  In this paper, we generalize the exponential energy-preserving integrator
proposed in the recent paper [SIAM J. Sci. Comput. 38(2016) A1876-A1895] for
conservative systems, which now becomes linearly implicit by further utilizing
the idea of the scalar auxiliary variable approach. Comparing with the original
exponential energy-preserving integrator which usually leads to a nonlinear
algebraic system, our new method only involve a linear system with constant
coefficient matrix. Taking the nonlinear Klein-Gordon equation for example, we
derive the concrete energy-preserving scheme and demonstrate its high
efficiency through numerical experiments.
