Three-dimensional systems posessing a homoclinic orbit associated to a
saddle focus with eigenvalues rho +/- iomega, -lambda and giving rise
to homoclinic chaos when the Shil'nikov condition rho < lambda is sat
isfied are studied. The 2D Poincare map and its 1D contractions captur
ing the essential features of the flow are given. At homoclinicity, th
ese 1D maps are found to be piecewise linear. This property allows one
to reduce the Frobenius-Perron equation to a master equation whose so
lution is analytically known. The probabilistic properties such as the
time autocorrelation function of the state variable x are explicitly
derived.