Statistics 12–27
82D315~1.DOC TI-83 international English Bob Fedorisko Revised: 10/26/05 1:36 PM Printed: 10/27/05 2:53
PM Page 27 of 38
PwrReg (power regression) fits the model equation y=ax
b
to the
data using a least-squares fit and transformed values ln(x) and
ln(y). It displays values for
a and b; when DiagnosticOn is set, it
also displays values for
r
2
and r.
PwrReg [Xlistname,Ylistname,freqlist,regequ]
Logistic fits the model equation y=c / (1+aäe
Lbx
) to the data using
an iterative least-squares fit. It displays values for
a, b, and c.
Logistic [Xlistname,Ylistname,freqlist,regequ]
SinReg (sinusoidal regression) fits the model equation
y=a sin(bx+c)+d to the data using an iterative least-squares fit. It
displays values for
a, b, c, and d. At least four data points are
required. At least two data points per cycle are required in order
to avoid aliased frequency estimates.
SinReg [iterations,Xlistname,Ylistname,period,regequ]
iterations is the maximum number of times the algorithm will
iterate to find a solution. The value for iterations can be an
integer ‚ 1 and 16; if not specified, the default is 3. The
algorithm may find a solution before iterations is reached.
Typically, larger values for iterations result in longer execution
times and better accuracy for
SinReg, and vice versa.
A period guess is optional. If you do not specify period, the
difference between time values in Xlistname must be equal and
the time values must be ordered in ascending sequential order. If
you specify period, the algorithm may find a solution more
quickly, or it may find a solution when it would not have found
one if you had omitted a value for period. If you specify period,
the differences between time values in Xlistname can be
unequal.
Note: The output of SinReg is always in radians, regardless of the
Radian/Degree mode setting.
A SinReg example is shown on the next page.
PwrReg
(ax
b
)
Logistic
c / (1+aä
ää
äe
Lbx
)
SinReg
a sin(bx+c)+d
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