How to get this equation to plot

I am trying to plot this equation and matlab thinks it is matrix multiplication when it is not. I have included my code. I also included a screen shot of what matlab is telling me.

%x1'=10e^-3t*-sin(200t)+2e^-3t*cos(200t)

%x2'=-10e^-3t*cos(200t)+2e^-3t*sin(200t)

tspan=[-10 10];

x1=10*exp(-3*t)*(-sin(200*t))+2*exp(-3*t)*cos(200*t);

x2=-10*exp(-3*t)*cos(200*t)+2*exp(-3*t)*sin(200*t);

figure

hold on

fplot(x1,tspan,'r');

fplot(x2,tspan,'b');

xlim([0 1]);

ylim([-10 10]);

xlabel('Time');

ylabel('Solutions')

title('{x1(t)}, {x2(t)}');

grid on

hold off

[Torsten]

You are given the derivatives x1' and x2' of x1 and x2. You need to apply MATLAB's "int" to determine their antiderivatives first before plotting.

Answer 1

[Voss]

Use .* for element-wise multiplication, and if you want to use fplot then x1 and x2 should be function handles (I've added "@(t)" at the beginning of their definitions to do so).

%x1'=10e^-3t*-sin(200t)+2e^-3t*cos(200t)
%x2'=-10e^-3t*cos(200t)+2e^-3t*sin(200t)
tspan=[-10 10];
x1=@(t)10*exp(-3*t).*(-sin(200*t))+2*exp(-3*t).*cos(200*t);
x2=@(t)-10*exp(-3*t).*cos(200*t)+2*exp(-3*t).*sin(200*t);
figure
hold on
fplot(x1,tspan,'r');
fplot(x2,tspan,'b');
xlim([0 1]);
ylim([-10 10]);
xlabel('Time');
ylabel('Solutions')
title('{x1(t)}, {x2(t)}');
grid on
hold off