Any one of the following:

  • gain : float

    A system that multiplies its input by a constant gain.

    \[F(s) = \texttt{gain}\]
  • (num : array_like, den : array_like)

    A transfer function with numerator polynomial num and denominator polynomial den.

    \[F(s) = \frac{\sum_{i=0}^{\texttt{len(num)-1}} \texttt{num[-i-1]} s^i} {\sum_{i=0}^{\texttt{len(den)-1}} \texttt{den[-i-1]} s^i}\]
  • (zeros : array_like, poles : array_like, gain : float)

    A transfer function with numerator roots zeros, denominator roots poles, and scalar gain.

    \[F(s) = \texttt{gain} \ \frac{\prod_{i=0}^{\texttt{len(zeros)-1}} (s - \texttt{zeros[i]})} {\prod_{i=0}^{\texttt{len(poles)-1}} (s - \texttt{poles[i]})}\]
  • (A : array_like, B : array_like, C : array_like, D : array_like)

    A state-space model described by four 2–dimensional matrices (A, B, C, D).

    \[\begin{split}\dot{{\bf x}}(t) &= A{\bf x}(t) + B{\bf u}(t) \\ {\bf y}(t) &= C{\bf x}(t) + D{\bf u}(t)\end{split}\]

    This has the transfer function \(F(s) = C (sI - A)^{-1} B + D\).

  • An instance of LinearSystem.

  • An instance of nengo.LinearFilter.

Note: The above equations are for the continuous time-domain. For the discrete time-domain, replace \(s \rightarrow z\) and \(\dot{{\bf x}} \rightarrow {\bf x}[k+1]\).