roundscale

eve::roundscale = {}

inlineconstexpr

Computes the scaled input rounding.

Defined in Header

#include <eve/module/core.hpp>

Callable Signatures

namespace eve
{
   template< eve::value T, int scale >
   T roundscale(T x, int scale) noexcept;
}

Parameters

• x: floating value.
• scale : int or std::integral_constant of int type limited to the range [0, 15].

Return value

• Returns the elementwise scaled input. The number of fraction bits retained is specified by scale. By default the internal rounding after scaling is done to nearest integer. ldexp(round(ldexp(a0,scale),-scale))

Example

#include <eve/module/core.hpp>
#include <eve/wide.hpp>
#include <iostream>
#include <iomanip>
 
using wide_ft = eve::wide<float, eve::fixed<4>>;
 
int main()
{
  wide_ft pf( [](auto i, auto) { return 1.2345678+i; } );
 
  std::cout << "---- simd" << '\n'
            << "<- pf            = " << pf << '\n'
            << "-> roundscale(pf, 4) = " << eve::roundscale(pf, 4) << '\n';
 
  float xf = 0x1.fffffep0f;
 
  std::cout << "---- scalar" << '\n'
                << "<- xf                             = " << std::hexfloat << xf << '\n';
    for (int i = 0;  i < 16; ++i)
      std::cout << "-> toward_zero(roundscale)(xf," << std::setw(2) << i << ")  = " << std::hexfloat << eve::toward_zero(eve::roundscale)(xf, i) << '\n';
  return 0;
}

Semantic Modifiers

• Masked Call

  The call eve;roundscale[mask](x, scale) provides a masked version of eve::roundscale which is equivalent to if_else (mask, roundscale(x, scale), x).

  Example

  #include <eve/module/core.hpp>
  #include <eve/wide.hpp>
  #include <iostream>
  #include <iomanip>
   
  using wide_ft = eve::wide<float, eve::fixed<4>>;
   
  int main()
  {
    wide_ft pf( [](auto i, auto) { return 1.2345678+i; } );
   
    std::cout << "---- simd" << '\n'
              << "<- pf                                 = " << pf << '\n'
              << "-> roundscale[ignore_first(2)](pf, 4) = " << eve::roundscale[eve::ignore_first(2)](pf, 4) << '\n';
    return 0;
  }

  • eve::to_nearest, eve::toward_zero, eve::upward, eve::downward

    If d is one of these 4 decorators The call d(roundscale)(x), call is equivalent to eve::ldexp(d(eve::round)(eve::ldexp(a0,scale), -scale))