HP -28S Manual 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