Revisiting multifractal analysis

New proofs of theorems on the multifractal formalism are given. They yield results even at points q for which Olsen's functions b(q) and B(q) differ. Indeed, we provide an example of measure for which functions b and B differ and for which the Hausdorff dimension of the level sets of the local Holder exponent are given by the Legendre transform of b and their packing dimension by the Legendre transform of B.