fit.hpp

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// Copyright (C) 2021-2022 Petter Nilsson. MIT License.
 
#pragma once
 
#include <ranges>
 
#include "bspline.hpp"
#include "spline.hpp"
 
SMOOTH_BEGIN_NAMESPACE
 
template<typename T>
concept SplineSpec = requires(T t) {
  // clang-format off
  { T::Degree } -> std::convertible_to<int>;
  { T::OptDeg } -> std::convertible_to<int>;
  { T::InnCnt } -> std::convertible_to<int>;
  { t.LeftDeg };
  { t.RghtDeg };
  // clang-format on
};
 
namespace spline_specs {
 
template<LieGroup G, int K>
struct NoConstraints
{
  static constexpr int Degree = K;
  static constexpr int OptDeg = -1;
  static constexpr int InnCnt = int(K) - 1;
 
  static constexpr std::array<int, 0> LeftDeg{};
  std::array<Tangent<G>, 0> left_values{};
 
  static constexpr std::array<int, 0> RghtDeg{};
  std::array<Tangent<G>, 0> rght_values{};
};
 
template<LieGroup G>
using PiecewiseConstant = NoConstraints<G, 0>;
 
template<LieGroup G>
using PiecewiseLinear = NoConstraints<G, 1>;
 
template<LieGroup G, int P1 = 2, int P2 = P1>
struct FixedDerCubic
{
  static constexpr int Degree = 3;
  static constexpr int OptDeg = -1;
  static constexpr int InnCnt = 2;
 
  static constexpr std::array<int, 1> LeftDeg{P1};
  std::array<Tangent<G>, 1> left_values{Tangent<G>::Zero()};
 
  static constexpr std::array<int, 1> RghtDeg{P2};
  std::array<Tangent<G>, 1> rght_values{Tangent<G>::Zero()};
};
 
template<LieGroup G, int K = 6, int O = 3, int P = 3>
struct MinDerivative
{
  static constexpr int Degree = K;
  static constexpr int OptDeg = O;
  static constexpr int InnCnt = P;
 
  static constexpr std::array<int, std::size_t(P - 1)> LeftDeg = []() {
    std::array<int, std::size_t(P - 1)> ret;
    for (auto i = 0; i + 1 < P; ++i) { ret[static_cast<std::size_t>(i)] = i + 1; }
    return ret;
  }();
 
  std::array<Tangent<G>, std::size_t(P - 1)> left_values = []() {
    std::array<Tangent<G>, std::size_t(P - 1)> ret;
    ret.fill(Tangent<G>::Zero());
    return ret;
  }();
 
  static constexpr std::array<int, std::size_t(P - 1)> RghtDeg = LeftDeg;
  std::array<Tangent<G>, std::size_t(P - 1)> rght_values = left_values;
};
 
}  // namespace spline_specs
 
Eigen::VectorXd
fit_spline_1d(std::ranges::sized_range auto && dt_r, std::ranges::sized_range auto && dx_r, const SplineSpec auto & ss);
 
auto fit_spline(
  std::ranges::random_access_range auto && ts, std::ranges::random_access_range auto && gs, const SplineSpec auto & ss);
 
auto fit_spline_cubic(std::ranges::range auto && ts, std::ranges::range auto && gs);
 
template<int K>
auto fit_bspline(std::ranges::range auto && ts, std::ranges::range auto && gs, const double dt);
 
SMOOTH_END_NAMESPACE
#include "detail/fit_impl.hpp"