve::pi(eve::as<float>());
  auto e  = eve::euler(eve::as<float>());
  auto l2 = eve::log_2(eve::as<float>());
  auto tup = kumi::tuple{pi, e, 1.2345f, l2, pi, e, 1.2345f, l2, 1.35f*pi, l2+pi,  0.07856f};
  std::cout << "-> mul[kahan](tup)  = " << eve::mul[eve::kahan](tup) << "\n";
  std::cout << "-> mul(tup)         = " << eve::mul(tup) << "\n";
  std::cout << "-> mul[widen](tup)  = " << float(eve::mul[eve::widen](tup)) << "\n";
  auto z = kumi::tuple{wf0, wf1, wf1};
  std::cout << "-> mul[kahan](wf0, wf1, wf1)  = " << eve::mul[eve::kahan](z) << "\n";
  std::cout << "-> mul[kahan](wf0, wf1, wf1)  = " << eve::mul[eve::kahan](wf0, wf1, wf1) << "\n";
 
}