R-alpha: not precisely linux bug

Thomas Lumley (thomas@biostat.washington.edu)
Sun, 17 Nov 1996 10:18:41 -0800 (PST)


Date: Sun, 17 Nov 1996 10:18:41 -0800 (PST)
From: Thomas Lumley <thomas@biostat.washington.edu>
To: r-testers@stat.math.ethz.ch
Subject: R-alpha: not precisely linux bug
In-Reply-To: <Pine.SUN.3.91.961115074650.18484B-100000@shadows>


The bug I mentioned last week turns out not to be a garbage collection 
problem.  I though the program was crashing on the call to a dyn.loaded 
function because nothing appeared from printf statements inserted in the 
code. In fact, the bug is much further down the loaded code.

It is still an R incompatibility of sorts: 
R0.13 for Linux has different floating point error handling from earlier 
versions and from SunOS versions.  At least in dyn.loaded code, division 
by zero triggers a floating point exception.  The survival4 code contains 
a calculation that involves zero division for censored observations with 
no failure at the same time.  As the result of this calculation is only 
referenced for failures it is harmless and works perfectly well as long 
as zero division doesn't trigger an exception. Using gdb to mask floating 
point exceptions allows the code to run properly, but there should be an 
easier way.

thomas lumley
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