In this paper we shall introduce a simple, effective numerical method for
finding differential operators for scalar and vector-valued functions on
surfaces. The key idea of our algorithm is to develop an intrinsic and unified
way to compute directly the partial derivatives of functions defined on
triangular meshes which are the discretization of regular surfaces under
consideration. Most importantly, the divergence theorem and conservation laws
on triangular meshes are fulfilled.Comment: 18 pages, 9 figure