| // Ceres Solver - A fast non-linear least squares minimizer |
| // Copyright 2023 Google Inc. All rights reserved. |
| // http://ceres-solver.org/ |
| // |
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| // |
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| // |
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| // |
| // Author: sameeragarwal@google.com (Sameer Agarwal) |
| // |
| // A simple example of optimizing a sampled function by using cubic |
| // interpolation. |
| |
| #include "ceres/ceres.h" |
| #include "ceres/cubic_interpolation.h" |
| #include "glog/logging.h" |
| |
| using Interpolator = ceres::CubicInterpolator<ceres::Grid1D<double>>; |
| |
| // A simple cost functor that interfaces an interpolated table of |
| // values with automatic differentiation. |
| struct InterpolatedCostFunctor { |
| explicit InterpolatedCostFunctor(const Interpolator& interpolator) |
| : interpolator(interpolator) {} |
| |
| template <typename T> |
| bool operator()(const T* x, T* residuals) const { |
| interpolator.Evaluate(*x, residuals); |
| return true; |
| } |
| |
| static ceres::CostFunction* Create(const Interpolator& interpolator) { |
| return new ceres::AutoDiffCostFunction<InterpolatedCostFunctor, 1, 1>( |
| new InterpolatedCostFunctor(interpolator)); |
| } |
| |
| private: |
| const Interpolator& interpolator; |
| }; |
| |
| int main(int argc, char** argv) { |
| google::InitGoogleLogging(argv[0]); |
| |
| // Evaluate the function f(x) = (x - 4.5)^2; |
| const int kNumSamples = 10; |
| double values[kNumSamples]; |
| for (int i = 0; i < kNumSamples; ++i) { |
| values[i] = (i - 4.5) * (i - 4.5); |
| } |
| |
| ceres::Grid1D<double> array(values, 0, kNumSamples); |
| Interpolator interpolator(array); |
| |
| double x = 1.0; |
| ceres::Problem problem; |
| ceres::CostFunction* cost_function = |
| InterpolatedCostFunctor::Create(interpolator); |
| problem.AddResidualBlock(cost_function, nullptr, &x); |
| |
| ceres::Solver::Options options; |
| options.minimizer_progress_to_stdout = true; |
| ceres::Solver::Summary summary; |
| ceres::Solve(options, &problem, &summary); |
| std::cout << summary.BriefReport() << "\n"; |
| std::cout << "Expected x: 4.5. Actual x : " << x << std::endl; |
| return 0; |
| } |