  Field equations with time and coordinates derivatives of noninteger order are
derived from stationary action principle for the cases of power-law memory
function and long-range interaction in systems. The method is applied to obtain
a fractional generalization of the Ginzburg-Landau and nonlinear Schrodinger
equations. As another example, dynamical equations for particles chain with
power-law interaction and memory are considered in the continuous limit. The
obtained fractional equations can be applied to complex media with/without
random parameters or processes.
