Pseudo-random numbers/Splitmix64: Difference between revisions

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</pre>

=={{header|Swift}}==

{{works with|swift|5.1}}

Swift has standard methods for producing random floating point numbers in a range,

but they produce different numbers than the task expects.

<syntaxhighlight lang="Swift">

struct SplitMix64: RandomNumberGenerator {

var state: UInt64

init(seed: UInt64) {

state = seed

}

mutating func next() -> UInt64 {

state &+= 0x9e3779b97f4a7c15

var z = state

z = (z ^ (z >> 30)) &* 0xbf58476d1ce4e5b9

z = (z ^ (z >> 27)) &* 0x94d049bb133111eb

return z ^ (z >> 31)

}

mutating func nextFloat() -> Float64 {

Float64(next() >> 11) * 0x1.0p-53

}

}

do {

var split = SplitMix64(seed: 1234567)

print(split)

for _ in 0..<5 {

print(split.next())

}

split = .init(seed: 987654321)

print("\n\(split)")

var counts = [0, 0, 0, 0, 0]

for _ in 0..<100_000 {

let i = Int(split.nextFloat() * 5.0)

counts[i] += 1

}

for (i, count) in zip(0..., counts) {

print("\(i): \(count)")

}

}

</syntaxhighlight>

{{out}}

<pre>

SplitMix64(state: 1234567)

6457827717110365317

3203168211198807973

9817491932198370423

4593380528125082431

16408922859458223821

SplitMix64(state: 987654321)