Boundary correlations for the Z-invariant Ising Model

Consider the natural graph associated to a rhombus tiling of a polygonal regionin the plane. The spin correlations between boundary vertices of this graph inthe Z-invariant Ising model do not depend on the choice of the rhombus tilingbut only on the region. We provide a matrix formula depending on the regionwhich allows practical computations of boundary correlations in this setting,extending the results of Galashin in the critical case.