Preconditioned Implicit-Exponential (IMEXP) Time Integrators for Stiff   Differential Equations
  We propose two new classes of time integrators for stiff DEs: the implicit-explicit exponential (IMEXP) and the hybrid exponential methods. In contrast to the existing exponential schemes, the new methods offer significant computational advantages when used with preconditioners. Any preconditioner can be used with any of these new schemes. This leads to a broader applicability of exponential methods. The proof of stability and convergence of these integrators and numerical demonstration of their efficiency are presented. 
Vu Thai Luan, Mayya Tokman, Greg Rainwater
math.NA