Texas Instruments PLUS TI-89 - Manual (Page 175)

158 Chapter 10: 3D Graphing
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 158 of 22 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 158 of 22
The Window Editor maintains an independent set of Window
variables for each
Graph mode setting (just as the Y= Editor
maintains independent function lists). 3D graphs use the following
Window variables.
Variable Description
eye q , eye f ,
eye ψ
Angles (always in degrees) used to view the graph.
Refer to “Rotating and/or Elevating the Viewing Angle”
on page 162.
xmin , xmax ,
ymin , ymax,
zmin, zmax
Boundaries of the viewing cube.
xgrid, ygrid The distance between xmin and xmax and between ymin
and ymax is divided into the specified number of grids.
The z(x,y) equation is evaluated at each grid point
where the grid lines (or grid wires) intersect.
The incremental value along x and y is calculated as:
x increment =
xmax ì xmin
xgrid
y increment =
ymax ì ymin
ygrid
The number of grid wires is xgrid + 1 and ygrid + 1 . For
example, when xgrid = 14 and ygrid = 14 , the xy grid
consists of 225 (15
×
15) grid points.
ncontour The number of contours evenly distributed along the
displayed range of z values. Refer to page 168.
Standard values (set when you select 6:ZoomStd from the „ Zoom
toolbar menu) are:
eye q = 20. xmin = ë 10. ymin = ë 10. zmin = ë 10.
eye f = 70. xmax = 10. ymax = 10. zmax = 10.
eye
ψ
= 0. xgrid = 14. ygrid = 14. ncontour = 5.
You may need to increase the standard values for the grid variables
( xgrid , ygrid ) to ensure that enough points are plotted.
Window Variables
Note: If you enter a
fractional number for xgrid
or ygrid, it is rounded to the
nearest whole number
‚ 1.
Note: The 3D mode does
not have scl Window
variables, so you cannot set
tick marks on the axes.
Note: Increasing the grid
variables decreases the
graphing speed.
z(xmin,ymax)
z(xmax,ymin)
z(xmin,ymin)
z(xmax,ymax)