Define the ODE equals the matrix. Runge Kutta 4

I have velocity vector in matrix form [ 1, 2, 3,4 ];

Velocity is dx/dt 1) first matlab function f = func(t,x)

 f= [1,2,3,4]

2) Second matlab

dt=0.001;

t=[0:dt:20];

xinital= [ 0 0 -2 0.4]

use the Runge Kutta to estimate the final x

for i = 1: 20/dt

    k1 = dt*func(t(i),x(i)); 

    k2 = dt*func(t(i)+dt/2,x(i)+dt*k1/2);

    k3 = dt*func(t(i)+dt/2,x(i)+dt*k2/2);

    k4 = dt*func(t(i)+dt,x(i)+dt*k3);

    x(2,:) =xintial(1,:) + (k1 + 2*k2 + 2*k3 + k4)/6;

end

I keep getting error message dimension mismatch on xinitial.

Please help

Answer 1

[Babak]

Change

xinital= [ 0 0 -2 0.4]

to

xinital= [ 0 0 -2 0.4]'

or

xinital= [ 0;0;-2;0.4]