Texas Instruments TITANIUM TI-89 - Manual (Page 400)

3D Graphing 400
Drawing a Contour for the Z Value of a Selected Point Interactively Drawing a Contour for the Z Value of a Selected Point Interactively Drawing a Contour for the Z Value of a Selected Point Interactively Drawing a Contour for the Z Value of a Selected Point Interactively
If a contour graph is currently displayed, you can specify a point on the graph and draw a
contour for the corresponding z value.
2. Select 7:Draw Contour .
3. Either:
• Type the point’s x value and press ¸, and then type the y value and press
¸.
– or –
• Move the cursor to the applicable point. (The cursor moves along the grid lines.)
Then press
¸.
For example, suppose the current graph is z1(x,y)=x
2
+.5y
2
–5. If you specify x=2 and
y=3, a contour is drawn for z=3.5.
Note: Any existing contours remain on the graph. To remove the default contours, display
the Window editor ( 8 $) and set
ncontour=0 .
1. To display the Draw menu, press:
2 ˆ