It's the hard task of trying to figure out the magnitude of the expected errors (which can accumulate), in the simplest case of a single operation you compare w

It's the hard task of trying to figure out the magnitude of the expected errors (which can accumulate), in the simplest case of a single operation you compare within epsilon distance : https://en.wikibooks.org/wiki/Floating_Point/Epsilon https://en.wikibooks.org/wiki/Floating_Point/Epsilon