Logarithmic Curve Fit - HP 12c Platinum Reference Manual

102 Statistics

Logarithmic Curve Fit

If your data does not fit a line or an exponential curve, try the following logarithmic curve
fit. This is calculated according to the equation y = A + B (ln x ), and all x values must be
positive.
A typical logarithmic curve is shown below.
Y
The procedure is as follows:
1. Press f CLEAR H .
2. Key in the first y-value and press \ ( ³ ). Key in the first x-value and press
g°_ . Repeat this step for each data pair.
3. After all data pairs are input, press gR~ to obtain the correlation coefficient
(between y and ln x).
4. Press 1 gR 0 gR to obtain A in the equation above.
5. RPN: Press ~d- to obtain B.
5. ALG: Press -~d³ to obtain B.
6. To make a y-estimate, key in the x-value and press g°gR .
X