problem related to for loop

I am trying to plot x and v equation for different value of m ... please take alook and kindly guid me through this

m = [10,20,30,40];

k = 50;

x0=0.01;

v0=0.2;

d=size(m);

dt = 0.001;

t = 0:dt:10;

for l=0:d

wn(l) = sqrt(k(l)/m(l));

s1(l) = 1i*sqrt(k(l)/m(l));

s2(l) = -1i*sqrt(k(l)/m(l));

C1(l) = (-v0+x0*s2(l))/(s2(l)-s1(l));

C2(l) = (v0-x0*s1(l))/(s2(l)-s1(l));

x(l) = C1(l)*exp(s1(l)*t)+C2(l)*exp(s2(l)*t);

v(l) = C1(l)*s1(l)*exp(s1(l)*t)+C2(l)*s2(l)*exp(s2(l)*t);

end

figure;

subplot(211),plot(t,x,'r--'); xlabel('Time'), ylabel('Displacement')

subplot(212),plot(t,v,'r--'); xlabel('Time'), ylabel('Displacement')

Answer 1

[the cyclist]

You have at least three problems with your code that I can see.

First, in the line

wn(l) = sqrt(k(l)./m(l));

you are trying to access the "0th" element of the array wn, but that does not exist. MATLAB uses 1-based indexing, so you need to start from 1.

Second, you are using the "/" and "*" operators, but those are for matrix division and multiplication. You probably want "./" and ".*" for all of those.

Third, I think you want to use "t(l)" instead of "t" in your for loop.

Answer 2

[Chad Greene]

You can't start indexing with zero. You'll have to do for l = 1:length(m)

[ashkan hosseini]

thanks ... but there is a problem with loop and this error ''the number of elements in B and I must be the same''