Flat top weighted window
w = flattopwin(L)
w = flattopwin(L,sflag)
Flat top windows have very low passband ripple (< 0.01 dB) and are used primarily for calibration purposes. Their bandwidth is approximately 2.5 times wider than a Hann window.
w = flattopwin(L) returns
L-point symmetric flat top window in column
w = flattopwin(L,sflag) returns
L-point symmetric flat top window using
sflag is either
'periodic' flag is useful for DFT/FFT purposes,
such as in spectral analysis. The DFT/FFT contains an implicit periodic
extension and the periodic flag enables a signal windowed with a periodic
window to have perfect periodic extension. When
flattopwin computes a length
and returns the first
L points. When using windows
for filter design, the
'symmetric' flag should
Create a 64-point symmetric flat top window. View the result using
N = 64; w = flattopwin(N); wvtool(w)
Flat top windows are summations of cosines. The coefficients of a flat top window are computed from the following equation:
where . The coefficient values are
 D'Antona, Gabriele, and A. Ferrero. Digital Signal Processing for Measurement Systems. New York: Springer Media, 2006, pp. 70–72.
 Gade, Svend, and Henrik Herlufsen. "Use of Weighting Functions in DFT/FFT Analysis (Part I)." Windows to FFT Analysis (Part I): Brüel & Kjær Technical Review, No. 3, 1987, pp. 1–28.
Usage notes and limitations:
All inputs must be constants. Expressions or variables are allowed if their values do not change.