Bill Page wrote:
>
> Just to confirm in FriCAS the 'totalGroebner' routine which apparently
> uses degree reverse lexical ordering takes much less time:
>
> Time: 1718.35 (EV) + 0.53 (OT) = 1718.88 sec
>
> and finds a basis with 28 polynomials (although that is still a lot
> longer than Singular needs for this computation).
There is a simple trick to make this about 10-20 time faster:
clear denominator and use coefficients in the ring. I profiled
the groebner basis computation and 95% of time goes into
gcd-s needed for fraction arithmetic. I also did computation
over a ring and then fraction of time spent computing gcd-s
went down to 5%.
> But as you say, even with this result I am a bit stuck since there I
> could not find any convenient way to change the ordering of a given
> basis.
>
> In computing 'groebnerFactorize' is there some way to keep the basis
> in degree reverse lexical order? Maybe it I use some other polynomial
> type rather than 'Polynomial'?
IIUC 'groebnerFactorize' uses order from the polynomial type:
++ The term ordering is determined by the polynomial type used.
OTOH I am not sure how term order affects the result you will get...
--
Waldek Hebisch
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