Hi Leandro,
As per my understanding the error is caused since you are passing symbolic variables to the "mat2str" and the "num2str" functions. These functions are updated and they take only numeric values as input. The following change in your code gives the correct output.
disp(['X(transposed)=',mat2str(double(X)),' Error=',num2str(double(e)),' iteration=',num2str(it)]);
The "double" function ensures that the symbolic variables are converted to corresponding double values leading to error free execution of the code.
I hope this helps!
Thank you.