/// <summary>
/// Evaluate impulse response
/// </summary>
/// <param name="length">Ignored for FIR filters (where IR is full copy of numerator)</param>
/// <returns></returns>
public double[] ImpulseResponse(int length = 512)
{
if (Denominator.Length == 1)
{
return(Numerator.FastCopy());
}
var b = Numerator;
var a = Denominator;
var response = new double[length];
for (var n = 0; n < response.Length; n++)
{
if (n < b.Length)
{
response[n] = b[n];
}
for (var m = 1; m < a.Length; m++)
{
if (n >= m)
{
response[n] -= a[m] * response[n - m];
}
}
}
return(response);
}