[geos-devel] Thoughts on in/outlining and robustness

[Martin Davis]

strk, while I commend your valiant efforts to reconcile the behaviour of
inlined VS outlined functions and their effect on GEOS robustness, I'm
wondering whether this effort can ever pay off.
 
As I understand the problem, you're worried that inlined VS outlined
code sometimes produces incorrect results rather than throws exceptions,
or perhaps even produces correct results.  It makes sense that this is
due to subtle differences in the way the FP computations are done.  But
even if you managed to get the two implementations to behave
identically, there would still be a whole set of test cases which would
still either get the wrong answer or throw an exception.  JTS has the
same problem right now.  
 
I think the best place to direct effort is in solving the overall
problem of robustness in the fundamental algorithms.  Hopefully this
will be solid enough that it will be immune to the inline/outline FP
differences.  
 
My impression is that it would be a lot of incredibly finicky work to
"solve" the inline/outline difference, without improving robustness all
that much.  Or am I missing something?
 
Martin Davis, Senior Technical Architect
Vivid Solutions Inc.      www.vividsolutions.com
Suite #1A-2328 Government Street Victoria, B.C. V8T 5G5
Phone: (250) 385 6040 - Local 308 Fax: (250) 385 6046
 
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