  We introduce a two-parameter version of the two-step scale-splitting
iteration method, called TTSCSP, for solving a broad class of complex symmetric
system of linear equations. We present some conditions for the convergence of
the method. An upper bound for the spectral radius of the method is presented
and optimal parameters which minimize this bound are given. Inexact version of
the TTSCSP iteration method (ITTSCSP) is also presented. Some numerical
experiments are reported to verify the effectiveness of the TTSCSP iteration
method and the numerical results are compared with those of the TSCSP, the SCSP
and the PMHSS iteration methods. Numerical comparison of the ITTSCSP method
with the inexact version of TSCSP, SCSP and PMHSS are presented. We also
compare the numerical results of the BiCGSTAB method in conjunction with the
TTSCSP and the ILU preconditioners.
