Auto Scale - HP 39g Master Manual

Auto Scale

Auto Scale is an good way to ensure that you get a reasonable picture of the
graph if you are not sure in advance of the scale. After using Auto Scale you
can then use the PLOT SETUP view to adjust the results.
It is important to understand two points about how Auto Scale works.
1. It works by using the X-axis range that is currently chosen in PLOT
SETUP to adjust the Y-axis range to include as much of the graph as
possible. It will not adjust the x axis.
2. Auto Scale is done only for the first
graph with a
graphs and they don't fit the scale then
they will not benefit. As you can see in
the example shown right, the quadratic
shows well but the second graph (a
cubic) shows only an ascending section. Zooming out would be an
option at this stage, as would un-
that Auto Scaling the cubic might give better results (unlikely).
3. The resulting y scale is
often not a very 'nice'
one. You will usually
have to adjust it in the
PLOT SETUP view to
make it look good.
The excessively thick axis in
the first screen shot of the
sequence of three on the right
is a common result of Auto
Scale and is caused by the value of
Ytick being too small. The third graph
has a Ytick value of 10 instead of 1.
. If there are other
96
ing the quadratic in the hopes