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In mathematics, a Hurwitz polynomial, named after Adolf Hurwitz, is a polynomial whose coefficients are positive real numbers and whose roots (zeros) are located in the left half-plane of the complex plane or on the ''jω'' axis, that is, the real part of every root is zero or negative. The term is sometimes restricted to polynomials whose roots have real parts that are strictly negative, excluding the axis (i.e., a Hurwitz stable polynomial). A polynomial function ''P''(''s'') of a complex variable ''s'' is said to be Hurwitz if the following conditions are satisfied: :1. ''P''(''s'') is real when ''s'' is real. :2. The roots of ''P''(''s'') have real parts which are zero or negative. Hurwitz polynomials are important in control systems theory, because they represent the characteristic equations of stable linear systems. Whether a polynomial is Hurwitz can be determined by solving the equation to find the roots, or from the coefficients without solving the equation by the Routh–Hurwitz stability criterion. == Examples == A simple example of a Hurwitz polynomial is the following: : The only real solution is −1, as it factors to : 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hurwitz polynomial」の詳細全文を読む スポンサード リンク
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