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QCaml/common/util.org
2021-01-01 16:39:33 +01:00

688 lines
21 KiB
Org Mode

#+begin_src elisp tangle: no :results none :exports none
(setq pwd (file-name-directory buffer-file-name))
(setq name (file-name-nondirectory (substring buffer-file-name 0 -4)))
(setq lib (concat pwd "lib/"))
(setq testdir (concat pwd "test/"))
(setq mli (concat lib name ".mli"))
(setq ml (concat lib name ".ml"))
(setq c (concat lib name ".c"))
(setq test-ml (concat testdir name ".ml"))
(org-babel-tangle)
#+end_src
* Util
:PROPERTIES:
:header-args: :noweb yes :comments both
:END:
Utility functions.
** Test header :noexport:
#+begin_src ocaml :tangle (eval test-ml) :exports none
open Common.Util
open Alcotest
#+end_src
** External C functions
| ~erf_float~ | Error function ~erf~ from =libm= |
| ~erfc_float~ | Complementary error function ~erfc~ from =libm= |
| ~gamma_float~ | Gamma function ~gamma~ from =libm= |
| ~popcnt~ | ~popcnt~ instruction |
| ~trailz~ | ~ctz~ instruction |
| ~leadz~ | ~bsf~ instruction |
#+begin_src c :tangle (eval c) :exports none
#include <math.h>
#include <caml/mlvalues.h>
#include <caml/alloc.h>
#+end_src
*** Erf
#+begin_src c :tangle (eval c) :exports none
CAMLprim value erf_float_bytecode(value x) {
return copy_double(erf(Double_val(x)));
}
CAMLprim double erf_float(double x) {
return erf(x);
}
#+end_src
#+begin_src ocaml :tangle (eval mli)
external erf_float : float -> float = "erf_float_bytecode" "erf_float" [@@unboxed] [@@noalloc]
#+end_src
#+begin_src ocaml :tangle (eval ml) :exports none
external erf_float : float -> float = "erf_float_bytecode" "erf_float" [@@unboxed] [@@noalloc]
#+end_src
*** Erfc
#+begin_src c :tangle (eval c) :exports none
CAMLprim value erfc_float_bytecode(value x) {
return copy_double(erfc(Double_val(x)));
}
CAMLprim double erfc_float(double x) {
return erfc(x);
}
#+end_src
#+begin_src ocaml :tangle (eval mli)
external erfc_float : float -> float = "erfc_float_bytecode" "erfc_float" [@@unboxed] [@@noalloc]
#+end_src
#+begin_src ocaml :tangle (eval ml) :exports none
external erfc_float : float -> float = "erfc_float_bytecode" "erfc_float" [@@unboxed] [@@noalloc]
#+end_src
*** Gamma
#+begin_src c :tangle (eval c) :exports none
CAMLprim value gamma_float_bytecode(value x) {
return copy_double(tgamma(Double_val(x)));
}
CAMLprim double gamma_float(double x) {
return tgamma(x);
}
#+end_src
#+begin_src ocaml :tangle (eval mli)
external gamma_float : float -> float = "gamma_float_bytecode" "gamma_float" [@@unboxed] [@@noalloc]
#+end_src
#+begin_src ocaml :tangle (eval ml) :exports none
external gamma_float : float -> float = "gamma_float_bytecode" "gamma_float" [@@unboxed] [@@noalloc]
#+end_src
*** Popcnt
#+begin_src c :tangle (eval c) :exports none
CAMLprim int32_t popcnt(int64_t i) {
return __builtin_popcountll (i);
}
CAMLprim value popcnt_bytecode(value i) {
return caml_copy_int32(__builtin_popcountll (Int64_val(i)));
}
#+end_src
#+begin_src ocaml :tangle (eval mli)
val popcnt : int64 -> int
#+end_src
#+begin_src ocaml :tangle (eval ml) :exports none
external popcnt : int64 -> int32 = "popcnt_bytecode" "popcnt"
[@@unboxed] [@@noalloc]
let popcnt i = (popcnt [@inlined] ) i |> Int32.to_int
#+end_src
*** Trailz
#+begin_src c :tangle (eval c) :exports none
CAMLprim int32_t trailz(int64_t i) {
return __builtin_ctzll (i);
}
CAMLprim value trailz_bytecode(value i) {
return caml_copy_int32(__builtin_ctzll (Int64_val(i)));
}
#+end_src
#+begin_src ocaml :tangle (eval mli)
val trailz : int64 -> int
#+end_src
#+begin_src ocaml :tangle (eval ml) :exports none
external trailz : int64 -> int32 = "trailz_bytecode" "trailz" "int"
[@@unboxed] [@@noalloc]
let trailz i = trailz i |> Int32.to_int
#+end_src
*** Leadz
#+begin_src c :tangle (eval c) :exports none
CAMLprim int32_t leadz(int64_t i) {
return __builtin_clzll(i);
}
CAMLprim value leadz_bytecode(value i) {
return caml_copy_int32(__builtin_clzll (Int64_val(i)));
}
#+end_src
#+begin_src ocaml :tangle (eval mli)
val leadz : int64 -> int
#+end_src
#+begin_src ocaml :tangle (eval ml) :exports none
external leadz : int64 -> int32 = "leadz_bytecode" "leadz" "int"
[@@unboxed] [@@noalloc]
let leadz i = leadz i |> Int32.to_int
#+end_src
*** Test
#+begin_src ocaml :tangle (eval test-ml) :exports none
let test_external () =
check (float 1.e-15) "erf" 0.842700792949715 (erf_float 1.0);
check (float 1.e-15) "erf" 0.112462916018285 (erf_float 0.1);
check (float 1.e-15) "erf" (-0.112462916018285) (erf_float (-0.1));
check (float 1.e-15) "erfc" 0.157299207050285 (erfc_float 1.0);
check (float 1.e-15) "erfc" 0.887537083981715 (erfc_float 0.1);
check (float 1.e-15) "erfc" (1.112462916018285) (erfc_float (-0.1));
check (float 1.e-14) "gamma" (1.77245385090552) (gamma_float 0.5);
check (float 1.e-14) "gamma" (9.51350769866873) (gamma_float (0.1));
check (float 1.e-14) "gamma" (-3.54490770181103) (gamma_float (-0.5));
check int "popcnt" 6 (popcnt @@ Int64.of_int 63);
check int "popcnt" 8 (popcnt @@ Int64.of_int 299605);
check int "popcnt" 1 (popcnt @@ Int64.of_int 65536);
check int "popcnt" 0 (popcnt @@ Int64.of_int 0);
check int "trailz" 3 (trailz @@ Int64.of_int 8);
check int "trailz" 2 (trailz @@ Int64.of_int 12);
check int "trailz" 0 (trailz @@ Int64.of_int 1);
check int "trailz" 64 (trailz @@ Int64.of_int 0);
check int "leadz" 60 (leadz @@ Int64.of_int 8);
check int "leadz" 60 (leadz @@ Int64.of_int 12);
check int "leadz" 63 (leadz @@ Int64.of_int 1);
check int "leadz" 64 (leadz @@ Int64.of_int 0);
()
#+end_src
** General functions
#+begin_src ocaml :tangle (eval mli)
val fact : int -> float
(* @raise Invalid_argument for negative arguments or arguments >100. *)
val binom : int -> int -> int
val binom_float : int -> int -> float
val chop : float -> (unit -> float) -> float
val pow : float -> int -> float
val float_of_int_fast : int -> float
val of_some : 'a option -> 'a
exception Not_implemented of string
val not_implemented : string -> 'a
(* @raise Not_implemented. *)
#+end_src
| ~fact~ | Factorial function. |
| ~binom~ | Binomial coefficient. ~binom n k~ = $C_n^k$ |
| ~binom_float~ | float variant of ~binom~ |
| ~pow~ | Fast implementation of the power function for small integer powers |
| ~chop~ | In ~chop a f~, evaluate ~f~ only if the absolute value of ~a~ is larger than ~Constants.epsilon~, and return ~a *. f ()~. |
| ~float_of_int_fast~ | Faster implementation of float_of_int for small positive ints |
| ~not_implemented~ | Fails if some functionality is not implemented |
| ~of_some~ | Extracts the value of an option |
#+begin_src ocaml :tangle (eval ml) :exports none
let memo_float_of_int =
Array.init 64 float_of_int
let float_of_int_fast i =
if Int.logand i 63 = i then
memo_float_of_int.(i)
else
float_of_int i
let factmax = 150
let fact_memo =
let rec aux accu_l accu = function
| 0 -> (aux [@tailcall]) [1.] 1. 1
| i when (i = factmax) ->
let x = (float_of_int factmax) *. accu in
List.rev (x::accu_l)
| i -> let x = (float_of_int i) *. accu in
(aux [@tailcall]) (x::accu_l) x (i+1)
in
aux [] 0. 0
|> Array.of_list
let fact = function
| i when (i < 0) ->
raise (Invalid_argument "Argument of factorial should be non-negative")
| i when (i > 150) ->
raise (Invalid_argument "Result of factorial is infinite")
| i -> fact_memo.(i)
let binom =
let memo =
let m = Array.make_matrix 64 64 0 in
for n=0 to Array.length m - 1 do
m.(n).(0) <- 1;
m.(n).(n) <- 1;
for k=1 to (n - 1) do
m.(n).(k) <- m.(n-1).(k-1) + m.(n-1).(k)
done
done;
m
in
let rec f n k =
assert (k >= 0);
assert (n >= k);
if k = 0 || k = n then
1
else if n < 64 then
memo.(n).(k)
else
f (n-1) (k-1) + f (n-1) k
in f
let binom_float n k =
binom n k
|> float_of_int_fast
let rec pow a = function
| 0 -> 1.
| 1 -> a
| 2 -> a *. a
| 3 -> a *. a *. a
| -1 -> 1. /. a
| n when n > 0 ->
let b = pow a (n / 2) in
b *. b *. (if n mod 2 = 0 then 1. else a)
| n when n < 0 -> (pow [@tailcall]) (1./.a) (-n)
| _ -> assert false
let chop f g =
if (abs_float f) < Constants.epsilon then 0.
else f *. (g ())
exception Not_implemented of string
let not_implemented string =
raise (Not_implemented string)
let of_some = function
| Some a -> a
| None -> assert false
#+end_src
#+begin_src ocaml :tangle (eval test-ml) :exports none
let test_general () =
check int "of_some_of_int_fast" 1 (of_some (Some 1)) ;
check int "binom" 35 (binom 7 4);
check (float 1.e-15) "fact" 5040. (fact 7);
check (float 1.e-15) "binom_float" 35.0 (binom_float 7 4);
check (float 1.e-15) "pow" 729.0 (pow 3.0 6);
check (float 1.e-15) "float_of_int_fast" 10.0 (float_of_int_fast 10);
()
#+end_src
** Functions related to the Boys function
#+begin_src ocaml :tangle (eval mli)
val incomplete_gamma : alpha:float -> float -> float
(* @raise Failure when the calculation doesn't converge. *)
#+end_src
The lower [[https://en.wikipedia.org/wiki/Incomplete_gamma_function][Incomplete Gamma function]] is implemented :
\[
\gamma(\alpha,x) = \int_0^x e^{-t} t^{\alpha-1} dt
\]
p: $\frac{1}{\Gamma(\alpha)} \int_0^x e^{-t} t^{\alpha-1} dt$
q: $\frac{1}{\Gamma(\alpha)} \int_x^\infty e^{-t} t^{\alpha-1} dt$
Reference : Haruhiko Okumura: C-gengo niyoru saishin algorithm jiten
(New Algorithm handbook in C language) (Gijyutsu hyouron sha,
Tokyo, 1991) p.227 [in Japanese]
#+begin_src ocaml :tangle (eval ml) :exports none
let incomplete_gamma ~alpha x =
assert (alpha >= 0.);
assert (x >= 0.);
let a = alpha in
let a_inv = 1./. a in
let gf = gamma_float alpha in
let loggamma_a = log gf in
let rec p_gamma x =
if x >= 1. +. a then 1. -. q_gamma x
else if x = 0. then 0.
else
let rec pg_loop prev res term k =
if k > 1000. then failwith "p_gamma did not converge."
else if prev = res then res
else
let term = term *. x /. (a +. k) in
(pg_loop [@tailcall]) res (res +. term) term (k +. 1.)
in
let r0 = exp (a *. log x -. x -. loggamma_a) *. a_inv in
pg_loop min_float r0 r0 1.
and q_gamma x =
if x < 1. +. a then 1. -. p_gamma x
else
let rec qg_loop prev res la lb w k =
if k > 1000. then failwith "q_gamma did not converge."
else if prev = res then res
else
let k_inv = 1. /. k in
let kma = (k -. 1. -. a) *. k_inv in
let la, lb =
lb, kma *. (lb -. la) +. (k +. x) *. lb *. k_inv
in
let w = w *. kma in
let prev, res = res, res +. w /. (la *. lb) in
(qg_loop [@tailcall]) prev res la lb w (k +. 1.)
in
let w = exp (a *. log x -. x -. loggamma_a) in
let lb = (1. +. x -. a) in
qg_loop min_float (w /. lb) 1. lb w 2.0
in
gf *. p_gamma x
#+end_src
#+begin_src ocaml :tangle (eval mli)
val boys_function : maxm:int -> float -> float array
#+end_src
The [[https://link.springer.com/article/10.1007/s10910-005-9023-3][Generalized Boys function]] is implemented, ~maxm~ is the maximum total angular momentum.
\[
F_m(x) = \frac{\gamma(m+1/2,x)}{2x^{m+1/2}}
\]
where $\gamma$ is the incomplete gamma function.
- $F_0(0.) = 1$
- $F_0(t) = \frac{\sqrt{\pi}}{2\sqrt{t}} \text{erf} ( \sqrt{t} )$
- $F_m(0.) = \frac{1}{2m+1}$
- $F_m(t) = \frac{\gamma{m+1/2,t}}{2t^{m+1/2}}$
- $F_m(t) = \frac{ 2t\, F_{m+1}(t) + e^{-t} }{2m+1}$
#+begin_src ocaml :tangle (eval ml) :exports none
let boys_function ~maxm t =
assert (t >= 0.);
match maxm with
| 0 ->
begin
if t = 0. then [| 1. |] else
let sq_t = sqrt t in
[| (Constants.sq_pi_over_two /. sq_t) *. erf_float sq_t |]
end
| _ ->
begin
assert (maxm > 0);
let result =
Array.init (maxm+1) (fun m -> 1. /. float_of_int (2*m+1))
in
let power_t_inv = (maxm+maxm+1) in
try
let fmax =
let t_inv = sqrt (1. /. t) in
let n = float_of_int maxm in
let dm = 0.5 +. n in
let f = (pow t_inv power_t_inv ) in
match classify_float f with
| FP_normal -> (incomplete_gamma ~alpha:dm t) *. 0.5 *. f
| FP_zero
| FP_subnormal -> 0.
| _ -> raise Exit
in
let emt = exp (-. t) in
result.(maxm) <- fmax;
for n=maxm-1 downto 0 do
result.(n) <- ( (t+.t) *. result.(n+1) +. emt) *. result.(n)
done;
result
with Exit -> result
end
#+end_src
#+begin_src ocaml :tangle (eval test-ml) :exports none
let test_boys () =
check (float 1.e-15) "incomplete_gamma" 0.0 (incomplete_gamma ~alpha:0.5 0.);
check (float 1.e-15) "incomplete_gamma" 1.114707979049507 (incomplete_gamma ~alpha:0.5 0.4);
check (float 1.e-15) "incomplete_gamma" 1.4936482656248544 (incomplete_gamma ~alpha:0.5 1.);
check (float 1.e-15) "incomplete_gamma" 1.7724401246392805 (incomplete_gamma ~alpha:0.5 10.);
check (float 1.e-15) "incomplete_gamma" 1.7724538509055159 (incomplete_gamma ~alpha:0.5 100.);
check (float 1.e-15) "boys" 1.0 (boys_function ~maxm:0 0.).(0);
check (float 1.e-15) "boys" 0.2 (boys_function ~maxm:2 0.).(2);
check (float 1.e-15) "boys" (1./.3.) (boys_function ~maxm:2 0.).(1);
check (float 1.e-15) "boys" 0.8556243918921488 (boys_function ~maxm:0 0.5).(0);
check (float 1.e-15) "boys" 0.14075053682591263 (boys_function ~maxm:2 0.5).(2);
check (float 1.e-15) "boys" 0.00012711171070276764 (boys_function ~maxm:3 15.).(3);
()
#+end_src
** List functions
#+begin_src ocaml :tangle (eval mli)
val list_some : 'a option list -> 'a list
val list_range : int -> int -> int list
val list_pack : int -> 'a list -> 'a list list
#+end_src
| ~list_some~ | Filters out all ~None~ elements of the list, and returns the elements without the ~Some~ |
| ~list_range~ | Creates a list of consecutive integers |
| ~list_pack~ | ~list_pack n l~ Creates a list of ~n~-elements lists |
#+begin_src ocaml :tangle (eval ml) :exports none
let list_some l =
List.filter (function None -> false | _ -> true) l
|> List.rev_map (function Some x -> x | _ -> assert false)
|> List.rev
let list_range first last =
if last < first then [] else
let rec aux accu = function
| 0 -> first :: accu
| i -> (aux [@tailcall]) ( (first+i)::accu ) (i-1)
in
aux [] (last-first)
let list_pack n l =
assert (n>=0);
let rec aux i accu1 accu2 = function
| [] -> if accu1 = [] then
List.rev accu2
else
List.rev ((List.rev accu1) :: accu2)
| a :: rest ->
match i with
| 0 -> (aux [@tailcall]) (n-1) [] ((List.rev (a::accu1)) :: accu2) rest
| _ -> (aux [@tailcall]) (i-1) (a::accu1) accu2 rest
in
aux (n-1) [] [] l
#+end_src
#+begin_src ocaml :tangle (eval test-ml) :exports none
let test_list () =
check bool "list_range" true ([ 2; 3; 4 ] = list_range 2 4);
check bool "list_some" true ([ 2; 3; 4 ] =
list_some ([ None ; Some 2 ; None ; Some 3 ; None ; None ; Some 4]) );
check bool "list_pack" true (list_pack 3 (list_range 1 20) =
[[1; 2; 3]; [4; 5; 6]; [7; 8; 9]; [10; 11; 12]; [13; 14; 15];
[16; 17; 18]; [19; 20]]);
()
#+end_src
** Array functions
#+begin_src ocaml :tangle (eval mli)
val array_range : int -> int -> int array
val array_sum : float array -> float
val array_product : float array -> float
#+end_src
| ~array_range~ | Creates an array of consecutive integers |
| ~array_sum~ | Returns the sum of all the elements of the array |
| ~array_product~ | Returns the product of all the elements of the array |
#+begin_src ocaml :tangle (eval ml) :exports none
let array_range first last =
if last < first then [| |] else
Array.init (last-first+1) (fun i -> i+first)
let array_sum a =
Array.fold_left ( +. ) 0. a
let array_product a =
Array.fold_left ( *. ) 1. a
#+end_src
#+begin_src ocaml :tangle (eval test-ml) :exports none
let test_array () =
check bool "array_range" true ([| 2; 3; 4 |] = array_range 2 4);
check (float 1.e-15) "array_sum" 9. (array_sum [| 2.; 3.; 4. |]);
check (float 1.e-15) "array_product" 24. (array_product [| 2.; 3.; 4. |]);
()
#+end_src
** Stream functions
#+begin_src ocaml :tangle (eval mli)
val stream_range : int -> int -> int Stream.t
val stream_to_list : 'a Stream.t -> 'a list
val stream_fold : ('a -> 'b -> 'a) -> 'a -> 'b Stream.t -> 'a
#+end_src
| ~stream_range~ | Creates a stream returning consecutive integers |
| ~stream_to_list~ | Read a stream and put items in a list |
| ~stream_fold~ | Apply a fold to the elements of the stream |
#+begin_src ocaml :tangle (eval ml) :exports none
let stream_range first last =
Stream.from (fun i ->
let result = i+first in
if result <= last then
Some result
else None
)
let stream_to_list stream =
let rec aux accu =
let new_accu =
try
Some (Stream.next stream :: accu)
with Stream.Failure -> None
in
match new_accu with
| Some new_accu -> (aux [@tailcall]) new_accu
| None -> accu
in List.rev @@ aux []
let stream_fold f init stream =
let rec aux accu =
let new_accu =
try
let element = Stream.next stream in
Some (f accu element)
with Stream.Failure -> None
in
match new_accu with
| Some new_accu -> (aux [@tailcall]) new_accu
| None -> accu
in
aux init
#+end_src
** Printers
#+begin_src ocaml :tangle (eval mli)
val pp_float_array_size : Format.formatter -> float array -> unit
val pp_float_array : Format.formatter -> float array -> unit
val pp_float_2darray_size : Format.formatter -> float array array -> unit
val pp_float_2darray : Format.formatter -> float array array -> unit
val pp_bitstring : int -> Format.formatter -> Z.t -> unit
#+end_src
| ~pp_float_array~ | Printer for float arrays |
| ~pp_float_array_size~ | Printer for float arrays with size |
| ~pp_float_2darray~ | Printer for matrices |
| ~pp_float_2darray_size~ | Printer for matrices with size |
| ~pp_bitstring~ | Printer for bit strings (used by ~Bitstring~ module) |
#+begin_example
pp_float_array_size:
[ 6: 1.000000 1.732051 1.732051 1.000000 1.732051 1.000000 ]
pp_float_array:
[ 1.000000 1.732051 1.732051 1.000000 1.732051 1.000000 ]
pp_float_2darray_size
[
2:[ 6: 1.000000 1.732051 1.732051 1.000000 1.732051 1.000000 ]
[ 4: 1.000000 2.000000 3.000000 4.000000 ] ]
pp_float_2darray:
[ [ 1.000000 1.732051 1.732051 1.000000 1.732051 1.000000 ]
[ 1.000000 2.000000 3.000000 4.000000 ] ]
pp_bitstring 14:
+++++------+--
#+end_example
#+begin_src ocaml :tangle (eval ml) :exports none
let pp_float_array ppf a =
Format.fprintf ppf "@[<2>[@ ";
Array.iter (fun f -> Format.fprintf ppf "@[%10f@]@ " f) a;
Format.fprintf ppf "]@]"
let pp_float_array_size ppf a =
Format.fprintf ppf "@[<2>@[ %d:@[<2>" (Array.length a);
Array.iter (fun f -> Format.fprintf ppf "@[%10f@]@ " f) a;
Format.fprintf ppf "]@]@]"
let pp_float_2darray ppf a =
Format.fprintf ppf "@[<2>[@ ";
Array.iter (fun f -> Format.fprintf ppf "@[%a@]@ " pp_float_array f) a;
Format.fprintf ppf "]@]"
let pp_float_2darray_size ppf a =
Format.fprintf ppf "@[<2>@[ %d:@[" (Array.length a);
Array.iter (fun f -> Format.fprintf ppf "@[%a@]@ " pp_float_array_size f) a;
Format.fprintf ppf "]@]@]"
let pp_bitstring n ppf bs =
String.init n (fun i -> if (Z.testbit bs i) then '+' else '-')
|> Format.fprintf ppf "@[<h>%s@]"
#+end_src
** Test footer :noexport:
#+begin_src ocaml :tangle (eval test-ml) :exports none
let tests = [
"External", `Quick, test_external;
"General" , `Quick, test_general;
"Boys" , `Quick, test_boys;
"List" , `Quick, test_list;
"Array" , `Quick, test_array;
]
#+end_src