login  home  contents  what's new  discussion  bug reports help  links  subscribe  changes  refresh  edit

# Edit detail for #212 substituting for an operator in a sum does not apply the summation algorithms revision 2 of 2

 1 2 Editor: test1 Time: 2014/05/06 17:09:55 GMT+0 Note:

added:

From test1 Tue May 6 17:09:55 +0000 2014
From: test1
Date: Tue, 06 May 2014 17:09:55 +0000
Subject:
Message-ID: <20140506170955+0000@axiom-wiki.newsynthesis.org>

Severity: serious => minor



 Submitted by : (unknown) at: 2007-11-17T22:09:32-08:00 (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 :

Original Savannah bug 9217

Submitted by: Martin Rubey

Submitted on: Fri 06/04/04 at 08:18

Summary:

Although axiom can evaluate this sum, it does not.

Example of code trigerring the bug:

axiom
f := operator 'f
 (1)
Type: BasicOperator?
axiom
sum(f(i),i=a..b)
 (2)
Type: Expression(Integer)
axiom
eval(%,f,x+->x)
 (3)
Type: Expression(Integer)

## Internal Cause

first the sum is evaluated. Since the argument f(x) is not a polynomial or rational function, using first iidsum, than idsum of COMBF. Afterwards the substitution is performed. Now the sum has the internal format '%defsum [%A, %A, i, a, b]?', which is again evaluated with iidsum and idsum of COMBF. The function sum\$InnerPolySum is never called, of course. A general solution is to call sum from within idsum, but in this case, care has to be taken that summation algorithms that can fail (such as Gosper's) do not produce an infinite loop. (In fact I think this is OK, I only did not have the time to check)

property change --kratt6, Tue, 04 Oct 2005 05:47:07 -0500 reply
Category: => Axiom Library Severity: => serious Status: => open

Severity: serious => minor