Texas Instruments TI-92 Getting Started page 11

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Graphing Technology Guide: TI-92
Figure 5.23: ToolBar menu Figure 5.24: Format menu
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Figure 5.25: Grid turned on for y = –x + 4x
F and turning the Grid option to OFF, then
In general, you'll want the grid turned off, so do that now by pressing
pressing ENTER.
5.2.3 Graphing Step and Piecewise-Defined Functions: The greatest integer function, written [[x]] , gives the
greatest integer less than or equal to a number x. On the TI-92, the greatest integer function is called floor( and is
located under the Number sub-menu of the MATH menu (Figure 5.8). From the Home screen, calculate [[6.78]] = 6
by pressing 2nd MATH 6[floor(] 6.78) ENTER.
To graph y = [[x]], go into the Y= menu, move beside y1 and press CLEAR 2nd MATH 6[floor(] X ) ENTER
GRAPH. Figure 5.26 shows this graph in a viewing rectangle from –5 to 5 in both directions.
The true graph of the greatest integer function is a step graph, like the one in Figure 5.27. For the graph of y = [[x]],
a segment should not be drawn between every pair of successive points. You can change this graph from a Line to a
Dot graph on the TI-92 by going to the Y= screen, moving up until this function is selected (highlighted) and then
pressing F6. This opens the Graph Style menu. Move the cursor down to the second line and press ENTER or
press 2; to have the selected graph plotted in Dot style. Now press GRAPH to see the result.
Figure 5.26: Connected graph of y = [[x]] Figure 5.27: Dot graph of y = [[x]]
Technology Tip: When graphing functions in the Dot style, it improves the appearance of the graph to set xres to 1.
Figure 5.27 was graphed with xres = 1. Also, the default graph style is Line, so you have to set the style to Dot
each time you wish to graph a function in Dot mode.
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