HP 39g hp 39g+ (39g & 40g)_mastering the hp 39g+_English_E_F2224-90010.pdf - Page 96

Auto Scale Auto Scale is an good way to ensure that you get a reasonable picture of the graph if you are not sure in advance of the scale. After using Auto Scale you can then use the PLOT SETUP view to adjust the results. It is important to understand two points about how Auto Scale works. 1. It works by using the X-axis range that is currently chosen in PLOT SETUP to adjust the Y-axis range to include as much of the graph as possible. It will not adjust the x axis. 2. Auto Scale is done only for the first graph with a . If there are other graphs and they don't fit the scale then they will not benefit. As you can see in the example shown right, the quadratic shows well but the second graph (a cubic) shows only an ascending section. Zooming out would be an option at this stage, as would un- ing the quadratic in the hopes that Auto Scaling the cubic might give better results (unlikely). 3. The resulting y scale is often not a very 'nice' one. You will usually have to adjust it in the PLOT SETUP view to make it look good. The excessively thick axis in the first screen shot of the sequence of three on the right is a common result of Auto Scale and is caused by the value of Ytick being too small. The third graph has a Ytick value of 10 instead of 1. 96