snippet27.fs

let findPerfectSquareAndCube array1 =
    let delta = 1.0e-10
    let isPerfectSquare (x:int) =
        let y = sqrt (float x)
        abs(y - round y) < delta
    let isPerfectCube (x:int) =
        let y = System.Math.Pow(float x, 1.0/3.0)
        abs(y - round y) < delta
    // intFunction : (float -> float) -> int -> int
    // Allows the use of a floating point function with integers.
    let intFunction function1 number = int (round (function1 (float number)))
    let cubeRoot x = System.Math.Pow(x, 1.0/3.0)
    // testElement: int -> (int * int * int) option
    // Test an element to see whether it is a perfect square and a perfect
    // cube, and, if so, return the element, square root, and cube root
    // as an option value. Otherwise, return None.
    let testElement elem =
        if isPerfectSquare elem && isPerfectCube elem then
            Some(elem, intFunction sqrt elem, intFunction cubeRoot elem)
        else None
    match Array.tryPick testElement array1 with
    | Some (n, sqrt, cuberoot) -> printfn "Found an element %d with square root %d and cube root %d." n sqrt cuberoot
    | None -> printfn "Did not find an element that is both a perfect square and a perfect cube."

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