Texas Instruments TI-89 Manual De Usuario

3D Graphing

 385

For example, consider a saddle shape z1(x,y) = (x

2

Ny

2

) / 3. The following graph shows 

the view looking down the y axis.

Now look at the same shape at 10¡ from the x axis (eyeq = 10).

 To cut away the front of the saddle in this example, set 

 to show only 

negative x values.

Example of an “Off the Curve” Cursor

Example of an “Off the Curve” Cursor

Example of an “Off the Curve” Cursor

Example of an “Off the Curve” Cursor

Although the cursor can move only along a grid wire, you will see many cases where the 
cursor does not appear to be on the 3D surface at all. This occurs when the z axis is too 
short to show 

 for the corresponding x and y values.

You can move the cursor so 
that it does not appear to be 
on a grid point.

If you cut away the front side, 
you can see the cursor is 
actually on a grid point on the 
hidden back side.