Texas Instruments TI-89 Manual Book page 197

Setting Graph
Formats
Important: The Fields
graph format is critical in
successfully graphing
differential equations. Refer
to "Troubleshooting with the
Fields Graph Format" on
page 197.
Tip: If you press ¸
while a slope or direction
field is being drawn, the
graph pauses after the field
is drawn but before the
solutions are plotted. Press
¸ again to continue.
Tip: To cancel graphing,
press ´ .
180 Chapter 11: Differential Equation Graphing
From the Y= Editor, Window
Editor, or Graph screen, press:
ƒ
9
— or —
¥ Í
TI-89:
¥
TI-92 Plus: F
The formats affected by differential equations are:
Graph format Description
Graph Order Not available.
Specifies the method used to solve the differential
Solution
Method equations.
¦
RK
about the algorithm used for this method, refer
to Appendix B.
¦
EULER
The method lets you choose either greater
accuracy or speed. Typically,
than
Specifies whether to draw a field for the
Fields
differential equation.
¦
SLPFLD
order equation, with
solution on the y axis. To see how a slope field
is used, refer to the example starting on
page 176.
¦
DIRFLD
2nd-order equation (or system of two 1st-order
equations), with axes determined by the
custom axes settings. To see how a direction
field is used, refer to the example starting on
page 187.
¦
FLDOFF
valid for equations of any order, but you must
use it for 3rd- or higher-order. You must enter
the same number of initial conditions for all
equations in the Y= Editor (page 184). For an
example, refer to page 189.
— Runge-Kutta method. For information
— Euler method.
but takes longer to find the solution.
EULER
— Draws a slope field for only one 1st-
t on the x axis and the
— Draws a direction field for only one
— Does not display a field. This is
is more accurate
RK