HP 40gs HP 39gs_40gs_Mastering The Graphing Calculator_English_E_F2224-90010.p - Page 55

The Zoom Sub-menu The next menu key we'll examine is . Pressing the key under pops up a new menu, shown right. The list which follows covers the purpose of the first nine options shown right, down to "Set Factors". The four final options which follow these are also on the VIEWS menu and are covered on page 85 as part of the detailed examination of the VIEWS menu. Center This redraws the graph with proportionally the same scale for each axis but re-centered around the current position of the cursor. If you already have a 'nice' scale, this will preserve it, while perhaps showing a more interesting section of graph. In/Out These two options zoom in or out by adjusting the scales by the factor shown. The default factor is 4 for both axes but this can be adjusted through the Set Zoom Factor option later in the menu. The most useful settings are either 5x5 or 2x2 as these are more likely to preserve nice scales. Box... This is the most useful of the commands. When you choose this option a message will appear at the bottom of the screen asking you to Select first corner. If you use the arrow keys to move the cursor to one corner of a rectangle containing the part of the graph you want to zoom into and then press ENTER, the message will change to Select second corner. The cursor is positioned at one corner of a box. 55