Comment by sva_
24 days ago
> floating point accumulation doesn't commute
It is commutative (except for NaN). It isn't associative though.
24 days ago
> floating point accumulation doesn't commute
It is commutative (except for NaN). It isn't associative though.
I think it commutes even when one or both inputs are NaN? The output is always NaN.
NaNs are distinguishable. /Which/ NaN you get doesn't commute.
I guess at the bit level, but not at the level of computation? Anything that relies on bit patterns of nans behaving in a certain way (like how they propagate) is in dangerous territory.
10 replies →
Unless you compile with fast-math ofc, because then the compiler will assume that NaN never occurs in the program.