[Numpy-discussion] Random int64 and float64 numbers
David Warde-Farley
dwf@cs.toronto....
Thu Nov 5 17:26:53 CST 2009
On 5-Nov-09, at 4:54 PM, David Goldsmith wrote:
> Interesting thread, which leaves me wondering two things: is it
> documented
> somewhere (e.g., at the IEEE site) precisely how many *decimal*
> mantissae
> are representable using the 64-bit IEEE standard for float
> representation
> (if that makes sense);
IEEE-754 says nothing about decimal representations aside from how to
round when converting to and from strings. You have to provide/accept
*at least* 9 decimal digits in the significand for single-precision
and 17 for double-precision (section 5.6). AFAIK implementations will
vary in how they handle cases where a binary significand would yield
more digits than that.
David
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