Bill Allombert on Sat, 08 May 2004 19:32:33 +0200

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Re: round4 performance

On Wed, May 05, 2004 at 08:35:40PM +0200, Xavier-François Roblot wrote:
> Well, I have modified update_alpha (after Karim pointed out a strange
> behavior in this function) and that kind of miraculously speed up
> dramatically that example!... As you will see, the computing time is now
> very reasonable and it runs with a small stack too (I hope the result is
> still correct though, I haven't checked yet). Igor, Karim and I still
> have some ideas for improvements for nilord but you need some new bad
> polynomials to test them. Please send me your worst examples!

Well, I have retested and now this is much faster, also respm was
improved, so galoisinit() is a bit faster also.
Igor example needs 41s and 16MB of RAM.

I have made some test: 2.2.7 with gmp against CVS with gmp.
Both version give the same discriminants on all the polynomial
I have tested. I used nfdisc(,1) to avoid getting stuck in the

Some timing:
Degree: nb pol.| 2.2.7| 2.2.8
24    : 30     |  2730|  2030
32    : 102    | 53600| 44090
40    : 28     | 33240| 25340

However they are easy example. On harder one, the new version is much
faster and use less memory, it is really impressive.