In designing an aplet for the HP 38...

In designing an aplet for the HP 38% calculator, it's important to remember sum of two units guiding principles of the HP 38G design. First, the design recognizes that in a classroom setting there is (and should be) a large discrepancy between the amount of information registered into a graphing calculator and the amount of information produc on the calculator. We sought to minimize the calculator input required of the close examiner and the teacher and maximize the answered information. Secondly, we sought to bar irrelevaht possibilities. By reducing irrelevant choices you focus the user's attention forward the subject of interest and avoid distractions from things that don't matter. Many choices made during the design of the HP 38G were based forward this goal.

Aplets contain information and have views. The information in an aplet consists of each major piece required to bring into view the views: the equations, setup information, modification information, sketch or text annotations, and attached libraries or programs. In this article we'll explore a simple aplet, then direct the eye at an aplet called Polysides and examine by what means it was constructed.

Using Built-in Aplets

When the HP 38G is first make go rounded on, the built-in aplets are devoid of contents There's no equation, note, or portray When the user adds this information, these aplets arrive alive. You can save an aplet at any time, to such a degree it's easy to start single project, change in midstream to another, then follow back to the first. (Because the appearance of the shields depends on the information you record the screens on your calculator may gaze different from the example veils in this article.

A simple way to illustrate the aplet general [i]or[/i] abstract notion is to explore the equation SIN(X2)/X. preferable the function aplet, press SYMB and set in the equation.

At this point, you have an aplet that's completely dedicated to your interest in the function SIN(X2)/X, and the aplet can be saved beneath a unique name or transmitted to another HP 38G or a computer When the aplet is restarted in succession the original or another HP 38G aH accidents and scales are set just the way they were saved.

Exploring the PolySides Aplet

The PolySides aplet is designed to explore for what cause a regular polygon can approximate a circle as the number of sides increases. PolySides can be loaded from a disk or another HP 38G in a single operation from the LIB catalog. one time loaded, PolySides appears in the aplet library.

We are now just a single keystroke away from exploying the aplet. To begin the exploration, pres START. The motivation for the task is displayed first.

After the introduction has been read and a elucidation pressed, the next step is to jot down the radius of the circle to be approximated.

After the radius has been take downed the properties of the circle are displayed.

After the circle properties have been viewed, the note view of the aplet is displayed. The PAGE menu elucidation switches between the pages of the note.

To behold a sketch of the puzzle press SKETCH.

So far we have seen a beautiful complete summary of the lecturing with less than a dozen keystroke Now we can begin to explore for what cause may sides are needed to approximate a circle.

Our central point of departure for Polysides is VIEWS (as mentioned in the note view).

These choices give leave to you determine what aspect of a many-sided figure approximation to a circle you'd like to explore. To explore in what manner the perimeter of the many-sided figure approximates the circle, move the highlight down to Perimeter and pres OK The plottable view is at handed automatically.

This is one of the HP 38G split views, showing the draught and numeric views of the perimeter approximation at the same time. The variable X exhibits the number of sides, and the equation stored in F2 go [i]or[/i] come backs the perimeter as a function of X Pressing the left or right arrowkey prompts the cursors for the scheme and numeric views simultaneously. When the cursor is at the left brink; beginning [i]or[/i] end of the plot, the table upon the right shows the rapid change of the perimeter from a triangle to a nonagon.

To view the equation, just press SYMB

The symbolic view is where aplet equations are stored. The check mark beside F2 indicates that when a cabal or numeric view is displayed, F2 will be used. Another view of the equation is available according to pressing SHOW.

Notice that after the introduction there is no three order of ends You can change to any of the views at any time or pres family circle at any time to do a short calculation. Part of the design philosophy of aplets is to obstacle the student explore the lecture at will, without following any particular algorithm. formerly you've explored the approximations to the perimeter and area, and perhaps explored the drift on side lengths, you may decide that a many-sided figure with 57 sides yields a fair approximation to the circumference of a unit circle.

Now you can direct the eye at a summary of a 57-sided many-sided figure by selecting Polygon Props (for many-sided figure properties) from the VIEWS choices.

Pres OK to chosen this choice. Since the cursor was last upon X = 57, the number of sides defaults to 57

After the user accepts (or alters) the number of sides, the many-sided figure data is displayed.