Hi I'm trying to plot using a for loop. don't see syntax errors but plot comes out empty. appreciate your guidance.

for t = 0:30/100:30
y1 = 6*exp(-0.2)*t*sin(7*t+3);
y2 = 4*exp(-0.1)*t*sin(3*t-1); 
end
plot(y1,t); 
hold on; 
plot(y2,t); 
hold off;
legend ('y1(t)=6e^-0.2tsin(7t+3)','y2(t)=4e^-0.1tsin(3t-1)');

axis([0 30 -6 6])

Answer 1

[Voss]

The plot comes out empty because you're only plotting the last point. Try it like this:

t = 0:30/100:30;
y1 = 6*exp(-0.2)*t.*sin(7*t+3);
y2 = 4*exp(-0.1)*t.*sin(3*t-1); 

plot(y1,t); 
hold on; 
plot(y2,t); 
hold off;
legend ('y1(t)=6e^-0.2tsin(7t+3)','y2(t)=4e^-0.1tsin(3t-1)');
axis([0 30 -6 6])

[Wesley Lei]

Great. it works now. Thanks so much. so i can use for loop? the assignment asks to practice loops.

[Voss]

Yeah, you can use a for loop:

t = 0:30/100:30;
y1 = zeros(size(t));
y2 = zeros(size(t));
for i = 1:numel(t)
    y1(i) = 6*exp(-0.2)*t(i)*sin(7*t(i)+3);
    y2(i) = 4*exp(-0.1)*t(i)*sin(3*t(i)-1); 
end
plot(y1,t); 
hold on; 
plot(y2,t); 
hold off;
legend ('y1(t)=6e^-0.2tsin(7t+3)','y2(t)=4e^-0.1tsin(3t-1)');
axis([0 30 -6 6])

[Wesley Lei]

You are amazing. Thanks again.

[Image Analyst]

Can you click the "Accept this answer" link to give him his "reptuation points"?