From: Ryan Davis <ryand-ruby@...>
Date: 2012-01-24T10:23:36+09:00
Subject: Re: Microrant on Ruy's Math Skills


On Jan 23, 2012, at 16:57 , Chad Perrin wrote:

> On Tue, Jan 24, 2012 at 08:19:06AM +0900, Ryan Davis wrote:
>> 
>> Except for that whole "parse time is different from run time" part you
>> seem to be blithely ignoring. If you've already parsed float literals,
>> then they're floats and are already lossy.
> 
> Are you telling me that 1.1 is automatically lossy, regardless of how you
> got there?  I guess I need to go back and refresh my understanding of the
> math, because I thought a literal decimal number was fine but one
> achieved by arithmetic was likely to contain subtle errors due to the way
> the binary math is handled.

It'd be nice if you read the thread before chipping in. Adam Prescott nailed this one. Here's another example:

% ruby -e 'puts "%.60f" % 1.1'
1.100000000000000088817841970012523233890533447265625000000000