NAME

     zderiv  - Calculate the derivative (in the sample direction)
     of the input file.

SYNOPSIS

     zderiv [ -Nntap ] [ -Ootap ] [ -abs ] [ -? ]

DESCRIPTION

     zderiv zderiv calculate the derivative of the input file  in
     the  sample direction. It is namely used to create a reflec-
     tor section from a velocity model.   zderiv  gets  both  its
     data  and its parameters from command line arguments.  These
     arguments specify the inputs and output.

  Command line arguments
     -N ntap [default = stdin]
          Enter the input data set name or file immediately after
          typing -N.  This input file should include the complete
          path name if the file resides in a different directory.
          Example -N/vsp/dummy tells the program to look for file
          'dummy' in directory 'vsp'.

     -O otap [default = stdout]
          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.

     -abs If present, take the absolute value of the z-derivative
          instead of the z-derivative

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

BUGS

      Unknown

AUTHOR

     B. Duquet [ATTC]