Porblem with ode 45 solver

hi I am trying to solve nonlinear state space int the form

xdot= Ax+R(x,u)
y= S(x,u)
i have written a function given below

   function xdot = system(t,x,u)
    Tab=sqrt(2/3)*[cos(x(1)) cos(x(1)-2*pi/3) cos(x(1)+2*pi/3)
    -sin(x(1)) -sin(x(1)-2*pi/3) -sin(x(1)+2*pi/3)
    1/sqrt(2) 1/sqrt(2) 1/sqrt(2)]

    wc=2*pi*50;
    L=1.35e-3;
    R=.056;
    C=50e-6;
    Rc=.131;
    Lc=0.96e-3;
    P=10e3;
    Q=5e3;
    KpllI=5000;
    KpPPL=2.1;
    Kid2=460;
    Kpd2=1;
    Kiq2=460;
    Kpq2=1;

    udq= Tab*u;

    A=[0 KpllI 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
    0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
    0 0 -sqrt(2)*wc 0 wc*wc 0 0 0 0 0 0 0 0 0 0 0 0
    0 0 0 -sqrt(2)*wc 0 wc*wc 0 0 0 0 0 0 0 0 0 0 0
    0 0 -1 0 0 0 0 0 1 0 0 0 0 0 -1 0 0
    0 0 0 -1 0 0 0 0 0 1 0 0 0 0 0 -1 0
    0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0 0 0
    0 0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0 0
    0 0 0 0 0 0 0 0 -R/L 0 0 -1/L 0 0 0 0 0
    0 0 0 0 0 0 0 0 0 -R/L 0 0 -1/L 0 0 0 0
    0 0 0 0 0 0 0 0 0 0 -R/L 0 0 -1/L 0 0 0
    0 0 0 0 0 0 0 0 1/C 0 0 0 0 0 -1/C 0 0
    0 0 0 0 0 0 0 0 0 1/C 0 0 0 0 0 -1/C 0
    0 0 0 0 0 0 0 0 0 0 1/C 0 0 0 0 0 -1/C
    0 0 0 0 0 0 0 0 0 0 0 1/Lc 0 0 -Rc/Lc 0 0
    0 0 0 0 0 0 0 0 0 0 0 0 1/Lc 0 0 -Rc/Lc 0 
    0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -Rc/Lc];

    w= KpllI*x(2)+KpPPL*udq(2);
    vld=Kid2*x(7)+Kpd2*(x(3)-x(9))+udq(1)-w*L*x(10);

    vlq=Kiq2*x(8)+Kpq2*(x(4)-x(10))+udq(2)-w*L*x(9);
    ;

R=[KpPPL*udq(2) % u(2)= voq
udq(2)
0
0
(udq(1)*P-udq(2)*Q)/((udq(2).^2)+(udq(1).^2))
(udq(1)*P+udq(2)*Q)/((udq(2).^2)+(udq(1).^2))
0
0
(vld*1/L)+w*x(10)
(vlq*1/L)-w*x(9)
0
w*x(13)
-w*x(12)
0
(-udq(1)*1/Lc)+w*x(16)
(-udq(2)*1/Lc)+w*x(15)
0];
xdot=A*x+R;
and the main file with 

t=0:100e-5:5;
wc=50;
u= [240*sqrt(2)*sin(wc*t+pi/2)
240*sqrt(2)*sin(wc*t-2*pi/3+pi/2)
240*sqrt(2)*sin(wc*t+2*pi/3+pi/2)];
x0=zeros(17,1);
odeOptions = odeset('RelTol',1e-6);
[t,y]      = ode45(@system,t,x0,odeOptions,u);
Tab=sqrt(2/3)*[cos(y(:,1)) cos(y(:,1)-2*pi/3) cos(y(:,1)+2*pi/3)
-sin(y(:,1)) -sin(y(:,1)-2*pi/3) -sin(y(:,1)+2*pi/3)
1/sqrt(2) 1/sqrt(2) 1/sqrt(2)];
udq= Tab*u;
The problem i am facing is that multiplication in the last line of code is giving error while in function file it gives no error but do not save the result. Kindly any body suggest me what i am doing wrong. Thanks

Answer 1

[Torsten]

y(:,1), y(:,2) and y(:,3) are vectors of length numel(t).

So your matrix Tab is no longer 3x3.

Best wishes

Torsten.

[imran]

so then what do you suggest i have to use a for loop to compute Tab at each time step using a for loop or is there any other way around this problem?

[Torsten]

so then what do you suggest i have to use a for loop to compute Tab at each time step using a for loop

That's exactly what I suggest you should do.

Best wishes

Torsten.