1 // Ceres Solver - A fast non-linear least squares minimizer
2 // Copyright 2015 Google Inc. All rights reserved.
3 // http://ceres-solver.org/
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29 // Author: sameeragarwal@google.com (Sameer Agarwal)
31 #include "ceres/ceres.h"
32 #include "glog/logging.h"
34 // f(x,y) = (1-x)^2 + 100(y - x^2)^2;
35 class Rosenbrock : public ceres::FirstOrderFunction {
37 virtual ~Rosenbrock() {}
39 virtual bool Evaluate(const double* parameters,
41 double* gradient) const {
42 const double x = parameters[0];
43 const double y = parameters[1];
45 cost[0] = (1.0 - x) * (1.0 - x) + 100.0 * (y - x * x) * (y - x * x);
46 if (gradient != NULL) {
47 gradient[0] = -2.0 * (1.0 - x) - 200.0 * (y - x * x) * 2.0 * x;
48 gradient[1] = 200.0 * (y - x * x);
53 virtual int NumParameters() const { return 2; }
57 int main(int argc, char** argv) {
58 google::InitGoogleLogging(argv[0]);
60 double parameters[2] = {-1.2, 1.0};
62 ceres::GradientProblemSolver::Options options;
63 options.minimizer_progress_to_stdout = true;
65 ceres::GradientProblemSolver::Summary summary;
66 ceres::GradientProblem problem(new Rosenbrock());
67 ceres::Solve(options, problem, parameters, &summary);
69 std::cout << summary.FullReport() << "\n";
70 std::cout << "Initial x: " << -1.2 << " y: " << 1.0 << "\n";
71 std::cout << "Final x: " << parameters[0]
72 << " y: " << parameters[1] << "\n";