NAME

     fft2d  - forward/reverse 2-d fast fourier transform

SYNOPSIS

     fft2d [ -Nntap ] [ -Ootap ] [ -sist ] [ -eiend ] [ -nsnstr ]
     [ -nenetr ] [ -rsnrst ] [ -renred ] [ -R ] [ -V ] [ -? ]

DESCRIPTION

     fft2d implements the MathAdvantage forward/reverse FFT in  a
     two  dimensional  sense  and outputs the data in SIS format.
     The number of output traces are twice the  number  requested
     on  input.  This is because real values and imaginary values
     of the transform are output as separate traces.

     fft2d 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.

  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).

     -ns nstr
          Enter the start trace number.  The default is the first
          trace of the record.

     -ne netr
          Enter the end trace number. The  default  is  the  last
          trace of the record.

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

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

     -R   Enter the command line argument '-R' to do the  reverse
          transform


     -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.

BUGS

     to operate on the output of this program you must  recognize
     that the traces are alternating real and imaginary pairs

SEE ALSO

     freqtim, timfreq

AUTHOR

     Paul Gutowski, x3146, TRC

COPYRIGHT

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