HP HP-28S - Page 270

Create the covariance matrix 2::COv.
I USER I
SUMS
Calculate 2::x
2
.
IX2
Calculate 2::y2.
IY2
Calculate 2::xy.
IXY
3:
2: 1831
1: 2791
m:mIImlIIE:IIDWI~DF;I
3: 1831
2: 2791
1:
2089
m:mIImlIIE:IIDWI~DF;I
If the statistics matrix had more than two columns, you could specify
new values for C
1
and C
2
.
For practice, specify C
1
= 1 and C
2
= 2
(the
current values).
The command COL2:: is available in the STAT menu, but here it's eas-
ier to spell
out the command name and stay in the USER menu.
1 I ENTER I 3: 1831
2: 2791
1:
2089
2 COL~ I ENTER I
m:mIImlIIE:IIDWI~DF;I
You could now execute 2::X2, 2::Y2, and 2::XY for the new pair of col-
umns C
1
and C
2
.
Don't forget to execute SUMS again whenever you add or delete data
from the statistics matrix 2::DAT.
28: Programming Examples 269