nxn matrix as an input argument in function

function x = matrix(b, L, U)
A= L * U
x= inv(A)*b
end

I am trying to write a function that solves for A an matrix, b a known vector and x an unknown vector. How can I make the above work? In what form am I to input b, L and U into the function arguments?

For

b = $ \begin{pmatrix}a\\ b \\ c \end{pmatrix} $.

L =$ \begin{pmatrix} d & e & f\\ g & h & i \\ j & k & l\end{pmatrix} $

U=$ \begin{pmatrix} m & n & o\\ p & q & r \\ s & t & u\end{pmatrix} $

would my input be like this: matrix([a][b][c], [d,e,f][g,h,i][j,k,l], [m,n,o][p,q,r][s,t,u]) ??

Answer 1

[Adriano Filippo Inno]

I'm a bit confused by your question. Do you need to solve a linear system with the LU method?

If yes, this function will work:

function x = linSys(A, b)

[L,U,P] = lu(A);            % LU decomposition
y = L\(P*b);                
x = U\y;

end

To use it:

A = magic(5);               % define your A here
b = ones(5, 1);             % define your b here

x = linSys(A, b);