HP 39gs Master Manual page 356

One additional step is required. For some reason the Parametric aplet doesn't seem to properly accept
the functions. If you press
highlight each function in turn and press
This seems to make the calculator accept that it is a valid
function, since it has had the chance to examine the function as
if you had typed it in yourself. Pressing
produce the screen shown right. The symmetry we predicted
earlier is now visible. This may not be the best possible view
and you may wish to use
ix. The final step is to accurately evaluate f ⎜ ⎟ . To do this, return to the CAS and enter the following:
ALPHA X 1 ( SHIFT 3
ALPHA Y 1 ( SHIFT 3
(Notice the brackets appear when you press
We can now evaluate the left hand coordinate,
then the other. The first enter substitutes the
value, the second gives the answer.
ENTER ENTER
now you will receive the "Undefined Name" error. The trick is to
PLOT
PLOT
to change this.
PLOT SETUP
π
⎛ ⎞
⎝ ⎠
3
3 SHIFT
3 SHIFT
ENTER ENTER
. Don't make any changes, just press
at this point will
.)
356
or .
ENTER