reserve
  x for object, X for set,
  i, n, m for Nat,
  r, s for Real,
  c, c1, c2, d for Complex,
  f, g for complex-valued Function,
  g1 for n-element complex-valued FinSequence,
  f1 for n-element real-valued FinSequence,
  T for non empty TopSpace,
  p for Element of TOP-REAL n;

theorem
  |.<*r*>.| = |.r.|
  proof
    set f = <*r*>;
    sqr f = <*r^2*> by RVSUM_1:55;
    then Sum sqr f = r^2 by RVSUM_1:73;
    hence thesis by COMPLEX1:72;
  end;
