1// Ceres Solver - A fast non-linear least squares minimizer
2// Copyright 2010, 2011, 2012 Google Inc. All rights reserved.
3// http://code.google.com/p/ceres-solver/
4//
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6// modification, are permitted provided that the following conditions are met:
7//
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28//
29// Author: keir@google.com (Keir Mierle)
30//
31// A simple example of using the Ceres minimizer.
32//
33// Minimize 0.5 (10 - x)^2 using jacobian matrix computed using
34// automatic differentiation.
35
36#include <vector>
37#include "ceres/ceres.h"
38#include "gflags/gflags.h"
39#include "glog/logging.h"
40
41using ceres::AutoDiffCostFunction;
42using ceres::CostFunction;
43using ceres::Problem;
44using ceres::Solver;
45using ceres::Solve;
46
47// A templated cost functor that implements the residual r = 10 -
48// x. The method operator() is templated so that we can then use an
49// automatic differentiation wrapper around it to generate its
50// derivatives.
51class QuadraticCostFunctor {
52 public:
53  template <typename T> bool operator()(const T* const x, T* residual) const {
54    residual[0] = T(10.0) - x[0];
55    return true;
56  }
57};
58
59int main(int argc, char** argv) {
60  google::ParseCommandLineFlags(&argc, &argv, true);
61  google::InitGoogleLogging(argv[0]);
62
63  // The variable to solve for with its initial value.
64  double initial_x = 5.0;
65  double x = initial_x;
66
67  // Build the problem.
68  Problem problem;
69
70  // Set up the only cost function (also known as residual). This uses
71  // auto-differentiation to obtain the derivative (jacobian).
72  problem.AddResidualBlock(
73      new AutoDiffCostFunction<QuadraticCostFunctor, 1, 1>(
74          new QuadraticCostFunctor),
75      NULL,
76      &x);
77
78  // Run the solver!
79  Solver::Options options;
80  options.max_num_iterations = 10;
81  options.linear_solver_type = ceres::DENSE_QR;
82  options.minimizer_progress_to_stdout = true;
83  Solver::Summary summary;
84  Solve(options, &problem, &summary);
85  std::cout << summary.BriefReport() << "\n";
86  std::cout << "x : " << initial_x
87            << " -> " << x << "\n";
88  return 0;
89}
90