From: Robert Klemme <shortcutter@...>
Date: 2007-03-20T06:40:12+09:00
Subject: Re: truncate trouble

On 19.03.2007 20:37, Greg Lorriman wrote:
> This
> 
> ('40.12'.to_f*100).to_i
> 
> results in this integer :
> 
> 4011
> 
> This is a bit of surprise. I'm using 1.8.4 on windows. Is this a bug?
> Is there another floating type that avoids this problem? I;m not
> seeing anything in the docs that might have warned me.

No, that's a normal rounding error that comes with floats:

irb(main):001:0> f='40.12'.to_f
=> 40.12
irb(main):002:0> "%20.10f" % f
=> "       40.1200000000"
irb(main):003:0> "%40.30f" % f
=> "       40.119999999999997442046151263639"
irb(main):004:0> "%40.30f" % (f*100)
=> "     4011.999999999999545252649113535881"

If you look at the last line it becomes clear why you get 4011 as result.

Kind regards

	robert