Example Aplet #2 - HP 39g Master Manual

Example aplet #2

If you haven't already, read pages 194 which explain how to create a copy of
the Parametric aplet to explore geometric transformations using matrices.
We will now look at using programming to enhance this aplet by automating
the process.
Start by highlighting the Parametric aplet and
pressing . Now
the new name 'Transformer'. Press SHIFT
NOTE (not NOTEPAD) and enter some
explanatory text into the aplet's Note view.
You can use the text shown right.
The next step is to create the 'helper'
programs for the aplet, including the one
containing the SETVIEWS command used to
create a new VIEWS menu for the aplet.
These programs are shown on the next page.
When you have typed them all in then
the program .TRANSF.SV to create the VIEWS menu.
Programs for the aplet 'Transformer' are given below.
.TRANSF.SV
This program sets up the VIEWS
menu to call each of the other
programs. It need only be run once
at the creation of the aplet, but is
attached via the final line so that it
will be sent with all the others if the
aplet is transmitted. The new user
does not have to re-run it: it will
never normally be run again.
the aplet under
.TRANSF.S
This program sets up the required
axes using variables from the PLOT
SETUP view. It then loads the
equations and ensures they are
ed and ready for use.
Finally it loads the initial values into
the matrices.
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.TRANSF.PLOT
This program changes the value of
Xmin and then changes it back. In
the original version the user had to
press PLOT to force a re-draw. This
technique fools the hp 39g+ into
thinking that the PLOT view has
changed and therefore forces a re-
draw without the need to press a
key. It also re-multiplies the
matrices in case the user has
changed one by hand instead of
going through the VIEWS menu.