This enhancement has been incorporated in Release 2006b (R2006b). For previous product releases, read below for any possible workarounds:
Documentation on the HAMMING, HANN, BLACKMAN, and FLATTOPWIN function is missing information about the 'periodic' option. Here is some additional information:
The periodic flag is useful for DFT/FFT purposes such as in spectral analysis.
Because there is an implicit periodic extension in the DFT/FFT, the periodic flag enables a signal that is windowed with a periodic window to have perfect periodic extension. When using windows for spectral analysis or other DFT/FFT purposes, the periodic option can be useful. When using windows for filter design, the symmetric flag should be used.
Please refer to the following for more information:
Harris, F., "On the use of windows for harmonic analysis with the discrete Fourier transform" Proceedings of the IEEE , vol. 66, No. 1, January 1978.