HP 39g+ - Manual (Page 104)

8-12 Statistics aplet
Fit models
Eight fit models are available:
To define your
own fit
1. In Numeric view, make sure !W6S•Ã is set.
2. Display the Symbolic view.
3. Highlight the Fit expression ( Fit1 , etc.) for the desired
data set.
4. Type in an expression and press
>(17(5@.
The independent variable must be X, and the expression
must not contain any unknown variables.
Example:
.
This automatically changes the Fit type ( S1FIT , etc.) in the
Symbolic Setup view to User Defined .
Fit model Meaning
Linear (Default.) Fits the data to a straight
line, y = mx+b. Uses a least-squares
fit.
Logarithmic Fits to a logarithmic curve,
y = m lnx + b.
Exponential Fits to an exponential curve, y = be
mx
.
Power Fits to a power curve, y = bx m .
Quadratic Fits to a quadratic curve,
y = ax
2
+bx+c. Needs at least three
points.
Cubic Fits to a cubic curve,
y = ax
3 +bx 2 +cx+d. Needs at least
four points.
Logistic Fits to a logistic curve,
,
where L is the saturation value for
growth. You can store a positive real
value in L, or—if L=0—let L be
computed automatically.
User Defined Define your own expression (in
Symbolic view.)
y
L
1 ae
bx –
( )
+
-------------------------- =
1.5 x cos
×
0.3 x sin
Ч
+