| /* Ceres Solver - A fast non-linear least squares minimizer |
| * Copyright 2015 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: mierle@gmail.com (Keir Mierle) |
| * |
| * This is a port of curve_fitting.cc to the minimal C API for Ceres. |
| */ |
| |
| #include <math.h> |
| #include <stdio.h> |
| #include <string.h> // For NULL |
| #include "ceres/c_api.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']; |
| * |
| */ |
| |
| int num_observations = 67; |
| 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, |
| }; |
| |
| /* This is the equivalent of a use-defined CostFunction in the C++ Ceres API. |
| * This is passed as a callback to the Ceres C API, which internally converts |
| * the callback into a CostFunction. */ |
| int exponential_residual(void* user_data, |
| double** parameters, |
| double* residuals, |
| double** jacobians) { |
| double* measurement = (double*) user_data; |
| double x = measurement[0]; |
| double y = measurement[1]; |
| double m = parameters[0][0]; |
| double c = parameters[1][0]; |
| |
| residuals[0] = y - exp(m * x + c); |
| if (jacobians == NULL) { |
| return 1; |
| } |
| if (jacobians[0] != NULL) { |
| jacobians[0][0] = - x * exp(m * x + c); /* dr/dm */ |
| } |
| if (jacobians[1] != NULL) { |
| jacobians[1][0] = - exp(m * x + c); /* dr/dc */ |
| } |
| return 1; |
| } |
| |
| int main(int argc, char** argv) { |
| /* Note: Typically it is better to compact m and c into one block, |
| * but in this case use separate blocks to illustrate the use of |
| * multiple parameter blocks. */ |
| double m = 0.0; |
| double c = 0.0; |
| |
| double *parameter_pointers[] = { &m, &c }; |
| int parameter_sizes[] = { 1, 1 }; |
| int i; |
| |
| ceres_problem_t* problem; |
| |
| /* Ceres has some internal stuff that needs to get initialized. */ |
| ceres_init(); |
| |
| problem = ceres_create_problem(); |
| |
| /* Add all the residuals. */ |
| for (i = 0; i < num_observations; ++i) { |
| ceres_problem_add_residual_block( |
| problem, |
| exponential_residual, /* Cost function */ |
| &data[2 * i], /* Points to the (x,y) measurement */ |
| NULL, /* No loss function */ |
| NULL, /* No loss function user data */ |
| 1, /* Number of residuals */ |
| 2, /* Number of parameter blocks */ |
| parameter_sizes, |
| parameter_pointers); |
| } |
| |
| ceres_solve(problem); |
| ceres_free_problem(problem); |
| |
| printf("Initial m: 0.0, c: 0.0\n"); |
| printf("Final m: %g, c: %g\n", m, c); |
| return 0; |
| } |