% cellEdges - Find edges attached to specified cells
% 
% 
% cellEdges(GEOM,REGIONID,FILTERTYPE) finds edges attached to cells with ID 
% numbers listed in REGIONID. Here, GEOM is a 3-D DiscreteGeometry. 
% REGIONID is a single cell ID or a vector of cell IDs.
% FILTERTYPE is the optional argument specifying the type of the returned edges:
% 'internal' - return edges attached only to internal faces. Internal faces 
%     are faces shared between multiple cells.
% 'external' - return edges attached only to external faces. External faces 
%     are faces not shared between multiple cells.
% 'all' - return all edges attached to the specified cells. This is the 
%     default option.
% 
% 
% Example 1: Find all edges of a single-cell geometry
% 
% geom = multicuboid(1,1,1);
% cellEdges(geom,1)
% pdegplot(geom,'CellLabels','on','EdgeLabels','on','FaceAlpha',0.2)
% 
% 
% Example 2: Find external edges attached to cells 1 and 2 of this geometry.
% 
% geom = multicuboid(1,1,[1 1],'Zoffset',[0 1]);
% cellEdges(geom,[1 2],'external')
% pdegplot(geom,'CellLabels','on','EdgeLabels','on','FaceAlpha',0.2)
% 
% 
% Example 3: Find internal edges attached to cells 1 and 2 of this geometry.
% 
% geom = multicuboid(1,1,[1 1],'Zoffset',[0 1]); 
% cellEdges(geom,[1 2],'internal')
% pdegplot(geom,'CellLabels','on','EdgeLabels','on','FaceAlpha',0.2)
%
%
% See also cellFaces, faceEdges, nearestEdge

%  Copyright 2020 The MathWorks, Inc.
%  Built-in function.