Improve transfer function, discrete sys and poly Added - Implementation of transfer function arithmetic operations - Implementation of transfer function feedback - Check for system stability - Common input signals - Transfer function static gain - Transfer function positive and negative feedback - Transfer function sensitivity functions - Transfer function delay - Equilibrium for discrete systems - Root locus plot - Controllability and observability matrices - Autoregressive moving average (ARMA) model of discrete transfer function - Polynomial division - Polynomial root finding using iterative Aberth-Ehrlich method. - Polynomial multiplication using fast fourier transform Changed - Split type for continuous and discrete transfer functions - Split type for continuous and discrete state space representation