[Jprogramming] jwiki/Essays/FFT

[Raul Miller]

On Tue, Jul 17, 2012 at 2:07 PM,  <henryhrich at nc.rr.com> wrote:
> My roots-of-unity verb was designed to get higher accuracy than simpler approaches.  If you just take numbers from 0 to pi you in effect lose an ULP or two of significance.  So, I calculated over a smaller & more accurate interval & used reflection and sign-change.  The results of FFT using the more accurate method were noticeably better.  There is Forum traffic about it.

Can you point at the relevant parts of this traffic?

If we define:

rouwiki=:  [: (, j.) [: (, (j.~%:0.5) , |."1&.:+.@|.@}.) [: ^@o.@:j.
i.@(%&8) % -:

rouforum=: [: (* * |)&.+. [: ^ 0j2p1 * % * i.

I would like to compare fft results generated using (rou=: -: {.
rouforum) with fft results from (rou=: rouwiki).

(I had earlier suggested something like using rou=: rouforum at -: but
that was wrong.)

I feel that having the previous problem cases in hand would be more
meaningful than testing cases which might not be relevant.

Thanks,

-- 
Raul