

   CCoommppuutteess tthhee SShhoorrtt TTiimmee FFoouurriieerr TTrraannssffoorrmm ooff aa VVeeccttoorr

        stft(X, win=min(80,floor(length(X)/10)), inc=min(24,
        floor(length(X)/30)), coef=64, wtype="hanning")

   AArrgguummeennttss::

          X: The vector from which the stft is computed.

        win: Length of the window. For long vectors the default
             window size is 80, for short vectors the window
             size is chosen so that 10 windows fit in the vec-
             tor.

        inc: Increment by which the window is shifted. For long
             vectors the default increment is 24, for short
             vectors the increment is chosen so that 30 incre-
             ments fit in the vector.

       coef: Number of Fourier coefficients

      wtype: Type of window used

   DDeessccrriippttiioonn::

        This function computes the Short Time Fourier Transform
        of a given vector `X'.

        First, time-slices of length `win' are extracted from
        the vector. The shift of one time-slice to the next one
        is given by `inc'. The values of these time-slices are
        smoothed by mulitplying them with a window function
        specified in `wtype'. For the thus obtained windows,
        the Fast Fourier Transform is computed.

   VVaalluuee::

        Object of type stft. Contains the values of the stft
        and information about the parameters.

     values: A matrix containing the results of the stft. Each
             row of the matrix contains the `coef' Fourier
             coefficients of one window.

   windowsize: The value of the parameter `win'

   increment: The value of the parameter `inc'

   windowtype: The value of the parameter `wtype'

   AAuutthhoorr((ss))::

        Andreas Weingessel

   SSeeee AAllssoo::

        plot.stft

   EExxaammpplleess::

        x<-rnorm(500)
        y<-stft(x)
        plot(y)

