NAME

     hspect  - evaluate F(f,k) (acoustic) based on data output of
     dspec8

SYNOPSIS

     hspect [ -P]

DESCRIPTION

     The purpose of this program  is  to  evaluate  the  acoustic
     medium  (f,k)  response for ten basic Green's functions as a
     function of wavenumber and frequency.   Currently  only  the
     source may be buried.

     The sequence of steps for computing seismograms is  as  fol-
     lows:

     dspec8
                - model specification and diagnostics
     hspect
                - evaluate (f,k) response
     [m]rhwvinta
                - integrate (f,k) to (f,x) offset response
     [rh,tp]foc
                - compute (x,t) or (p-tau) from (f,k) or (f,p)


     Plane layered homogeneous media are assumed with both source
     and  recivers  on  the  surface  (the  source restriction is
     relaxed for hspec8 and hspecp). A Haskell-Thompson  propaga-
     tor   technique   is  used.  For  each  frequency,  selected
     wavenumbers are sampled.  The  sampling  in  the  subroutine
     "excit"  is  designed  to  provide  adequate sampling of the
     functions so that later numerical integration by the "wvint"
     programs will be as noise free as possible.

     The computations are stable for high frequencies because  of
     the  use  of  compound  matrices and because of the extended
     floating point notation. When the eigenfunction response  in
     a  layer  becomes  exponential,  the propagator matrices are
     normalized and the logarithm of the normalization  parameter
     is  carried in the variables exel, exll, exe and exl.  Since
     the medium response is of the  form  NUM/DENOM,  the  medium
     response   with   the   extended   floating  point  is  just
     (NUM/DENOM) * exp (exl - exe).  Thus  none  of  the  numbers
     become  larger  than  is  permitted by the machine hardware.
     This factorization is taken into account by  the  subroutine
     "var".

     The sampling in the wavenumber domain is essentially equally
     spaced, but differs from the suggestion of Bouchon (1981) in
     that a trapezoidal integration rule is not  used,  rather  a
     shifted rectangular rule in the program rhwvinta (the direct
     arrival is not calculated so one doesn't use mrhwvinta).

  Command line arguments
     -P   Enter the command line argument '-P' to  generate  pri-
          maries  only,  otherwise  primaries  plus all multiples
          will computed.

INPUT (UNIT 05)

     All input is on this file unit is generated using dspec8  to
     output  a  properly  formatted parameter file to be input on
     stdin.  The next step may be simply invoked by typing

               hspect  < hspec8.dat


     where hspect.out contains the basic printout info.  The file
     name  for  the  integration step was specified in the dspec8
     step.

AUTHOR

     A. G. Nekut, Geophysical Research, Tulsa, 1990

SEE ALSO

     dspec8, rhwvinta, rhfoc

COPYRIGHT

     copyright 2001, Amoco Production Company
               All Rights Reserved
          an affiliate of BP America Inc.