updated to latest nicefloats (0.9.0)
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alisdair sullivan
parent
a2bc7dc6c0
commit
4483a55f9e
4 changed files with 96 additions and 61 deletions
4
deps/nicefloats/README.markdown
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4
deps/nicefloats/README.markdown
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@ -1,5 +1,5 @@
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nicefloats
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==========
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nicefloats (v0.9.0)
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===================
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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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2
deps/nicefloats/ebin/nicefloats.app
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deps/nicefloats/ebin/nicefloats.app
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@ -1,7 +1,7 @@
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{application, nicefloats,
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[
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{description, "'nice' decimal representations of floating point numbers"},
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{vsn, "0.9"},
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{vsn, "0.9.0"},
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{modules, [
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nicefloats
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]},
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BIN
deps/nicefloats/rebar
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BIN
deps/nicefloats/rebar
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deps/nicefloats/src/nicefloats.erl
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deps/nicefloats/src/nicefloats.erl
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@ -1,6 +1,7 @@
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%% The MIT License
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%% Copyright (c) 2010 Alisdair Sullivan <alisdairsullivan@yahoo.ca>
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%% 2007 Bob Ippolito <bob@mochimedia.com>
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%% Permission is hereby granted, free of charge, to any person obtaining a copy
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%% of this software and associated documentation files (the "Software"), to deal
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@ -29,10 +30,14 @@
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%% operations produce badarg exceptions. with that in mind, this function
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%% makes no attempt to handle special values (except for zero)
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%% although this is a from scratch implementation of burger & dybvig's algorithm
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%% bob ippolito's implementation in mochiweb did provide signifigant guidance
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%% and is reflected in the choice of license and copyright attribution
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-module(nicefloats).
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-export([format/1]).
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-export([format/1, format/2]).
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-ifdef(TEST).
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@ -40,23 +45,47 @@
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-endif.
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-record(opts, {
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exp_limit = 6,
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base = 10
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}).
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-spec format(Float::float()) -> string().
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format(Float) when is_float(Float) ->
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nice_decimal(Float).
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format(Float, []).
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-spec format(Float::float(), OptsList::list()) -> string().
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format(Float, OptsList) when is_float(Float) ->
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nice_decimal(Float, parse_opts(OptsList)).
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parse_opts(OptsList) ->
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parse_opts(OptsList, #opts{}).
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parse_opts([{exp_limit, Val}|Rest], Opts) when is_integer(Val), Val >= 0 ->
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parse_opts(Rest, Opts#opts{exp_limit = Val});
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parse_opts([{base, N}|Rest], Opts) when is_integer(N), N >= 2, N =< 16 ->
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parse_opts(Rest, Opts#opts{base = N});
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parse_opts([], Opts) ->
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Opts;
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parse_opts(_, _) ->
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{error, badarg}.
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%% algorithm from "Printing FLoating-Point Numbers Quickly and Accurately" by
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%% algorithm from "Printing Floating-Point Numbers Quickly and Accurately" by
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%% Burger & Dybvig
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nice_decimal(0.0) -> "0.0";
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nice_decimal(Num) ->
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nice_decimal(0.0, _) -> "0.0";
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nice_decimal(Num, Opts) ->
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{F, E} = extract(<<Num:64/float>>),
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{R, S, MP, MM} = initial_vals(F, E),
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K = ceiling(math:log10(abs(Num)) - 1.0e-10),
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K = ceiling((math:log(abs(Num)) / math:log(Opts#opts.base)) - 1.0e-10),
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Round = F band 1 =:= 0,
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{Dpoint, Digits} = scale(R, S, MP, MM, K, Round),
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if Num >= 0 -> format(Dpoint, Digits)
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; Num < 0 -> "-" ++ format(Dpoint, Digits)
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{Dpoint, Digits} = scale(R, S, MP, MM, K, Opts#opts.base, Round),
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if Num >= 0 -> digits_to_list(Dpoint, Digits)
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; Num < 0 -> "-" ++ digits_to_list(Dpoint, Digits)
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end.
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@ -64,14 +93,6 @@ extract(<<_:1, 0:11, Frac:52>>) -> {Frac, -1074};
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extract(<<_:1, Exp:11, Frac:52>>) -> {Frac + (1 bsl 52), Exp - 1075}.
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ceiling(X) ->
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Y = trunc(X),
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case X - Y of
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Z when Z > 0 -> Y + 1
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; _ -> Y
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end.
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initial_vals(F, E) when E >= 0, F /= 1 bsl 52 ->
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BE = 1 bsl E,
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{F * BE * 2, 2, BE, BE};
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@ -84,35 +105,43 @@ initial_vals(F, E) ->
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{F * 4, 1 bsl (-E + 2), 2, 1}.
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scale(R, S, MP, MM, K, Round) ->
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ceiling(X) ->
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Y = erlang:trunc(X),
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case X - Y of
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Z when Z > 0 -> Y + 1
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; _ -> Y
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end.
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scale(R, S, MP, MM, K, B, Round) ->
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case K >= 0 of
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true -> fixup(R, S * pow(10, K), MP, MM, K, Round)
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true -> fixup(R, S * pow(B, K), MP, MM, K, B, Round)
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; false ->
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Scale = pow(10, -1 * K),
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fixup(R * Scale, S, MP * Scale, MM * Scale, K, Round)
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Scale = pow(B, -1 * K),
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fixup(R * Scale, S, MP * Scale, MM * Scale, K, B, Round)
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end.
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fixup(R, S, MP, MM, K, true) ->
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fixup(R, S, MP, MM, K, B, true) ->
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case (R + MP >= S) of
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true -> {K + 1, generate(R, S, MP, MM, true)}
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; false -> {K, generate(R * 10, S, MP * 10, MM * 10, true)}
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true -> {K + 1, generate(R, S, MP, MM, B, true)}
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; false -> {K, generate(R * B, S, MP * B, MM * B, B, true)}
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end;
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fixup(R, S, MP, MM, K, false) ->
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fixup(R, S, MP, MM, K, B, false) ->
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case (R + MP > S) of
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true -> {K + 1, generate(R, S, MP, MM, true)}
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; false -> {K, generate(R * 10, S, MP * 10, MM * 10, true)}
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true -> {K + 1, generate(R, S, MP, MM, B, true)}
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; false -> {K, generate(R * B, S, MP * B, MM * B, B, true)}
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end.
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generate(RT, S, MP, MM, Round) ->
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generate(RT, S, MP, MM, B, Round) ->
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D = RT div S,
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R = RT rem S,
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TC1 = case Round of true -> (R =< MM); false -> (R < MM) end,
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TC2 = case Round of true -> (R + MP >= S); false -> (R + MP > S) end,
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case TC1 of
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false -> case TC2 of
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false -> [D | generate(R * 10, S, MP * 10, MM * 10, Round)]
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false -> [D | generate(R * B, S, MP * B, MM * B, B, Round)]
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; true -> [D + 1]
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end
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; true -> case TC2 of
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@ -135,33 +164,39 @@ pow(B, E, Acc) when E band 1 == 1 -> pow(B * B, E bsr 1, B * Acc);
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pow(B, E, Acc) -> pow(B * B, E bsr 1, Acc).
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format(0, Digits) ->
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format(Digits, ignore, ".0");
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format(Dpoint, Digits) when Dpoint =< length(Digits), Dpoint > 0 ->
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format(Digits, Dpoint, []);
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format(Dpoint, Digits) when Dpoint > 0 ->
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digits_to_list(0, Digits) ->
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digits_to_list(Digits, ignore, ".0");
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digits_to_list(Dpoint, Digits) when Dpoint =< length(Digits), Dpoint > 0 ->
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digits_to_list(Digits, Dpoint, []);
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digits_to_list(Dpoint, Digits) when Dpoint > 0 ->
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Pad = Dpoint - length(Digits),
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case Pad of
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X when X > 6 ->
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format(Digits, 1, []) ++ "e" ++ integer_to_list(Dpoint - 1)
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digits_to_list(Digits, 1, []) ++ "e" ++ integer_to_list(Dpoint - 1)
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; _ ->
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format(Digits ++ [ 0 || _ <- lists:seq(1, Pad)], Dpoint, [])
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digits_to_list(Digits ++ [ 0 || _ <- lists:seq(1, Pad)], Dpoint, [])
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end;
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format(Dpoint, Digits) when Dpoint < 0 ->
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format(Digits, 1, []) ++ "e" ++ integer_to_list(Dpoint - 1).
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digits_to_list(Dpoint, Digits) when Dpoint < 0 ->
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digits_to_list(Digits, 1, []) ++ "e" ++ integer_to_list(Dpoint - 1).
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format([], 0, Acc) ->
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digits_to_list([], 0, Acc) ->
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lists:reverse("0." ++ Acc);
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format([], ignore, Acc) ->
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digits_to_list([], ignore, Acc) ->
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lists:reverse(Acc);
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format(Digits, 0, Acc) ->
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format(Digits, ignore, "." ++ Acc);
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format([Digit|Digits], Dpoint, Acc) ->
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format(Digits,
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digits_to_list(Digits, 0, Acc) ->
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digits_to_list(Digits, ignore, "." ++ Acc);
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digits_to_list([Digit|Digits], Dpoint, Acc) ->
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digits_to_list(Digits,
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case Dpoint of ignore -> ignore; X -> X - 1 end, to_ascii(Digit) ++ Acc
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).
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to_ascii(10) -> "a";
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to_ascii(11) -> "b";
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to_ascii(12) -> "c";
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to_ascii(13) -> "d";
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to_ascii(14) -> "e";
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to_ascii(15) -> "f";
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to_ascii(X) -> [X + 48]. %% ascii "1" is [49], "2" is [50], etc...
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@ -171,36 +206,36 @@ to_ascii(X) -> [X + 48]. %% ascii "1" is [49], "2" is [50], etc...
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nice_decimal_test_() ->
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[
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{"0.0", ?_assert(nice_decimal(0.0) =:= "0.0")},
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{"1.0", ?_assert(nice_decimal(1.0) =:= "1.0")},
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{"-1.0", ?_assert(nice_decimal(-1.0) =:= "-1.0")},
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{"0.0", ?_assert(format(0.0) =:= "0.0")},
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{"1.0", ?_assert(format(1.0) =:= "1.0")},
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{"-1.0", ?_assert(format(-1.0) =:= "-1.0")},
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{"3.1234567890987654321",
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?_assert(
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nice_decimal(3.1234567890987654321) =:= "3.1234567890987655")
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format(3.1234567890987654321) =:= "3.1234567890987655")
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},
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{"1.0e23", ?_assert(nice_decimal(1.0e23) =:= "1.0e23")},
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{"0.3", ?_assert(nice_decimal(3.0/10.0) =:= "0.3")},
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{"0.0001", ?_assert(nice_decimal(0.0001) =:= "1.0e-4")},
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{"0.00000001", ?_assert(nice_decimal(0.00000001) =:= "1.0e-8")},
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{"1.0e-323", ?_assert(nice_decimal(1.0e-323) =:= "1.0e-323")},
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{"1.0e308", ?_assert(nice_decimal(1.0e308) =:= "1.0e308")},
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{"1.0e23", ?_assert(format(1.0e23) =:= "1.0e23")},
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{"0.3", ?_assert(format(3.0/10.0) =:= "0.3")},
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{"0.0001", ?_assert(format(0.0001) =:= "1.0e-4")},
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{"0.00000001", ?_assert(format(0.00000001) =:= "1.0e-8")},
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{"1.0e-323", ?_assert(format(1.0e-323) =:= "1.0e-323")},
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{"1.0e308", ?_assert(format(1.0e308) =:= "1.0e308")},
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{"min normalized float",
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?_assert(
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nice_decimal(math:pow(2, -1022)) =:= "2.2250738585072014e-308"
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format(math:pow(2, -1022)) =:= "2.2250738585072014e-308"
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)
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},
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{"max normalized float",
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?_assert(
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nice_decimal((2 - math:pow(2, -52)) * math:pow(2, 1023))
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format((2 - math:pow(2, -52)) * math:pow(2, 1023))
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=:= "1.7976931348623157e308"
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)
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},
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{"min denormalized float",
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?_assert(nice_decimal(math:pow(2, -1074)) =:= "5.0e-324")
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?_assert(format(math:pow(2, -1074)) =:= "5.0e-324")
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},
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{"max denormalized float",
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?_assert(
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nice_decimal((1 - math:pow(2, -52)) * math:pow(2, -1022))
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format((1 - math:pow(2, -52)) * math:pow(2, -1022))
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=:= "2.225073858507201e-308"
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)
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}
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