@swift-4.2.4
// https://github.com/apple/swift/blob/9286b3627d90523752cb1a2ffc02f7500ead0ea8/stdlib/public/core/FloatingPoint.swift.gyb#L2405-L2466 func test<T: BinaryFloatingPoint>(range: Range<T>) { print("\(T.self): \(range)") let delta = range.upperBound - range.lowerBound let maxSignificand = T.RawSignificand(1) << (T.significandBitCount + 1) // rand = generator.next(upperBound: maxSignificand) \in 0...maxSignificand-1 let zero: T.RawSignificand = 0 let maxx = maxSignificand - 1 let minimum = T(zero) * .ulpOfOne / 2 print("minimum == 0: \(minimum == 0)") let lb = delta * minimum + range.lowerBound print("lb == range.lowerBound: \(lb == range.lowerBound)") let maximum = T(maxx) * .ulpOfOne / 2 print("maximum < 1: \(maximum < 1)") let ub = delta * maximum + range.lowerBound print("ub < range.upperBound: \(ub < range.upperBound)") print("") } let floatRanges: [Range<Float>] = [1..<2, 2..<4] for range in floatRanges { test(range: range) } let doubleRanges: [Range<Double>] = [1..<2, 2..<4] for range in doubleRanges { test(range: range) }