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Edit detail for #294 Infinite recursion during integration revision 1 of 8

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Editor:
Time: 2007/11/17 22:22:32 GMT-8
Note: elementary integration really should be one of the strengths...

changed:
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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.

From kratt6 Sat Jun 3 07:52:55 -0500 2006
From: kratt6
Date: Sat, 03 Jun 2006 07:52:55 -0500
Subject: elementary integration really should be one of the strengths...
Message-ID: <20060603075255-0500@wiki.axiom-developer.org>

Category: Aldor Library Compiler => Axiom Library 
Severity: normal => serious 


Submitted by : (unknown) at: 2007-11-17T22:22:32-08:00 (16 years ago)
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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