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QCaml/Utils/Util.ml

442 lines
11 KiB
OCaml

(** All utilities which should be included in all source files are defined here *)
(** {1 Functions from libm} *)
open Constants
open Lacaml.D
let factmax = 150
external erf_float : float -> float = "erf_float_bytecode" "erf_float"
[@@unboxed] [@@noalloc]
external erfc_float : float -> float = "erfc_float_bytecode" "erfc_float"
[@@unboxed] [@@noalloc]
external gamma_float : float -> float = "gamma_float_bytecode" "gamma_float"
[@@unboxed] [@@noalloc]
external popcnt : int64 -> int32 = "popcnt_bytecode" "popcnt"
[@@unboxed] [@@noalloc]
(** popcnt instruction *)
let popcnt i = popcnt i |> Int32.to_int
external trailz : int64 -> int32 = "trailz_bytecode" "trailz"
[@@unboxed] [@@noalloc]
(** ctz instruction *)
let trailz i = trailz i |> Int32.to_int
external leadz : int64 -> int32 = "leadz_bytecode" "leadz"
[@@unboxed] [@@noalloc]
(** bsf instruction *)
let leadz i = leadz i |> Int32.to_int
(* Incomplete gamma function : Int_0^x exp(-t) t^(a-1) dt
p: 1 / Gamma(a) * Int_0^x exp(-t) t^(a-1) dt
q: 1 / Gamma(a) * Int_x^inf exp(-t) t^(a-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] *)
let incomplete_gamma ~alpha x =
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 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 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
let fact_memo =
let rec aux accu_l accu = function
| 0 -> aux [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 (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 n k =
(*TODO : slow function *)
assert (n >= k);
let rec aux n k =
if k = 0 || k = n then
1
else
aux (n-1) (k-1) + aux (n-1) k
in aux n k
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 (1./.a) (-n)
| _ -> assert false
let chop f g =
if (abs_float f) < Constants.epsilon then 0.
else f *. (g ())
(** Generalized Boys function.
maxm : Maximum total angular momentum
*)
let boys_function ~maxm t =
match maxm with
| 0 ->
begin
if t = 0. then [| 1. |] else
let sq_t = sqrt t in
[| (sq_pi_over_two /. sq_t) *. erf_float sq_t |]
end
| _ ->
begin
let result =
Array.init (maxm+1) (fun m -> 1. /. float_of_int (2*m+1))
in
(*
assert (abs_float t > 1.e-10);
*)
if t <> 0. then
begin
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 (maxm+maxm+1) ) in
match classify_float f with
| FP_zero
| FP_subnormal
| FP_normal ->
(incomplete_gamma dm t) *. 0.5 *. f
| _ -> invalid_arg "zero_m overflow"
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
end;
result
end
let of_some = function
| Some a -> a
| None -> assert false
(** {2 List functions} *)
let list_some l =
List.filter (function None -> false | _ -> true) l
|> List.map (function Some x -> x | _ -> assert false)
let list_range first last =
if last < first then [] else
let rec aux accu = function
| 0 -> first :: accu
| i -> aux ( (first+i)::accu ) (i-1)
in
aux [] (last-first)
let list_pack n l =
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 (n-1) [] ((List.rev (a::accu1)) :: accu2) rest
| _ -> aux (i-1) (a::accu1) accu2 rest
in
aux (n-1) [] [] l
(** {2 Stream functions} *)
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 =
try aux (Stream.next stream :: accu) with
Stream.Failure -> List.rev accu
in aux []
(** {2 Linear algebra} *)
let array_sum a =
Array.fold_left ( +. ) 0. a
let array_product a =
Array.fold_left ( *. ) 0. a
let diagonalize_symm m_H =
let m_V = lacpy m_H in
let result =
syevd ~vectors:true m_V
in
m_V, result
let xt_o_x ~o ~x =
gemm o x
|> gemm ~transa:`T x
let x_o_xt ~o ~x =
gemm o x ~transb:`T
|> gemm x
let canonical_ortho ?thresh:(thresh=1.e-6) ~overlap c =
let d, u, _ = gesvd (lacpy overlap) in
let d_sqrt = Vec.sqrt d in
let n = (* Number of non-negligible singular vectors *)
Vec.fold (fun accu x -> if x > thresh then accu + 1 else accu) 0 d
in
let d_inv_sq = (* D^{-1/2} *)
Vec.map (fun x ->
if x >= thresh then 1. /. x
else 0. ) ~y:d d_sqrt
in
if n < Vec.dim d_sqrt then
Printf.printf "Removed linear dependencies below %f\n" (1. /. d.{n})
;
Mat.scal_cols u d_inv_sq ;
gemm c u
let qr_ortho m =
(** Performed twice for precision *)
let result = lacpy m in
let tau = geqrf result in
orgqr ~tau result;
let tau = geqrf result in
orgqr ~tau result;
result
let normalize v =
let result = copy v in
scal (1. /. (nrm2 v)) result;
result
let normalize_mat m =
Mat.to_col_vecs m
|> Array.map (fun v -> normalize v)
|> Mat.of_col_vecs
(** {2 Bitstring functions} *)
let bit_permtutations m n =
let rec aux k u rest =
if k=1 then
List.rev (u :: rest)
else
let t = Z.(logor u (u-one)) in
let t' = Z.(t+one) in
let t'' = Z.(shift_right ((logand (lognot t) t') - one)) (Z.trailing_zeros u + 1) in
aux (k-1) (Z.logor t' t'') (u :: rest)
in
aux (binom n m) Z.(shift_left one m - one) []
(** {2 Printers} *)
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_array ppf a =
Format.fprintf ppf "@[<2>[@ ";
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_matrix ppf m =
let open Lacaml.Io in
let rows = Mat.dim1 m
and cols = Mat.dim2 m
in
let rec aux first last =
if (first <= last) then begin
Format.fprintf ppf "@[\n\n %a@]@ " (Lacaml.Io.pp_lfmat
~row_labels:
(Array.init rows (fun i -> Printf.sprintf "%d " (i + 1)))
~col_labels:
(Array.init (min 5 (cols-first+1)) (fun i -> Printf.sprintf "-- %d --" (i + first) ))
~print_right:false
~print_foot:false
() ) (lacpy ~ac:first ~n:(min 5 (cols-first+1)) m);
aux (first+5) last
end
in
aux 1 cols
let pp_bitstring n ppf bs =
String.init n (fun i -> if (Z.testbit bs i) then '+' else '-')
|> Format.fprintf ppf "@[<h>%s@]"
let string_of_matrix m =
Format.asprintf "%a" pp_matrix m
let debug_matrix name a =
Format.printf "@[%s =\n@[%a@]@]@ " name pp_matrix a
let matrix_of_file filename =
let ic = Scanf.Scanning.open_in filename in
let rec read_line accu =
let result =
try
Some (Scanf.bscanf ic " %d %d %f" (fun i j v ->
(i,j,v) :: accu))
with End_of_file -> None
in
match result with
| Some accu -> read_line accu
| None -> List.rev accu
in
let data = read_line [] in
Scanf.Scanning.close_in ic;
let isize, jsize =
List.fold_left (fun (accu_i,accu_j) (i,j,v) ->
(max i accu_i, max j accu_j)) (0,0) data
in
let result =
Lacaml.D.Mat.of_array
(Array.make_matrix isize jsize 0.)
in
List.iter (fun (i,j,v) -> result.{i,j} <- v) data;
result
let sym_matrix_of_file filename =
let result =
matrix_of_file filename
in
for j=1 to Mat.dim1 result do
for i=1 to j do
result.{j,i} <- result.{i,j}
done;
done;
result
let test_case () =
let test_external () =
Alcotest.(check (float 1.e-15)) "erf" 0.842700792949715 (erf_float 1.0);
Alcotest.(check (float 1.e-15)) "erf" 0.112462916018285 (erf_float 0.1);
Alcotest.(check (float 1.e-15)) "erf" (-0.112462916018285) (erf_float (-0.1));
Alcotest.(check (float 1.e-15)) "erfc" 0.157299207050285 (erfc_float 1.0);
Alcotest.(check (float 1.e-15)) "erfc" 0.887537083981715 (erfc_float 0.1);
Alcotest.(check (float 1.e-15)) "erfc" (1.112462916018285) (erfc_float (-0.1));
Alcotest.(check (float 1.e-14)) "gamma" (1.77245385090552) (gamma_float 0.5);
Alcotest.(check (float 1.e-14)) "gamma" (9.51350769866873) (gamma_float (0.1));
Alcotest.(check (float 1.e-14)) "gamma" (-3.54490770181103) (gamma_float (-0.5));
Alcotest.(check int) "popcnt" 6 (popcnt @@ Int64.of_int 63);
Alcotest.(check int) "popcnt" 8 (popcnt @@ Int64.of_int 299605);
Alcotest.(check int) "popcnt" 1 (popcnt @@ Int64.of_int 65536);
Alcotest.(check int) "popcnt" 0 (popcnt @@ Int64.of_int 0);
in
[
"External", `Quick, test_external;
]