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[Gcl-devel] Bad news on Maxima and proclaim


From: James Amundson
Subject: [Gcl-devel] Bad news on Maxima and proclaim
Date: Tue, 27 Jul 2004 12:47:20 -0500

On Sun, 2004-07-25 at 18:07, James Amundson wrote:

> Having followed all your directions, I finally see what you were talking
> about: GCL Maxima runs roughly twice as fast as it used to! I am very
> impressed. For the first time, GCL is beating CMUCL in my timings. I
> have committed the necessary changes to the build system.

Sadly, it appears that these initial reports of spectacular success were
ill-founded. The mistaken impression that including proper proclaims
sped up maxima by a factor of 2 came from a deficiency in the test
suite. Here's what I now know:

1) Maxima 5.9.0.9beta2 compiled with GCL 2.6.3 has a bug. The command 
        trigrat(sin(3*a)/sin(a+%pi/3));
unexpectedly waits for user input. We have a report that this behavior
is not seen in GCL 2.7.0. It seems that this must be a bug in 2.6.3.

2) The bug goes away if the reference to MAXIMA::TYIPEEK is removed from
sys-proclaim.lisp.

3) The apparent large speed increase with the proclaims was an artifact
of a flaw in the maxima test suite. When the test suite is run via "make
check", it quietly stops running further tests when it hits the above
command and its spurious request for user input. The decrease in time
was primarily due to the large number of omitted tests!

I have now tried comparing

  a) Maxima 5.9.0.9beta2 with MAXIMA::TYIPEEK removed from
sys-proclaims.lisp

  b) Maxima 5.9.0.9beta2 with an empty sys-proclaims.lisp.

After five runs, I conclude that the former is (6 +/- 3)% faster than
the latter on my machine.

--Jim





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