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updated to latest nicefloats (0.9.0)

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alisdair sullivan 2010-09-22 23:22:55 -07:00
parent a2bc7dc6c0
commit 4483a55f9e
4 changed files with 96 additions and 61 deletions
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4
deps/nicefloats/README.markdown vendored
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@ -1,5 +1,5 @@
nicefloats nicefloats (v0.9.0)
========== ===================
an erlang implementation of nice decimal representations of floating point numbers, based on "Printing FLoating-Point Numbers Quickly and Accurately" by Burger & Dybvig an erlang implementation of nice decimal representations of floating point numbers, based on "Printing FLoating-Point Numbers Quickly and Accurately" by Burger & Dybvig

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deps/nicefloats/ebin/nicefloats.app vendored
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@ -1,7 +1,7 @@
{application, nicefloats, {application, nicefloats,
[ [
{description, "'nice' decimal representations of floating point numbers"}, {description, "'nice' decimal representations of floating point numbers"},
{vsn, "0.9"}, {vsn, "0.9.0"},
{modules, [ {modules, [
nicefloats nicefloats
]}, ]},

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deps/nicefloats/rebar vendored
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deps/nicefloats/src/nicefloats.erl vendored
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@ -1,6 +1,7 @@
%% The MIT License %% The MIT License
%% Copyright (c) 2010 Alisdair Sullivan <alisdairsullivan@yahoo.ca> %% Copyright (c) 2010 Alisdair Sullivan <alisdairsullivan@yahoo.ca>
%% 2007 Bob Ippolito <bob@mochimedia.com>
%% Permission is hereby granted, free of charge, to any person obtaining a copy %% Permission is hereby granted, free of charge, to any person obtaining a copy
%% of this software and associated documentation files (the "Software"), to deal %% of this software and associated documentation files (the "Software"), to deal
@ -29,10 +30,14 @@
%% operations produce badarg exceptions. with that in mind, this function %% operations produce badarg exceptions. with that in mind, this function
%% makes no attempt to handle special values (except for zero) %% makes no attempt to handle special values (except for zero)
%% although this is a from scratch implementation of burger & dybvig's algorithm
%% bob ippolito's implementation in mochiweb did provide signifigant guidance
%% and is reflected in the choice of license and copyright attribution
-module(nicefloats). -module(nicefloats).
-export([format/1]). -export([format/1, format/2]).
-ifdef(TEST). -ifdef(TEST).
@ -40,23 +45,47 @@
-endif. -endif.
-record(opts, {
exp_limit = 6,
base = 10
}).
-spec format(Float::float()) -> string(). -spec format(Float::float()) -> string().
format(Float) when is_float(Float) -> format(Float) when is_float(Float) ->
nice_decimal(Float). format(Float, []).
-spec format(Float::float(), OptsList::list()) -> string().
format(Float, OptsList) when is_float(Float) ->
nice_decimal(Float, parse_opts(OptsList)).
parse_opts(OptsList) ->
parse_opts(OptsList, #opts{}).
parse_opts([{exp_limit, Val}|Rest], Opts) when is_integer(Val), Val >= 0 ->
parse_opts(Rest, Opts#opts{exp_limit = Val});
parse_opts([{base, N}|Rest], Opts) when is_integer(N), N >= 2, N =< 16 ->
parse_opts(Rest, Opts#opts{base = N});
parse_opts([], Opts) ->
Opts;
parse_opts(_, _) ->
{error, badarg}.
%% algorithm from "Printing FLoating-Point Numbers Quickly and Accurately" by %% algorithm from "Printing Floating-Point Numbers Quickly and Accurately" by
%% Burger & Dybvig %% Burger & Dybvig
nice_decimal(0.0) -> "0.0"; nice_decimal(0.0, _) -> "0.0";
nice_decimal(Num) -> nice_decimal(Num, Opts) ->
{F, E} = extract(<<Num:64/float>>), {F, E} = extract(<<Num:64/float>>),
{R, S, MP, MM} = initial_vals(F, E), {R, S, MP, MM} = initial_vals(F, E),
K = ceiling(math:log10(abs(Num)) - 1.0e-10), K = ceiling((math:log(abs(Num)) / math:log(Opts#opts.base)) - 1.0e-10),
Round = F band 1 =:= 0, Round = F band 1 =:= 0,
{Dpoint, Digits} = scale(R, S, MP, MM, K, Round), {Dpoint, Digits} = scale(R, S, MP, MM, K, Opts#opts.base, Round),
if Num >= 0 -> format(Dpoint, Digits) if Num >= 0 -> digits_to_list(Dpoint, Digits)
; Num < 0 -> "-" ++ format(Dpoint, Digits) ; Num < 0 -> "-" ++ digits_to_list(Dpoint, Digits)
end. end.
@ -64,14 +93,6 @@ extract(<<_:1, 0:11, Frac:52>>) -> {Frac, -1074};
extract(<<_:1, Exp:11, Frac:52>>) -> {Frac + (1 bsl 52), Exp - 1075}. extract(<<_:1, Exp:11, Frac:52>>) -> {Frac + (1 bsl 52), Exp - 1075}.
ceiling(X) ->
Y = trunc(X),
case X - Y of
Z when Z > 0 -> Y + 1
; _ -> Y
end.
initial_vals(F, E) when E >= 0, F /= 1 bsl 52 -> initial_vals(F, E) when E >= 0, F /= 1 bsl 52 ->
BE = 1 bsl E, BE = 1 bsl E,
{F * BE * 2, 2, BE, BE}; {F * BE * 2, 2, BE, BE};
@ -84,35 +105,43 @@ initial_vals(F, E) ->
{F * 4, 1 bsl (-E + 2), 2, 1}. {F * 4, 1 bsl (-E + 2), 2, 1}.
scale(R, S, MP, MM, K, Round) -> ceiling(X) ->
Y = erlang:trunc(X),
case X - Y of
Z when Z > 0 -> Y + 1
; _ -> Y
end.
scale(R, S, MP, MM, K, B, Round) ->
case K >= 0 of case K >= 0 of
true -> fixup(R, S * pow(10, K), MP, MM, K, Round) true -> fixup(R, S * pow(B, K), MP, MM, K, B, Round)
; false -> ; false ->
Scale = pow(10, -1 * K), Scale = pow(B, -1 * K),
fixup(R * Scale, S, MP * Scale, MM * Scale, K, Round) fixup(R * Scale, S, MP * Scale, MM * Scale, K, B, Round)
end. end.
fixup(R, S, MP, MM, K, true) -> fixup(R, S, MP, MM, K, B, true) ->
case (R + MP >= S) of case (R + MP >= S) of
true -> {K + 1, generate(R, S, MP, MM, true)} true -> {K + 1, generate(R, S, MP, MM, B, true)}
; false -> {K, generate(R * 10, S, MP * 10, MM * 10, true)} ; false -> {K, generate(R * B, S, MP * B, MM * B, B, true)}
end; end;
fixup(R, S, MP, MM, K, false) -> fixup(R, S, MP, MM, K, B, false) ->
case (R + MP > S) of case (R + MP > S) of
true -> {K + 1, generate(R, S, MP, MM, true)} true -> {K + 1, generate(R, S, MP, MM, B, true)}
; false -> {K, generate(R * 10, S, MP * 10, MM * 10, true)} ; false -> {K, generate(R * B, S, MP * B, MM * B, B, true)}
end. end.
generate(RT, S, MP, MM, Round) -> generate(RT, S, MP, MM, B, Round) ->
D = RT div S, D = RT div S,
R = RT rem S, R = RT rem S,
TC1 = case Round of true -> (R =< MM); false -> (R < MM) end, TC1 = case Round of true -> (R =< MM); false -> (R < MM) end,
TC2 = case Round of true -> (R + MP >= S); false -> (R + MP > S) end, TC2 = case Round of true -> (R + MP >= S); false -> (R + MP > S) end,
case TC1 of case TC1 of
false -> case TC2 of false -> case TC2 of
false -> [D | generate(R * 10, S, MP * 10, MM * 10, Round)] false -> [D | generate(R * B, S, MP * B, MM * B, B, Round)]
; true -> [D + 1] ; true -> [D + 1]
end end
; true -> case TC2 of ; true -> case TC2 of
@ -135,33 +164,39 @@ pow(B, E, Acc) when E band 1 == 1 -> pow(B * B, E bsr 1, B * Acc);
pow(B, E, Acc) -> pow(B * B, E bsr 1, Acc). pow(B, E, Acc) -> pow(B * B, E bsr 1, Acc).
format(0, Digits) -> digits_to_list(0, Digits) ->
format(Digits, ignore, ".0"); digits_to_list(Digits, ignore, ".0");
format(Dpoint, Digits) when Dpoint =< length(Digits), Dpoint > 0 -> digits_to_list(Dpoint, Digits) when Dpoint =< length(Digits), Dpoint > 0 ->
format(Digits, Dpoint, []); digits_to_list(Digits, Dpoint, []);
format(Dpoint, Digits) when Dpoint > 0 -> digits_to_list(Dpoint, Digits) when Dpoint > 0 ->
Pad = Dpoint - length(Digits), Pad = Dpoint - length(Digits),
case Pad of case Pad of
X when X > 6 -> X when X > 6 ->
format(Digits, 1, []) ++ "e" ++ integer_to_list(Dpoint - 1) digits_to_list(Digits, 1, []) ++ "e" ++ integer_to_list(Dpoint - 1)
; _ -> ; _ ->
format(Digits ++ [ 0 || _ <- lists:seq(1, Pad)], Dpoint, []) digits_to_list(Digits ++ [ 0 || _ <- lists:seq(1, Pad)], Dpoint, [])
end; end;
format(Dpoint, Digits) when Dpoint < 0 -> digits_to_list(Dpoint, Digits) when Dpoint < 0 ->
format(Digits, 1, []) ++ "e" ++ integer_to_list(Dpoint - 1). digits_to_list(Digits, 1, []) ++ "e" ++ integer_to_list(Dpoint - 1).
format([], 0, Acc) -> digits_to_list([], 0, Acc) ->
lists:reverse("0." ++ Acc); lists:reverse("0." ++ Acc);
format([], ignore, Acc) -> digits_to_list([], ignore, Acc) ->
lists:reverse(Acc); lists:reverse(Acc);
format(Digits, 0, Acc) -> digits_to_list(Digits, 0, Acc) ->
format(Digits, ignore, "." ++ Acc); digits_to_list(Digits, ignore, "." ++ Acc);
format([Digit|Digits], Dpoint, Acc) -> digits_to_list([Digit|Digits], Dpoint, Acc) ->
format(Digits, digits_to_list(Digits,
case Dpoint of ignore -> ignore; X -> X - 1 end, to_ascii(Digit) ++ Acc case Dpoint of ignore -> ignore; X -> X - 1 end, to_ascii(Digit) ++ Acc
). ).
to_ascii(10) -> "a";
to_ascii(11) -> "b";
to_ascii(12) -> "c";
to_ascii(13) -> "d";
to_ascii(14) -> "e";
to_ascii(15) -> "f";
to_ascii(X) -> [X + 48]. %% ascii "1" is [49], "2" is [50], etc... to_ascii(X) -> [X + 48]. %% ascii "1" is [49], "2" is [50], etc...
@ -171,36 +206,36 @@ to_ascii(X) -> [X + 48]. %% ascii "1" is [49], "2" is [50], etc...
nice_decimal_test_() -> nice_decimal_test_() ->
[ [
{"0.0", ?_assert(nice_decimal(0.0) =:= "0.0")}, {"0.0", ?_assert(format(0.0) =:= "0.0")},
{"1.0", ?_assert(nice_decimal(1.0) =:= "1.0")}, {"1.0", ?_assert(format(1.0) =:= "1.0")},
{"-1.0", ?_assert(nice_decimal(-1.0) =:= "-1.0")}, {"-1.0", ?_assert(format(-1.0) =:= "-1.0")},
{"3.1234567890987654321", {"3.1234567890987654321",
?_assert( ?_assert(
nice_decimal(3.1234567890987654321) =:= "3.1234567890987655") format(3.1234567890987654321) =:= "3.1234567890987655")
}, },
{"1.0e23", ?_assert(nice_decimal(1.0e23) =:= "1.0e23")}, {"1.0e23", ?_assert(format(1.0e23) =:= "1.0e23")},
{"0.3", ?_assert(nice_decimal(3.0/10.0) =:= "0.3")}, {"0.3", ?_assert(format(3.0/10.0) =:= "0.3")},
{"0.0001", ?_assert(nice_decimal(0.0001) =:= "1.0e-4")}, {"0.0001", ?_assert(format(0.0001) =:= "1.0e-4")},
{"0.00000001", ?_assert(nice_decimal(0.00000001) =:= "1.0e-8")}, {"0.00000001", ?_assert(format(0.00000001) =:= "1.0e-8")},
{"1.0e-323", ?_assert(nice_decimal(1.0e-323) =:= "1.0e-323")}, {"1.0e-323", ?_assert(format(1.0e-323) =:= "1.0e-323")},
{"1.0e308", ?_assert(nice_decimal(1.0e308) =:= "1.0e308")}, {"1.0e308", ?_assert(format(1.0e308) =:= "1.0e308")},
{"min normalized float", {"min normalized float",
?_assert( ?_assert(
nice_decimal(math:pow(2, -1022)) =:= "2.2250738585072014e-308" format(math:pow(2, -1022)) =:= "2.2250738585072014e-308"
) )
}, },
{"max normalized float", {"max normalized float",
?_assert( ?_assert(
nice_decimal((2 - math:pow(2, -52)) * math:pow(2, 1023)) format((2 - math:pow(2, -52)) * math:pow(2, 1023))
=:= "1.7976931348623157e308" =:= "1.7976931348623157e308"
) )
}, },
{"min denormalized float", {"min denormalized float",
?_assert(nice_decimal(math:pow(2, -1074)) =:= "5.0e-324") ?_assert(format(math:pow(2, -1074)) =:= "5.0e-324")
}, },
{"max denormalized float", {"max denormalized float",
?_assert( ?_assert(
nice_decimal((1 - math:pow(2, -52)) * math:pow(2, -1022)) format((1 - math:pow(2, -52)) * math:pow(2, -1022))
=:= "2.225073858507201e-308" =:= "2.225073858507201e-308"
) )
} }