Hi,

Imre wrote:

>I'm very interested in this topics as I want to make a FFT with PIC.
>However, it is a bit unclear for me how to make add/subtract using LNS.
>Would you please give additional information regarding this topic (you
>mentioned lookup table. What is to look for and with what argument?)

Me to was a bit intrigued about this subject, I performed some minor
searches and that turned up:

This will breifly explain why you need the table/interpolation:
http://napier.ncl.ac.uk/HSLA/LNSIntro/

This covers some techniques (semi-logarithmic system ) to
'circumvent' the *large* table required for accuracy and high bit numbers:
http://www.ens-lyon.fr/~jmmuller/IEEETC-Fev98.pdf

And there were alot others,
make an seach for either:

logarithmic number system

or:

Digital Filtering Using Logarithmic Arithmetic

On google, you'll be surprised of how much there are available :)
Really intriguing stuff, almost to the extent that I feel like
putting down my current project just to dwell into this ( well
I said almost :) )

/Tony

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