From: "Anton Hörnquist" <anton@...>
Date: 2008-09-12T02:59:39+09:00
Subject: Re: Array#pack and String#unpack query

I forgot a thing: I expected the output to be the same for "e*" and 
"E*":

[1.0, 0.75, 0.5, 0.1, 0.025, 0.01]
[1.0, 0.75, 0.5, 0.1, 0.025, 0.01]

Am I wrong?

/Anton


Anton Hörnquist wrote:
> 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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