Hi, Floating point numbers are just inaccurate, so the results you see aren't too surprisingly. Interestingly enough, using Hugs, I get the right answer in both cases - so its possible it's a bug, but unlikely. If you do want exact floating point manipulation then use rational numbers instead, for example:

3.0 * 0.2 :: Rational 3%5

Which should be read as a fraction, 3/5, which is the right answer. Thanks Neil

-----Original Message----- From: glasgow-haskell-users-bounces@haskell.org [mailto:glasgow-haskell-users-bounces@haskell.org] On Behalf Of José Pedro Correia Sent: 14 November 2008 2:33 pm To: glasgow-haskell-users@haskell.org Subject: Re: Bug in GHC6.10.1?

Hello

I was wondering if there is a bug in GHC 6.10.1 regarding number precision.

As an example, in GHCi with:

...

3.0 * 0.2

I get: 0.6000000000000001

Although:

...

2.0 * 0.2 0.4

I have GHC 6.10.1 on Mac OS X 10.5.

Is this a known bug or should I report it?

Best regards Zé Pedro _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users

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Hello José, Friday, November 14, 2008, 5:32:52 PM, you wrote:

0.6000000000000001

computers store floating-point numbers in binary form, and it's imposiible to represent 3/5 in binary form exactly for the same reasons as impossibility to represent 1/3 exactly in decimal form (sorry for awkward english) -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com