[Numpy-discussion] Questions about the array interface.

konrad.hinsen at laposte.net konrad.hinsen at laposte.net
Fri Apr 8 23:46:00 CDT 2005


On 09.04.2005, at 01:04, Scott Gilbert wrote:

> I think something we've been assuming is that the array data is  
> basically
> IEEE-754 compliant (maybe it needs to be byteswapped).  If that's not  
> true,
> then we're going to need some new typecodes.  We're not supporting the
> ability to pass VAX floating point around (Are we????).

This discussion has been coming up regularly for a few years. Until now  
the concensus has always been that Python should make no assumptions  
that go beyond what a C compiler can promise. Which means no  
assumptions about floating-point representation.

Of course the computing world is changing, and IEEE format may well be  
ubiquitous by now. Vaxes must be in the museum by now. But how about  
mainframes? IBM mainframes didn't use IEEE when I used them (last time  
15 years ago), and they are still around, possibly compatible to their  
ancestors.

Another detail to consider is that although most machines use the IEEE  
representation, hardly any respects the IEEE rules for floating point  
operations in all detail. In particular, trusting that Inf and NaN will  
be treated as IEEE postulates is a risky business.

Konrad.
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