Time- and space-efficient evaluation of the complex exponential function   using series expansion
  An algorithm for the evaluation of the complex exponential function is proposed which is quasi-linear in time and linear in space. This algorithm is based on a modified binary splitting method for the hypergeometric series and a modified Karatsuba method for the fast evaluation of the exponential function. The time complexity of this algorithm is equal to that of the ordinary algorithm for the evaluation of the exponential function based on the series expansion: O(M(n)log(n)^2). 
Sergey V. Yakhontov
cs.DS