HP 40gs HP 39gs_40gs_Mastering The Graphing Calculator_English_E_F2224-90010.p - Page 355

viii. We can see symmetry visually if the function is graphed and the aplet best suited to this is the Parametric aplet. When a function is sent to the Parametric aplet the real part is sent to the x and the imaginary part to the y component of the parametric equation selected. Calculator Tip Although X1 and Y1 were chosen as names for the functions defined earlier this has no relevance for the pasting into the Parametric aplet. They could just as easily have been defined as Fred(t) and Jim(t). However, it is suggested that you not define a function as simply X(t). This is because X is defined as the current variable by default and this means that the contents of your function definition will be purged as soon as you perform any operation that uses the current variable. On the screen, define an expression X1(T ) + i ⋅Y1(T ) which can be sent to the aplet, evaluating it and changing back to large font too. SHIFT SHIFT ALPHA CLEAR ALPHA X 1 ( ALPHA T + SHIFT 1 ALPHA Y 1 ( ALPHA T SHIFT ENTER Now store to the aplet using the PLOT button on the keyboard, choosing X1,Y1 in the Parametric aplet. PLOT ENTER ENTER Note: The reason that we used capital T instead of lower case t here is because that is the variable used by the Parametric aplet. We now change out of the CAS and activate the Parametric aplet in the usual fashion. When you do you should see the screen shown right. Each of these expressions needs to be simplified before graphing or it will significantly slow down the process. Highlight each in turn and press the screen button. Then press the button. 355