smooth-1norm.hpp

// BSD 3-Clause License
//
// Copyright (C) 2019-2026, LAAS-CNRS, University of Edinburgh,
// Heriot-Watt University
// Copyright note valid unless otherwise stated in individual files.
// All rights reserved.

#ifndef CROCODDYL_CORE_ACTIVATIONS_SMOOTH_1NORM_HPP_
#define CROCODDYL_CORE_ACTIVATIONS_SMOOTH_1NORM_HPP_

#include "crocoddyl/core/activation-base.hpp"
#include "crocoddyl/core/fwd.hpp"

namespace crocoddyl {

template <typename _Scalar>
class ActivationModelSmooth1NormTpl
 : public ActivationModelAbstractTpl<_Scalar> {
 public:
 EIGEN_MAKE_ALIGNED_OPERATOR_NEW
 CROCODDYL_DERIVED_CAST(ActivationModelBase, ActivationModelSmooth1NormTpl)

 typedef _Scalar Scalar;
 typedef MathBaseTpl<Scalar> MathBase;
 typedef ActivationModelAbstractTpl<Scalar> Base;
 typedef ActivationDataAbstractTpl<Scalar> ActivationDataAbstract;
 typedef ActivationDataSmooth1NormTpl<Scalar> Data;
 typedef typename MathBase::VectorXs VectorXs;
 typedef typename MathBase::MatrixXs MatrixXs;

 explicit ActivationModelSmooth1NormTpl(const std::size_t nr,
 const Scalar delta = Scalar(1.))
 : Base(nr), delta_(delta) {
 if (delta_ <= Scalar(0.)) {
 throw_pretty(
 "Invalid argument: delta should be a strictly positive value");
 }
 };
 virtual ~ActivationModelSmooth1NormTpl() = 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_) + ")");
 }
 std::shared_ptr<Data> d = std::static_pointer_cast<Data>(data);

 d->a = (r.array().square() + delta_ * delta_).sqrt().matrix();
 data->a_value =
 delta_ * (r.array().square() / (d->a.array() + delta_)).sum();
 };

 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_) + ")");
 }

 std::shared_ptr<Data> d = std::static_pointer_cast<Data>(data);
 const VectorXs a_inv = d->a.cwiseInverse();

 data->Ar = delta_ * r.cwiseProduct(a_inv);
 data->Arr.diagonal() = delta_ * delta_ * delta_ *
 a_inv.cwiseProduct(a_inv).cwiseProduct(a_inv);
 };

 virtual std::shared_ptr<ActivationDataAbstract> createData() override {
 return std::allocate_shared<Data>(Eigen::aligned_allocator<Data>(), this);
 };

 template <typename NewScalar>
 ActivationModelSmooth1NormTpl<NewScalar> cast() const {
 typedef ActivationModelSmooth1NormTpl<NewScalar> ReturnType;
 ReturnType res(nr_, scalar_cast<NewScalar>(delta_));
 return res;
 }

 Scalar get_delta() const { return delta_; }

 virtual void print(std::ostream& os) const override {
 os << "ActivationModelSmooth1Norm {nr=" << nr_ << ", delta=" << delta_
 << "}";
 }

 protected:
 using Base::nr_;
 Scalar delta_;
};

template <typename _Scalar>
struct ActivationDataSmooth1NormTpl
 : public ActivationDataAbstractTpl<_Scalar> {
 EIGEN_MAKE_ALIGNED_OPERATOR_NEW

 typedef _Scalar Scalar;
 typedef ActivationDataAbstractTpl<Scalar> Base;
 typedef MathBaseTpl<Scalar> MathBase;
 typedef typename MathBase::VectorXs VectorXs;
 typedef typename MathBase::MatrixXs MatrixXs;
 typedef typename MathBase::DiagonalMatrixXs DiagonalMatrixXs;

 template <typename Activation>
 explicit ActivationDataSmooth1NormTpl(Activation* const activation)
 : Base(activation), a(VectorXs::Zero(activation->get_nr())) {}
 virtual ~ActivationDataSmooth1NormTpl() = default;

 VectorXs a;

 using Base::a_value;
 using Base::Ar;
 using Base::Arr;
};

} // namespace crocoddyl

CROCODDYL_DECLARE_EXTERN_TEMPLATE_CLASS(
 crocoddyl::ActivationModelSmooth1NormTpl)
CROCODDYL_DECLARE_EXTERN_TEMPLATE_STRUCT(
 crocoddyl::ActivationDataSmooth1NormTpl)

#endif // CROCODDYL_CORE_ACTIVATIONS_SMOOTH_1NORM_HPP_