Post new topic Reply to topic  [ 2 posts ] 
Author Message
 Post subject: "Factor" question
PostPosted: Thu Aug 11, 2005 5:33 pm 
Hi,

My question is certainly a simple one, however I did not guessed the point.

In the Help Manual "D.7.5.2 Factor" you give the following Example:

LIB "zeroset.lib";
ring R = (0,a), x, lp;
minpoly = a2+1;
poly f = x4 - 1;
list fl = Factor(f);
fl;
==> [1]:
==> _[1]=1
==> _[2]=(40a+60)*x+(40a+60)
==> _[3]=(1/65a-29/130)*x+(-1/65a+29/130)
==> _[4]=(4a)*x+4
==> _[5]=(7/520a+1/130)*x+(1/130a-7/520)
....

- which is just (x-1)*(x+1)*(x-a)*(x+a) where the factors are modified by some invertible elements of Q(a)[x] having their product = 1. (some complex rationals actually)

My question is: what is the property that single out the Singular answer in the above example, out of the many others, which all just differ by invertible factors?

Thanks for the answer,
Horvath Sandor


email: shorvath@ms.sapientia.ro
Posted in old Singular Forum on: 2005-02-01 11:59:03+01


Report this post
Top
  
Reply with quote  
 Post subject:
PostPosted: Tue Sep 20, 2005 5:05 pm 
Site Admin

Joined: Fri Apr 29, 2005 12:02 am
Posts: 24
Location: Germany, Kaiserslautern
Dear Sandor Horvath,

the command "Factor" from zeroset.lib is obsolete. Nowadays you should use the function "factorize":

Code:
> ring R = (0,a), x, lp;
> minpoly = a2+1;
> poly f = x4 - 1;
> factorize(f);
[1]:
   _[1]=1
   _[2]=x-1
   _[3]=x+1
   _[4]=x+(a)
   _[5]=x+(-a)
[2]:
   1,1,1,1,1


Sincerely,

The Singular Team


Report this post
Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2 posts ] 

You can post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

It is currently Fri May 13, 2022 10:55 am
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group