### 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−a1cos

  ⎛
  ⎜
  ⎜
  ⎝

  2kπ
  N−1

  ⎞
  ⎟
  ⎟
  ⎠

  +a2cos

  ⎛
  ⎜
  ⎜
  ⎝

  4kπ
  N−1

  ⎞
  ⎟
  ⎟
  ⎠

  −a3cos

  ⎛
  ⎜
  ⎜
  ⎝

  6kπ
  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]))