On Fri, 15 Jul 2016 21:39:31 +1000, Steven D'Aprano wrote:
> prod *= (m1*m2)
Should be:
prod = m1*m2
or:
prod *= m1
(in the latter case, there's no point in decomposing prod).
Of course, if the result overflows, it's going to overflow whether you use
the naive approach or frexp(); in the latter case, it's the 2.0**scale
which will overflow.
One advantage of processing the scale separately is that you can use e.g.
return ((int(prod * 2**53) * (2**(scale-53))) if scale >= 53
else prod * 2**scale)
which will return a (long) integer if the exponent is such that the
fractional bits are lost.
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