NAME

     ramp  - apply a linear or cosine ramp function to a record

SYNOPSIS

     ramp [ -Nntap ] [ -Ootap ] [ -cic0 ] [ -nsns ] [ -nene  ]  [
     -rsirs ] [ -reire ] [ -U ] [ -C ] [ -V ] [ -? ]

DESCRIPTION

     ramp apply a linear spatial ramp function  (time  invariant)
     to a seismic record.  The same ramp factor is applied to all
     samples of each trace.  By specifying the appropriate  hinge
     point ( ic0 ) the ramp can be two sided, one sided, or ramp-
     ing up or down with increasing trace number (the -U  parame-
     ter).  A ramp may be applied to part of a record.

     ramp is useful for applications requiring weighting  of  the
     spread.   An  example  might be attenuating a portion of the
     tau-p spectrum by applying ramp to the output of taupf prior
     to  reconstruction using taupr.  Note that nonlinear weight-
     ing is accomplished by cascading ramps in a pipeline.

     ramp gets its parameters from command line arguments.  These
     arguments  specify  the  input,  output,  the  start and end
     traces, the processing parameters, and verbose printout,  if
     desired.

  Command line arguments
     -N ntap
          Enter the input data set name or file immediately after
          typing  -N.   If  piping into this program do not enter
          this command line argument.   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.  If piping out of this program do not
          enter this command line argument.  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).

     -ns ns
          Enter the start trace  number  of  the  ramp  function.
          Trace  numbers  below  this  value will have a constant
          weight applied ( 1.0 for  no  -U;  0.0  for  -U).   The
          default is 1.

     -ne ne
          Enter the end trace number of the ramp function.  Trace
          numbers  above  this  value will have a constant weight
          applied ( 1.0 for no -U; 0.0 for -U).  The  default  is
          the last trace number on the input data set.

     -c ic0
          Enter the trace number (sequentially, the  first  trace
          being  1)  corresponding to the hinge point of the ramp
          function (i.e. the point at  which  the  ramp  function
          changes  slope).   If  the  hinge  point coincides with
          either ns or ne a one-sided ramp will be applied on the
          left  or right sides of the spread depending on whether
          ic0 coincides with ns or ne.  The remaining portions of
          the  weights  will either be zero or unity depending on
          whether or not -C is present.

     -rs irs
          Enter start record number.  Default value is the  first
          record.

     -re ire
          Enter end record number.  Default value is last record.

     -U   Enter the command line argument '-U' to cause the  ramp
          function  to  peak  at  1.0 at the hinge point ( ic0 );
          otherwise the ramp will be a minimum (  0.0  )  at  the
          hinge point.

     -C   Enter the command line argument '-C' to  use  a  cosine
          weighting  fuction,  otherwise  a linear weight will be
          used.

     -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.

EXAMPLES

     Suppose we are given a 240 trace spread called indata.

     1. To ramp left side up from zero to unity at trace 40
          ramp -Nindata -Ooutdata -ns1 -ne40 -c40 -U

     2. To ramp right side of the spread down  to  zero  starting
     with trace 200
          ramp -Nindata -Ooutdata -ns200 -ne240 -c240

     3. To preserve only the center 80 traces of the spread using
     a cosine bell
          ramp -Nindata -Ooutdat -ns80 -c120 -ne160 -U -C

COPYRIGHT

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