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III. Working With A Graph
F. ZOOM and MEMORY
The ZOOM menu is a very useful tool when working with graphs. It not only offers preset windows, but other ways of looking at a graph. The MEMORY menu offers you a quick way to return to a window and to change the Zoom In and Zoom Out factors.
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1: ZBox allows you to box in a part of the graph. This is useful when you need to look at a small part of the graph. ZPrevious will restore the previous window.
Example: Graph the function
using ZOOM4 and then use ZBox to examine the graph close to the origin.
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The graph is close to the x-axis
around the origin,
so using ZBox will help with the analysis. |
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Access ZBox.
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Hit ENTER and you will see
the cursor
blinking at the origin. |
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Use the cursor keys to move
the cursor to the indicated
point and hit ENTER. You will see the cursor change to a rectangle. Once you hit enter, that corner of the box is anchored and cannot be moved. |
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Now move the cursor to the
indicated value.
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Now hit ENTER, and the graph
will be redrawn
to show only the part inside the box. |
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Access MEMORY and select 1:ZPrevious
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The graph is restored to the
previous window.
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2: Zoom In will zoom in on the graph with the position of the cursor serving as the new center. The default for Zoom In is a factor of 4, but this can be changed by accessing the MEMORY menu and using 4: SetFactors.
Example: Use the function from the previous example to access the Zoom In function and then use ZPrevious to restore the graph.
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Graph the function.
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Access the Zoom In key.
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When you hit ENTER you
will see the cursor blinking at the origin. |
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You can move the cursor to
any point that you want to be the center of the new graph. This has been left at the origin. |
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You can change the zoom in
factor by accessing MEMORY and 4: SetFactors. |
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You can set these to any
number you need. |
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3: Zoom Out works exactly like Zoom In.
4: ZDecimal is a "friendly window" which means that TRACE moves in increments of 0.1. This is a useful window to use when the graph will fit because you can move to particular X-values easily. The use of this window is demonstrated in the polynomial examples in the Setting Windows section.
5: ZSquare will redraw the graph by adjusting [Xmin,Xmax] so that the tick marks are an equal distance apart on each axes. This is particularly useful when you need to see an accurate shape, such as a circle. ZDecimal is also a square window.
Example: Graph the circle
by entering the functions
and
using ZStandard and ZSquare.
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Enter the functions.
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Use ZStandard.
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Use ZSquare.
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6: ZStandard is a preset window of [-10,10] by [-10,10] with tick marks set at integers. The use of this window is demonstrated in the polynomial examples in the Setting Windows section.
7: ZTrig is a trigonometry preset window with [Xmin,Xmax]=
. This window is covered in the trigonometry examples in the Setting Windows section.
8: ZInteger will redraw the graph and reset the window to Xscl=10 and Yscl=10. The TRACE key will move in increments of 1.
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Enter the function.
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Use ZDecimal.
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Access ZInteger.
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Cursor will be at (0,0).
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Press ENTER to
redraw the graph. |
These are the new
window settings. |
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9: ZoomStat will change the graph window so that statistical points will all be shown. This window is generally not used in algebra, trigonometry or calculus.
10: ZoomFit will redraw the graph by resetting [YMin, YMax] to include the maximum and minimum values of the function over the interval [Xmin, Xmax]. This window can produce some rather distorted graphs and should be used with care.
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Enter the function.
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Use ZDecimal.
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Use ZFit.
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This is the new window.
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