Calculator Notes for TI-89, TI-92 Plus, and Voyage 200

Note 13G • LSL Program
The program lsl allows you to adjust a line until the sum of the squares of
the residuals is minimized. Follow these steps:
a. Store your data into lists l1 and l2.
b. Run the program.
c. A short set of instructions are displayed. Arrow up or down to change the
intercept of the line. Arrow left or right to change the slope of the line.
Press CLEAR to reset the line and start over. Press ESC to quit the program.
d. Press ENTER to see a scatter plot of your data, a line, and a physical
representation of the squares of the residuals. (Note: The graphing
window may not be square, so the squares may look like rectangles.) Keep
adjusting the line until you have found the line with the smallest sum of
the squared residuals, the value of sqr sum in the upper-left corner.
Clean-Up
After you quit the program, Plots 1, 2, and 3 remain on. Go to the
Y Editor screen to clear them or turn them off so they do not interfere
with future graphing activities.
lsl()
Prgm
© Displays line of fit for data
in l1, l2 and squares of
residuals; allows adjustment
© Instructions
ClrIO
Disp "Find line of fit"
Disp "Up and dn:change intercept"
Disp "Rt and left:change slope"
Disp "CLEAR:reset ESC:quit"
Disp ""
Pause "To begin, press ENTER."
PlotsOff
FnOff
setMode("Graph","FUNCTION")
setMode("Angle","DEGREE")
NewPlot 1,1,l1,l2,,,,3 © Plots
data points
ZoomData
TI-89/TI-92 Plus/Voyage 200
Discovering Advanced Algebra Calculator Notes for the Texas Instruments TI-89, TI-92 Plus, and Voyage 200 CHAPTER 13 81
©2004 Key Curriculum Press
© Get stats for data
dim(l1)ánum
TwoVar l1,l2
(num*∑xy-∑x*∑y)/(num*∑x2-∑x^2)áslope © Slope of least squares line
© Store means in lists for
plotting
mean(l1)ámeanx:mean(l2)ámeany
{meanx}ál3:{meany}ál 4
NewPlot 2,1,l3,l4,,,,4
© Copy vertical mean, slope for
changing line
slopeásl
meanyáw
© Set up lists for line of fit
and residual squares
seq(l1[int(x/5)+1],x,0,5*num-1)ál 5
seq(l2[int(x/5)+1],x,0,5*num-1)ál 6
(continued)