  We derive from first principles (without resorting to the replica trick) a
density functional theory for fluids in quenched disordered matrices (QA-DFT).
We show that the disorder-averaged free energy of the fluid is a functional of
the average density profile of the fluid as well as the pair correlation of the
fluid and matrix particles. For practical reasons it is preferable to use
another functional: the disorder-averaged free energy plus the fluid-matrix
interaction energy, which, for fixed fluid-matrix interaction potential, is a
functional only of the average density profile of the fluid. When the matrix is
created as a quenched configuration of another fluid, the functional can be
regarded as depending on the density profile of the matrix fluid as well. In
this situation, the replica-Ornstein-Zernike equations which do not contain the
blocking parts of the correlations can be obtained as functional identities in
this formalism, provided the second derivative of this functional is
interpreted as the connected part of the direct correlation function. The
blocking correlations are totally absent from QA-DFT, but nevertheless the
thermodynamics can be entirely obtained from the functional. We apply the
formalism to obtain the exact functional for an ideal fluid in an arbitrary
matrix, and discuss possible approximations for non-ideal fluids.
