Functions to generate the points of a regular n-gon with side length s

N-Gon.swift

import Darwin

func positionOfPoint(_ i: Int, sideLength s: Double, exteriorAngle alpha: Double) -> (x: Double, y: Double) {
    if i == 0 {
        return (0, 0)
    }
    let previousResult = positionOfPoint(i - 1, sideLength: s, exteriorAngle: alpha)
    return (previousResult.x + (s * cos(Double(i - 1) * alpha)), previousResult.y + (s * sin(Double(i - 1) * alpha)))
}

positionOfPoint(0, sideLength: 5, exteriorAngle: Double.pi / 2)

positionOfPoint(1, sideLength: 5, exteriorAngle: Double.pi / 2)
positionOfPoint(2, sideLength: 5, exteriorAngle: Double.pi / 2)

positionOfPoint(3, sideLength: 5, exteriorAngle: Double.pi / 2)

func listOfPoints(sides n: Int, sideLength s: Double) -> [(x: Double, y: Double)] {
    let alpha = Double.pi * 2 / Double(n)

    var array: [(x: Double, y: Double)] = [(0, 0)]
    for i in 1..<n {
        array.append((array[i-1].x + (s * cos(Double(i - 1) * alpha)), array[i-1].y + (s * sin(Double(i - 1) * alpha))))
    }

    return array
}

listOfPoints(sides: 4, sideLength: 5)