The purpose of this paper is to study the differentiability properties of e
quilibrium prices and allocations in a linear exchange economy when the ini
tial endowments and utility vectors vary. We characterize an open dense sub
set of full measure of the initial endowment and utility vector space on wh
ich the equilibrium price vector is a real analytic function, hence infinit
ely differentiable function. We provide an explicit formula to compute the
equilibrium price and allocation around a point where it is known. We also
show that the equilibrium price is a locally Lipschitzian mapping on the wh
ole space. Finally, using the notion of the Clarke generalized gradient, we
prove that linear exchange economies satisfy a property of gross substitut
ion.