/// <summary>
/// Lanczos window.
/// Periodic version, useful e.g. for FFT purposes.
/// </summary>
public static double[] LanczosPeriodic(int width)
{
double phaseStep = 2.0 / width;
var w = new double[width];
for (int i = 0; i < w.Length; i++)
{
w[i] = Trig.Sinc((i * phaseStep) - 1.0);
}
return(w);
}
