“…Normal systems are unitarily diagonalizable systems, which include symmetric, skew-symmetric, and orthogonal systems, and can be seen in a wide variety of application domains including in electric power (Lunze [1986]), spacecraft (Wu et al [1999]), and internet congestion (Zhang and Loguinov [2009]). Circulant systems are a subclass of normal systems that arise in vehicle formations (Marshall et al [2004]), paper machines (Laughlin et al [1993]), and from the discretization of partial differential equations (Brockett and Willems [1974], Kishida and Braatz [2010]). For circulant systems, the unitary matrix is the Fourier matrix regardless of the dynamics of the system (Hovd and Skogestad [1994]).…”