Add an example for IterationCallback
iteration_callback_example.cc uses the curve_fitting.cc example
and uses a custom IterationCallback to log the values of the
parameter blocks are they change over the course of the optimization.
Change-Id: I6a478a8418e237aff576ca627d9b5c0b751b8088
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index 8807cd4..3be34a1 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -75,6 +75,9 @@
add_executable(bicubic_interpolation_analytic bicubic_interpolation_analytic.cc)
target_link_libraries(bicubic_interpolation_analytic PRIVATE Ceres::ceres)
+add_executable(iteration_callback_example iteration_callback_example.cc)
+target_link_libraries(iteration_callback_example PRIVATE Ceres::ceres)
+
if (GFLAGS)
add_executable(powell powell.cc)
target_link_libraries(powell PRIVATE Ceres::ceres gflags)
diff --git a/examples/iteration_callback_example.cc b/examples/iteration_callback_example.cc
new file mode 100644
index 0000000..2e8a2fb
--- /dev/null
+++ b/examples/iteration_callback_example.cc
@@ -0,0 +1,192 @@
+// Ceres Solver - A fast non-linear least squares minimizer
+// Copyright 2023 Google Inc. All rights reserved.
+// http://ceres-solver.org/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// * Redistributions of source code must retain the above copyright notice,
+// this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above copyright notice,
+// this list of conditions and the following disclaimer in the documentation
+// and/or other materials provided with the distribution.
+// * Neither the name of Google Inc. nor the names of its contributors may be
+// used to endorse or promote products derived from this software without
+// specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+//
+// Author: sameeragarwal@google.com (Sameer Agarwal)
+
+#include "ceres/ceres.h"
+#include "glog/logging.h"
+
+// Data generated using the following octave code.
+// randn('seed', 23497);
+// m = 0.3;
+// c = 0.1;
+// x=[0:0.075:5];
+// y = exp(m * x + c);
+// noise = randn(size(x)) * 0.2;
+// y_observed = y + noise;
+// data = [x', y_observed'];
+
+const int kNumObservations = 67;
+// clang-format off
+const double data[] = {
+ 0.000000e+00, 1.133898e+00,
+ 7.500000e-02, 1.334902e+00,
+ 1.500000e-01, 1.213546e+00,
+ 2.250000e-01, 1.252016e+00,
+ 3.000000e-01, 1.392265e+00,
+ 3.750000e-01, 1.314458e+00,
+ 4.500000e-01, 1.472541e+00,
+ 5.250000e-01, 1.536218e+00,
+ 6.000000e-01, 1.355679e+00,
+ 6.750000e-01, 1.463566e+00,
+ 7.500000e-01, 1.490201e+00,
+ 8.250000e-01, 1.658699e+00,
+ 9.000000e-01, 1.067574e+00,
+ 9.750000e-01, 1.464629e+00,
+ 1.050000e+00, 1.402653e+00,
+ 1.125000e+00, 1.713141e+00,
+ 1.200000e+00, 1.527021e+00,
+ 1.275000e+00, 1.702632e+00,
+ 1.350000e+00, 1.423899e+00,
+ 1.425000e+00, 1.543078e+00,
+ 1.500000e+00, 1.664015e+00,
+ 1.575000e+00, 1.732484e+00,
+ 1.650000e+00, 1.543296e+00,
+ 1.725000e+00, 1.959523e+00,
+ 1.800000e+00, 1.685132e+00,
+ 1.875000e+00, 1.951791e+00,
+ 1.950000e+00, 2.095346e+00,
+ 2.025000e+00, 2.361460e+00,
+ 2.100000e+00, 2.169119e+00,
+ 2.175000e+00, 2.061745e+00,
+ 2.250000e+00, 2.178641e+00,
+ 2.325000e+00, 2.104346e+00,
+ 2.400000e+00, 2.584470e+00,
+ 2.475000e+00, 1.914158e+00,
+ 2.550000e+00, 2.368375e+00,
+ 2.625000e+00, 2.686125e+00,
+ 2.700000e+00, 2.712395e+00,
+ 2.775000e+00, 2.499511e+00,
+ 2.850000e+00, 2.558897e+00,
+ 2.925000e+00, 2.309154e+00,
+ 3.000000e+00, 2.869503e+00,
+ 3.075000e+00, 3.116645e+00,
+ 3.150000e+00, 3.094907e+00,
+ 3.225000e+00, 2.471759e+00,
+ 3.300000e+00, 3.017131e+00,
+ 3.375000e+00, 3.232381e+00,
+ 3.450000e+00, 2.944596e+00,
+ 3.525000e+00, 3.385343e+00,
+ 3.600000e+00, 3.199826e+00,
+ 3.675000e+00, 3.423039e+00,
+ 3.750000e+00, 3.621552e+00,
+ 3.825000e+00, 3.559255e+00,
+ 3.900000e+00, 3.530713e+00,
+ 3.975000e+00, 3.561766e+00,
+ 4.050000e+00, 3.544574e+00,
+ 4.125000e+00, 3.867945e+00,
+ 4.200000e+00, 4.049776e+00,
+ 4.275000e+00, 3.885601e+00,
+ 4.350000e+00, 4.110505e+00,
+ 4.425000e+00, 4.345320e+00,
+ 4.500000e+00, 4.161241e+00,
+ 4.575000e+00, 4.363407e+00,
+ 4.650000e+00, 4.161576e+00,
+ 4.725000e+00, 4.619728e+00,
+ 4.800000e+00, 4.737410e+00,
+ 4.875000e+00, 4.727863e+00,
+ 4.950000e+00, 4.669206e+00,
+};
+// clang-format on
+
+struct ExponentialResidual {
+ ExponentialResidual(double x, double y) : x_(x), y_(y) {}
+
+ template <typename T>
+ bool operator()(const T* const m, const T* const c, T* residual) const {
+ residual[0] = y_ - exp(m[0] * x_ + c[0]);
+ return true;
+ }
+
+ private:
+ const double x_;
+ const double y_;
+};
+
+// MyIterationCallback prints the iteration number, the cost and the value of
+// the parameter blocks every iteration.
+class MyIterationCallback : public ceres::IterationCallback {
+ public:
+ MyIterationCallback(const double* m, const double* c) : m_(m), c_(c) {}
+
+ ~MyIterationCallback() = default;
+
+ ceres::CallbackReturnType operator()(
+ const ceres::IterationSummary& summary) final {
+ std::cout << "Iteration: " << summary.iteration << " cost: " << summary.cost
+ << " m: " << *m_ << " c: " << *c_ << std::endl;
+ return ceres::SOLVER_CONTINUE;
+ }
+
+ private:
+ const double* m_ = nullptr;
+ const double* c_ = nullptr;
+};
+
+int main(int argc, char** argv) {
+ google::InitGoogleLogging(argv[0]);
+
+ const double initial_m = 0.0;
+ const double initial_c = 0.0;
+
+ double m = initial_m;
+ double c = initial_c;
+
+ ceres::Problem problem;
+ for (int i = 0; i < kNumObservations; ++i) {
+ problem.AddResidualBlock(
+ new ceres::AutoDiffCostFunction<ExponentialResidual, 1, 1, 1>(
+ new ExponentialResidual(data[2 * i], data[2 * i + 1])),
+ nullptr,
+ &m,
+ &c);
+ }
+
+ ceres::Solver::Options options;
+ options.max_num_iterations = 25;
+ options.linear_solver_type = ceres::DENSE_QR;
+
+ // Turn off the default logging from Ceres so that it does not interfere with
+ // MyIterationCallback.
+ options.minimizer_progress_to_stdout = false;
+
+ MyIterationCallback callback(&m, &c);
+ options.callbacks.push_back(&callback);
+
+ // Tell Ceres to update the value of the parameter blocks on each each
+ // iteration (successful or not) so that MyIterationCallback will be able to
+ // see them when called.
+ options.update_state_every_iteration = true;
+
+ ceres::Solver::Summary summary;
+ ceres::Solve(options, &problem, &summary);
+ std::cout << summary.BriefReport() << "\n";
+ std::cout << "Initial m: " << initial_m << " c: " << initial_c << "\n";
+ std::cout << "Final m: " << m << " c: " << c << "\n";
+ return 0;
+}
