Start your M$-$file by defining the variable A to hold the matrix

$A=\left[\begin{array}{ccc}1& 5& 1\\ -2& 1& 0\\ 3& 2& -5\end{array}\right]$

Variables: A

Add the command

$[$ LLA $,UA]=1u(A)$;

Variables: LA$,$ UA

Execute the M$-$file and examine the contents of the matrices LA and UA$.$ Observe that UA is upper triangular.

Q$1$: Is LA lower triangular? Why?

Hint: Type doc lu and look at the difference between the commands

$[L,U,P]=lu(A)$