Texas Instruments TI-89 Manual Book page 199

Window Variables
(Continued)
Note: For information about
how the Fields graph format
affects whether ncurves is
used, refer to page 184.
182 Chapter 11: Differential Equation Graphing
, , Boundaries of the viewing window.
xmin xmax
,
ymin ymax
, Distance between tick marks on the x and y axes.
xscl yscl
Number of solution curves (0 through 10) that will be
ncurves
drawn automatically if you do not specify an initial
condition. By default,
When
ncurves
of the screen and initial conditions are distributed
evenly along the y axis, where:
increment =
The values for the initial conditions are:
y
ymin + increment
ymin + 2ù (increment)
©
ymin + ncurvesù (increment)
(
diftol Solution Method = RK
method to help select a step size for solving the
equation; must be ‚1
fldres ( Fields = SLPFLD
(1 through 80) used to draw a slope or direction field
across the full width of the screen.
(
Estep Solution Method = EULER
between
accuracy, you can increase
additional points.
(
dtime Fields = DIRFLD
direction field is drawn.
Standard values (set when you select
toolbar menu) are:
xmin = ë 1.
t0 = 0.
tmax = 10. xmax = 10.
tstep = .1 xscl = 1.
tplot = 0.
You may need to change the standard values for the
ensure that sufficient points are plotted.
ncurves = 0
is used, is set temporarily at the middle
t0
ymax ì ymin
ncurves + 1
only) Tolerance used by the
ë 14.
E
or DIRFLD only) Number of columns
only) Euler iterations
tstep values; must be an integer >0. For more
Estep
only) Point in time at which a
6:ZoomStd
ymin = ë 10.
ymax = 10.
yscl = 1.
.
RK
without plotting
from the „
Zoom
ncurves = 0.
diftol = .001
Estep = 1.
fldres = 14.
dtime = 0.
variables to
t