From: Paul Lutus <nospam@...>
Date: 2006-12-04T17:00:08+09:00
Subject: Re: number format

Daniel Finnie wrote:

> You can use the number.round method, but this doesn't take a number of
> decimal places.
> 
> To round 1.234 to 1.23 use this code:
> x = 1.234
> x = x * 100 # -> 123.4
> x = x.round -> 123
> x = x / 100.0 => 1.23
> 
> At least, that's the best method I can find from the Ruby docs...

This is not a good idea. Because the number being manipulated is binary but
the display is decimal, the multiplication and division steps will fail on
some numbers -- many, in fact -- and those numbers will print more decimal
places than was intended.

It's better to retain the full binary resolution of a number internally, and
only show certain decimal places while printing a number -- don't try to
truncate the number itself.

-- 
Paul Lutus
http://www.arachnoid.com