HP 39g Graphing Calculator - Manual (Page 106)

Fit models
Eight fit models are available:
To define your
own fit
Fit model Meaning
Linear (Default.) Fits the data to a straight
line, y = mx+h. Uses a least-squares
fit.
Logarithmic Fits to a logarithmic curve,
y = m Inx + h.
Exponential Fits to an exponential curve, y = he'"^.
Power Fits to a power curve, y = bx"’.
Quadratic Fits to a quadratic curve,
y = ax^+bx+c. Needs at least three
points.
Cubic Fits to a cubic curve,
y = ax^+hx^+cx+d. Needs at least
four points.
Logistic Fits to a logistic curve.
L
^ , (-hx)’
l + a e
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.)
1. In Numeric view, make sure t~-WiilM is set.
2. Display the Symbolic view.
3. Highlight the Fit expression (Fitl, etc.) for the desired
data set.
4. Type in an expression and press |
enter |.
The independent variable must be X , and the expression
must not contain any unknown variables.
Example: 1.5 x cos.r + 0.3 x sina'.
This automatically changes the Fit type (SIFIT, etc.) in the
Symbolic Setup view to User Defined.
8-12 Statistics aplet