# HP 48gII User Manual Page 408

Graphing calculator.

of differential equations of the form Y'(T) = F(T,Y). For our case, we let Y x
and T t, therefore, F(T,Y) f(t,x) = exp(-t
Before plotting the solution, x(t), for t = 0 to 5, delete the variables EQ and
PPAR.
Press „ô, simultaneously if in RPN mode, to access to the PLOT
SETUP window.
Change
to
TYPE
Diff Eq
Press ˜ and type ³„ ¸-~ „tQ2@@@OK@@@.
The cursor is now in the
. This is the code used by the calculator to identify the variables to
Var:1
be plotted.
H-Var:0
will be plotted in the horizontal axis.
dependent variable (default name 'Y') will be plotted in the vertical axis.
Press ˜ . The cursor is now in the
„t@@@OK@@@ to change the independent variable to t.
Press „ò, simultaneously if in RPN mode, to access the PLOT
window (in this case it will be called PLOT WINDOW – DIFF EQ).
Change the H-VIEW and V-VIEW parameters to read:
V-VIEW: -1
1.5
value to 0, and the Final value to 5 by using: 0@@@OK@@@
Change the
Init
5@@@OK@@@.
The values Step and Tol represent the step in the independent variable
and the tolerance for convergence to be used by the numerical solution.
Let's leave those values with their default settings (if the word default is
not shown in the Step: field, use L @RESET to reset that value to its
The Init-Soln value represents the initial value of the solution to start the
numerical result. For the present case, we have for initial conditions x(0)
= 0, thus, we need to change this value to 0.0, by using 0@@@OK@@@.
Press @ERASE @DRAW to plot the solution to the differential equation.
Press @EDIT L @LABEL @MENU to see the graph with labels.
2
).
.
field. It should show
H-Var
means the independent variable (to be selected later)
Indep
and also
H-Var:0
Also,
means the
V-Var:1
field. Press ‚³~
H-VIEW: -1
Page 12-27
V-
5,