Re: [Haskell-beginners] How to improve the accuracy of floating point calculation?

Thanks! I'll try CReal. But can I set *significant figures **myself?* On Wed, Feb 6, 2013 at 6:50 AM, Brandon Allbery wrote:

On Tue, Feb 5, 2013 at 5:41 PM, yi lu wrote:

...

I found that in ghci, I input [0.1,0.2..2] and run, I get a result of

[0.1,0.2,0.30000000000000004,0.4000000000000001,0.5000000000000001,0.6000000000000001,0.7000000000000001,0.8,0.9,1.0,1.1,1.2000000000000002,1.3000000000000003,1.4000000000000004,1.5000000000000004,1.6000000000000005,1.7000000000000006,1.8000000000000007,1.9000000000000008,2.000000000000001]

But, as you know, it is not the exact answer.

So, I wonder if there is something I can do to achieve a better performance and get [0.1,0.2,0.3,0.4..] as the result.

Welcome to the world of floating point numbers. Perfect accuracy is not possible; the CReal type from the "numbers" package may handle cases you care about, or may not. (Other languages often use output formats that can largely hide the errors, but they're still there and will eventually accumulate into visibility.)

-- brandon s allbery kf8nh sine nomine associates allbery.b@gmail.com ballbery@sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net

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