This error happens when you try to concatenate arrays that can't be concatenated. For instance, trying to vertically concatenate arrays with different numbers of columns, or trying to horizontally concatenate arrays with different numbers of rows.
x = [1 2 3];
y = [4 5 6];
% vertically concatenate x and y -> works
% because x and y have the same number of columns
z = [x; y]
x = [1 2 3];
y = [4 5 6; ...
7 8 9];
% vertically concatenate x and y -> works
% because x and y have the same number of columns
z = [x; y]
x = [1 2 3];
y = [4 5 6 7];
% vertically concatenate x and y -> does not work
% because x and y do not have the same number of columns
z = [x; y]
For more specific help, please post the relevant code.
