Linear.hh

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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
 * Copyright (c) 2025, Davide Stocco and Enrico Bertolazzi.                  *
 *                                                                           *
 * The Optimist project is distributed under the BSD 2-Clause License.       *
 *                                                                           *
 * Davide Stocco                                           Enrico Bertolazzi *
 * University of Trento                                 University of Trento *
 * davide.stocco@unitn.it                         enrico.bertolazzi@unitn.it *
\* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 
#pragma once
 
#ifndef OPTIMIST_TESTSET_LINEAR_HH
#define OPTIMIST_TESTSET_LINEAR_HH
 
#include "Optimist/Function.hh"
 
namespace Optimist {
 
  namespace TestSet {

    template <typename Scalar>
      requires TypeTrait<Scalar>::IsScalar
    class Linear : public Function<Scalar, Scalar, Linear<Scalar>> {
      Scalar m_m{-1.0}; 
      Scalar m_q{1.0};  
 
     public:
      OPTIMIST_BASIC_CONSTANTS(Scalar)
 
      
      Linear() {
        this->m_solutions.emplace_back(-this->m_q / this->m_m);
        this->m_guesses.emplace_back(0.0);
      }

      constexpr std::string name_impl() const {
        return "Linear";
      }

      bool evaluate_impl(const Scalar x, Scalar &out) const {
        out = this->m_m * x + this->m_q;
        return std::isfinite(out);
      }

      bool first_derivative_impl(const Scalar /*x*/, Scalar &out) const {
        out = this->m_m;
        return std::isfinite(out);
      }

      bool second_derivative_impl(const Scalar /*x*/, Scalar &out) const {
        out = 0.0;
        return std::isfinite(out);
      }
 
    };  // class Linear

    template <typename Vector>
      requires TypeTrait<Vector>::IsEigen && (!TypeTrait<Vector>::IsFixed ||
                                              TypeTrait<Vector>::Dimension == 1)
    class Linear1 : public Function<Vector, Vector, Linear1<Vector>> {
     public:
      using VectorTrait = TypeTrait<Vector>;
      using Scalar      = typename Vector::Scalar;
      using typename Function<Vector, Vector, Linear1<Vector>>::FirstDerivative;
      using
          typename Function<Vector, Vector, Linear1<Vector>>::SecondDerivative;
 
     private:
      Scalar m_m{1.0}; 
      Scalar m_q{1.0}; 
 
     public:
      OPTIMIST_BASIC_CONSTANTS(Scalar)
 
      
      Linear1() {
        this->m_solutions.resize(1);
        this->m_guesses.resize(1);
        Scalar tmp{-this->m_q / this->m_m};
        if constexpr (VectorTrait::IsFixed) {
          this->m_solutions[0] << tmp;
          this->m_guesses[0] << 0.0;
        } else if constexpr (VectorTrait::IsDynamic) {
          this->m_solutions[0].resize(1);
          this->m_solutions[0] << tmp;
          this->m_guesses[0].resize(1);
          this->m_guesses[0] << 0.0;
        } else if constexpr (VectorTrait::IsSparse) {
          this->m_solutions[0].resize(1);
          this->m_solutions[0].reserve(1);
          this->m_solutions[0].coeffRef(0) = tmp;
          this->m_guesses[0].resize(1);
          this->m_guesses[0].reserve(1);
          this->m_guesses[0].coeffRef(0) = 0.0;
        }
      }

      constexpr std::string name_impl() const {
        return "Linear1";
      }

      bool evaluate_impl(const Vector &x, Vector &out) const {
#define CMD "Optimist::TestSet::Linear1::evaluate_impl(...): "
 
        if constexpr (VectorTrait::IsFixed) {
          out << this->m_m * x(0) + this->m_q;
          return std::isfinite(out(0));
        } else if constexpr (VectorTrait::IsDynamic) {
          out.resize(1);
          out << this->m_m * x(0) + this->m_q;
          return std::isfinite(out(0));
        } else if constexpr (VectorTrait::IsSparse) {
          out.resize(1);
          out.reserve(1);
          out.coeffRef(0) = this->m_m * x.coeff(0) + this->m_q;
          return std::isfinite(out.coeff(0));
        } else {
          OPTIMIST_ERROR(CMD "input type not supported.");
          return false;
        }
 
#undef CMD
      }

      bool first_derivative_impl(const Vector & /*x*/,
                                 FirstDerivative &out) const {
#define CMD "Optimist::TestSet::Linear1::first_derivative_impl(...): "
 
        if constexpr (VectorTrait::IsFixed) {
          out << this->m_m;
        } else if constexpr (VectorTrait::IsDynamic) {
          out.resize(1, 1);
          out << this->m_m;
        } else if constexpr (VectorTrait::IsSparse) {
          out.resize(1, 1);
          out.reserve(1);
          out.coeffRef(0, 0) = this->m_m;
        } else {
          OPTIMIST_ERROR(CMD "input type not supported.");
          return false;
        }
        return std::isfinite(this->m_m);
 
#undef CMD
      }

      bool second_derivative_impl(const Vector & /*x*/,
                                  SecondDerivative &out) const {
#define CMD "Optimist::TestSet::Linear1::second_derivative_impl(...): "
 
        out.resize(1);
        if constexpr (VectorTrait::IsFixed) {
          out[0] << 0.0;
        } else if constexpr (VectorTrait::IsDynamic) {
          out[0].resize(1, 1);
          out[0] << 0.0;
        } else if constexpr (VectorTrait::IsSparse) {
          out[0].resize(1, 1);
          out[0].reserve(1);
          out[0].coeffRef(0, 0) = 0.0;
        } else {
          OPTIMIST_ERROR(CMD "input type not supported.");
          return false;
        }
        return true;
 
#undef CMD
      }
 
    };  // class Linear1
 
  }  // namespace TestSet
 
}  // namespace Optimist
 
#endif  // OPTIMIST_TESTSET_LINEAR_HH