NAME

     seelines - Produces MEM spectral analysis of a trace using a
     range of values for the MEM order.

SYNOPSIS

     seelines [ -Nntap ] [ -Ggraphfile ] [ -rir  ]  [  -tit  ]  [
     -nsnumc  ] [ -ndnumcdiff ] [ -nnnumcnum ] [ -Fnfreq ] [ -V ]
     [ '-?' ]

DESCRIPTION

     seelines is useful for identifying a reasonable order (for a
     MEM analysis) to be used as a parameter in program linespec.
     It also permits the user who is knowledgable and experienced
     with MEM methods to gain some appreciation for the nature of
     the data being analysed.

     Intended Uses of seelines

     Program seelines is meant to be used by those  who  wish  to
     verify  the default value for the MEM order in linespec pro-
     gram is reasonable or by  those  who  wish  to  select  this
     parameter  based  on  their  own  on  analysis  of the data.
     ADVISEMENT: (as in program linespec)  In  order  to  prevent
     certain  technical  problems, it is recommended that data be
     scaled so that the maximum absolute floating point value  is
     somewhere  between  1.0 and 1000.0 . Data that is scaled for
     plotting is USUALLY scaled sufficently. The  usual  symptoms
     of  problems due to this cause are floating point error mes-
     sages and/or unplotable graph files due to NAN answers  pro-
     duced.  We advise the user to investigate MEM methods as MEM
     is not the same 'tame' beast that we  encounter  when  using
     Fourier  methods.  What  you do not know may definately hurt
     you, in this case, and this is the price that  is  extracted
     for  the  potential  benefits  of a more powerful tool.  The
     defaults included in this program were selected  after  con-
     siderable  experimentation  and  practical  experience  with
     (mostly) land data having 750  to  3000  samples.  The  user
     should  decide  on  a  relevent range (ns, nd, nn) for them-
     selves as the defaults will almost never  be  optimal.   The
     default  for nfreq may look like overkill, but is a response
     to the fact that line spectral noise  events  often  have  a
     very narrow peak width and their true relationship to signal
     (which usually has some notches but few spikes) may  not  be
     realistically determined without fine sampling.

  Command line arguments
     -N ntap
          Enter the input data set name or file immediately after
          typing  -N,  unless  the input is from a pipe, in which
          case the -N entry must be  omitted.   This  input  file
          should  include  the  complete  path  name  if the file
          resides in a different directory.

     -G graphfile
          Enter the graphical output data  set  name  immediately
          after  typing -G.  Default is graph.out . Use full path
          name if necessary.  This is an ASCII suitable for  plot
          with program XGRAPH.

     -r ir
          Enter the record number of the record to  be  analyzed.
          Default is first record of the data set.

     -t it
          Enter the trace number of the  trace  to  be  analysed.
          Default is first trace of the record.

     -ns numc
          Enter MEM order (integer) to  be  used  for  the  first
          analysis of the trace.  Default is 10.

     -nd numcdiff
          Enter the increment (integer) in the order of  the  MEM
          coefficent to be added before each subsequent analysis.
          Default is 10.

     -nn numcnum
          Enter the number of analysis to be done.  This  is  the
          number  of  curves that is output to the graph file. As
          the size of the MEM  coefficient  increases,  more  and
          more line spectral events become representable.  At the
          extreme,  systematic  and  numerical  noise   will   be
          represented  which causes undesired complexity and con-
          fusion and takes more time to compute. As the range  10
          to  20  was arbitrarily selected, the user should prob-
          ably try other values to find a range  suitable for the
          data used.  Default is 20.

     -F nfreq
          Enter the number of frequency samples to plot between 0
          Hz  and the Nyquist frequency. The default was selected
          so that it is unlikely that significant lines  will  be
          missed  with most seismic traces.  The size of the out-
          put file and execution time increase in direct  propor-
          tion to this parameter.  Default is 2001.

     -V   Enter the command line argument -V  to  get  additional
          printout.

     '-?' Enter the command line argument '-?'  to  get  on  line
          help.  Note the single quotes must be typed by the user
          to prevent the shell from interpreting the -?. The pro-
          gram terminates after the help screen is printed.

BUGS

AUTHOR

     Dennis Bjerstedt, Calgary, 1992.

COPYRIGHT

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