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Specific Features of the HP-33E
27
Correlation Coefficient
To establish how well the data used fits the linear regression, you may
wantto calculate the correlation coefficient, r, by using | (correlation
coefficient).
The correlation coefficient is a value between —1 and 1. Atr = 0 you
have no fit, while at r = =1 you have a perfect fit.
Example: Calculate the correlation coefficient for the previously
calculated linear regression.
Keystrokes
Display
™
0.9967
A very good fit.
Vector Arithmetic
You can use your HP-33E to add or subtract vectors by combining the
polar/rectangular conversion functions (the
and the ('
keys)
with the summation functions (the
and ' " keys).
To use only the 2x and 2y that you have accumulated in the storage
registers, you can press
followed by
. This brings %x into the
displayed X-register and 2y into the Y-register, overwriting the contents
of those two stack registers. The stack does not lift. This feature is
particularly useful when performing vector arithmetic.
Example: On his way to search for an
albino caribou, grizzled bush pilot
Apeneck Sweeney's converted Sword-
fish aircraft has a true air speed of 150
knots and an estimated heading of
45°. The Swordfish is also being buf-
feted by a head wind of 40 knots from a
bearing of 25°. What is the actual ground
speed and true course of the Swordfish?
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