Texas Instruments TITANIUM TI-89 - Manual (Page 386)

3D Graphing 386
For example, suppose you trace the paraboloid z(x,y) = x
2
+ .5y
2
graphed with the
indicated Window variables. You can easily move the cursor to a position such as:
Although the cursor is actually tracing the paraboloid, it appears off the curve because
the trace coordinates:
• xc and yc are within the viewing cube.
– but –
• zc is outside the viewing cube.
Note: QuickCenter lets you center the viewing cube on the cursor’s location. Simply
press ¸.
When zc is outside the z boundary of the viewing cube, the cursor is physically displayed
at zmin or zmax (although the screen shows the correct trace coordinates).
Rotating and/or Elevating the Viewing Angle Rotating and/or Elevating the Viewing Angle Rotating and/or Elevating the Viewing Angle Rotating and/or Elevating the Viewing Angle
In 3D graphing mode, the eye q and eye f Window variables let you set viewing angles that
determine your line of sight. The eye
ψ Window variable lets you rotate the graph around
that line of sight.
Trace cursor
Valid trace
coordinates