Why do I receive "Index exceeds the number of array elements (1)" ?

This function is giving me an "Index exceeds the number of array elements (1)" error, and I have looked through it for over an hour but I can't figure out where my error is. For some background, m and t are both defined already in my workplace and they are both vectors. I would appreciate any pointers so I can fix this error. Thank you!

function v = velocity(m,t)
    ve = -2000;
    g = 9.81;
    cd = 0.1;
    dt = t(2) - t(1);
    tf = max(t);
    tbar = 0.4*tf;
    x = 0:dt:tbar;
    m = length(x)+1;
    n = length(t);
    v=zeros(1, n);
    
    for w = 2:m 
        v(w) = v(w-1) + dt*((100/m(w-1))*(v(w-1)-ve)-g-(cd/m(w-1))*abs(v(w-1))*v(w-1));
           % v(i) = v(i-1)+dt*((v(i-1)-ve)*(100/(m(i-1)))-g-(cd/(m(i-1)))*abs(v(i-1))*(v(i-1)));
           % v(i) = v(i-1) + dt*(-g-(cd/m(i-1))*abs(v(i-1))*v(i-1));
    end    
       
    for w = m:n
        v(w) = v(w-1) + dt*(-g-(cd/m(w-1))*abs(v(w-1))*v(w-1));
    end
end

Answer 1

[the cyclist]

m is a scalar -- the length of the vector x, plus one.

You try to index into it as if it is a vector, for example in the expression

m(w-1)

So this fails with the error you see, when w==3.

[Mercedes Milke]

Thank you! That helped that error stop showing and I was actually able to run it now. I changed the name of the vector from m to another unrelated letter, and then I also changed it from the second for loop. I am now getting some very small values in comparison to what I need, but at least I have a point to go forward from. Thank you very much, again!

Answer 2

[Dave B]

You wrote:

For some background, m and t are both defined already in my workplace and they are both vectors.

But you redefined m as:

m = length(x)+1;

Doesn't that mean m is now a scalar? and when you point to m(w-1) it won't be valid?

[Mercedes Milke]

You're absolutely right. I needed to change the name of that so as to not redefine all my m values. Thank you for your response!