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let _ =
Gsl_error.init ()
let quad a b c x =
(* Gc.major () ; *)
(a *. x +. b) *. x +. c
let quad_deriv a b x =
2. *. a *. x +. b
let quad_fdf a b c x =
let y = (a *. x +. b) *. x +. c in
let dy = 2. *. a *. x +. b in
(y, dy)
let (a, b, c) = (1., 0., -5.0)
let r_expected = sqrt 5.0
open Gsl_root.Bracket
let find_f ?(max_iter=100) s =
Printf.printf "\nusing %s method\n" (name s) ;
Printf.printf "%5s [%9s, %9s] %9s %10s %9s\n"
"iter" "lower" "upper" "root" "err" "err(est)" ;
let rec proc i = function
| true -> ()
| _ when i >= max_iter -> ()
| _ ->
iterate s ;
let r = root s in
let (x_lo, x_hi) = interval s in
let status = Gsl_root.test_interval x_lo x_hi 0. 0.001 in
if status
then Printf.printf "Converged:\n" ;
Printf.printf "%5d [%.7f, %.7f] %.7f %+.7f %.7f\n"
i x_lo x_hi r (r -. r_expected) (x_hi -. x_lo) ;
proc (succ i) status
in
proc 1 false
open Gsl_root.Polish
let find_fdf ?(max_iter=100) s x_init =
Printf.printf "\nusing %s method\n" (name s) ;
Printf.printf "%-5s %10s %10s %10s\n"
"iter" "root" "err" "err(est)" ;
let rec proc i x0 = function
| true -> ()
| _ when i >= max_iter -> ()
| _ ->
iterate s ;
let x = root s in
let status = Gsl_root.test_delta x x0 0. 1e-3 in
if status
then Printf.printf "Converged:\n" ;
Printf.printf "%5d %10.7f %+10.7f %10.7f\n"
i x (x -. r_expected) (x -. x0) ;
proc (succ i) x status
in
proc 1 x_init false
let _ =
let gslfun = quad a b c in
List.iter
(fun t ->
let s = Gsl_root.Bracket.make t gslfun 0. 5. in
find_f s)
[ Gsl_root.Bracket.BISECTION ;
Gsl_root.Bracket.FALSEPOS ;
Gsl_root.Bracket.BRENT ]
let _ =
print_newline () ;
flush stdout
let _ =
let gslfun_fdf = {
Gsl_fun.f = quad a b c ;
Gsl_fun.df = quad_deriv a b ;
Gsl_fun.fdf = quad_fdf a b c ; } in
List.iter
(fun t ->
let s = Gsl_root.Polish.make t gslfun_fdf 5. in
find_fdf s 5.)
[ Gsl_root.Polish.NEWTON ;
Gsl_root.Polish.SECANT ;
Gsl_root.Polish.STEFFENSON ]
|
