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bug#14905: rationalize not returning the simplest rational
From: |
Göran Weinholt |
Subject: |
bug#14905: rationalize not returning the simplest rational |
Date: |
Fri, 19 Jul 2013 13:18:41 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.4 (gnu/linux) |
Hello schemers,
the procedure (rationalize x1 x2) from (rnrs) takes a number x1 and
returns the simplest rational that doesn't differ from x1 by more than
x2. The implementation in guile has this behavior:
scheme@(guile-user)> (rationalize #e-0.67 1/4)
$1 = -2/3
The problem here is that -1/2 is simpler than -2/3 (since 1<2 and 2<3)
and it also doesn't differ from #e-0.67 by more than 1/4 (even though
the difference is larger than for -2/3, it is still less than 1/4). So
the result from the expression above should be -1/2.
Tested with Guile 2.0.9.40-824b-dirty.
Regards,
--
Göran Weinholt <address@hidden>
"On your own and though you feel alone you are alive.
Don't you know it's just another day." -- You Are Alive, Fragma
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- bug#14905: rationalize not returning the simplest rational,
Göran Weinholt <=