### 21.5.12 Riemann window

The riemann_window command applies the Riemann window function to a sequence or its segment.

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

  wk= |
  ⎧ ⎪ ⎪ ⎪ ⎨ ⎪ ⎪ ⎪ ⎩ |
  1, |
  k= |
  N−1
  2
  | ,
  sin(π xk)
  π xk
  | ,
  | otherwise,

  where xk=2 k/N−1−1 for k=0,1,…,N−1.

#### Example

listplot(riemann_window([1$1000]))