smooth-2norm.hpp

// BSD 3-Clause License
//
// Copyright (C) 2020-2025, LAAS-CNRS, Heriot-Watt University
// Copyright note valid unless otherwise stated in individual files.
// All rights reserved.
 
#ifndef CROCODDYL_CORE_ACTIVATIONS_SMOOTH_2NORM_HPP_
#define CROCODDYL_CORE_ACTIVATIONS_SMOOTH_2NORM_HPP_
 
#include "crocoddyl/core/activation-base.hpp"
#include "crocoddyl/core/fwd.hpp"
 
namespace crocoddyl {
 
template <typename _Scalar>
class ActivationModelSmooth2NormTpl
    : public ActivationModelAbstractTpl<_Scalar> {
 public:
  EIGEN_MAKE_ALIGNED_OPERATOR_NEW
  CROCODDYL_DERIVED_CAST(ActivationModelBase, ActivationModelSmooth2NormTpl)
 
  typedef _Scalar Scalar;
  typedef MathBaseTpl<Scalar> MathBase;
  typedef ActivationModelAbstractTpl<Scalar> Base;
  typedef ActivationDataAbstractTpl<Scalar> ActivationDataAbstract;
  typedef typename MathBase::VectorXs VectorXs;
  typedef typename MathBase::MatrixXs MatrixXs;
 
  explicit ActivationModelSmooth2NormTpl(const std::size_t nr,
                                         const Scalar eps = Scalar(1.))
      : Base(nr), eps_(eps) {
    if (eps < Scalar(0.)) {
      throw_pretty("Invalid argument: " << "eps should be a positive value");
    }
  };
  virtual ~ActivationModelSmooth2NormTpl() = default;
 
  virtual void calc(const std::shared_ptr<ActivationDataAbstract>& data,
                    const Eigen::Ref<const VectorXs>& r) override {
    if (static_cast<std::size_t>(r.size()) != nr_) {
      throw_pretty(
          "Invalid argument: " << "r has wrong dimension (it should be " +
                                      std::to_string(nr_) + ")");
    }
    using std::sqrt;
    data->a_value = sqrt(r.squaredNorm() + eps_);
  };
 
  virtual void calcDiff(const std::shared_ptr<ActivationDataAbstract>& data,
                        const Eigen::Ref<const VectorXs>& r) override {
    if (static_cast<std::size_t>(r.size()) != nr_) {
      throw_pretty(
          "Invalid argument: " << "r has wrong dimension (it should be " +
                                      std::to_string(nr_) + ")");
    }
 
    data->Ar = r / data->a_value;
    data->Arr.diagonal().array() = Scalar(1) / pow(data->a_value, Scalar(3));
  };
 
  virtual std::shared_ptr<ActivationDataAbstract> createData() override {
    return std::allocate_shared<ActivationDataAbstract>(
        Eigen::aligned_allocator<ActivationDataAbstract>(), this);
  };
 
  template <typename NewScalar>
  ActivationModelSmooth2NormTpl<NewScalar> cast() const {
    typedef ActivationModelSmooth2NormTpl<NewScalar> ReturnType;
    ReturnType res(nr_, scalar_cast<NewScalar>(eps_));
    return res;
  }
 
 protected:
  virtual void print(std::ostream& os) const override {
    os << "ActivationModelSmooth2Norm {nr=" << nr_ << ", eps=" << eps_ << "}";
  }
 
  using Base::nr_;  
  Scalar eps_;      
};
 
}  // namespace crocoddyl
 
CROCODDYL_DECLARE_EXTERN_TEMPLATE_CLASS(
    crocoddyl::ActivationModelSmooth2NormTpl)
 
#endif  // CROCODDYL_CORE_ACTIVATIONS_SMOOTH_2NORM_HPP_