MATLAB: Do I receive a “cannot use set default dimension function” error when using the Matrix Concatenate block in a subsystem in Simulink 6.5 (R2006b)

simulink

I receive the following error message when using the Matrix Concatenate block:

 cannot use 'set default dimension' function

However, when I move the problematic subsystem out of the larger model into its own standalone model, it works fine.

Best Answer

The reason you receive the error is because one or more of the input signals to the "Matrix Concatenate" block do(es) not have defined dimensions.

To work around this issue, you can explicitly define the dimensions of the signal(s) by using the Signal Specification block in line with the signal(s). For more information on the Signal Specification block, please refer to the documentation for the same, by typing the following on MATLAB command window.

doc signalspecification

Related Solutions

MATLAB: Do I receive an “Error in port widths or dimensions” error when I set default input dimensions in Simulink when the input ports are initialized dynamically

In order to use several ports which inherit their dimensions from the input ports, you can use the SetInpPortDims method as follows
block.RegBlockMethod('SetInputPortDimensions',  @SetInpPortDims); 
function SetInpPortDims(Block, port, dims) 
   Block.InputPort(port).Dimensions = dims;

The attached example illustrates this.

MATLAB: “Cannot find explicit solution”

Sometimes, you have to lead it gently by the hand:

syms x n b r a 
eqn = x*(1+n)==(b/(b+1))*r*(1-a)*x^a ;
eqn = rewrite(eqn,'log');
solx = solve(eqn, x, 'IgnoreAnalyticConstraints',1)
pretty(solx)
solx =
(-((b + 1)*(n + 1))/(b*r*(a - 1)))^(1/(a - 1))
                         1
                       -----
  /   (b + 1) (n + 1) \a - 1
  | - --------------- |
  \     b r (a - 1)   /

Best Answer

Related Solutions

MATLAB: Do I receive an “Error in port widths or dimensions” error when I set default input dimensions in Simulink when the input ports are initialized dynamically

MATLAB: “Cannot find explicit solution”

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