LinearInterpolation.h

// Copyright 2024, UChicago Argonne, LLC
// All Rights Reserved
// Software Name: NEML2 -- the New Engineering material Model Library, version 2
// By: Argonne National Laboratory
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#pragma once
 
#include "neml2/models/Interpolation.h"
#include "neml2/tensors/Scalar.h"
 
namespace neml2
{
template <typename T>
class LinearInterpolation : public Interpolation<T>
{
public:
  static OptionSet expected_options();
 
  LinearInterpolation(const OptionSet & options);
 
  template <typename T2>
  static T2 mask(const T2 & in, const Scalar & m);
 
protected:
  void set_value(bool out, bool dout_din, bool d2out_din2) override;
 
  const Scalar & _X;
 
  const Variable<Scalar> & _x;
};
 
template <typename T>
template <typename T2>
T2
LinearInterpolation<T>::mask(const T2 & in, const Scalar & m)
{
  // Resulting batch shape
  const auto B = m.batch_sizes().slice(0, -1);
  // Use advanced (boolean) indexing to select the correct interval
  return T2(in.batch_expand_as(m).index({m})).batch_reshape(B);
}
} // namespace neml2