Return the Bartlett window.
The Bartlett window is a taper formed by using a weighted cosine.
\[w(n) = 1 - \frac{2|n - (M-1)/2|}{M-1}
\qquad 0 \le n \le M-1\]
- Parameters:
M (int) – Number of points in the output window.
- Returns:
- The window, with the maximum value normalized to one (the value one
appears only if the number of samples is odd).
- Return type:
array
