Extension BidirectionalCollection.swift

extension BidirectionalCollection where Iterator.Element: FloatingPoint {
   

    func multiplied(by multiplier: Iterator.Element) -> [Iterator.Element] {
        return map{$0 * multiplier}
    }
    var squared: [Iterator.Element]  {
        return map{$0 * $0}
    }
    var cubed: [Iterator.Element] {
        return map{ $0 * $0 * $0 }
    }
    var progressivePow: [Iterator.Element] {
        return enumerated().map{ $0.element * Iterator.Element($0.offset) }
    }
    var acumulate: [Iterator.Element] {
        var sum: Iterator.Element = 0
        return map {
            sum += $0
            return sum
        }
    }
}

let array = (1...10).map(Double.init)    // [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
array.multiplied(by: 2.5)   // [2.5, 5, 7.5, 10, 12.5, 15, 17.5, 20, 22.5, 25]