\section{Introduction}

OASES is a general purpose computer code for modeling seismo-acoustic
propagation in horizontally stratified waveguides using {\em
wavenumber integration} in combination with the {\em Direct Global Matrix
} solution technique \cite{sj:jasa85,st:gjras86,jkps}. It is
basically 
an upgraded
version 
of SAFARI \cite{hs:saf}. Compared to SAFARI
version 3.0 distributed by SACLANTCEN, OASES provides improved
numerical efficiency, and the global matrix mapping has been
re-defined to ensure unconditional numerical stability in the few
extreme cases where the original SAFARI has proved unstable.
OASES is downward compatible with SAFARI, and the preparation
of input files follows the guidelines of the SAFARI manual
\cite{hs:saf}. The SAFARI manual focused on VMS implementation, but
this note will assume UNIX to be the operating system. However, the
bulk of the code is operating system independent and is easily
implementyed under VMS, MS-DOS etc. 




























