Kívülnullák

Kívülnullák is a Hungarian term that is used in mathematical contexts to refer to zeros of a function that lie outside a predefined reference region. The phrase is not tied to a single formal definition and its exact meaning can vary by discipline or text, but it commonly appears in discussions of root locations relative to a chosen boundary such as the unit circle, a stability region, or a contour in the complex plane.

In complex analysis and algebra, a typical use is to describe zeros of a polynomial or an analytic function that do not belong to the region of interest. For example, with respect to the unit circle, zeros whose modulus exceeds one can be described as kívülnullák. This contrasts with zeros inside the region, which are often of particular interest for stability or convergence properties. The concept helps analysts categorize and compare the distribution of zeros.

Applications of considering kívülnullák include control theory, signal processing, and numerical analysis, where the location of zeros relative to a boundary influences system stability, filter behavior, and convergence of algorithms. Methods for locating zeros and for assessing their placement often address both the inside and outside sets to evaluate overall performance.

Terminology varies across Hungarian literature; some authors may use alternative expressions such as outer zeros or non-inside zeros. Regardless of terminology, the underlying idea is to distinguish zeros outside a specified region from those inside or on the boundary. See also zeros, root location, unit circle, stability criteria.