Unit test error with numpy rc3

Charles R Harris charlesr.harris at gmail.com
Thu Oct 26 10:20:34 CDT 2006


On 10/26/06, Ted Horst <ted.horst at earthlink.net> wrote:
>
> On Mac OS X tiger (10.4) ppc, long double has increased precision but
> the same range as double (it really is 128 bits not 80, btw),


Looks like you are right:
http://www.freestandards.org/spec/ELF/ppc64/PPC-elf64abi-1.9.html#PREC
Actually two doubles with some strange rules, the quad value is the sum.
Hmmm, I can see why compiler support was problematic. The extended precision
also has some oddities.

This "Extended precision" differs from the IEEE 754 Standard in the
following ways:

   -

   The software support is restricted to round-to-nearest mode. Programs
   that use extended precision must ensure that this rounding mode is in effect
   when extended-precision calculations are performed.
   -

   Does not fully support the IEEE special numbers NaN and INF. These
   values are encoded in the high-order double value only. The low-order value
   is not significant.
   -

   Does not support the IEEE status flags for overflow, underflow, and
   other conditions. These flag have no meaning in this format.


so
> e**1000 is inf, so this is not really an error.
>
> I'm not sure what is the right thing to do in the test, check for
> overflow?  Also, finfo has never worked properly for this type.


See above.

Chuck
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