I understand that you are trying to solve a system of linear equations for every angle using the backslash operator. I am assuming that the unknowns are velocity, acceleration and force in the three dimensions for each angle.
A possibly better approach in this case is to first use three dimensional arrays A, B and X to store the values. Then, solve (A_theta)*(X_theta)=B_theta, where A_theta=9x9, X_theta=9x1 and B_theta=9x1, for every angle theta using a 'for' loop.
Using this approach the unknown vector x can be determined for each angle. For example, take a simple case (for three values of theta) of A(2x2x3), B(2x1x3) and X(2x1x3), the for loop would look like,
>> for ind = 1:3
x(:,:,ind) = A(:,:,ind)\B(:,:,ind);
end
In your specific case, the matrices can have dimensions of A(9x9x361), B(9x1x361) and x(9x1x361). Using a for loop simplifies indexing of values in your case.
However, if you are trying to do something else, provide more details about the modeling approach and the physical interpretation of A, B and X.
