MaplePrimes - answers and comments on Question, Error, (in factors) Bad inputs to diophant.

evala/Factors/efactor

roman_pearce — Fri, 15 Feb 2013 11:40:04 Z

It's possibly a bug or a bad case for `evala/Factors/efactor` which is the final factorization method used by Maple with algebraic extensions. You can see the code:

kernelopts(opaquemodules=false): interface(verboseproc=3):

eval(`evala/Factors/efactor`:-diophant);

The help page for ?evala,Factors says you can try different factorization methods, but I don't see this in the code. I think the documentation is out of date.

evala(Factor(f,{I,sqrt(3)}), trager);

evala(Factor(f,{I,sqrt(3)}), lenstra);

You should try to post some source code that we can run.

Example

ErikP — Thu, 28 Mar 2013 15:11:49 Z

Hello,

at last I can reproduce the error reliably. On all four machines I could test it, the following commands result in the error mentioned above upon the very last factors()-call:

L := [t+x[1],t+x[2],t+x[3],x[3]*t+x[2]*x[1],t+x[1]+x[2]+x[3],x[3]*(t+x[1]),x[1]*x[3]+x[2]*t,x[2]+t+x[3],x[2]+x[3],t+x[1]+x[2],x[1]+x[2],x[1]*x[2]+x[3]+t,x[1]*(x[2]+x[3]),x[1]+x[2]+x[3]*t,x[1]*x[3]+(t+x[2])^2]:

K := {I,sqrt(2),sqrt(3),sqrt(5)}:
#K := {sqrt(2),sqrt(3),sqrt(5)}:

for p in L do
print(p):
factors(p, K):
end do:

The error disappears when I remove any of the four roots in K (e.g. replacing K by the commented line). Most distractlingly, the error also vanishes upon renaming any of the variables x[1], x[2], x[3] by s (or u or v or ...)!

I have no idea how this is possible and would very much appreciate any help.

Thank you and best wishes,

Erik

Note: Removing any of the polynomials in L also makes the error go away.

Hello,could anyone else reproduce this error? Oth...

ErikP — Tue, 21 May 2013 13:01:50 Z

Hello,

could anyone else reproduce this error? Otherwise I have to search the problem in my Maple installation.

Thanks,

Erik

reproducible

Alejandro Jakubi — Tue, 21 May 2013 13:49:55 Z

Yes, I can reproduce it in Maple 16.02. It does not occur in Maple 17 nor in earlier versions that I have tried (15.01, 14.01, etc)

Workaround

ErikP — Wed, 29 May 2013 11:22:32 Z

Hello,

as this issue is a severe obstacle to my calculations (I can not factor reliably over extensions of Q) I was wondering if there is at least some work-around available?

Unfortunately I can not resort to previous or newer versions of Maple.

So in short, is there any (correctly working) way in Maple 16 to factor polynomials over algebraic extensions of the rationals?

Thanks,

Erik