> -----Original Message-----
> From: Pierre Abbat [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, June 17, 1999 2:24 PM
> To: Blosser, Jeremy; Mersenne discussion list
> Subject: RE: Mersenne: Thoughts on Merced / IA-64
>
>
> > You could go with a NTT instead of a FFT. Thus foregoing any double
> > precision floats. Going with an NTT would also eliminate
> any precision
> > problems...
>
> What's NTT? And is DWT Discrete Walsh Transform?
>
NTT = Number Theoretic Transform (Wow, my fingers got twisted)
See: http://www.hut.fi/~mtommila/ntt.html for a decent explanation of an NTT
and how it relates to FFTs. At some point GIMPS would either have to move to
quad precision primes or an NTT algorithm because of round-off errors (not
enough bits... I think it'll die around 32-bit? And right now we're at 19 or
something?)
DWT is the discrete walsh transform... of which there is of course the FWHT
(Fast Walsh-Hadamard Tranform). Which is considered a "poor man's FFT" a lot
of the time. Its faster than an FFT, but I think the issue is that there is
no real way to do a convolution via FWHT (that has been found yet?)
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