Trig Functions - HP 39g Master Manual

However, for the scale of -6 to 6 the pixels are no longer 'nice' values of 0.1.
If you try to trace the circle you'll see that the pixels fall on 0, 0.0923077,
0.1846154..... In particular, near x=3 the pixel values are 2.953846 and
3.046154. This means that the calculator can't draw anything past 2.953846
because the next value doesn't exist, being outside the circle. This is what
causes the gap in the circle. There's nothing to join to past that last point.
The solution is to use scales which allow the end points of your circle to fall
on a pixel point. If your circle has an integer radius then this is easily done
by starting with the default axes and then ZOOM in or out to show the circle.
This will tend to give 'nice' pixel points. If your circle is not centered on the
origin then just check/tick the box in the Set Zoom Factors box to Recenter.
That will allow you to turn off TRACE, move the cursor closer to the point
where you'd like the centre of screen to be and then ZOOM.

Trig functions

If graphing a trig function using
radian measure then you should
choose a scale which will cause
pixel values (screen dots) to fall at
convenient points. A good scale to
use is provided on the VIEWS menu
(see right).
This scale sets each dot to be
that multiples and most factors of
want to trace values on the graph.
Ensure the angle measure is set to Radians in the MODES view if you intend
to use this scale.
π
, ensuring
24
π
will fall on dots and thus helping if you
Calculator Tip
Make sure you set angle measure after you have
the aplet, not before, so as to ensure you are setting the
correct aplet.
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