BinaryFloating+Scaling.swift

public extension BinaryFloatingPoint {

    public func scaled(from source: ReversibleRange<Self>, to destination: ReversibleRange<Self>) -> Self {

        let destinationStart = destination.lowerBound
        let destinationEnd = destination.upperBound

        let selfMinusLower = self - source.lowerBound
        let sourceUpperMinusLower = source.upperBound - source.lowerBound
        let destinationUpperMinusLower = destinationEnd - destinationStart

        let percentThroughSource = (selfMinusLower / sourceUpperMinusLower)
        let curvedPercent = percentThroughSource
        return curvedPercent * destinationUpperMinusLower + destinationStart
    }

}