HP 50g Calculator - The Basics of Plotting Functions

Plotting on the HP 50g

The HP 50g calculator provides a host of plots to allow the user to visualize data or relationships between them. The white shifted-functions of the top row of keys on the HP 50g allow access to many of the input forms where plotting specifications may be entered.

2D/3D (PLOT SETUP) form

This example is performed in RPN mode. To set RPN mode:

  1. Press .
  2. With the field to the right of ‘Operating Mode’ highlighted, press the menu key. Use the key to highlight ‘RPN’ in the Choose Box.
  3. Press .
  4. Press again to return to the ‘HOME’ screen.
The 2D/3D (PLOT SETUP) form is accessed by pressing left shift, , and simultaneously pressing and holding the (F4) key. When pressed, a form titled ‘PLOT SETUP’ is displayed with a number of choices related to plotting as shown in following figure.

Figure 1: PLOT SETUP screen
NOTE: To access the 'PLOT SETUP' form using an emulator, right-click left shift key, ( ), followed by a left-click of .
The first option allows selecting the plot type from a number of options. The selections for plot type are displayed by pressing the menu key. The plot types include:
Functions
Scatter charts
Polar plots
Slopefield charts
Parametric plots
Fast 3D charts
Differential equation plots
Wireframe plots
Conic plots
Ps-contour plots
Truth plots
Y-slice plots
Histograms
Gridmap plots
Bar charts
Pr-surface plots
After pressing the menu key, a choose box appears as shown below in Figure 2. Use the cursor keys to highlight the option and press . For this example, use the ‘Function’ option.

Figure 2: CHOOSE box
The ‘PLOT SETUP’ form also allows the user to specify the equation being plotted. Place the cursor on the ‘EQ:’ field using the cursor keys and press the menu label to invoke the EquationWriter used for constructing the equation to be plotted. See Figure 3.

Figure 3: EquationWriter
With the EquationWriter screen displayed, key in the desired equation using the keypad and the right-arrow cursor key ( ) to move from one part of the equation to another. Press to input the equation.

For example, to enter y = x2-4, with ‘Function’ highlighted in the ‘PLOT SETUP’ screen, press:

  1. and the menu key to invoke the EquationWriter.
  2. With the EquationWriter open, as shown in Figure 3, press .
  3. Press (the X key) .

This returns to the ‘PLOT SETUP’ screen with the equation in the 'EQ:' field. The form also allows to change the angle measure and the independent variable to be specified.

NOTE: The default is often 'X,' but for parametric plots, this will be changed to ‘t’.

For this example, be sure the independent variable (Indep:) is ‘X’. In addition, several check boxes indicate whether the plotted points should be automatically connected together by the calculator and the settings for the horizontal and vertical tick marks used for the graph. The form also allows for the plotting of more than one function at a time. For this example, leave all these settings in their defaults.

The WIN form

The WIN form allows for the ‘PLOT WINDOW’ specifications to be entered and changed. The lower and upper horizontal and vertical values displayed on the graph can be changed. The lower and upper value for the independent variable can also be specified on this form. Use the arrow keys to move around the form.

To open the WIN form, press followed by the (F2) key.

Figure 4: PLOT WINDOW
In the fields of the ‘PLOT WINDOW’ screen, enter the desired upper and lower values for the plot followed by . For this example, set the x values from -3 to 3 (in the fields 'Indep Low:' and 'High:') and the y values -6 to 6 (in the fields 'H-View:' and 'V-View:').

With the ‘PLOT WINDOW’ displayed, and the cursor to the right of 'H-View:', press:

  2. Press
  3. Press
  4. Press
  5. Press
  6. Press .

Figure 5: PLOT WINDOW with values entered
Once these parameters have been updated, press to discard the results of a previous plot, and to begin the plot. The plot should appear in the display as shown in the following figure. Note the new menu options.

Figure 6: PLOT

What Can I Do with the Plot?

  1. Use the arrow keys to move the cursor around the plot. Press to open a zoom menu and zoom in and out, select a region using a box, etc. Press to see more options. Press (zoom default) to return to the default zoom size, but note that these settings differ from those entered for the previous example. To leave the Zoom menu, press until the menu option is displayed. Press it to return to the main plot screen and menu. To re-enter the values for the plot window used in this example, press to exit the graph screen and open the 'PLOT WINDOW'. Once the values are entered, press to discard the results of a previous plot, and to plot.
  2. Press to move the cursor along the graph and read the x-y coordinates with the cursor keys. Press to return to the main plot menu.
  3. Once back to the main plot screen, press . The small white box to the left of indicates the tracer is active. With the Tracer active, the cursor traces along the function by pressing the left and right arrow keys.
  4. Press for functions for finding roots, areas, intersections, etc. For example, press and the closest root will be calculated. Press the key so the menu appears again, then again to see more options. Press to return to the main plot window.
  5. Press to access functions for marking points, drawing, and creating lines in the graph. Press again to see more options, and to return to the main plot window.
  6. Press to exit the graph screen.
  7. From here, press followed by (the F1) key to return to the 'PLOT FUNCTION' screen. Select the top function(s) (the derivatives) and press to delete any entries, if any, from the previous steps so that only the original equation remains, y=x2-4.
  8. Now press followed by (F6) key to enter the table. Here view the table of the 'X' and function values. Select an item in the 'X' column and type 1.215.
  9. Press and note the table jumps to that value and displays again.
  10. Press followed by (F2) key to return to the 'PLOT WINDOW' screen, or followed by (F3) key to return to the graph. Press the CANCEL key ( ) on the keyboard to return to the 'HOME' screen.