Dimension mismatch for using Runge Kutta 4 order methods

No longer available

[Walter Roberson]

When you encounter the problem, what are the size() of k1, k2, k3, k4 ?

[Walter Roberson]

Please do not delete the content of questions after they are responded to. Content should only be removed if it is inappropriate for the forum (for example if it was not about MATLAB); otherwise it should be left for future reference.

Some of the volunteers get quite frustrated when people remove content that the volunteers have expended time and energy to answer; it makes them feel like their efforts were a waste of everyone's time, and that leads some of the volunteers to withdraw.

Answer 1

[Kye Taylor]

If dx/dt = [0,0,.4,0] for a vector x, then the exact solution is

x(t) = [x0, x1, 0.4*t+x2, x3]

where x0,x1,x2,x3 are initial conditions (position).

Is func really indepenent of t and x(i)?

The issue with your code is that func will return a row vector, but x(:,1) is intialized as a column vector. Then the right-hand-side defining x(:,2) is column vector plus row vector -- this produces an error.

It is because func seemingly returns a row vector, independent of its inputs size or value, that your code is actually working. Perhaps there is more to func?

[Kye Taylor]

You mean U = A\B, not U = A\B'...

Try replacing the x(i) in the for loop with x(i,:)