From: Stefan Rusterholz <apeiros@...>
Date: 2007-06-25T01:52:07+09:00
Subject: Re: Ruby doesn't know how to multiply

Shot (Piotr Szotkowski) wrote:
> MenTaLguY:
> 
>> The best you can do is test whether the result is
>> within some interval (epsilon) of the expected result:
> 
>>  ( ( 14.95 * 0.6 ) - 8.97 ).abs < 1e-6
> 
>> (Here, we've chosen 1e-6 as our epsilon, which is arbitrary but
>> probably "small enough" in this case. For mathematically intensive
>> code, you may need to be more careful.)
> 
> Any particular reason against using Float::EPSILON here? :)
> 
> Maybe Float#== could simply be extended to consider the above? That
> would most probably open another can of worms, though, and extending
> Float#<=> would open yet another, I guess.
> 
> -- Shot

I think Float#== as it is is fine. Arguably it could use delta 
comparison with Float::EPSILON and leave the exact comparison to eql?
But I'd like it if Float#in_delta(other, delta=Float::EPSILON) was in 
core (personally I add it in my libs as Numeric#in_delta).

Regards
Stefan

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