File absolutevalue.h

File List > algebra > operators > absolutevalue.h

Go to the documentation of this file

#ifndef TEMPLAT_LATTICE_ALGEBRA_OPERATORS_ABSOLUTEVALUE_H
#define TEMPLAT_LATTICE_ALGEBRA_OPERATORS_ABSOLUTEVALUE_H

/* This file is part of TempLat, available at https://cosmolattice.github.io/templat .
   Copyright 2021-2026 The TempLat authors, see AUTHORS.md.
   Released under the MIT license, see LICENSE.md. */

// File info: Main contributor(s): Wessel Valkenburg, Franz R. Sattler, Year: 2025

// imperative to include this:
// otherwise abs might be defined for integers only, with possibly desastrous consequences.

#include "TempLat/lattice/algebra/helpers/getfloattype.h"
#include "TempLat/lattice/algebra/helpers/getgetreturntype.h"
#include "TempLat/lattice/algebra/operators/unaryoperator.h"

#include "TempLat/lattice/algebra/helpers/getderiv.h"
#include "TempLat/lattice/algebra/operators/heavisidestepfunction.h"

#include "TempLat/lattice/algebra/constants/halftype.h"
#include "TempLat/lattice/algebra/constants/zerotype.h"
#include "TempLat/lattice/algebra/constants/onetype.h"

namespace TempLat
{
  using device::abs;

  namespace Operators
  {
    template <typename R> class AbsoluteValue : public UnaryOperator<R>
    {
    public:
      // Put public methods here. These should change very little over time.
      using UnaryOperator<R>::mR;

      AbsoluteValue(const R &a) : UnaryOperator<R>(a) {}

      template <typename... IDX>
        requires requires(std::decay_t<R> r, IDX... idx) {
          requires IsVariadicIndex<IDX...>;
          DoEval::eval(r, idx...);
        }
      DEVICE_FORCEINLINE_FUNCTION auto eval(const IDX &...idx) const
      {
        return abs(DoEval::eval(mR, idx...));
      }

      virtual std::string operatorString() const override { return "abs"; }

      template <typename U> auto d(const U &other)
      {
        return GetDeriv::get(mR, other) * (-heaviside(-mR) + heaviside(mR));
      }
    };
  } // namespace Operators

  template <typename T>
    requires ConditionalUnaryGetter<T>
  auto abs(const T &a)
  {
    return Operators::AbsoluteValue<T>(a);
  }

  constexpr inline ZeroType abs(ZeroType a) { return ZeroType(); }
  constexpr inline OneType abs(OneType a) { return OneType(); }
  constexpr inline HalfType abs(HalfType a) { return HalfType(); }
} // namespace TempLat

#endif