LTI block in simulink with State Space eq's from matlab

I'm trying to use the LTI block in simulink to get the results (and plot them) from a state space representation, but don't know how.

I'm thinking staggered grid by the way, and it's all about flow through a 1D pipe.

This is my setup:

 x = [x1, x2, ... , xN-1, xN, y1, y2, ... , yN-1, yN]'

 A = 2N-by-2N matrix determined by two discretized PDE's

 B = 2N-by-2 matrix (yes 2N-by-2)

 u = [y_in, x_out]' (known boundary conditions)

 C = eye(2*N)

 D = 0

 x_dot = Ax+Bu

I'm supposed to use the LTI block to solve this, but I can't seem to get it to work.

I'm using the u as input to the block, to get the y_in.

I've tried to use the sys = ss(A,B,C,D) but I'm getting problems with the dimensions.

How do I put this into the LTI block and get the correct response?

[Ryan G]

The LTI block expects an LTI object. If you have issues with dimensions in your state space matrices, then you cannot create a state space LTI object. You need to figure out what's missing in your state space model.