Texas Instruments TI-84 PLUS SILV Guidebook - Page 89

To use ZBox to define another box within the new graph, repeat steps 2 through 4. To cancel ZBox, press '. Zoom In, Zoom Out Zoom In magnifies the part of the graph that surrounds the cursor location. Zoom Out displays a greater portion of the graph, centered on the cursor location. The XFact and YFact settings determine the extent of the zoom. To zoom in on a graph, follow these steps. 1. Check XFact and YFact; change as needed. 2. Select 2:Zoom In from the ZOOM menu. The zoom cursor is displayed. 3. Move the zoom cursor to the point that is to be the center of the new viewing window. 4. Press Í. The TI-83 Plus adjusts the viewing window by XFact and YFact; updates the window variables; and replots the selected functions, centered on the cursor location. 5. Zoom in on the graph again in either of two ways. • To zoom in at the same point, press Í. • To zoom in at a new point, move the cursor to the point that you want as the center of the new viewing window, and then press Í. To zoom out on a graph, select 3:Zoom Out and repeat steps 3 through 5. To cancel Zoom In or Zoom Out, press '. ZDecimal ZDecimal replots the functions immediately. It updates the window variables to preset values, as shown below. These values set @X and @Y equal to 0.1 and set the X and Y value of each pixel to one decimal place. Xmin=L4.7 Xmax=4.7 Xscl=1 Ymin=L3.1 Ymax=3.1 Yscl=1 ZSquare ZSquare replots the functions immediately. It redefines the viewing window based on the current values of the window variables. It adjusts in only one direction so that @X=@Y, which makes the graph of a circle look like a circle. Xscl and Yscl remain unchanged. The midpoint of the current graph (not the intersection of the axes) becomes the midpoint of the new graph. Chapter 3: Function Graphing 82