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Edit detail for #294 Infinite recursion during integration revision 3 of 8

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Editor: kratt6
Time: 2007/12/20 01:17:58 GMT-8
Note: Fixed in FriCAS

added:

From kratt6 Thu Dec 20 01:17:58 -0800 2007
From: kratt6
Date: Thu, 20 Dec 2007 01:17:58 -0800
Subject: Fixed in FriCAS
Message-ID: <20071220011758-0800@axiom-wiki.newsynthesis.org>

Status: open => fix proposed 


Submitted by : (unknown) at: 2007-11-17T22:22:32-08:00 (17 years ago)
Name :
Axiom Version :
Category : Severity : Status :
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The following input causes infinite recursion in rischNormalize:

  integrate(simplify(D((log((x)+1)+a)/(2*((((x*(exp(exp(x)/2)))-(a*(x+exp(-x/2))))*(2/x))-3)), x)), x)

AFAICS goodCoef chooses to rewrite simpler kernel in terms of a more complex one. More precisely, rischNormalize is supposed to eliminate kernels which are algebraically dependent on other kernels. If a dependent kernel is found rischNormalize should eliminate it and recurse. So the recursion depth is limited by the number of kernels. However, in this example rischNormalize eliminates simpler kernel, but causes new kernels to appear.

elementary integration really should be one of the strengths... --kratt6, Sat, 03 Jun 2006 07:52:55 -0500 reply
Category: Aldor Library Compiler => Axiom Library Severity: normal => serious

Fixed in FriCAS? --kratt6, Thu, 20 Dec 2007 01:17:58 -0800 reply
Status: open => fix proposed