  Recently, Popa and Rasa [18,19] have shown the (in)stability of some
classical operators defined on [0,1] and found best constant when the positive
linear operators are stable in the sense of Hyers-Ulam. In this paper we show
Hyers-Ulam (in)stability of complex Bernstein-Schurer operators, complex
Kantrovich-Schurer operators and Lorentz operators on compact disk. In the case
when the operator is stable in the sense of Hyers and Ulam, we find the infimum
of Hyers-Ulam stability constants for respective operators.
