* [sup-talk] Util - Fixnum num_digits is wrong
@ 2007-12-03 8:25 Ian Taylor
2007-12-03 10:52 ` Shot (Piotr Szotkowski)
0 siblings, 1 reply; 3+ messages in thread
From: Ian Taylor @ 2007-12-03 8:25 UTC (permalink / raw)
Probably wasn't causing any problems, but is wrong.
===================================================================
--- lib/sup/util.rb (revision 737)
+++ lib/sup/util.rb (working copy)
@@ -299,7 +299,7 @@
class Fixnum
def num_digits base=10
return 1 if self == 0
- 1 + (Math.log(self) / Math.log(10)).floor
+ 1 + (Math.log(self) / Math.log(base)).floor
end
def to_character
--
Ian Taylor
^ permalink raw reply [flat|nested] 3+ messages in thread* [sup-talk] Util - Fixnum num_digits is wrong
2007-12-03 8:25 [sup-talk] Util - Fixnum num_digits is wrong Ian Taylor
@ 2007-12-03 10:52 ` Shot (Piotr Szotkowski)
2007-12-08 22:13 ` William Morgan
0 siblings, 1 reply; 3+ messages in thread
From: Shot (Piotr Szotkowski) @ 2007-12-03 10:52 UTC (permalink / raw)
Ian Taylor:
> class Fixnum
> def num_digits base=10
> return 1 if self == 0
> - 1 + (Math.log(self) / Math.log(10)).floor
> + 1 + (Math.log(self) / Math.log(base)).floor
> end
Math.log and Float#/ returning Floats means the above
approach is prone to the IEEE 754 representation inaccuracy.
Wouldn?t the below make more sense?
class Fixnum
def num_digits base = 10
to_s(base).size
end
end
-- Shot
--
> Who wants to recommend a Usenet reader for little ol' me?
I recommend Garrett Morris, particularly if you're hard-of-hearing.
-- jennifer friedoff and Joseph Nebus, rec.arts.tv.mst3k.misc
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^ permalink raw reply [flat|nested] 3+ messages in thread* [sup-talk] Util - Fixnum num_digits is wrong
2007-12-03 10:52 ` Shot (Piotr Szotkowski)
@ 2007-12-08 22:13 ` William Morgan
0 siblings, 0 replies; 3+ messages in thread
From: William Morgan @ 2007-12-08 22:13 UTC (permalink / raw)
Excerpts from Shot (Piotr Szotkowski)'s message of Mon Dec 03 02:52:10 -0800 2007:
> Math.log and Float#/ returning Floats means the above approach is
> prone to the IEEE 754 representation inaccuracy.
>
> Wouldn?t the below make more sense?
>
> class Fixnum
> def num_digits base = 10
> to_s(base).size
> end
> end
Yes, but not as much as simply deleting the method. :)
--
William <wmorgan-sup at masanjin.net>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2007-12-03 8:25 [sup-talk] Util - Fixnum num_digits is wrong Ian Taylor
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