Numerical integration Legendre Polynomials MATLAB -

the legendre polynomials implemented in matlab vectors, associated legendre polynomials evaluated @ particular point x. thus, don't know how can use these functions inside integral. question is:

how can evaluate (numerically calcualted(!)) integral -1 1 on n-th legendre polynomial in matlab?

edit: received answer not want: want use implementation of legendre polynomials in matlab cause other suggestions may highly unstable.

n=3 % degree of legendre polynomial step=0.1 % integration step trapz(legendre(n,-1:step:1)')*step 

this should want