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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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 analytic jacobian matrix.
34
35 #include <vector>
36 #include "ceres/ceres.h"
37 #include "gflags/gflags.h"
38 #include "glog/logging.h"
39
40 using ceres::SizedCostFunction;
41 using ceres::Problem;
42 using ceres::Solver;
43 using ceres::Solve;
44
45 class SimpleCostFunction
46 : public SizedCostFunction<1 /* number of residuals */,
47 1 /* size of first parameter */> {
48 public:
~SimpleCostFunction()49 virtual ~SimpleCostFunction() {}
Evaluate(double const * const * parameters,double * residuals,double ** jacobians) const50 virtual bool Evaluate(double const* const* parameters,
51 double* residuals,
52 double** jacobians) const {
53 double x = parameters[0][0];
54
55 // f(x) = 10 - x.
56 residuals[0] = 10 - x;
57
58 // f'(x) = -1. Since there's only 1 parameter and that parameter
59 // has 1 dimension, there is only 1 element to fill in the
60 // jacobians.
61 if (jacobians != NULL && jacobians[0] != NULL) {
62 jacobians[0][0] = -1;
63 }
64 return true;
65 }
66 };
67
main(int argc,char ** argv)68 int main(int argc, char** argv) {
69 google::ParseCommandLineFlags(&argc, &argv, true);
70 google::InitGoogleLogging(argv[0]);
71
72 // The variable with its initial value that we will be solving for.
73 double x = 5.0;
74
75 // Build the problem.
76 Problem problem;
77 // Set up the only cost function (also known as residual).
78 problem.AddResidualBlock(new SimpleCostFunction, NULL, &x);
79
80 // Run the solver!
81 Solver::Options options;
82 options.max_num_iterations = 10;
83 options.linear_solver_type = ceres::DENSE_QR;
84 options.minimizer_progress_to_stdout = true;
85 Solver::Summary summary;
86 Solve(options, &problem, &summary);
87 std::cout << summary.BriefReport() << "\n";
88 std::cout << "x : 5.0 -> " << x << "\n";
89 return 0;
90 }
91