Abstract: | It is shown that for A?(??) functions f1 and f2 with and f1 being positive on real zeros of f2 then there exists A?(??) functions g2 and g1, g1–1 with and This result is connected to the computation of the stable rank of the algebra A?(??) and to Control Theory (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) |