Blaschke factorization of a bounded holomorphic function
ID: blaschke-factorization-of-a-bounded-holomorphic-function
Every nonzero bounded holomorphic function on the unit disc has this factorization, with the Blaschke product of its zeros and zero-free and holomorphic. The Blaschke condition follows from Jensen's formula. Dividing by any finite partial zero product gives a holomorphic function; the maximum modulus principle and the finite product's boundary modulus one bound that quotient by . Locally uniform convergence of the partial products gives the same bound for , with removable extensions at their zeros. This factorization alone does not make constant or a full inner-outer factorization.
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