Cosine window function: cosine_window

### 15.2.17 Cosine window function: cosine_window

The cosine_window command finds a cosine window of a sequence.

- cosine_window takes one mandatory argument and two optional arguments:
  - v, a real vector with length n.
  - Optionally, α, a real number (by default 1).
  - Optionally, an interval n0..n1 (by default 0..(n−1)).
- cosine_window(v ⟨,α,n1..n2⟩) returns the elementwise product of [vn1,…,vn2] and the vector w of length N=n2−n1+1 defined by

  wk=sinα | ⎛ ⎜ ⎜ ⎝ |
  k π
  N−1
  | ⎞ ⎟ ⎟ ⎠

  for k=0,1,…,N−1.

Example.
Input:

L0:=randvector(1000,0..1):;
scatterplot(L0);

Output:

Input:

L:=cosine_window(L0,1.5):;
scatterplot(L);

Output: