Quadric equation roots printing method. There were to restrictions on type and ranges so it's a basic example.

QuadricEquationRootsPrint.swift

func printRoots(a: Double, b: Double, c: Double, showImaginaryRoots: Bool = false) {
    
    let b2 = b * b
    let disc = b2 - (4 * a * c)
    
    let discSqrt = sqrt(fabs(disc))
    let isImage = disc < 0
    
    let result = b * b - 4.0 * a * c
    
    guard result >= 0.0 else {
        print("no roots")
        return
    } 
    
    if isImage {
        if showImaginaryRoots {
       print("(\(-b) + \(discSqrt)i)/\(2*a)\n(\(-b) - \(discSqrt)i)/\(2*a)")
        } else {
             print("no roots")
        }
    } else {
        let top = -b + discSqrt
        guard top != 0 else {
            print("no roots")
            return
        }
        let bottom = 2 * a
        let total = top / bottom
        
        let top2 = -b - discSqrt
        let total2 = top2 / bottom
        print("\(total)\n\(total2)")
    }
}

printRoots(a: 1.0, b: 3.0, c: -4.0)

1.0
-4.0