not using float or not compare ==.

(or using abs($x-$y) < $epsilon as you already shown which is not the compare anyway)

I know my position is a bit strong, but using == on floats is going to make troubles, which depends on values, host, compiler, libc and so on. very hard to predict and replicate.

maybe a nice gift would be to have a warning?

Update: ops! i've replied to my node instead of moritz's 806454.