[Numpy-discussion] float128 in fact float80

Matthew Brett matthew.brett@gmail....
Sat Oct 15 18:29:39 CDT 2011


Hi,

After getting rather confused, I concluded that float128 on a couple
of Intel systems I have, is in fact an 80 bit extended precision
number:

http://en.wikipedia.org/wiki/Extended_precision

>>> np.finfo(np.float128).nmant
63
>>> np.finfo(np.float128).nexp
15

That is rather confusing.   What is the rationale for calling this
float128?  It is not IEEE 754 float128, and yet it seems to claim so.

Best,

Matthew


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