I am looking at Palm's "Introduction to MatLab 7 for Engineers" page 511. The problem involves solving a Second Order Diff Equation. The solution to the diff equation is straight forward. What I am wondering is what Plam is doing in the plot function?(adsbygoogle = window.adsbygoogle || []).push({});

[tex] \ddot{\Theta} + \frac {g} {l} sin \Theta = 0 [/tex]

His answer is below:

in the m file pendul:

function xdot = pendul(t,x)

global g L

xdot = [x(2); -(g/L)*sin(x(1))];

in the m file example8_6_1

global g L

g = 9.81;

L = 1;

[ta, xa] = ode('pendul', [0,5], [0.5,0]);

plot(ta,xa(:,1), xlabel('Time (s)'), ylabel('Angle(rad)')

Question:

In the plot(ta,xa(:,1) what is the (:,1)? What is he doing? And why couldn't he just put an xa without the (:,1)?

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# MatLab Question

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