I have what I thought was a pretty simple model that intentionally includes algebraic loops which I wanted to use to explore how Simulink deals with circular dependencies. But, Simulink 2011a can't seem to solve it and I'm not sure why or what to do to fix the problem. Here's what the model looks like in Simulink (mdl file link here): 
The model is supposed to represent two poles (physical, rigid objects), each of which have one of their ends pinned to the X axis, and their other ends are pinned together. The components to the left of the XY Graph represent the behavior of the left pole. It accepts the X coordinate of its end not pinned to the X axis and computes the Y coordinate of that end based on the X coordinate of the end pinned to the X axis (-3 in this case) and the length of the pole (5 in this case). The components to the right of the XY Graph represent the behavior of the right pole. It accepts the Y coordinate of its non-X-axis end and computes the X coordinate of that end, which is fed back into the input of the left pole. Here's what the situation looks like physically -- black indicates given information and green is what Simulink should compute as the unique solution:
So, I expect the XY Graph to display a point at (0,4) which is time-invariant. Instead, I get this error message:
I'm new to Simulink and don't know how to go about resolving that error. What step size? There seem to be multiple step parameters, but all of them that I see seem to be related to time rather than algebraic loops, and almost all are set at 'auto' -- how can I figure out what a reasonable order of magnitude would be? Likewise, where can I set the error tolerance?
