HP 39gs Master Manual page 126

Choosing from available fit models
The Statistics aplet is the only one which has a
even then only in
specify what type of fit equation is to be used. The choices are:
Linear
Logarithmic
Exponential
Power
Quadratic
Cubic
Logistic
Exponent
Trigonometric
User Defined
Calculator Tip
1.
2.
SYMB SETUP
mode. This view is supplied to allow you to
-
m*X+b
-
m*LN(X)+b
-
b*EXP(m*X)
-
b*X^m
-
a*X^2+b*X+c
-
a*X^3+b*X^2+cX+d
-
L/(1+a*exp(-b*X))
This fits the data to a logistic curve where L is the saturation value. See tip below.
-
b*m^X
-
a*SIN(b*X+c)+d
This model fits a possible trigonometric curve to the data. Because
the sine curve is periodic the answer will not be unique.
- discussed on the following page.
If you want the value of L calculated automatically for the Logistic
model then store a value of zero into
known, you can store a positive real value into memory L prior to
the curve fit and this will be used.
If you calcu ate a line of best fit and want to remove the resulting l
equation from the
SYMB
then just position the highlight on the relevant
the key. When you do this, the
DEL
will have to be reset.
view, and
= +
( )
Y mX b
( )
= + b
( )
Y m ln X
=
( )
mX
Y b e
=
( )
m
Y b X
= + bX c +
( )
2
Y aX
= + bX + cX
( 3 2
Y aX
L
Y =
( )
−bX
1+ a e
= ×
( ) This model is essentially the same as the
X
Y b m
Exponential version but without the use of e. This
caters for students who have been exposed to
exponential equations but not to the extent of e.
= + +
(
Y a sin( bx c ) d
in
L HOME
display and return to the
will be removed and
126
+
)
d
)
. If the value is
display
m*X+b
line and press
Fit: