dom
                       error; eps_r=1/sqrt(Nw). For logarithmic frequency
                       resolution, Nw is a vector with length(f) with the smoothing
                       window length for each frequency bin in Pxx.

            x          Time data in column
            fs         Sampling frequency in Hz
            N          'Blocksize', as for Welch (see apsdw)
            winstr     String with window function, e.g. 'boxcar' (default)
            fmin       First frequency value
        