On the residue calculus evaluation of the 3-D anisotropic elastic Green's function

An algorithm based upon the residue calculus for computing three-dimensional anisotropic elastic Green's function and its derivatives has been presented in Sales and Gray (Comput. Structures 1998; 69:247-254). It has been shown that the algorithm runs three to four times faster than the standard Wilson-Cruse interpolation scheme. However, the main concern of the Sales-Gray algorithm is its numerical instability that could lead to significant errors due to the existence of multiple poles of the residue. This paper proposes a remedy for the problem by adding the capability to evaluate the Green's function in case of multiple poles of the residue. Further, an improved numerical implementation based on the use of double-subscript-notation elastic constants in determining the Christoffel tensor is also at issue. Copyright (C) 2004 John Wiley Sons, Ltd.