HP 40gs HP 39gs_40gs_Mastering The Graphing Calculator_English_E_F2224-90010.p - Page 48

The NUM view If you now press the NUM key, you will see the screen on the right. It shows the calculated function values for F1(X), starting at zero and increasing in steps of 0.1 Make sure the highlight is in the X column as shown on the previous page, and then press 4 and ENTER. You will find that the numbers will now start at four instead of zero. It is also possible to change the step size via the key, which can be convenient at times, particularly for trig functions. The simplest way to set the start value and increment is in the NUM SETUP view. This is covered in detail on page 70. The PLOT view Now press the PLOT key. The graph you'll see will not be a terribly useful one (see right) because the axes will not be set up correctly. We'll look next at how to do this. One of the easiest ways to set up the axes properly for a function whose shape is not known in advance is to let the calculator suggest a suitable scale using the Auto Scale option in the VIEWS menu covered on the next page. However, its suggested scales are not always very helpful. There are a number of ways of working out a 'nice' scale. See page 78 for a discussion of this. Another method is to use the NUM view to investigate the range of values that will be required for the function. More complete information on the VIEWS menu can be found on page 85. 48