Advances in aggregate-functions MoM approaches

Aggregate-functions approaches construct efficient MoM basis functions by suitably grouping standard (e.g. Rao-Wilton-Glisson, RWG) functions. The application domains, objectives and related means of achieving them can be significantly different. In this communication we review some recent advances in aggregate-functions methods. We will discuss matrix compression, multi-resolution sets, and high-frequency constructs. They can reduce the degrees of freedom of the problem so as to allow a direct, iteration-free solution, or can accelerate the convergence rate of iterative methods. They are complementary in nature, and can be combined together.