From: "Anton Hörnquist" <anton@...>
Date: 2008-09-12T02:51:25+09:00
Subject: Array#pack and String#unpack query

Hi,

In order to learn a bit of ruby I'm trying to make a module for reading
and writing audio files in WAV format. First and foremost I'd like to
read and write files with 32-bit float bitdepth.

I'm using Array#pack and String#unpack but run into trouble with
precision.

The following of code..

arr = [ 1.0, 0.75, 0.5, 0.1, 0.025, 0.01 ]
p arr.pack("e*").unpack("e*")
p arr.pack("E*").unpack("E*")

...will output this:

[1.0, 0.75, 0.5, 0.100000001490116, 0.025000000372529,
0.00999999977648258]
[1.0, 0.75, 0.5, 0.1, 0.025, 0.01]

How come?

/Anton
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