A = Matrix.New({{1,2,3},
                {2,3,5},
                {3,5,1}})
val, fun = Eigensystem(A)
print("The eigenvalues are\n",val)
print("The eigenfunctions are\n",fun)
print("The matrix transformed to a diagonal matrix by its eigenfunctions is\n",Chop( Matrix.Conjugate(fun) * A * Matrix.Transpose(fun)) )