HP 15c - Manual (Page 124)

124 Section 4: Using Matrix Operations
124
8. Optionally, press C|x to calculate and display the residual sum of squares q
2
and to calculate the current solution b. Then press lCp times to display b
1
, b
2
,
…, b
p
in turn.
9. Repeat steps 5 through 8 for each additional row.
Example: Use this program and the CPI data from the previous example to fit the model
y = b
l
+ b
2
x
2
+ b
3
x
3
+ r,
where y, x
2
, and x
3
represent the CPI, PPI, and UR (all as percentages).
This problem involves p = 3 parameters, so matrix A should be 5 × 4. The rows of matrix A
are (1, x
m2
, x
m3
, y
m
) for m = 1,2, ... , 11. Each row has weight w
m
= 1.
Keystrokes Display
|¥ Run mode.
2
´m% 2.0000 Reserves R
0
through R
2
.
´U 2.0000 Activates User mode.
´>0 2.0000 Clears matrix memory.
5
v4 4
´mA 4.0000 Dimensions matrix A to 5 ×4.
0
O>A 0.0000 Stores zero in all elements.
1
A 1.0000 Enters weight for row 1.
1 ¦ 2.0000 Enters x
11
.
3.9
¦ 3.0000 Enters x
12
.
3.5
¦ 4.0000 Enters x
13
.
5.4 ¦ 1.0000 Enters y
1
.
B 5.0000 Updates factorization.
⋮ ⋮
1 A 1.0000 Enters weight for row 11.
1
¦ 2.0000 Enters x
11,1
.
19.3 ¦ 3.0000 Enters x
11,2
.
5.8
¦ 4.0000 Enters x
11,3
.
11.5
¦ 1.0000 Enters y
11
.
B 5.0000 Updates factorization.
C 3.6759 Calculates current estimates and q.
´•9 3.675891055
|x 13.51217505 Calculates residual sum of squares
q
2
.
lC 1.245864306
Displays ) 11 (
1
b .
lC 0.379758235
Displays ) 11 (
2
b .
lC 0.413552221
Displays ) 11 (
3
b .