  We consider the inflation produced by two coupled fluids in the flat
Friedmann-Robertson-Walker universe. Different cosmological models for
describing inflation by use of an inhomogeneous equation of state for the fluid
are investigated. The gravitational equations for energy and matter are solved,
and analytic representations for the Hubble parameter and the energy density
are obtained. Corrections in the energy density for matter inducing the
inflation and the coupling with energy are discussed. We analyze the
description of inflation induced by non-constant equation-of-state parameters
from fluid viscosity. The correspondence between the spectral index and the
tensor-to-scalar ratio recently observed by the Planck satellite is considered.
