Texas Instruments TI-89 Titanium User Manual page 376

How the Viewing Angle Is Measured
The viewing angle has three components:
• q — angle in degrees from the
eye
positive x axis.
• f — angle in degrees from the
eye
positive z axis.
ψ — angle in degrees by which the
•
eye
graph is rotated counter-clockwise
around the line of sight set by
and
eye f.
ψ
When
Note: eye =0
rotated 90¡ counterclockwise and is horizontal.
In the Window Editor (8 $), always enter
regardless of the current angle mode.
3D Graphing
eye
, the z axis is vertical on the screen. When
eye
eye
X
q
Do not enter a
example, type 20, 70, and
0, not 20 , 70
¡
eye q, eye
Z
f
Y
eye
q
¡ symbol. For
and 0 .
¡ ¡
ψ
, the z axis is
eye =90
ψ in degrees,
f, and
eye
373