245. M-Md-N

Damped mult. trend, mult. errors

Example:

Given

  • Smoothing parameters: , ,
  • Initial states: ,
  • Data:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
12 10 8 11 14 12 9 13 16 14 11 15 18 16 13 17

Step 1 — formula

Observation:

Conditional mean (one-step-ahead forecast ):

Innovation:

State updates:

Forecast steps ahead from time (using current-period states):

where is the forecast horizon (how many steps ahead).

Step 2 — apply at

Step 3 — iterate

Each column header is the equation that produced its values. Values rounded to 4 decimal places; arithmetic performed at full precision.

1 12
2 10
3 8
4 11
5 14
6 12
7 9
8 13
9 16
10 14
11 11
12 15
13 18
14 16
15 13
16 17