Operators and Matrices · Volume 14, Issue 4 On a functional calculus for unitary operators in Pontryagin spaces 14-61 Pages 971-999 DOI 10.7153/oam-2020-14-61 Downloads Short PDF Full PDF PNG Authors Vladimir Strauss Keywords Pontryagin spaces unitary operators function model weakly closed operator algebra Hardy class Subject classes 46C20 47B50 47A60 47L75