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curve_fit.cpp
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curve_fit.cpp
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#include "curve_fit.hpp"
auto internal_solve_system(gsl_vector* initial_params, gsl_multifit_nlinear_fdf *fdf,
gsl_multifit_nlinear_parameters *params) -> std::vector<double>
{
// This specifies a trust region method
const gsl_multifit_nlinear_type *T = gsl_multifit_nlinear_trust;
const size_t max_iter = 200;
const double xtol = 1.0e-8;
const double gtol = 1.0e-8;
const double ftol = 1.0e-8;
auto *work = gsl_multifit_nlinear_alloc(T, params, fdf->n, fdf->p);
int info;
// initialize solver
gsl_multifit_nlinear_init(initial_params, fdf, work);
//iterate until convergence
gsl_multifit_nlinear_driver(max_iter, xtol, gtol, ftol, nullptr, nullptr, &info, work);
// result will be stored here
gsl_vector * y = gsl_multifit_nlinear_position(work);
auto result = std::vector<double>(initial_params->size);
for(int i = 0; i < result.size(); i++)
{
result[i] = gsl_vector_get(y, i);
}
auto niter = gsl_multifit_nlinear_niter(work);
auto nfev = fdf->nevalf;
auto njev = fdf->nevaldf;
auto naev = fdf->nevalfvv;
// nfev - number of function evaluations
// njev - number of Jacobian evaluations
// naev - number of f_vv evaluations
//logger::debug("curve fitted after ", niter, " iterations {nfev = ", nfev, "} {njev = ", njev, "} {naev = ", naev, "}");
gsl_multifit_nlinear_free(work);
gsl_vector_free(initial_params);
return result;
}
auto internal_make_gsl_vector_ptr(const std::vector<double>& vec) -> gsl_vector*
{
auto* result = gsl_vector_alloc(vec.size());
int i = 0;
for(const auto e: vec)
{
gsl_vector_set(result, i, e);
i++;
}
return result;
}