* Alexander Monakov: >> > Contracting 'x + x - x' to fma(x, 2, -x) would be fine. >> >> It still changes the result, doesn't it? > > I don't follow. I doesn't change the result for infinities (produces > a NaN). It changes the result when x is so large that 'x + x' is > not representable (exponent would overflow), but that's exactly what > contraction is about?
Okay, you meant “changing the result” as in “changing the result in a permitted way”. Sorry, was confused. So this is a bad example all around. Are there better ones (that don't involve FMA)? Thanks, Florian
