Plotting Surfaces with Grapher
Warren Weckesser
September 9, 2005
These brief notes explain how to plot surfaces with Grapher, an application that is avail-
able on the computers in the Computer Lab.
Plotting the graph of z=f(x, y).
1. Start Grapher by clicking on the Grapher icon. A window with the title New Graph
will appear.
2. Click on 3D Graph, then click on Open. A larger window with the title Untitled will
appear. There will be an empty set of yellow axes visible. Above the axes is an area
where you can define your equation. It will initially contain z=. You can type your
function here.
3. After z=, enter, for example, (x−2y)(x+ 2y)x. When you hit Enter, the graph will
be drawn with a light and dark green checkerboard pattern.
Note: When you type the first opening parenthesis, the program automatically adds
the closing parenthesis, and puts the cursor inside them. You can use the right-arrow
key to move out of the parentheses.
4. The surface will looked “stretched out” vertically. A quick way to see a nicer view is
to click on Zoom In two or three times.
Note: This plot is an example of a “monkey saddle”.
5. Move the mouse into the plotting region, and click-and-drag on the plot to change the
point of view.
6. Optional, but possibly useful: We can control the view more precisely by changing the
“Frame Limits”. In the menu bar at the top of the screen, select View, and then Frame
Limits.... In the small window that pops up, you can set the x,yand zlimits of the
plot. Change the xand ylower and upper limits to be, say, −1 and 1, respectively,
and change the zlimits to be −2 and 2. Click on OK (or just hit Enter).
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