On Jun 20, 2016, at 7:22 AM, Ben Rimmington via swift-evolution
<swift-evolution@swift.org> wrote:
> DEC64 <http://dec64.com <http://dec64.com/>> as the default number type!
At some danger of going off on a tangent, I should point out that DEC64 has
very little to recommend it. It’s not much more efficient performance-wise
than IEEE-754 decimal types and has significantly less exponent range (it
effectively throws away almost three bits in order to have the exponent fit in
a byte; 2**56 is ~7.2E16, which means that it can represent some, but not all,
17-digit significands; the effective working precision is 16 digits, which
actually requires only ~53.15 bits. Even if you weren’t going to use those
extra bits for exponent, they could be profitably used for other purposes. The
fact that the dec-64 scheme allows one to use byte operations has only a tiny
benefit, and really only on x86).
– Steve
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