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 Submitted by : (unknown) at: 2007-11-17T22:19:28-08:00 (15 years ago) Name : Axiom Version : default friCAS-20090114 Axiom-20050901 OpenAxiom-20091012 OpenAxiom-20110220 OpenAxiom-Release-141 Category : Axiom Aldor Interface Axiom Compiler Axiom Library Axiom Interpreter Axiom Documentation Axiom User Interface building Axiom from source lisp system MathAction Doyen CD Reduce Axiom on Windows Axiom on Linux Severity : critical serious normal minor wishlist Status : open closed rejected not reproducible fix proposed fixed somewhere duplicate need more info Optional subject :   Optional comment :

axiom
factor ((y-1) * x + y - 1)
is right
 (1)
Type: Factored(Polynomial(Integer))
axiom
factor ((y-1) * sin x + y - 1) -- does nothing
 (2)
Type: Factored(Expression(Integer))

This is "obvious" since EXPR is a field...

Martin

I think we can close this issue. Are you agree ?

well documented and more or less mathematically sound --kratt6, Mon, 03 Apr 2006 05:01:02 -0500 reply
Status: open => closed

For others who may find this --daniel, Mon, 08 Jan 2007 20:21:34 -0600 reply
While this is "mathematically sound", it can be very frustrating to new users of Axiom. Is this behavior explained in a FAQ somewhere? Maybe something should be added to section 8.2 of the 30-year book?

To get what the OP wanted, recast the problem as a Polynomial:
f:=(y-1)*sin(x)+y-1 -- original function
g:=subst(f, sin(x)=sx)::Polynomial Integer -- remove the nonlinear operators, then recast
h:=factor(g) -- yields (sx + 1)(y - 1)

Unfortunately, any conversion of h from a "Factored Polynomial Integer" to a "Factored Expression Integer" will destroy the factorization.

Category: Axiom Mathematics => Axiom Library

 Subject:   Be Bold !! ( 14 subscribers )