Parzen (de la Vallée Poussin) window
w = parzenwin(L)
w = parzenwin(L) returns
L-point Parzen (de la Vallée Poussin)
window in a column vector,
w. Parzen windows are
piecewise-cubic approximations of Gaussian windows. Parzen window
sidelobes fall off as 1/ω4.
See Definitions for the equation
that defines the Parzen window.
The following equation defines the
Parzen window over the interval :
 Harris, Fredric J. "On the Use of Windows for Harmonic Analysis with the Discrete Fourier Transform." Proceedings of the IEEE®. Vol. 66, January 1978, pp. 51–83.