### 21.5.9 Hann window

The hann_window command applies the Hann window function to a sequence or its segment.

- hann_window takes one mandatory argument and two optional arguments:
  - v, a real vector with length n.
  - Optionally, m, N, a sequence of two integers (by default, m=0 and N=n).
- hann_window returns the elementwise product of [vm,vm+1,…,vm+N−1] and the vector w of length N defined by

  wk=sin2 | ⎛ ⎜ ⎜ ⎝ |
  k π
  N−1
  | ⎞ ⎟ ⎟ ⎠ | , k=0,1,…,N−1.

#### Example

listplot(hann_window([1$1000]))