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Texas Instruments TI-85 User Manual

Page 22

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B-22

TI-85/TI-86 Graphing Calculators

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TI-86

Position the cursor over the

L

1

at the top of

the first column.

Replace the

L

1

values with

L

1

-

1992

values by

pressing

F3

(

NAMES

) , the menu key under

L

1

, and

then press

1992

ENTER

.

Instead of an actual year, the input now represents
the number of years after 1992.

1.4.5 PLOTTING DATA

Any functions you have in the

y(x)=

list will graph when you plot

data. Therefore, you should delete them or turn them off before drawing a scatter plot.

Access the

y(x)=

graphing list. If any entered function

is no longer needed, delete it with

F4

(

DELf

) or clear

it with

CLEAR

.

If you want the function to remain but do not want it to
graph, position the cursor in that function location and

press

F5

(

SELCT

) .

A Òturned offÓ function.

To graph data on the TI-85:

The TI-85 command

Scatter

L

1

,

L

2

draws a scatter plot of

L

1

versus

L

1

. However, you must set

an appropriate

RANGE

before using this command. Program

STPLT

found in the TI-85/TI-86

Appendix automates this task.

Press

PRGM

and then press

F1

(

NAMES

) .

Find the name

STPLT

(press

MORE

if necessary).

Press the

F

-key corresponding

to the location of

STPLT

to

run the program.

Press

CLEAR

to remove the menu from the bottom

of the screen for a better view.

A scatter plot is drawn of the data with the

L

1

data as the

input data and the

L

2

data as the output data.

¥ Program

STPLT

sets the x and y-axis tick marks to

0

so they do not interfere with your

view of the scatter plot.

¥ Because the dots the calculator uses to plot data are sometimes difficult to see when

overdrawing the model of best fit, the program places a small box around each data
point. (The boxes may appear a slightly different size with different screen settings.)

¥ Even though the TI-85 generally allows you to call lists by any names you want, you must

enter the input data in the list named

L

1

and the output data in the list named

L

2

when

using program

STPLT

.

¥ Lists

L

1

and

L

2

must be of the same length or an error message results.

¥ It is not possible to trace a scatter plot drawn on the TI-85.