[Maxima] Simplification of infinities

[Barton Willis]

For extended real number arithmetic, I think that both special
variables errorsw and limitp need to be considered--it seems that
limitp should override errorsw; thus no error when limitp is true.

I added a check for limitp in my altsimp code---that speed it up
considerably--before it would sometimes throw errorsw when limitp
was true. Now altsimp runs the testsuite in about 603 seconds and
allocates 1,296,248,744 bytes of memory; the standard simplus runs the
testsuite in about 587 seconds and allocates 4,167,894,632 bytes of
memory.

I'm surprised at the difference between the allocated memory with
and without altsimp.

Barton

-----maxima-bounces at math.utexas.edu wrote: -----

>To: Dieter Kaiser <drdieterkaiser at web.de>
>From: Dieter Kaiser <drdieterkaiser at web.de>
>Sent by: maxima-bounces at math.utexas.edu
>Date: 12/07/2009 06:35PM
>cc: "maxima at math.utexas.edu" <maxima at math.utexas.edu>
>Subject: Re: [Maxima] Simplification of infinities
>
>Am Montag, den 07.12.2009, 23:05 +0100 schrieb Dieter Kaiser:
>
>I have replaced the function intersection with the following
>implementation:
>
>(defun not-freeof-infinities-p (expr)
>  (let ((flag nil))
>  (dolist (sym '($inf $minf $infinity $ind $und))
>    (if (member sym expr :test #'eq)
>      (return (setq flag t))))
>  flag))
>
>This functions seems to be somewhat more efficient than the function
>intersection. These are the results for one of the examples:
>
>(%i2) qq: ratsimp((x^50000-1)/(x-1))$
>Evaluation took 2.1121 seconds (2.1806 elapsed) using 7.631 MB.
>
>We test the expressions to be free of infinities:
>
>(%i3) for i thru 1000 do qq:qq+1$
>Evaluation took 22.4814 seconds (22.5831 elapsed) using 381.737 MB.
>(%i4) for i thru 1000 do qq:qq+1$
>Evaluation took 22.4614 seconds (22.5891 elapsed) using 381.737 MB.
>(%i5) for i thru 1000 do qq:qq+1$
>Evaluation took 22.2574 seconds (22.3724 elapsed) using 381.737 MB.
>
>We switch off the test:
>
>(%i6) for i thru 1000 do qq:qq+1,simpinfinities:false$
>Evaluation took 22.3414 seconds (22.7901 elapsed) using 381.738 MB.
>(%i7) for i thru 1000 do qq:qq+1,simpinfinities:false$
>Evaluation took 22.3614 seconds (22.4699 elapsed) using 381.738 MB.
>(%i8) for i thru 1000 do qq:qq+1,simpinfinities:false$
>Evaluation took 22.4134 seconds (22.5303 elapsed) using 381.738 MB.
>
>I do not get a significant increase of the runtime of the testsuite with
>this implementation.
>
>Dieter Kaiser
>
>
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