Texas Instruments PLUS TI-89 - Manual (Page 154)

Chapter 8: Polar Graphing 137
08POLAR.DOC TI-89/TI-92 Plus: Polar Graphing (English) Susan Gullord Revised: 02/23/01 10:57 AM Printed: 02/23/01 2:14 PM Page 137 of 6
The Window Editor maintains an independent set of Window
variables for each
Graph mode setting (just as the Y= Editor
maintains independent function lists). Polar graphs use the following
Window variables.
Variable Description
q min, q max Smallest and largest q values to evaluate.
q step Increment for the q value. Polar equations are
evaluated at:
r( q min)
r( q min+ q step)
r( q min+2( q step))
... not to exceed ...
r(
q max)
xmin , xmax ,
ymin , ymax
Boundaries of the viewing window.
xscl , yscl Distance between tick marks on the x and y axes.
Standard values (set when you select 6:ZoomStd from the „ Zoom
toolbar menu) are:
q min = 0. xmin = ë 10. ymin = ë 10.
q max = 2 p (6.2831853... radians
or 360 degrees) xmax = 10. ymax = 10.
q step = p /24 (.1308996... radians
or 7.5 degrees)
xscl = 1. yscl = 1.
You may need to change the standard values for the q variables
( q min , q max , q step ) to ensure that enough points are plotted.
To display coordinates as r and q values, use:
ƒ 9
— or —
TI - 89 : ¥ Í
TI - 92 Plus : ¥ F
to set Coordinates = POLAR . If Coordinates = RECT , the polar
equations will be graphed properly, but coordinates will be displayed
as
x and y .
When you trace a polar equation, the q coordinate is shown even if
Coordinates = RECT .
Window Variables
Note: You can use a
negative
q step. If so, q min
must be greater than q max.
Setting the Graph
Format