namespace FftSharp.Windows
{
    public class Welch : Window, IWindow
    {
        public override string Name => "Welch";
        public override string Description =>
            "The Welch window is typically used for antialiasing and resampling. " +
            "Its frequency response is better than that of the Bartlett windowed cosc function below pi, " +
            "but it shows again a rather distinctive bump above.";

        protected override double windowValue(int index, int size)
        {
            double halfN = (size - 1) / 2.0;
            double b = (index - halfN) / halfN;
            return 1 - b * b;
        }
    }
}