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(******************************************************************************
* Core *
* *
* Copyright (C) 2008- Jane Street Holding, LLC *
* Contact: opensource@janestreet.com *
* WWW: http://www.janestreet.com/ocaml *
* *
* *
* This library is free software; you can redistribute it and/or *
* modify it under the terms of the GNU Lesser General Public *
* License as published by the Free Software Foundation; either *
* version 2 of the License, or (at your option) any later version. *
* *
* This library is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this library; if not, write to the Free Software *
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA *
* *
******************************************************************************)
open Core.Std
open OUnit
let () = Random.self_init ()
(* round:
... <-)[-><-)[-><-)[-><-)[-><-)[-><-)[-> ...
... -+-----+-----+-----+-----+-----+-----+- ...
... -3 -2 -1 0 1 2 3 ...
so round x -. x should be in (-0.5,0.5]
*)
let round_test x =
let y = Float.round x in
-0.5 < y -. x && y -. x <= 0.5
(* Float.iround built so this should always be true *)
let iround_test x =
let y = Float.iround x in
match y with
| None -> true
| Some y ->
let y = float_of_int y in
-0.5 < y -. x && y -. x <= 0.5
(* round_down:
... )[<---)[<---)[<---)[<---)[<---)[<---)[ ...
... -+-----+-----+-----+-----+-----+-----+- ...
... -3 -2 -1 0 1 2 3 ...
so x -. round_down x should be in [0,1)
*)
let round_down_test x =
let y = Float.round_down x in
match y with
| None -> true
| Some y ->
let y = float_of_int y in
0. <= x -. y && x -. y < 1.
(* round_up:
... ](--->](--->](--->](--->](--->](--->]( ...
... -+-----+-----+-----+-----+-----+-----+- ...
... -3 -2 -1 0 1 2 3 ...
so round_up x -. x should be in [0,1)
*)
let round_up_test x =
let y = Float.round_up x in
match y with
| None -> true
| Some y ->
let y = float_of_int y in
0. <= y -. x && y -. x < 1.
(* round_towards_zero:
... ](--->](--->](---><--->)[<---)[<---)[ ...
... -+-----+-----+-----+-----+-----+-----+- ...
... -3 -2 -1 0 1 2 3 ...
so abs x -. abs (round_towards_zero x) should be in [0,1)
*)
let round_towards_zero_test x =
let y = Float.round_towards_zero x in
match y with
| None -> true
| Some y ->
let x = Float.abs x in
let y = Float.abs (float_of_int y) in
0. <= x -. y && x -. y < 1.
let special_values_test () =
Float.round (-.1.50001) = -.2. &&
Float.round (-.1.5) = -.1. &&
Float.round (-.0.50001) = -.1. &&
Float.round (-.0.5) = 0. &&
Float.round 0.49999 = 0. &&
Float.round 0.5 = 1. &&
Float.round 1.49999 = 1. &&
Float.round 1.5 = 2. &&
Float.round_up_exn (-.2.) = -2 &&
Float.round_up_exn (-.1.9999) = -1 &&
Float.round_up_exn (-.1.) = -1 &&
Float.round_up_exn (-.0.9999) = 0 &&
Float.round_up_exn 0. = 0 &&
Float.round_up_exn 0.00001 = 1 &&
Float.round_up_exn 1. = 1 &&
Float.round_up_exn 1.00001 = 2 &&
Float.round_down_exn (-.1.00001) = -2 &&
Float.round_down_exn (-.1.) = -1 &&
Float.round_down_exn (-.0.00001) = -1 &&
Float.round_down_exn 0. = 0 &&
Float.round_down_exn 0.99999 = 0 &&
Float.round_down_exn 1. = 1 &&
Float.round_down_exn 1.99999 = 1 &&
Float.round_down_exn 2. = 2 &&
Float.round_towards_zero_exn (-.2.) = -2 &&
Float.round_towards_zero_exn (-.1.99999) = -1 &&
Float.round_towards_zero_exn (-.1.) = -1 &&
Float.round_towards_zero_exn (-.0.99999) = 0 &&
Float.round_towards_zero_exn 0.99999 = 0 &&
Float.round_towards_zero_exn 1. = 1 &&
Float.round_towards_zero_exn 1.99999 = 1 &&
Float.round_towards_zero_exn 2. = 2
(* code for generating random floats on which to test functions *)
let absirand () =
let rec aux acc cnt =
if cnt = 0 then
acc
else
let bit = if Random.bool () then 1 else 0 in
aux (2 * acc + bit) (cnt / 2)
in
(* we only go to 2. ** 52. -. 1. since our various round functions lose precision after
this and our tests may (and do) fail when precision is lost *)
aux 0 (int_of_float (2. ** 52. -. 1.))
let frand () =
let x = (float (absirand ())) +. Random.float 1.0 in
if Random.bool () then
-1.0 *. x
else
x
let test =
let randoms = List.init ~f:(fun _ -> frand ()) 10_000 in
"core_float" >:::
[ "to_string_hum" >::
(fun () ->
"random iround" @? (randoms |! List.for_all ~f:iround_test);
"max_int iround" @? iround_test (float_of_int max_int);
"min_int iround" @? iround_test (float_of_int min_int);
"random round" @? (randoms |! List.for_all ~f:round_test);
"random round_towards_zero_exn" @?
(randoms |! List.for_all ~f:round_towards_zero_test);
"random round_down_exn" @? (randoms |! List.for_all ~f:round_down_test);
"random round_up_exn" @? (randoms |! List.for_all ~f:round_up_test);
"special values" @? special_values_test ();
)
]
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