mike - the error message is telling you that you are making an invalid assignment. For example, the following produces the same error
a = zeros(5,1);
a(:,1) = [1:4]';
because we are trying to assign a column of four elements to a column that is expecting five elements.
Which line of code is generating your error? How have you initialized a, b, and c? Try using the debugger to step through your code and make sure that the assignments that you are attempting make sense given the initialization of the variables.
