1550078481-Ordinary_Differential_Equations__Roberts_

CSODE User's Guide 513

Xmax, Y min, Y max}. Another option is for you to click on the third option

button: New Function and then click the OK button. This option begins

GRAPH anew. When you are done using the program GRAPH, click on the

box in the upper right-hand corner of the monitor with an X in it. This will

cause the selection screen (Figure A. l) to appear which will allow you to run

a different program in CSODE or to exit CSODE.

.;o GRAPH Sl!J ti

GRAPH g1@hs the equation y = f(x) inside the 1eclangfe bounded by the lines x = Xmin. x = Xmax. y = Ymin. and y = Ymax.

Entel'lhe function f(x) = V,...,.......,; 2·>:+exp(·x12)"<in(5...... ~...;.,~~.,,...~~~~----~~~~-~~~--i "x)

OPTIONS

Ente1 Xm.in = ,!~ --·5-...i and ente1 Xmax = ~j ---..I

The m.inimum and'm~aimum values of' f(I!'.) ~n. {Xmin, Xmax} are

'Yniin = ,_j _ _;-1.;_ 0 --" anii YmaK· = ----"^40 i'

Ymin Xmib '====================!==::=!=====::::I .xmax

Figure A.10 Graph of f(x) = x^2 - x + e-x/^2 sin5x on the Interval [-5,5]

Using DIRFIELD

The program DIRFIELD graphs the direction field of the differential equa-

tion y' = f(x, y) in the rectangular region R of the xy-plane bounded by the

lines x = Xmin, x = Xmax, y = Ymin, and y = Ymax. To graph the di-

rection field you need to enter an expression for the function f(x, y) and the
values for Xmin, Xmax, Ymin, and Ymax. The following example shows how
to enter the required data and illustrates the output of the program.