  In this letter, an approach to accelerate the matrix filling in method of
moment (MOM) is presented. Based on the fact that the Green function is
dependent on the Euclidean distance between the source and the observation
points, we constructed an efficient adaptive one-dimensional interpolation
approach to fast calculate the $Exp$ type function values. In the proposed
method, several adaptive interpolation tables are constructed based on the
maximum and minimum distance between any two integration points with local
refinement near zero function values to minimize the relative error. An
efficient approach to obtain the sampling points used in the interpolation
phase is carefully designed. Then, any function values can be efficiently
calculated through a linear interpolation method for Exp and a Lagrange
polynomial interpolation method for the Green function. In addition, the error
bound of the proposed method is rigorously investigated. The proposed method
can be quite easily integrated into the available MOM codes for different
integration equation (IE) formulations with few efforts. Comprehensive
numerical experiments validate its accuracy and efficiency through several IE
formulations. Results show that over 20% efficiency improvement can be achieved
without sacrificing the accuracy.
