Complex Pade approximants for wide-angle acoustic propagators

Procedures for constructing wide-angle propagators that attenuate evanescen t modes in parabolic equation (PE) models of underwater sound propagation a re examined. In this context, two new split-step Pade approximations to exp onentiated square-root operators are proposed. The first method involves a propagator derived from a Pade approximant of a square-root operator that h as been rotated in the complex plane while the propagator of the second met hod is obtained from a complex coefficient rational approximation of the sq uare-root operator. Numerical evidence confirms that these proposed methods yield improved behavior compared to previously suggested techniques in sel ected areas of the spectral domain. (C) 2000 Acoustical Society of America. [S0001-4966(00)02712-0].