/// <summary>
/// Runs a single sample through a Filter with initialState
/// </summary>
/// <param name="value"> The input value</param>
/// <param name="initialState">The initial state of the filter </param>
/// <param name="finalState"> The final State of the Filter</param>
/// <returns> the value of the filtered signal</returns>
public double Filt(double value, FilterState initialState, out FilterState finalState)
{
double[] s = initialState.StateValue;
if (s.Length < (m_A.Length + m_B.Length - 2))
{
s = new double[(m_A.Length + m_B.Length - 2) - s.Length];
Array.Fill(s, 0.0D);
s = initialState.StateValue.Concat(s).ToArray();
}
double fx = value * m_B[0] + m_B.Select((z, i) => (i > 0? z * s[i - 1] : 0.0D)).Sum();
fx += m_A.Select((z, i) => (i > 0 ? z * -s[i + m_B.Length - 2] : 0.0D)).Sum();
fx = fx / m_A[0];
finalState = new FilterState()
{
StateValue = new double[] { value }
.Concat(s.Take(m_B.Length - 2).ToArray())
.Concat(new double[] { fx })
.Concat(s.Skip(m_B.Length - 1).Take(m_A.Length - 2).ToArray())
.ToArray()
};
return(fx * m_gain);
}
/// <summary>
/// Runs an evenly sampled signal through the Filter
/// </summary>
/// <param name="signal"> f(t) for the signal </param>
/// <returns></returns>
public double[] Filt(double[] signal)
{
int n = signal.Count();
double[] output = new double[n];
FilterState state = new FilterState();
for (int i = 0; i < n; i++)
{
output[i] = Filt(signal[i], state, out state);
}
return(output);
}
