I am trying to get an interpolation function $f$ (in 3D) at all vertices of cells. I extract all vertices of cells and then I assign the value to each vertex: if it's in a sphere of radius $R$, then I assign the value, say 3.91. If it's outside the sphere, then I assign the value 0. I got it running without the error message, but then when I calculated the function value at points that are not vertices, it does not give me either 3.91 or 0. Am I doing something wrong here?Here is a part of my code:Extract vertices of all cells, then I export these points and use another software to       assign value for each point (say 3.91 for points inside sphere, 0 for points outside)coor = mesh.coordinates()numpy.savetxt('meshforE.txt',coor)I get the values at all vertices and then interpolate this to function fqvalues2 = numpy.loadtxt('qdata.txt')V = FunctionSpace(mesh, CG, 1)f = Function(V)f.vector()[:] = qvalues2then I read points (xp, yp) on $z=0$ plane and evaluate the funtion at these pointswith open('xpdata.txt') as g:    xp = g.readlines()print xp[1]=, xp[1]with open('ypdata.txt') as h:    yp = h.readlines()print yp[2]=, yp[2]for i in range(len(xp)):    g_in[i] = f(xp[i],yp[i],0.0)Now when I plot $g_i$ , it does not look like what it should be, i.e. constant (3.91) inside the circle $R=50$, and 0 outside.Any help would be appreciated.
FEniCS : How to interpolate data at vertices of (3D) cells?
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