From: Vu Nang Luc <vunangluc@...>
Date: 2007-08-10T10:20:08+09:00
Subject: Re: precision loss with pack/unpack ?

On 10 Tha ng T�m, 02:06, "Luis Parravicini" <lparr...@gmail.com>
wrote:
>And the result is different from the original
> value.
>
> ------------
> a = 0.1234567
> b = [a].pack('g').unpack('g')[0]
>
> puts "#{a} =? #{b} => #{a == b}"
> ------------
>
> outputs:
>
> 0.1234567 =? 0.123456701636314 => false
>

It's quite common with float or double representation. Because float/
double can not represent ALL value within its range so some loss
precision happens. It may happen right after assignment:
eg: On my machine:

> a = a= 100.1001001003333
>a
100.100100100333  (the last digit gone?)