Ruby on Rails

Colin Law wrote in post #970523:
> On 24 December 2010 16:36, Marnen Laibow-Koser <lists@ruby-forum.com>
> wrote:
>>> BigDecimal and for things that are not decimal then use Float and
>>> determine the errors if it is important.
>>
>> That's basically what I've been saying, except for "decimal" substitute
>> "rational". However, there's not always an a priori way to determine if
>> a given field will need to store irrational numbers.
>
> I am not quite sure that is that is the same as "never, ever use
> Floats for arithmetic" :)

Oh, now I see the difference. Even if I store something as a Float, I'd
probably use BigDecimal for arithmetic. I simply don't believe that
Float arithmetic has any place at all in a wise programmer's repertoire.
Consider it the 21st-century goto, if you like. :)

>
> Also as we have seen for rational numbers like 1/3 BigDecimal is no
> better than float, except that it is possible to specify a smaller or
> larger precision than that which float supplies,

That makes it better than Float right there. Also, you don't accumulate
any *more* error.

> and it is a decimal
> precision rather than a binary one.

...which is not generally better or worse.

>
> Colin

Best,
-- 
Marnen Laibow-Koser
http://www.marnen.org
marnen@marnen.org

Sent from my iPhone

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