From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-03-03T00:37:46+09:00
Subject: Re: Increase significant digits in Float

On Tue, Mar 2, 2010 at 4:26 PM, Jason Lillywhite
<jason.lillywhite@gmail.com> wrote:
> If I want to increase my significant digits beyond 15 in a result of a
> math expression involving floats, how do I do it? So, for example, I
> would like more than 15 sig digits in the result of:
>
> irb(main):001:0> 4.005 / 7
> => 0.572142857142857

irb is calling inspect on the value of the expression. It's the
inspect method the one that truncates to 15 digits when it creates the
string. You can create your own strings with greater precision like
this:

irb(main):001:0> result = 4.005 / 7
=> 0.572142857142857
irb(main):002:0> "%.20f" % result
=> "0.57214285714285717521"
irb(main):003:0> "%.30f" % result
=> "0.572142857142857175212213860505"

Check the String#% method:

http://ruby-doc.org/core/classes/String.html#M000770

and the Kernel#sprintf method:

http://ruby-doc.org/core/classes/Kernel.html#M005962

Jesus.