HP 40G manual Fit models To define your own fit, Fit model Meaning, = m lnx + b

Fit models

To define your own fit

Eight fit models are available:

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 = bemx.
Power	Fits to a power curve, y = bxm.
Quadratic	Fits to a quadratic curve,
	y = ax2+bx+c. Needs at least three
	points.
Cubic	Fits to a cubic curve,
	y = ax3+bx2+cx+d. Needs at least
	four points.
Logistic	Fits to a logistic curve,
	L
	y = -------------------------- ,
	1 + ae(– b x )
	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 ￿9$5￿_￿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: 1.5 ⋅ cos x + 0.3 ⋅ sin x .

This automatically changes the Fit type (S1FIT, etc.) in the Symbolic Setup view to User Defined.

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