On Wednesday, July 29, 2015 at 11:23:34 AM UTC-4, Scott Jones wrote: > > For me, the nice thing (if I understand this correctly) is that UNUMs let > me know that there *was* roundoff error, whereas with currently IEEE binary > *and* decimal standards, you have no way of telling. >
IEEE floating-point has the inexact exception flag to signal that a roundoff error occurred. The unum proposal would store an inexact bit in each number, and I'm skeptical that this adds much value. (In practice, almost all nontrivial computations with a fixed precision will incur a rounding error, and if one output is inexact usually all of them are.)
