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Another rounding problem in number_with_precision
Reported by Don Wilson | December 16th, 2010 @ 08:01 PM | in 3.0.5
Currently, if you run number_with_precision(9.995, :precision => 2) it returns "9.99". It should return "10.00". You can read a little more information here:
http://stackoverflow.com/questions/4241879/number-to-currency-round...
It basically comes down to this:
# File actionpack/lib/action_view/helpers/number_helper.rb, line 280
rounded_number = BigDecimal.new((number * (10 ** precision)).to_s).round.to_f / 10 ** precision
You can see here that the number is multiplied by 100 before it is converted to BigDecimal. When working with Floats, 9.995 * 100 = 999.4999999999999 which will obviously round down to 999, not up to 1000.
My Fix
I have attached a patch for this that just uses the BigDecimal round function which does this perfectly. In the case where significant is true, it just converts the number to BigDecimal before doing its rounding, etc.
Let me know what you think!
Comments and changes to this ticket
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Piotr Sarnacki December 17th, 2010 @ 11:05 AM
- Importance changed from “” to “Low”
I would apply this patch, but it works only on 1.9, on 1.8 I get one failure:
1) Failure: test_number_with_precision(NumberHelperTest) [./test/template/number_helper_test.rb:105:in `test_number_with_precision' /users/drogus/projekty/rails/activesupport/lib/active_support/testing/setup_and_teardown.rb:67:in `__send__' /users/drogus/projekty/rails/activesupport/lib/active_support/testing/setup_and_teardown.rb:67:in `run' /users/drogus/projekty/rails/activesupport/lib/active_support/callbacks.rb:426:in `_run_setup_callbacks' /users/drogus/projekty/rails/activesupport/lib/active_support/testing/setup_and_teardown.rb:65:in `run']: <"10.0"> expected but was <"9.99">. -
Repository December 17th, 2010 @ 03:11 PM
- State changed from “new” to “resolved”
(from [006ec77e60163d57d655479602230672d98e0f10]) Fixed number_with_precision rounding error [#6182 state:resolved] https://github.com/rails/rails/commit/006ec77e60163d57d655479602230...
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Repository December 17th, 2010 @ 03:13 PM
(from [07567aea5f0c6f14a53f511ab4cc46201b669795]) Revert "Fixed number_with_precision rounding error [#6182 state:resolved]"
This reverts commit 006ec77e60163d57d655479602230672d98e0f10.
https://github.com/rails/rails/commit/07567aea5f0c6f14a53f511ab4cc4... -
Piotr Sarnacki December 17th, 2010 @ 03:16 PM
- Milestone cleared.
- State changed from “resolved” to “open”
- Assigned user set to “Piotr Sarnacki”
Awww... sorry guys, I accidently applied that to master and pushed with other fix. I've reverted it now, so it's still open.
Don: please let me know on your findings about that failing test.
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Don Wilson December 17th, 2010 @ 05:06 PM
Good catch Piotr :)
In certain cases in Ruby 1.8, BigDecimal / Float = Float. So, I just had to convert the other side to a BigDecimal before the division.
Just a note, when I convert it to BigDecimal, I have a to_f before the to_s. This was necessary because in Ruby 1.9, many times it is not a Float already, it is a Rational. When you do to_s on a Rational it looks like this "(1/100)". Then, BigDecimal doesn't read it correctly and thinks that you meant 1.0 instead of 0.01.
I have attached a new patch.
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Repository December 18th, 2010 @ 09:55 AM
- State changed from “open” to “resolved”
(from [177749b8bfdbdca7bd996d2370c306b23a88f338]) Fixed number_with_precision rounding error [#6182 state:resolved] https://github.com/rails/rails/commit/177749b8bfdbdca7bd996d2370c30...
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Repository December 18th, 2010 @ 09:56 AM
(from [f71809f25761440cbec9463bbc082987c90a471b]) Fixed number_with_precision rounding error [#6182 state:resolved] https://github.com/rails/rails/commit/f71809f25761440cbec9463bbc082...
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People watching this ticket
Don Wilson
Jeremy Kemper
Piotr Sarnacki
Attachments
Referenced by
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6182
Another rounding problem in number_with_precision
(from [006ec77e60163d57d655479602230672d98e0f10])
Fixed n...
-
6182
Another rounding problem in number_with_precision
(from [07567aea5f0c6f14a53f511ab4cc46201b669795])
Revert ...
-
6182
Another rounding problem in number_with_precision
(from [177749b8bfdbdca7bd996d2370c306b23a88f338])
Fixed n...
-
6182
Another rounding problem in number_with_precision
(from [f71809f25761440cbec9463bbc082987c90a471b])
Fixed n...