|Bill Allombert on Fri, 21 May 2004 00:23:46 +0200|
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|Re: galoisinit() bug|
On Tue, May 18, 2004 at 09:11:23PM -0400, Igor Schein wrote: > Hi, > > ? galoisinit(x^4+272*x^3+40256*x^2+1740800*x+25397248); > *** prime too small in fixedfield. > > It was already broken in 2.2.4. ... and even in 2.2.0. The bug is in a function that include the following disclaimer: /*We try hard to find a polynomial R squarefree mod p. Unfortunately, it may be too much asked. A less bugprone way would be to only ask it to be squarefree mod p^e with e not too big. Most of the code is here, but I lack the theoretical knowledge to make it to work smoothly.B.A. */ and indeed, this is too much asked here. Now I have a better theoretical knowledge, but this is not very encouraging: the theoretical upper bound on the exponent e is so large than this would make the excercise rather pointless. So, barring rewriting the whole code to work at an higher level, I see no 100% solution that does not need a ridiculous amount of code to handle oddball case. So until I decide to rewrite galoisinit, I will add an extra pass to catch this one (the one implemented in 2.1). Cheers, Bill.