negative half-plane
81Lead-lag compensator — A lead lag compensator is a component in a control system that improves an undesirable frequency response in a feedback and control system. It is a fundamental building block in classical control theory. Applications Lead lag compensators… …
82Derivation of the Routh array — The Routh array is a tabular method permitting one to establish the stability of a system using only the coefficients of the characteristic polynomial. Central to the field of control systems design, the Routh–Hurwitz theorem and Routh array… …
83Bode plot — ; the straight line approximations are labeled Bode pole ; phase varies from 90° at low frequencies (due to the contribution of the numerator, which is 90° at all frequencies) to 0° at high frequencies (where the phase contribution of the… …
84Dirichlet L-function — In mathematics, a Dirichlet L series is a function of the form Here χ is a Dirichlet character and s a complex variable with real part greater than 1. By analytic continuation, this function can be extended to a meromorphic function on the whole… …
85Orr–Sommerfeld equation — The Orr–Sommerfeld equation, in fluid dynamics, is an eigenvalue equation describing the linear two dimensional modes of disturbance to a viscous parallel flow. The solution to the Navier–Stokes equations for a parallel, laminar flow can become… …
86Stable polynomial — A polynomial is said to be stable if either: * all its roots lie in the open left half plane, or * all its roots lie in the open unit disk.The first condition defines Hurwitz (or continuous time) stability and the second one Schur (or discrete… …
87Routh–Hurwitz theorem — In mathematics, Routh–Hurwitz theorem gives a test to determine whether a given polynomial is Hurwitz stable. It was proved in 1895 and named after Edward John Routh and Adolf Hurwitz.NotationsLet f(z) be a polynomial (with complex coefficients)… …
88Schwarzschild coordinates — In the theory of Lorentzian manifolds, spherically symmetric spacetimes admit a family of nested round spheres . In such a spacetime, a particularly important kind of coordinate chart is the Schwarzschild chart, a kind of polar spherical… …
89L-function — The theory of L functions has become a very substantial, and still largely conjectural, part of contemporary number theory. In it, broad generalisations of the Riemann zeta function and the L series for a Dirichlet character are constructed, and… …
90List of vampire traits in folklore and fiction — The following tables compare traits given to vampires in folklore and fiction. Over time, some attributes now regarded as integral became incorporated into the vampire s profile: fangs and vulnerability to sunlight appeared over the course of the …
