NAME

     cross  - crosscorrelation/convolution seismic traces

SYNOPSIS

     cross [ -N1ntap1 ] [ -N2ntap2 ] [ -Ootap ]  [  -Ssfile  ]  [
     -Llagl  ]  [  -Rlagr  ]  [  -tt0  ] [ -Hwihw ] [ -s1ist1 ] [
     -e1iend1 ] [ -ns1nstr1 ] [  -ne1netr1  ]  [  -rs1nrst1  ]  [
     -re1nred1  ]  [  -s2ist2  ]  [  -e2iend2  ]  [ -ns2nstr2 ] [
     -ne2netr2 ] [ -rs2nrst2 ] [ -re2nred2 ] [ -X  ]  [  -F  ]  [
     -flip1 ] [ -flip2 ] [ -V ] [ -? ]

DESCRIPTION

     cross computes the crosscorrelation (-X option) or  convolu-
     tion of selected range of input traces.  Note: inputs N1 and
     N2 cannot  both  be  pipelined!   Note:  this  routine  also
     replaces the old conv module.

     Generally for the convolution option is geared for  wavelets
     relatively  short compared to the big data set (N2) although
     you may invoke a crosscorrelation by putting a -flip1 on the
     command  like.   The crosscorelation option is geared for N1
     and N2 data sets which have the same trace length.

     Cross gets both its data and  its  parameters  from  command
     line  arguments.  These arguments specify the input, output,
     the start and end traces, and verbose printout, if  desired.
     Note  that data set 1 must have either 1 trace/record or the
     same traces/record as data set 2, and that if data set 1 has
     multiple  records it must have the same number of records as
     data set 2.

  Command line arguments
     -N1,2 ntap1,2
          Enter the input data set name or file immediately after
          typing  -N1  (or  -N2).   The N1 data set should be the
          wavelet or pilot signal; the N2 data set should be  the
          primary  data  set.  This input file should include the
          complete path name if the file resides in  a  different
          directory.   Example -N1/vsp/dummy tells the program to
          look for file 'dummy' in directory '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 sfile
          For X-correlation option  only:   file  name  to  store
          static  shifts.   Format  is  trace  number followed by
          static shift in ms. Records are  delimited  by  a  null
          line.   This  file  can be plotted by xgraph:  xgraph <
          [file name]

     -L lagl
          Enter the number of negative lags  of  the  left  sided
          crosscorrelogram you wish to compute.  If both this and
          the right side lags (below) are specified then the com-
          plete  tw-sided cross correlogram will be computed, the
          zero-lag being positioned at the t0 value  below.   The
          total  length  of  the crosscorelogram will then be the
          sum of the positive and negative lags + 1.  If only the
          -L  entry  is given then it is assumed only a one-sided
          correlation is to be computed.

     For convolution the total output samples may be specified by
     any combination of lagl or lagr or by the default below.

     Defaults  are:  cross-correlation  -   maximum   of   number
     samples/trc  from  data sets 1 & 2; convolution - sum of the
     windowed input samples/trace from ntap1 and ntap2 - 1

     -R lagr
          Enter the number of positive lags of  the  right  sided
          crosscorrelogram  you  wish  to compute.  Number output
          samples/trace will be the sum of lagl and lagr.

     For convolution  use  lagl,  and/or  lagr,  or  the  default
     (above).

     -t t0
          Enter  the  time  (ms)  position   of   zero-lag   (for
          crosscorelation)  or  the time to start outputting data
          (for convolution this is a means of accounting for  the
          filter  length or where on the filter trace the maximum
          energy occurs, e.g. set t0 =  1/2  length  of  windowed
          data1  traces  for  symmetrical  filters).   For  cross
          correlation this value is defaulted  to  (lagl+lagr)/2;
          for convolution it is defaulted to 0.

     -Hw ihw
          Enter trace header word (data set2) to stuff the  rela-
          tive cross correlation shift between data set1 and data
          set2.  The value in ms is put in  the  header  word  of
          choice.  Default = StaCor

     -s1 -s2 ist1 ist2
          Enter the start time of data sets 1 and 2.  The default
          is the beginning of the trace.

     -e1 -e2 iend1 iend2
          Enter the end time of data sets 1 and 2.   The  default
          is the end of the trace.

     -ns1 -ns2 nstr1 nstr2
          Enter the start trace number of  data  sets  1  and  2.
          Trace  numbers  below this value will not be processed.
          The default is 1.

     -ne1 -ne2 netr1 netr2
          Enter the end trace number of data sets 1 and 2.  Trace
          numbers  above  this  value will not be processed.  The
          default is the last trace number on the input data set.

     -rs1 and -rs2 nrst1 nrst2
          Enter start  record  number  of  data  sets  1  and  2.
          Default value is the first record.

     -re1 -re2 nred1 nred2
          Enter end record number of data sets 1 and 2.   Default
          value is last record.

     -X   Enter the command line argument '-X' to do  crosscorre-
          lation, otherwise convolution will be done

     -F   Enter the command line argument '-F'  to  time  reverse
          the output traces

     -flip1
          Enter  the  command  line  argument  '-flip1'  to  time
          reverse data set1 traces before processing

     -flip2
          Enter  the  command  line  argument  '-flip2'  to  time
          reverse data set2 traces before processing

     -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.