Texas Instruments TI-89 Voyage 200, User Manual

Page: 422 / 1008

Differential Equation Graphing 422
If You Do Not Enter an Initial Condition in the Y= Editor
If You Do Not Enter an Initial Condition in the Y= Editor If You Do Not Enter an Initial Condition in the Y= Editor
If You Do Not Enter an Initial Condition in the Y= Editor
If you do not enter initial conditions, the
ncurves
Window variable (
8 $
) specifies
the number of solution curves graphed automatically. By default,
ncurves = 0
. You can
enter a value from 0 through 10. However, the
Fields
graph format and the
Axes
setting
determine whether
ncurves
is used.
When
ncurves
is used,
t0
is set temporarily at the middle of the Graph screen. However,
the value of
t0
as set in the Y= Editor or Window Editor is not changed.
Notes:
• Without entering initial conditions, use SLPFLD (with
ncurves=0
) or DIRFLD to
display a slope or direction field only.
• SLPFLD is for a single 1st-order equation only. DIRFLD is for a 2nd-order equation
(or system of two 1st-order equations) only.
If Fields = Then:
SLPFLD Uses ncurves , if not set to 0, to graph curves.
DIRFLD Ignores ncurves . Does not graph any curves.
FLDOFF Uses ncurves if Axes = TIME (or if Axes = Custom and the
x axis is t). Otherwise, a Diff Eq setup error occurs.