Double's epsilon and scheduling artifacts

epsilon_and_scheduling.scala

/*
Consider two activities, A and B, both scheduled at the same time. When 
activated, they schedule themselves for reactivation in a time delta of 0.1 
and 0.2. If this is less than the ulp at a given time, both activities end 
up being scheduled at the same time.
*/
import scala.math.ulp

val MaxTime = 9.007199254740991E15

var a = MaxTime + 0.1
var b = MaxTime + 0.2

println(s"ulp(MaxTime)      => ${ulp(MaxTime)}")
println(s"a = MaxTime + 0.1 => $a")
println(s"b = MaxTime + 0.2 => $b")
println(s"a == b            => ${a == b}")

println("\n----------------------------------------------\n")

val HalfMax = 9.007199254740991E15 / 2.0
a = HalfMax + 0.1
b = HalfMax + 0.2

println(s"ulp(HalfMax)      => ${ulp(HalfMax)}")
println(s"a = HalfMax + 0.1 => $a")
println(s"b = HalfMax + 0.2 => $b")
println(s"a == b            => ${a == b}")