Mixture as its melting point, may differ from those of the components. Some mixtures can be separated into their components by using physical (mechanical or thermal) means. Azeotropes are one kind of mixture that usually pose considerable difficulties regarding the separation processes required to obtain their constituents (physical or chemical processes or, even a blend of them). Mixtures can be either homogeneous or heterogeneous. A homogeneous mixture is a type of mixture in which the composition is uniform and every part of the solution has the same properties. Examples of homogeneous mixtures include alloys and alcohol in water. A heterogeneous mixture
Phase-type distribution (the non-homogeneous case). The mixture of two Erlang distribution with parameter "E"(3,β), "E"(3,β) and (α,α) (such that α + α = 1 and for each "i", α ≥ 0) can be represented as a phase type distribution with and The Coxian distribution is a generalisation of the hypoexponential distribution. Instead of only being able to enter the absorbing state from state "k" it can be reached from any phase. The phase-type representation is given by, and where 0 < "p"...,"p" ≤ 1. In the case where all "p" = 1 we have the hypoexponential distribution. The Coxian distribution is extremely