How to get rid of the error: Error using horzcat. Dimensions of matrices being concatenated are not consistent.

Hi When i solve a second order differential equation with constant coefficients, i obtained a solution. But when i change these coefficients by the matrix form i have obtained this error: Error using horzcat. Dimensions of matrices being concatenated are not consistent. And my new code is a function : function xdot = equadif(t,x) % Function file for mass with spring and damping. % Position is first variable, velocity is second variable. F=[12;23:0]; M=[1,0,0;1,3,0;0,0,2]; cp = 1.38*10^-9; K = [5,-6,1;-6,2,20;4,2,5]; TETA = [1,1,0;2,0,0;1,0,0]; C =[2,10,0;5,4,0;1,5,0]; R = 10*10^3; A = [zeros(3,3), eye(3,3), zeros(3,1); -K*M^-1, -C*M^-1, TETA*M^-1; zeros(3,3), TETA/cp, -1/(R*cp)]; B = [0; M^-1 ; 0]; xdot = A*x+B*F; end

[t,x]=ode45(@equadif,[0,0.01,0.03],[0,1,0]); plot(t,x(:,1),'b',t,x(:,2),'r',t,x(:,3),'--')

Please help me

[Roger Stafford]

See my answer in Answers #277760.