GSL求根

发布时间:2016-12-10 5:35:37 编辑:www.fx114.net 分享查询网我要评论
本篇文章主要介绍了"GSL求根",主要涉及到GSL求根方面的内容,对于GSL求根感兴趣的同学可以参考一下。

demo_fn.h#ifndef ___DEMO_FN_HHH_HH_H_ #define ___DEMO_FN_HHH_HH_H_ struct quadratic_params { double a, b, c; }; double quadratic (double x, void *params); double quadratic_deriv (double x, void *params); void quadratic_fdf (double x, void *params, double *y, double *dy); #endifdemo_fn.c#include "demo_fn.h" double quadratic (double x, void *params) { struct quadratic_params *p = (struct quadratic_params *) params; double a = p->a; double b = p->b; double c = p->c; return (a * x + b) * x + c; } double quadratic_deriv (double x, void *params) { struct quadratic_params *p = (struct quadratic_params *) params; double a = p->a; double b = p->b; double c = p->c; return 2.0 * a * x + b; } void quadratic_fdf (double x, void *params, double *y, double *dy) { struct quadratic_params *p = (struct quadratic_params *) params; double a = p->a; double b = p->b; double c = p->c; *y = (a * x + b) * x + c; *dy = 2.0 * a * x + b; }main.c#include <stdio.h> #include <gsl/gsl_errno.h> #include <gsl/gsl_math.h> #include <gsl/gsl_roots.h> #include "demo_fn.h" // #include "demo_fn.c" #pragma comment(lib, "libgsl_d.lib") #pragma comment(lib, "libgslcblas_d.lib") int main (void) { int status; int iter = 0, max_iter = 100; const gsl_root_fsolver_type *T; gsl_root_fsolver *s; double r = 0, r_expected = sqrt (5.0); double x_lo = 0.0, x_hi = 5.0; gsl_function F; struct quadratic_params params = {1.0, 0.0, -5.0}; F.function = &quadratic; F.params = ¶ms; T = gsl_root_fsolver_brent; s = gsl_root_fsolver_alloc (T); gsl_root_fsolver_set (s, &F, x_lo, x_hi); printf ("using %s method\n", gsl_root_fsolver_name (s)); printf ("%5s [%9s, %9s] %9s %10s %9s\n", "iter", "lower", "upper", "root", "err", "err(est)"); do { iter++; status = gsl_root_fsolver_iterate (s); r = gsl_root_fsolver_root (s); x_lo = gsl_root_fsolver_x_lower (s); x_hi = gsl_root_fsolver_x_upper (s); status = gsl_root_test_interval (x_lo, x_hi, 0, 0.001); if (status == GSL_SUCCESS) printf ("Converged:\n"); printf ("%5d [%.7f, %.7f] %.7f %+.7f %.7f\n", iter, x_lo, x_hi, r, r - r_expected, x_hi - x_lo); } while (status == GSL_CONTINUE && iter < max_iter); return status; }

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