2021-02-15 11:32:40 +0200 answered a question edge_list not working with IndexFaceSet Thanks a lot for the answer. I also found that IndexFaceSet allows to set enclosed=True so that implicit_plot3d also does. In this way, the sequence: pl = implicit_plot3d(x**2 + y**2 + z**2 - 1, (x, -1, 1), (y, -1, 1), (z, -1, 1), enclosed=True, plot_points=10) pl.triangulate() pl.edge_list()  is also working. Thanks again, Asier 2021-02-12 10:15:55 +0200 received badge ● Student (source) 2021-02-12 10:07:46 +0200 asked a question Problem with edge_list() with IndexFaceSet Consider the following example: pl=implicit_plot3d((lambda x,y,z: x^2+y^2+z^2-1),(x,-1,1),(y,-1,1),(z,-1,1), plot_points=[10,10,10]) pl.triangulate() Then, pl.vertex_list() and pl.index_faces() are ok. BUT, pl.edge_list() produces an error. Some help please, 2021-02-12 10:07:46 +0200 asked a question edge_list not working with IndexFaceSet Considering for example, pl=implicit_plot3d((lambda x,y,z: x^2+y^2+z^2-1), (x,-1,1),(y,-1,1),(z,-1,1), plot_points=[10,10,10]) pl.triangulate()  Then, pl.vertex_list() returns the vertex list and pl.index_faces() also works perfectly and returns the triangular faces. However, pl.edge_list() gives the following error: --------------------------------------------------------------------------- TypeError Traceback (most recent call last) in ----> 1 st.edge_list() .. site-packages/sage/plot/plot3d/index_face_set.pyx in sage.plot.plot3d.index_face_set.IndexFaceSet.edge_list (build/cythonized/sage/plot/plot3d/index_face_set.c:9602)() 745 ((1.0, -2.0, 3.0), (1.0, 2.0, 3.0)) 746 """ --> 747 return list(self.edges()) 748 749 def vertices(self): .. /site-packages/sage/plot/plot3d/index_face_set.pyx in sage.plot.plot3d.index_face_set.IndexFaceSet.edges (build/cythonized/sage/plot/plot3d/index_face_set.c:9522)() 732 ((1.0, -2.0, 3.0), (1.0, 2.0, 3.0)) 733 """ --> 734 return EdgeIter(self) 735 736 def edge_list(self): ... site-packages/sage/plot/plot3d/index_face_set.pyx in sage.plot.plot3d.index_face_set.EdgeIter.__init__ (build/cythonized/sage/plot/plot3d/index_face_set.c:21418)() 1735 self.set = face_set 1736 if not self.set.enclosed: -> 1737 raise TypeError("Must be closed to use the simple iterator.") 1738 self.i = 0 1739 self.j = 0 TypeError: Must be closed to use the simple iterator.