[Octave-task-tracker] [task #13313] MingW issues for Octave built w --enable-64

[Philip Nienhuis]

Follow-up Comment #7, task #13313 (project octave):

Sorry I didn't initially understand what you meant with "out of range inside
the test function itself". 
Only later on I found that all tests in eig.cc_tst pass when run by hand and
that the problem lies in test.m itself.

I stepped through Octave-3.8.2's test.m (applying it to eig.cc_tst with test
#17 uncommented); I found that as soon as the loop counter __i in L.244 gets >
16 it doesn't get to be 17 as expected, but instead turns into 1.0224e-314.
Looks like an erroneous cast from double to integer, or wraparound (but I'd
rather expect wraparound when __i goes from 15 to 16).

In libinterp/octave-value/ov.h there's the following (L. 180-191):

===========<QUOTE>===========
  // FIXME: these are kluges.  They turn into doubles
  // internally, which will break for very large values.  We just use
  // them to store things like 64-bit ino_t, etc, and hope that those
  // values are never actually larger than can be represented exactly
  // in a double..

#if defined (HAVE_LONG_LONG_INT)
  octave_value (long long int i);
#endif
#if defined (HAVE_UNSIGNED_LONG_LONG_INT)
  octave_value (unsigned long long int i);
#endif
===========</QUOTE>===========

Could that be related to what we see in test.m ? Or is it a problem in the
interpreter, triggered/provoked by the try-catch blocks in test.m?
Could that also be a relation with the tolerances seen in failing tests for
e.g., axis.m and assert.m in my original post?


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