III. Working With Graphs

B. F2 - Zoom

The Zoom menu is a very useful tool when working with graph. The Zoom menu offers you several preset windows and numerous other options. Zoom can be a very powerful tool when analyzing a graph. There are many times when one of these options will work well with the function you are graphing. To access the Zoom menu from the graph window press . To access the Zoom menu from the Window menu, press or .

From the graph
window press .


1:ZoomBox This allows you to box in a particular area of the graph
and then zoom in on that selected portion.
2:ZoomIn You can select a point on the graph and then zoom in or zoom
out with that point as the center. The amount of zoom is defined
by SetFactors (see below).
4:ZoomDec This is one of the most useful windows. It is also
called a friendly window because the Trace key
will move in set increments of .1 times the value of xres.
The window size is x:[-7.9,7.9] and y:[-3.8, 3.8].
5:ZoomSqr This adjusts the Window variables so that the ticks on each
axis are the same distance apart. This will allow squares and
circles to be shown in correct proportions.
6:ZoomStd Sets the Window variables to the default values.
x:[-10,10] and y:[-10,10].
7:ZoomTrig Sets the Window variables to increments using , and are
appropriate for many trigonometric functions.
8:ZoomInt You can select a new center point, and the scales are set to 10.
9:ZoomData This adjusts the Window variables so that all selected
statistical plots will be seen.
A:ZoomFit Sets a window that shows the maximum and minimum value of Y
with with given X window.
B:Memory 1:ZoomPrev - restores the window to the previous setting
2:ZoomSto - allows you to store a window
3:ZoomRcl - recalls a stored window
C:SetFactors Use this to set the factors by which the calculator zooms in or out.

1:ZoomBox is quite useful when you need to analyze a particular part of a graph without having to reset the window.

Example: Graph the function shown and then use ZoomBox to examine the graph close to the origin.

Enter the function.
Press 4 to graph
with ZoomDec. The graph
is close to the origin so
using ZoomBox will
help with the analysis.
Press 1 and you will
see the window shown here.
Use the cursor keys to move
the cursor to the indicated
point and press . You
will see the cursor change
to a rectangle. Once you
hit , that corner of
the box is set and cannot
be moved.
Now move the cursor to the
indicated value.

Now press and the
graph will be redrawn to
show only the part inside
the box.

Press and scroll to
B:Memory and then select
ZoomPrev restores the
graph to the previous

2:ZoomIn will zoom in on the graph with the position of the cursor serving as the new center. The default zoom factor is 4, but that can be changed using C:SetFactors.

Example: Use the function from the previous example to ZoomIn.

Graph the function.
Press 2. and you
will see the screen at the
right. If the cursor is
left where it is, the origin
will remain the center.
Press .

5:ZoomSqr will redraw the graph by adjusting xmin and xmax so that the tick marks are equal in distance on both axes. This is particularly useful when you need to see an accurate shape, such as a circle. ZoomDec is also a square window.

Example: Graph the circle by entering the functions and using ZoomSqr and ZoomStd.

Enter the functions.
Use ZoomStd.
Use ZoomSqr.