[Octave-bug-tracker] [bug #31512] Problem with code on Linux octave 3.2.3 and 3.2.4/// OK on mac w/ 3.2.3

[Rik]

Follow-up Comment #12, bug #31512 (project octave):

I didn't realize that you were running your own custom-compiled Octave with
custom-built libraries.  I think the first thing to do is try your code on a
vanilla system (i386, vendor-supplied libraries and Octave binaries).  You can
use any of the distros which support LiveCD such as Debian, Ubuntu, RedHat,
etc.

The compilation flags you list ("-O3 -fpmath=sse") are rather aggressive.  In
particular, "-O3" is known to occasionally break pieces of code.  I also quote
from the gcc documentation regarding "-fpmath=sse"

-- Start of Quote --
Use scalar floating point instructions present in the SSE instruction set.
This instruction set is supported by Pentium3 and newer chips, in the AMD line
by Athlon-4, Athlon-xp and Athlon-mp chips. The earlier version of SSE
instruction set supports only single precision arithmetics, thus the double
and extended precision arithmetics is still done using 387. Later version,
present only in Pentium4 and the future AMD x86-64 chips supports double
precision arithmetics too. 

 For the i386 compiler, you need to use -march=cpu-type, -msse or -msse2
switches to enable SSE extensions and make this option effective. For the
x86-64 compiler, these extensions are enabled by default. 

 The resulting code should be considerably faster in the majority of cases
and avoid the numerical instability problems of 387 code, *but may break some
existing code that expects temporaries to be 80bit.* [Emphasis mine]

 This is the default choice for the x86-64 compiler.

-- End of Quote --

This might be part of the problem as well.  Finally, I note my gcc is more
recent, 4.4.1, than yours.  But really, do start with a vanilla system and see
if that works.


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