HP (Hewlett-Packard) HP-12C Calculator User Manual


 
156
•Where S
1
, S
2
, and S
3
are:
a, b and c are determined by solving the three equations above simulta-
neously.
Forecasting With Exponential Smoothing
a = smoothing constant (0 < a < 1)
X
t
= actual current period usage
c
1
n
---
S
1
S
3
S
2
2
S
1
S
3
2S
2
+
------------------------------------



exp=
a
b1()S
2
S
1
()
bb
n
1()
2
------------------------------------------
exp=
S
1
Iny
i
ncb aln()+ln=
i1=
n
=
b
n
1
b1
---------------
S
2
Iny
i
ncb
n1+
aln()+ln=
in1+=
2n
=
b
n
1
b1
---------------
1
t1+
S
t
1
α
---


T
t
+=