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Re: [Chicken-users] Numbers weirdness
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From: |
Peter Bex |
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Subject: |
Re: [Chicken-users] Numbers weirdness |
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Date: |
Fri, 1 Apr 2016 18:51:16 +0200 |
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User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Fri, Apr 01, 2016 at 05:25:44PM +0100, Andy Bennett wrote:
> Hi,
>
> In CHICKEN 4.9.0rc1 and 4.10.0 both with numbers 4.6:
>
> -----
> #;1> (use numbers)
> #;2> (define (log2 n) (/ (log n) (log 2)))
> #;3> (= (log2 (expt 2 252)) (ceiling (log2 (expt 2 252))))
> #t
> #;4> (= (log2 (expt 2 251)) (ceiling (log2 (expt 2 251))))
> #f
> #;5> (log2 (expt 2 251))
> 251.0
> #;6> (ceiling (log2 (expt 2 251)))
> 252.0
> -----
>
> Is it just late on a Friday? Am I crazy?
Floating point numbers are weird enough to drive anyone bat shit:
#;1> (use numbers)
#;2> (define (log2 n) (/ (log n) (log 2)))
#;3> (log2 (expt 2 251))
251.0
#;4> (flonum-print-precision 100)
15
#;5> (log2 (expt 2 251))
251.000000000000028421709430404007434844970703125
Cheers,
Peter
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