Apply a moving average filter to a signal

### 19.3.3 Apply a moving average filter to a signal

The moving_average command applies a moving average to a signal.

- moving_average takes two arguments:
  - A, an array of numeric values representing a sampled signal.
  - n, a positive integer n.
- moving_average(A,n) returns an array B obtained by applying a moving average filter of length n to A. The elements of B are defined by

  B[i]= |
  1
  n
  n−1
  ∑
  j=0
  | A[i+j]

  for i=0,1,…,L−n, where L is the length of A.

Moving average filters are fast and useful for smoothing time-encoded signals.

#### Example

snd:=soundsec(2):; noise:=randvector(length(snd),normald,0,0.05):; data:=0.5*threshold(3*sin(2*pi*220*snd),[-1.0,1.0])+noise:;

plotwav(createwav(data),range=[1000,1500])

fdata:=moving_average(data,25):; plotwav(createwav(fdata),range=[1000,1500])