From: Marnen Laibow-Koser <marnen@...>
Date: 2009-11-15T23:01:53+09:00
Subject: Re: Trajectories

James Edward Gray II wrote:
> On Nov 14, 2009, at 7:41 PM, Marnen Laibow-Koser wrote:
> 
>> But that's where BigDecimal comes in.  It's clearly a floating-point 
>> number, but it's actually accurate.  Semantically clear, numerically 
> 
> If you put BigDecimal against Float, I'm pretty darn certain you will 
> notice a very real speed difference.

Ruby 1.8.7p72 on Mac OS 10.6.1:

$ time ruby -rbigdecimal -e "1000.times{x = BigDecimal.new('3.5') * 
BigDecimal.new('4.2')}"

real    0m0.009s
user    0m0.005s
sys     0m0.003s

$ time ruby -rbigdecimal -e "a = BigDecimal.new('3.5'); b = 
BigDecimal.new('4.2'); 1000.times{x = a * b}"

real    0m0.007s
user    0m0.004s
sys     0m0.003s

$ time ruby -e "1000.times{x = 3.5 * 4.2}"
real    0m0.008s
user    0m0.004s
sys     0m0.004s

Looks darn close to me.

> James Edward Gray II

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