From: "Victor H. Goff III" <keeperotphones@...>
Date: 2008-08-28T12:23:47+09:00
Subject: Re: BigDecimal with Float comparision bug.

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The simple test comparing BigDecimal.new('25') == 25.0 is true, but
BigDecimal.new('24') == 24.0 is false.

The numbers from 1 to 1000 that don't test like the rest of them on my
system are:
[3, 6, 12, 13, 21, 24, 26, 29, 31, 42, 45, 48, 51, 52, 55, 58, 61, 62, 69,
79, 84, 87, 90, 93, 96, 99, 101, 102, 104, 107, 110, 113, 116, 119, 121,
122, 124, 127, 138, 157, 158, 163, 168, 169, 174, 175, 180, 181, 185, 186,
191, 192, 197, 198, 202, 203, 204, 208, 209, 214, 215, 220, 221, 225, 226,
227, 231, 232, 237, 238, 242, 243, 244, 248, 249, 254, 255, 259, 276, 293,
299, 314, 316, 319, 321, 326, 331, 333, 336, 338, 343, 345, 348, 350, 353,
355, 360, 362, 365, 367, 370, 372, 377, 379, 382, 384, 387, 389, 394, 396,
399, 401, 404, 406, 408, 411, 413, 416, 418, 421, 423, 425, 428, 430, 433,
435, 440, 442, 445, 447, 450, 452, 454, 457, 459, 462, 464, 467, 469, 471,
474, 476, 479, 481, 484, 486, 488, 491, 493, 496, 498, 501, 503, 505, 508,
510, 518, 535, 552, 569, 581, 586, 598, 615, 627, 628, 632, 633, 637, 638,
642, 643, 647, 652, 657, 661, 662, 666, 667, 671, 672, 676, 677, 681, 686,
690, 691, 695, 696, 700, 701, 705, 706, 710, 715, 720, 724, 725, 729, 730,
734, 735, 739, 740, 744, 749, 753, 754, 758, 759, 763, 764, 768, 769, 773,
774, 778, 783, 787, 788, 792, 793, 797, 798, 802, 803, 807, 808, 812, 816,
817, 821, 822, 826, 827, 831, 832, 836, 837, 841, 842, 846, 850, 851, 855,
856, 860, 861, 865, 866, 870, 871, 875, 879, 880, 884, 885, 889, 890, 894,
895, 899, 900, 904, 905, 908, 909, 913, 914, 918, 919, 923, 924, 928, 929,
933, 934, 938, 939, 942, 943, 947, 948, 952, 953, 957, 958, 962, 963, 967,
968, 971, 972, 973, 976, 977, 981, 982, 986, 987, 991, 992, 996, 997]

Just thought I would share...  Running Ruby 1.8.6 on Windows.

The code I used to generate the output is:
failed = Array.new
(1..1000).each { |d| failed << d if BigDecimal.new("#{d}.0") != d.to_f }
p failed

The doctest code I used for testing for 24 is:
# doctest: Testing BigDecimal

# >> BigDecimal.new('24.0') == 24
# => true
# >> BigDecimal.new('24.0') == 24.0
# => false
# end

This passes, so indicates what is happening.  Why?  I don't know.



On Wed, Aug 27, 2008 at 9:15 PM, Shin guey Wong <sgwong513@hotmail.com>wrote:

> It works in my ruby in windows :)
>
> irb(main):003:0> BigDecimal.new("25.0") == 25.0
> => true
> irb(main):004:0> BigDecimal.new("25.0") == 25
> => true
> irb(main):005:0> exit
>
> C:\ruby --version
> ruby 1.8.6 (2008-07-17 patchlevel 279) [i386-mingw32]
>
>
>

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