|
In mathematics, a form (i.e. a homogeneous polynomial) ''h''(''x'') of degree 2''m'' in the real ''n''-dimensional vector ''x'' is sum of squares of forms (SOS) if and only if there exist forms of degree ''m'' such that : Explicit sufficient conditions for a form to be SOS have been found. However every real nonnegative form can be approximated as closely as desired (in the -norm of its coefficient vector) by a sequence of forms that are SOS. == Square matricial representation (SMR) == To establish whether a form ''h''(''x'') is SOS amounts to solving a convex optimization problem. Indeed, any ''h''(''x'') can be written as : is a vector containing a base for the forms of degree ''m'' in ''x'' (such as all monomials of degree ''m'' in ''x''), the prime ′ denotes the transpose, ''H'' is any symmetric matrix satisfying : The dimension of the vector whereas the dimension of the vector is given by : Then, ''h''(''x'') is SOS if and only if there exists a vector such that : meaning that the matrix is positive-semidefinite. This is a linear matrix inequality (LMI) feasibility test, which is a convex optimization problem. The expression was introduced in with the name square matricial representation (SMR) in order to establish whether a form is SOS via an LMI. This representation is also known as Gram matrix. 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「Polynomial SOS」の詳細全文を読む スポンサード リンク
|