On Bob's post, Thanks for a clear description of the classical linear
algebra for mod p DL. I recognize the Chinese Remaindering from Peter's
ecm/fft output. Does anyone know whether the method described is still
applied post-Lanczos (much less, post-Wiedemann)?

Looking at Thome's paper [url]http://www.loria.fr/~thome/php/dl.php/publis/papers/jsc.pdf[/url]
suggests that the Wiedemann calculation is done modulo the big prime, taking advantage of FFT there, and there's no CRT stage ... that paper is slightly vague about how things extend to F_2.

I'm having a little trouble seeing how the distribution into subclusters worked; I suppose the entries in a dlog matrix may be uniformly distributed over the big prime field, so 300M entries would take 300M 80-byte numbers and not fit on a single computer (300M * 80 bytes is a bit under 24GB, so splitting across 12 2GB or 24 1GB systems makes sense). My guess would be that the eight jobs computed the columns of a series of 8x8 matrices, and there was then a huge-memory FFT job rather like the one in Thome's paper to merge the results.

[QUOTE=fivemack;98280]

Looking at Thome's paper [url]http://www.loria.fr/~thome/php/dl.php/publis/papers/jsc.pdf[/url]
suggests that the Wiedemann calculation is done modulo the big prime, taking advantage of FFT there, and there's no CRT stage ... that paper is slightly vague about how things extend to F_2.

.[/QUOTE]

Thome's paper looks like very nice work. I was not aware of it.
I will start reading it.