NAME

     crossfilt  - filter amplitude values from two data sets X  &
     Y according to their crossplotted relationships

SYNOPSIS

     crossfilt [ -N1ntap1 ] [ -N1ntap2 ] [ -O1otap1 ] [  -O2otap2
     ]  [  -Cctap  ]  [ -QCIqtapi ] [ -QCOqtapo ] [ -QCEqtape ] [
     -Slogs ] [ -Tlogt ] [ -V ] [ -?  or  -h or -help ]

DESCRIPTION

     crossfilt takes two input data sets  X  and  Y  and  outputs
     amplitudes  according  to their Xy relationships.  Currently
     the user specifies four straight lines  defining  an  closed
     figure.  Amplitudes  will  be  passed (or rejected) from the
     inputs to the outputs according to whether their  XY  values
     lie within the defined figure.

     crossfilt gets both its data and its parameters from command
     line  arguments.  These arguments specify the input and out-
     put data sets, the coefficients file, and optional  QC  data
     files if desired.

  Command line arguments
     -N1 ntap1  [default: none]
          Enter the input data set name or file immediately after
          typing  -N1  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'.

  Command line arguments
     -N2 ntap2  [default: none]
          Enter the input data set name or file immediately after
          typing -N2. 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'.

     -O1 otap1  [default: none]
          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).

     -O2 otap2  [default: none]
          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).

     -C ctap  [default: none]
          Enter the input ascii file containing the  coefficients
          defining  the  four required straight lines. Four lines
          must be entered in the file.  The first two define  the
          lower  and  upper Y limits respectively; the second two
          define the lower and upper X limits. Each  line  is  of
          the form y = a x + b or Y = a X + B or x = a y + b or X
          = a Y + b, where a is the slope of  the  straight  line
          and  b  is  the  intercept.  If the line is flat a zero
          slope must be entered.

     -QCI qtapi  [opt]
          Enter the optional QC xgraph format  output  file  con-
          taining  the  unfiltered crossplotted values. This will
          result in a large file unless you  limit  the  data  by
          using  the  -S[] and -T[] sample and trace skip values.
          Display using  usp  xgraph  -nl  -P  -t  <title>  [file
          name(s)].  Note that both this file and the filtered QC
          file below may be displayed with a single  xgraph  com-
          mand.  Note  if  the  <title>  string contains embedded
          blanks the whole string  must  be  enclosed  by  qouble
          quotes.

     -QCO qtapo  [opt]
          Enter the optional QC xgraph format  output  file  con-
          taining  the  filtered  crossplotted  values. This will
          result in a large file unless you  limit  the  data  by
          using  the  -S[] and -T[] sample and trace skip values.
          Display using  usp  xgraph  -nl  -P  -t  <title>  [file
          name(s)].  Note  that  both  this file and the input QC
          file above may be displayed with a single  xgraph  com-
          mand.  Note  if  the  <title>  string contains embedded
          blanks the whole string  must  be  enclosed  by  qouble
          quotes.

     -QCE qtape  [opt]
          Enter the optional QC xgraph format  output  file  con-
          taining  the equations drawn using the minimum and max-
          imum X and Y values extracted from the input data read.
          Display using usp xgraph [filename].

     -S logs  [default: 10]
          Optional QC input: enter  the  number  of  samples  per
          trace to skip when outputting the QC values.

     -T logt  [default: 10]
          Optional QC input: enter the number of traces  to  skip
          when outputting the QC values.

     -R   Enter the command line argument '-R' to  reject  rather
          than  pass  amplitudes  whose XY values fall within the
          closed figure.

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

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

EXAMPLE

     crossfilt -N1 junk2 -N2 junk1 -O1 t1a -O2 t2a -C cfilex2 \
                 -QCI q1a -QCO q2a -T 1 -S 1


     where the coefficients file cfilex looks like
       y = -1.149 x - 172.
       y = -1.149 x + 413.
       y = 0.245 x - 350.
       x = 0.0 y + 1100.

BUGS

     unknown

SEE ALSO

     crossplot(1)

AUTHOR

     [Paul Gutowski, UTG, pgutowski@freeusp.org]

COPYRIGHT

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