1550078481-Ordinary_Differential_Equations__Roberts_

530 Ordinary Differential Equations

The first option, Graph solution of one or both components, is already
selected, so we click the OK button. We want to graph the solution of the
first IVP (the only one we have solved thus far), so in the box to the right of
"i = " we enter 1 and press the Enter key. Check boxes for yl and y2 appear.
Since we want to graph both solution components, we click the box to the left
of yl, we click the box to the left of y2, and then we click OK. An Information
for Graphing box appears. After reading the contents of the box, we click
OK. Since PORTRAIT was able to integrate over the entire interval [O, 4.5],

Xmin = 0 and Xmax = 4.5. We do not wish to change these values. However,

Ymin = 4.183726E-Ol and Ymax = l.723472E+Ol. Based on these values,

we decided to change Ymin to 0 and Ymax to 20 to produce the graph. After
changing the value of Ymin and Ymax, we click the VERIFY XMIN, XMAX,
YMIN, YMAX button. This causes the graph shown in Figure B.5 to appear
on the monitor.

, ii PORTRAIT l!fl!J 11'3

. Ente1-!he Sjlt!em·defming function• Fl. f2
y1 ·,,fl =, jy1.5'y 1 'y2
.. y'2 =•f.2 = ·2)'2•.25'y1"y2

y1-black

Ent~r !he numbe1 of initial ~alue p1oblem:Jo :olve '

N=f2

d2i =

y2'··blue

lnterval·of ·integ1a!ion

Xmin·= I O.OOOOOOE + 00

Xmax = J 4.500000E+OO_

Min/max of component~

!l'min=r-o-

Ymax=~

Cfl!llOKS

, ·Xmax

Figure B.5 Graph of the Solution Components of the System IVP (3)(i)

Observe that the colors the solution components appearing in the graph on
the monitor are listed at the bottom of the graph- yl is black and y2 is blue.