[Octave-cvsupdate] SF.net SVN: octave:[10659] trunk/octave-forge/extra/control-devel/inst/@ iddata/fft.m

[<par...@us...>]

Revision: 10659
          http://octave.svn.sourceforge.net/octave/?rev=10659&view=rev
Author:   paramaniac
Date:     2012-06-22 11:06:07 +0000 (Fri, 22 Jun 2012)
Log Message:
-----------
control-devel: finish doc of fft method

Modified Paths:
--------------
    trunk/octave-forge/extra/control-devel/inst/@iddata/fft.m

Modified: trunk/octave-forge/extra/control-devel/inst/@iddata/fft.m
===================================================================
--- trunk/octave-forge/extra/control-devel/inst/@iddata/fft.m	2012-06-22 09:17:22 UTC (rev 10658)
+++ trunk/octave-forge/extra/control-devel/inst/@iddata/fft.m	2012-06-22 11:06:07 UTC (rev 10659)
@@ -17,11 +17,35 @@
 
 ## -*- texinfo -*-
 ## @deftypefn {Function File} {@var{dat} =} fft (@var{dat})
-## @deftypefnx {Function File} {@var{dat} =} fft (@var{dat}, @var{ord})
-## Detrend outputs and inputs of dataset @var{dat} by
-## removing the best fit of a polynomial of order @var{ord}.
-## If @var{ord} is not specified, default value 0 is taken.
-## This corresponds to removing a constant.
+## @deftypefnx {Function File} {@var{dat} =} fft (@var{dat}, @var{n})
+## Compute the discrete Fourier transform of @var{dat} using a Fast Fourier
+## Transform (FFT) algorithm.
+##
+## @strong{Inputs}
+## @table @var
+## @item dat
+## iddata set containing signals in time-domain.
+## @item n
+## Length of the FFT transformations.  If @var{n} does not match
+## the signal length, the signals in @var{dat} are shortened or
+## padded with zeros.  @var{n} is a vector with as many elements
+## as there are experiments in @var{dat} or a scalar with a common
+## length for all experiments.
+## If not specified, the signal lengths are taken as default values.
+## @end table
+##
+## @strong{Outputs}
+## @table @var
+## @item dat
+## iddata identification dataset in frequency-domain.
+## In order to preserve signal power and noise level,
+## the FFTs are normalized by dividing each transform
+## by the square root of the signal length.
+## The frequency values are distributed equally from 0
+## to the Nyquist frequency.  The Nyquist frequency is
+## only included for even signal lengths.
+## @end table
+##
 ## @end deftypefn
 
 ## Author: Lukas Reichlin <luk...@gm...>

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