From: gwtmp01@...
Date: 2007-01-20T09:33:18+09:00
Subject: Re: Float to Fixnum (was: Negative Float conversion to Fixnum)


On Jan 19, 2007, at 4:50 PM, Drew Raines wrote:
> And how can 39.30*100 really be 3930.000000000000454747350886464...,
> but 39.31*100 be 3931.0?

Because 39.30 is a base 10 representation of a number and there
is no exact representation of that number in base 2. The Ruby
parser has to do a conversion to base 2 for 39.30 long before
the multiplication occurs so you aren't really multiplying
39.30*100 but instead you are multiplying

39.2999999999999971578290569595992565155029296875 * 100

to get

3929.99999999999971578290569595992565155029296875

which when truncated to an integer is

3929


Gary Wright