The infinite limit of matrix theory in four and 10 dimensions is descr
ibed in terms of Moyal brackets. In those dimensions there exists a Bo
gomol'nyi bound to the Euclideanized version of these equations, which
guarantees that solutions of the first-order equations also solve the
second-order matrix theory equations. A general construction of such
solutions in terms of a representation of the target space coordinates
as nonlocal spinor bilinears, which are generalisations of the standa
rd Wigner functions on phase space, is given.