Chapter 10: 3D Graphing 163
10_3D.DOC TI-89/TI-92 Plus: 3D Graphing (English) Susan Gullord Revised: 02/23/01 11:00 AM Printed: 02/23/01 4:22 PM Page 163 of 22
By changing eyef, you can elevate your viewing angle above the xy
plane. If 90 < eyef < 270, the viewing angle is below the xy plane.
z1(x,y) = (x3y - y3x) / 390 In this example, eyeq = 20
The view on the Graph screen is always oriented along the viewing
angles set by eyeq and eyef. You can change eyeψ to rotate the graph
around that line of sight.
z1(x,y)=(x3yìy3x) / 390 In this example,
eyeq=20 and eyef=70
The eye values are stored in the system variables eyeq, eyef, and
eyeψ. You can access or store to these variables as necessary.
TI-89: To type f or ψ, press ¥cj[F] or ¥cÚ, respectively.
You can also press 2¿and use the Greek menu.
TI-92 Plus: To type f or ψ, press 2G F or 2G Y respectively.
You can also press 2¿
and use the Greek menu.
Effect of Changing
eyef
Note: This example starts
on the xy plane (
eyef
=
90
)
and decrements
eyef
by
20
to elevate the viewing angle.
Effect of Changing
eyeψ
Note: During rotation, the
axes expand or contract to
fit the screen’s width and
height. This causes some
distortion as shown in the
example.
When
eyeψ=0
,
the z axis runs
the height of the
screen.
When
eyeψ=90
, the z axis
runs the width of the screen.
As the z axis rotates 90¡, its
range (ë10 to 10 in this
example) expands to almost
twice its original length.
Likewise, the x and y axes
expand or contract.
From the Home
Screen or a Program
eyeψ=0
eyeψ=45
eyeψ=90
eyef = 90
eyef = 70
eyef = 50
z=10
z=ë10
z=10 z=ë10