DOLFIN User Manual - FEniCS Project

DOLFIN User ManualHoffman, Jansson, Logg, Wellslinear combinations of basis functions:v =N∑v i φ i , (5.1)i=1where {φ i } N i=1 is the global basis of the finite element space defined by theMesh and the FiniteElement, and the nodal values {v i } N i=1 are given by thevalues of a Vector.Note that a discrete Function may not be evaluated at arbitrary points (onlyat each Vertex of a Mesh).5.2.1 Creating a discrete functionA discrete Function can be initialized in several ways. In the simplest case,only a Vector x of nodal values needs to be specified:Vector x;Function f(x);If possible, DOLFIN will then automatically try to determine the Mesh andthe FiniteElement.In some cases, it is necessary to also supply a Mesh when initializing a discreteFunction:Vector x;Mesh mesh;Function f(x, mesh);If possible, DOLFIN will then automatically try to determine the FiniteElement.37