### 21.5.2 Blackman-Harris window

The blackman_harris_window command applies the Blackman-Harris window to a sequence or its segment.

- blackman_harris_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).
- blackman_harris_window returns the elementwise product of [vm,vm+1,…,vm+N−1] and the vector w of length N defined by

  wk=a0−a1 cos | ⎛ ⎜ ⎜ ⎝ |
  2 k π
  N−1
  | ⎞ ⎟ ⎟ ⎠ | +a2 cos | ⎛ ⎜ ⎜ ⎝ |
  4 k π
  N−1
  | ⎞ ⎟ ⎟ ⎠ | −a3 cos | ⎛ ⎜ ⎜ ⎝ |
  6 k π
  N−1
  | ⎞ ⎟ ⎟ ⎠

  for k=0,1,…,N−1, where a0=0.35875, a1=0.48829, a2=0.14128 and a3=0.01168.

#### Example

listplot(blackman_harris_window([1$1000]))