Runge Kutta 4th order, Error: Subscripted assignment dimension mismatch

Hi I'm getting a Subscripted assignment dimension mismatch error when I'm running a Runge Kutta code. I have created this code:

%Define function handles
%y=[y1,y2,y3,y4]<= y(1,:),y(2:), y(3,:), y(4:) 
f=@(t,y) [...
    +0.95*y(1)*(1-(y(1)/3.44));
    ((18.73*y(1)*y(4))/(37.5+y(4)))-(0.9*1.2*y(2))
     1.2*y(2);
    -((18.73*y(1)*y(4))/(37.5+y(4)))];

% Initial conditions
t(1)=0;
y(:,1)=[0.5,0,0,50];

%Step size
h=0.1;
tfinal=10;
N=tfinal/h;

%Update loop
for i=1:N
    %Update time
    t(i+1)=t(i)+h;
    %Update for y
    k1 = f(t(i)      ,y(:,i)         );
    k2 = f(t(i)+0.5*h,y(:,i)+0.5*k1*h) ;
    k3 = f(t(i)+0.5*h,y(:,i)+0.5*k2*h) ;
    k4 = f(t(i)+h    ,y(:,i)+    k3*h) ;
    y(:,i+1)=y(:,i)+1/6*(k1+2*k2+2*k3+k4)*h ;
end

When I run the code i get this error:

>> rk4_systems Subscripted assignment dimension mismatch.

Error in rk4_systems (line 11) y(:,1)=[0.5,0,0,50];

Can someone help me please.

DB

Answer 1

[Kuifeng]

 %y(:,1) is the first column, and 
%[0.5,0,0,50] is a row vector. 
consider y(:,1)=[0.5,0,0,50]';

[Dianna B]

Thanks you for your help :) the code was successfully executed.