We study extension of -trigonometric functions and to complex domain. For , the function satisfies the initial value problem which is equivalent to (*)
in . In our recent paper, Girg, Kotrla (2014), we showed that is a real analytic function for on , where . This allows us to extend to complex domain by its Maclaurin series convergent on the disc . The question is whether this extensions satisfies (*) in the sense of differential equations in complex domain. This interesting...