gnupic: Re: [gnupic] Is 16-bit floating point library available ?
Subject:
Re: [gnupic] Is 16-bit floating point library available ?
From:
Walter Banks ####@####.####
Date:
14 May 2009 16:23:05 -0000
Message-Id: <4A0C44B5.909D47F@bytecraft.com>
Vaclav Peroutka wrote:
> my question is maybe slight off-topic, but, did anybody have implemented half-precision floating point library for PIC16F processors ?
> . . .
> I need to evaluate it somehow to find if such method fulfills my accuracy requirements. I simulated Goertzel and 8 samples were sufficient for me.
>
> Another idea was to use fixed point arithmetics 8-bit point 8-bit and rescale ADC values. But I-Q method is still simpler.
Scott may very well have the solution you need but some
comments on Fixed8:8 vs half IEEE 754R floats might be useful if
this comes back into consideration.
A couple years ago we did some work on fixed point libraries for
embedded processors. Part of this was benchmarking fixed
point against floating point. What we found was the real trade-off was
dynamic range vs precision. For data types of equal length
the computational complexity was order of magnitude the same.
In your example a half float has a dynamic range of 2^32 and a
precision of 11 bits. A fixed 8:8 has bit more than 15 bit precision
and a 2^8 dynamic range.
Regards,
--
Walter Banks
Byte Craft Limited
http://www.bytecraft.com
