HP 40gs HP 39gs_40gs_Mastering The Graphing Calculator_English_E_F2224-90010.p - Page 126

Choosing from available fit models, Linear, Logarithmic, Exponential, Power, Quadratic, Cubic

Page 126 highlights

Choosing from available fit models The Statistics aplet is the only one which has a SYMB SETUP view, and even then only in mode. This view is supplied to allow you to specify what type of fit equation is to be used. The choices are: Linear - m*X+b (Y = mX + b ) Logarithmic - m*LN(X)+b (Y = m ln ( X ) + b ) Exponential - b*EXP(m*X) ( Y = b emX ) Power - b*X^m (Y = b X m) Quadratic - a*X^2+b*X+c (Y = aX 2 + bX + c ) Cubic - a*X^3+b*X^2+cX+d ( Y = aX 3 + bX 2 + cX + d ) Logistic - L/(1+a*exp(-b*X)) ( Y = 1 + L a e−bX ) This fits the data to a logistic curve where L is the saturation value. See tip below. Exponent - b*m^X ( Y = b× mX ) This model is essentially the same as the 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. Trigonometric - a*SIN(b*X+c)+d ( Y = a sin(bx + c) + d ) This model fits a possible trigonometric curve to the data. Because the sine curve is periodic the answer will not be unique. User Defined - discussed on the following page. Calculator Tip 1. If you want the value of L calculated automatically for the Logistic model then store a value of zero into L in HOME. If the value is known, you can store a positive real value into memory L prior to the curve fit and this will be used. 2. If you calculate a line of best fit and want to remove the resulting equation from the SYMB display and return to the m*X+b display then just position the highlight on the relevant Fit: line and press the DEL key. When you do this, the will be removed and will have to be reset. 126

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Choosing from available fit models
The Statistics aplet is the only one which has a
SYMB SETUP
view, and
even then only in
mode. This view is supplied to allow you to
specify what type of fit equation is to be used. The choices are:
Linear
-
m*X+b
(
Y
mX
b
)
=
+
Logarithmic
-
m*LN(X)+b
(
Y
m
ln
(
X
)
+
b
)
=
Exponential
-
b*EXP(m*X)
(
Y
be
mX
)
=
Power
-
b*X^m
(
Y
bX
m
)
=
Quadratic
-
a*X^2+b*X+c
(
Y
aX
2
+
bX
c
)
=
+
2
Cubic
-
a*X^3+b*X^2+cX+d
(
Y
aX
3
+
bX
+
cX
d
)
=
+
L
Logistic
-
L/(1+a*exp(-b*X))
(
Y
=
)
1
+
ae
bX
This fits the data to a logistic curve where L is the saturation value. See tip below.
Exponent
-
b*m^X
(
Y
b
m
X
)
This model is essentially the same as the
=
×
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
.
Trigonometric
-
a*SIN(b*X+c)+d
(
Y
a
sin(
bx
c
)
d
)
=
+
+
This model fits a possible trigonometric curve to the data. Because
the
sine
curve
is
periodic the answer will not be unique.
User Defined
-
discussed on the following page.
Calculator Tip
1.
L
in
HOME
.
2.
l
SYMB
m*X+b
display
Fit:
line and press
the
DEL
will have to be reset.
If you want the value of L calculated automatically for the Logistic
model then store a value of zero into
If the value is
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
equation from the
display and return to the
then just position the highlight on the relevant
key.
When you do this, the
will be removed and
126