NAME

     lsqinv  - compute least squares inverse of trace data

SYNOPSIS

     lsqinv [ -Nntap ] [ -Ootap ] [ -sist ] [ -eiend ] [ -iisp  ]
     [  -dldsr  ] [ -pprew ] [ -M ] [ -W ] [ -A ] [ -B ] [ -C ] [
     -V ] [ -? ]

DESCRIPTION

     lsqinv does least squares  inverse  of  selected  window  of
     trace   data.    The  appropriate  subroutine,  shape(),  is
     described  in  the  Robinson   "Multichannel   Time   Series
     Analysis"  book (1967).  The normal equations are set up and
     solved given the input time series, the desired output,  and
     the  unknown  filter coefficients.  In this case the desired
     output is a spike at some location within the  data  window.
     This program is very useful for determining the wavelet when
     used in conjuction with the filter  output  of  minent  (-O2
     command line entry).  Use this output as the input to lsqinv
     with the other appropriate command line entries,  pipe  this
     into  a  filter  to knock down an unwanted high frequencies,
     and voila you have done wavelet processing!

     lsqinv gets both its data and its  parameters  from  command
     line  arguments.  These arguments specify the input, output,
     the data window, the spike position, and  verbose  printout,
     if desired.

  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.  Example -N/b/vsp/dummy tells  the
          program to look for file 'dummy' in directory '/b/vsp'.

     -O otap
          Enter the output data  set  name  or  file  immediately
          after typing -O.  This output file is not required when
          piping the output to another process.  The output  data
          set also requires the full path name (see above).

     -s ist
          Enter the start time of  the  data  window  (ms).   The
          default is the beginning of the trace.

     -e iend
          Enter the end  time  of  the  data  window  (ms).   The
          default is the end of the trace.


     -i isp
          Enter the position of the optimum position of the spike
          (ms).   This  is  relative  to  the  start  time of the
          analysis window and defaults to the  beginning  of  the
          window (0 ms).  It will always be an integral number of
          sample values. Note: if the -M  option  is  not  chosen
          (see below) choice of the spike position can often have
          a profound effect on the  operation  of  this  program.
          Here  it  is  important  that  the  data be windowed to
          minimize trace-to-trace variation of the wavelet  posi-
          tion  within  the  design window.  Then if manual spike
          positioning is desired the spike should correspond to a
          point of inflection of the waveform (e.g. peak, trough,
          ...).

     -d ldsr
          Enter the length (ms) of the desired output.   Defaults
          to the length of the design window.

     -p prew
          Enter the % prewhitening.  The default is .1%

     -M   Enter the command  line  argument  '-M'  to  cause  the
          inverse  spike to be placed at the position occupied by
          the absolute maximum of each input trace.  This  option
          overrides  any -i command line entry. Since this option
          results in variable length autocorrelation lengths  the
          weighting options will disconnected (no weighting).

     -W   Enter the command  line  argument  '-W'  to  cause  the
          design  window  to  be  centered on the spike position.
          This might cause the  specified  window  length  to  be
          shortened  if  the centering causes the window edges to
          move off the top or bottom of the input traces.

     -A   Enter the command line argument '-A' to cause the  pro-
          gram  to  output  the  actual output resulting from the
          convolution of the inverse filter and  the  input  data
          window.

     -B   Enter the command line  argument  '-B'  to  weight  the
          autocorrelation function using a triangular or Bartlett
          window.

     -C   Enter the command line  argument  '-C'  to  weight  the
          autocorrelation function using a Cosine bell window.

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

     -?   Enter the command line  argument  '-?'  to  get  online
          help.   The program terminates after the help screen is
          printed.

COPYRIGHT

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