NAME

     fkrad  - module to produce  a  log-normalized  radial  power
     spectrum from an input 2D FFT dataset.

SYNOPSIS

     fkrad [ -Nntap ] [ -Ootap ] [ -rsnrst ] [ -renred ] [  -dxDX
     ] [ -dyDY ] [ -nbinsnum ] [ -V ] [ -? -h -help  ]

DESCRIPTION

     fkrad builds a radial power spectrum display from  an  input
     2D  FFT dataset of the type output by the USP routine  fftxy
     .  The input amplitudes  are  summed  radially  into  output
     bins.  The bin radial spatial frequencies range between zero
     and the radial spatial Nyquist [ Xnyquist**2  +  Ynyquist**2
     ]**0.5  . The bin amplitudes are then squared and normalized
     to the smallest amplitude.  The number  of  bins  will  come
     from  the  command line entry  -nbins  or be determined from
     the spatial  nyquists  involved  [   the   default   ].  The
     natural  log  of  the  bin data is then taken and normalized
     relative to the largest value.  The bin upper wavenumber  is
     contained in the USP trace header entry  TrcNum .  Since the
     actual wavenumber is a fractional value the multiplier  used
     to  convert  to  a  value large enough to be displayed as an
     integer is stored in the USP trace header  entry   DpPtLt  .
     The  actual  log normalized bin amplitude value is stored in
     all live samples of each trace.  This enables  the  user  to
     key  on both the shape of the bar graph and the color of the
     trace as viewed with  xsd .

     fkrad gets both its data and  its  parameters  from  command
     line  arguments.  These arguments specify the input, output,
     the start and end records, the X and Y sample intervals, the
     number of bins to use, 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).

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

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

     -dx DX
          Enter the sample interval in the X [trace-wise]  direc-
          tion.

     -dy DY
          Enter the sample interval in the Y [sample-wise] direc-
          tion.

     -nbins num
          Enter the number of radial frequency bins for the  out-
          put display.

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

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

BUGS

     None Known

SEE ALSO

      fkshape(1) fftxy(1)

AUTHOR

     Paul Garossino [EPTG:Tulsa]

COPYRIGHT

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