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Benford's law: Difference between revisions
Add F# version
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8 0.053 0.05115252244738129
9 0.045 0.04575749056067514
</pre>
=={{header|F sharp|F#}}==
For Fibonacci code, see https://rosettacode.org/wiki/Fibonacci_sequence#F.89
<lang fsharp>open System
let fibonacci = Seq.unfold (fun (x, y) -> Some(x, (y, x + y))) (0I,1I)
let fibFirstNumbers nth =
fibonacci |> Seq.take nth |> Seq.map (fun n -> n.ToString().[0] |> string |> Int32.Parse)
let fibFirstNumbersFrequency nth =
let firstNumbers = fibFirstNumbers nth |> Seq.toList
let counts = firstNumbers |> List.countBy id |> List.sort |> List.filter (fun (k, _) -> k <> 0)
let total = firstNumbers |> List.length |> float
counts |> List.map (fun (_, v) -> float v/total)
let benfordLaw d = log10(1.0 + (1.0/float d))
let benfordLawFigures = [1..9] |> List.map benfordLaw
let run () =
printfn "Frequency of the first digit (1 through 9) in the Fibonacci sequence:"
fibFirstNumbersFrequency 1000 |> List.iter (fun f -> printf $"{f:N5} ")
printfn "\nBenford's law for 1 through 9:"
benfordLawFigures |> List.iter (fun f -> printf $"{f:N5} ")
</lang>
{{out}}
<pre>
Frequency of the first digit (1 through 9) in the Fibonacci sequence:
0.30100 0.17700 0.12500 0.09500 0.08000 0.06700 0.05600 0.05300 0.04500
Benford's law for 1 through 9:
0.30103 0.17609 0.12494 0.09691 0.07918 0.06695 0.05799 0.05115 0.04576
</pre>
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