Texas Instruments TITANIUM TI-89 - Manual (Page 418)

Differential Equation Graphing 418
When ncurves is used, t0 is set temporarily at the
middle of the screen and initial conditions are distributed
evenly along the y axis, where:
The y values for the initial conditions are:
ymin + increment
ymin + 2
ù
(increment)
©
ymin + ncurves
ù
(increment)
diftol (Solution Method = RK only) Tolerance used by the RK
method to help select a step size for solving the
equation; must be
‚ 1E L 14.
fldres (Fields = SLPFLD or DIRFLD only) Number of columns
(1 through 80) used to draw a slope or direction field
across the full width of the screen.
Estep (Solution Method = EULER only) Euler iterations
between tstep values; must be an integer >0. For more
accuracy, you can increase Estep without plotting
additional points.
dtime (Fields = DIRFLD only) Point in time at which a direction
field is drawn.
Variable Description
increment
ymax ymin –
ncurves 1 +
-------------------------------- =