Sure, you'd want to do this with 32 bit floats in production, the f64 was really for prototyping. I didn't compare smoothstep. It's worth doing an analysis of

Sure, you'd want to do this with 32 bit floats in production, the f64 was really for prototyping. I didn't compare smoothstep. It's worth doing an analysis of the tradeoff between performance and quality. In any case, I think in practice this erf approximation will be plenty fast, and probably a bit better quality, especially in the tail region.