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#272 functions +-> and blocks of instructions ←	↑	→ #274 Can't get a parameter in an anonymous function

#273 Factor Expression Integer does nothing

Edit detail for #273 Factor Expression Integer does nothing revision 1 of 2

	1 2
Editor: Time: 2007/11/17 22:19:28 GMT-8
Note: For others who may find this

changed:
-
\begin{axiom}
factor ((y-1) * x + y - 1)     -- is right
factor ((y-1) * sin x + y - 1) -- does nothing 
\end{axiom}

From MartinRubey Sat Mar 4 12:56:00 -0600 2006
From: Martin Rubey
Date: Sat, 04 Mar 2006 12:56:00 -0600
Subject: (new)
Message-ID: <85psl211hp.fsf@localhost.localdomain>
In-Reply-To: <20060304120530-0600@wiki.axiom-developer.org>

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

Martin

From greg Sun Apr 2 13:09:15 -0500 2006
From: greg
Date: Sun, 02 Apr 2006 13:09:15 -0500
Subject: status change
Message-ID: <20060402130915-0500@wiki.axiom-developer.org>

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

From kratt6 Mon Apr 3 05:01:02 -0500 2006
From: kratt6
Date: Mon, 03 Apr 2006 05:01:02 -0500
Subject: well documented and more or less mathematically sound
Message-ID: <20060403050102-0500@wiki.axiom-developer.org>

Status: open => closed 

From daniel Mon Jan 8 20:21:34 -0600 2007
From: daniel
Date: Mon, 08 Jan 2007 20:21:34 -0600
Subject: For others who may find this 
Message-ID: <20070108202134-0600@wiki.axiom-developer.org>

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:<br>
f:=(y-1)*sin(x)+y-1 -- original function<br>
g:=subst(f, sin(x)=sx)::Polynomial Integer -- remove the nonlinear operators, then recast<br>
h:=factor(g) -- yields (sx + 1)(y - 1)<br>
<p>
Unfortunately, any conversion of h from a "Factored Polynomial Integer" to a "Factored Expression Integer" will destroy the factorization.

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

(new) --Martin Rubey, Sat, 04 Mar 2006 12:56:00 -0600 reply

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

Martin

status change --greg, Sun, 02 Apr 2006 13:09:15 -0500 reply

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.