Texas Instruments TI-89 Titanium User Manual page 388

How Are Z Values Determined?
You can set the ncontour Window variable (8 $) to specify the number of
contours that will be evenly distributed along the displayed range of z values, where:
zmax zmin
increment =
-------------------------------- -
ncontour
The z values for the contours are:
zmin + increment
zmin + 2(increment)
zmin + 3(increment)
©
zmin + ncontour(increment)
If and you use the standard viewing window (
ncontour=5
increment is 3.333. Five contours are drawn for z=L6.666, L3.333, 0, 3.333, and 6.666.
Note, however, that a contour is not drawn for a z value if the 3D graph is not defined at
that z value.
3D Graphing
–
+ 1
The default is 5. You
can set this to 0
through 20.
zmin= L 10
and ) , the
zmax=10
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