Re: Build 2.1.64 on OS 10.3. error

[Michael Martin]

On Dec 21, 2004, at 12:22 PM, Per Persson wrote:

> Sorry if I'm sounding negative, but it is my experience that applying 
> something as agressive[1] as the -fast option will not work well on 
> something as complex as octave.

Caveat simulator!

	I second Per Persson's warning. I have had the -fast optimization 
optimize some of my loops right out of existence and thereby produce 
incorrect results.

	We have a number of spacecraft simulations, which have varying degrees 
of complexity. I ran an extensive set of test cases on our basic 
simulator, slowly increasing the optimization levels. The 
no-optimization compile was considered the baseline, and was shown to 
agree with the results from our solaris and sgi installations of the 
simulator. When I compiled on OSX, -O1 was fine, so was -O2, as was 
-O3, but -fast, while it was the fastest, it could not reproduce the 
numbers seen in the baseline. Since I would rather not have my 
spacecraft fall apart on me (bad for business, you know). Our make 
files are set to -O3 for OSX.

	OSX is not unique in this by any means. Our simulators run on several 
Unix platforms and tolerate different degrees of optimization on each 
platform. We run test cases to find what does and does not work for 
each simulator/platform/OS/compiler combination. It is different for 
each.



----------------------------------------------------------------------
Michael W. Martin                   Phone: (281) 333-2177
Draper Laboratory                   FAX:   (281) 333-5276
2200 Space Park Dr.                 EMail: address@hidden
Houston, TX 77058                   WWW: http://www.jsc.draper.com/
USA                                 Mail Code: EG/Draper
----------------------------------------------------------------------



-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
-------------------------------------------------------------