Figure 4.

Functions φ₀ (D), φ₁ (C), φ₂, φ₃ (B), φ₄ (A) introduced in (19) and (22) for decomposition of covariance c(t). In (B) φ₃(−t) is shown in gray and φ₂(t) in black. The two functions are continuations of each other, joint at t = 0. Both functions appear in the echo term for input noise. The function φ₀ in (D) describing the corresponding echo term in the case of output noise is shifted to be aligned with the function in (B) to facilitate the comparison of (B,D). Parameters in all panels are d = 3 ms, τ = 10 ms, L = −1.72.