Drawing a random double-CodePudding

I want to generate a random double between 0 and 5. I am doing

Double.random(in: 0.0…5.0)

In playground or debugging I get a very nice unified distribution. In the appstore so far after 100 draws the highest number I got was 0.59. Seems highly unlikely that it will suddenly draw higher numbers than that.

Anyone might know a reason for this not-so-random draw? and is there a better way to get a random double that will more random than this?

CodePudding user response：

The function Double.random(in: 0.0...5.0) seems fine and working on me when I try it on my playground, but if there's problem generating random double, try generating a random Int instead.

func randomDoubleFromInt() -> Double {
    let n1 = Int.random(in: 0...5)
    let n2 = Int.random(in: 0...9999999999)
    
    let nStr = "\(n1).\(n2)"
    
    return Double(nStr)!
}

CodePudding user response：

I could not replicate your issue. Here is the test code I used, it gives a wide range of numbers between 0.0 and 5.0. On macos 12.2-beta, using xcode 13.2, targets ios 15 and macCatalyst 12.

import SwiftUI
import Foundation

@main
struct TestApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}
struct ContentView: View {
    var body: some View {
        Text("tesing")
            .onAppear {
                for i in 0...100 {
                    let x = drand48() * 5.0  // <-- alternative
                 //   let x = Double.random(in: 0.0 ... 5.0)
                    print("---> \(i) => \(x)")
                }
            }
    }
}