GetMesh.m

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function Mesh=GetMesh(cFileName)
% function Mesh=GetMesh(cFileName)
% Initialization of the Mesh structure from a FreeFEM++ mesh file 
% - Basic version
%
% Parameters:
%  cFileName: FreeFEM++ mesh file name (string)
%
% Return values:
%  Mesh: mesh structure
%
% Generated fields of Mesh:
%  q: Array of vertices coordinates, `2\times\nq` array. <br/>
%  `{\q}(\il,j)` is the
%  `\il`-th coordinate of the `j`-th vertex, `\il\in\{1,2\}` and
%  `j\in\ENS{1}{\nq}`
%  me: Connectivity array, `3\times\nme` array. <br/>
%  `\me(\jl,k)` is the storage index of the
%  `\jl`-th  vertex of the `k`-th triangle in the array `\q` of vertices coordinates, `\jl\in\{1,2,3\}` and
%       `k\in{\ENS{1}{\nme}}`.
%  ql: Array of vertices labels, `1\times\nq` array.
%  mel: Array of elements labels, `1\times\nme` array.
%  be: Connectivity array for boundary edges, `2\times\nbe` array.<br/>
% `\be(\il,l)` is the storage index of the
%  `\il`-th  vertex of the `l`-th edge in the array `\q` of vertices coordinates, `\il\in\{1,2\}` and
%       `l\in{\ENS{1}{\nbe}}`.
%  bel: Array of boundary edges labels, `1\times\nbe` array.
%  nq: total number of vertices, also denoted by `\nq`.
%  nme: total number of elements, also denoted by `\nme`.
%  nbe: total number of boundary edges, also denoted by `\nbe`.
%  areas: Array of areas, `1\times\nme` array. areas(k) is the area of the `k`-th triangle.
%  lbe: Array of edges lengths,  `1\times\nbe` array. `lbe(j)`  is the length of the `j`-th edge.
%
% Example:
%  @verbatim 
%    Th=GetMesh('carre.msh')
%  @endverbatim
%
% OptFEM2DP1 [V1.2b1] -    Copyright (C) 2013  CJS (LAGA)
%
%   This file is part of OptFEM2DP1.
%   OptFEM2DP1 is free software: you can redistribute it and/or modify
%   it under the terms of the GNU General Public License as published by
%   the Free Software Foundation, either version 3 of the License, or
%   (at your option) any later version.
%
%   OptFEM2DP1 is distributed in the hope that it will be useful,
%   but WITHOUT ANY WARRANTY; without even the implied warranty of
%   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%   GNU General Public License for more details.
%
%   You should have received a copy of the GNU General Public License
%   along with this program.  If not, see <http://www.gnu.org/licenses/>.
[fid,message]=fopen(cFileName,'r');
if ( fid == -1 )
  error([message,' : ',cFileName]);
end
n=fscanf(fid,'%d',3); ; % n(1) -> number of vertices    
                      % n(2) -> number of triangles     
                      % n(3) -> number of boundary edges
me=zeros(3,n(2));
ql=zeros(1,n(1));
q=zeros(2,n(1));
mel=zeros(1,n(2));
for i=1:n(1)
  d_tmp=fscanf(fid,'%g',2);
  q(1,i)=d_tmp(1);
  q(2,i)=d_tmp(2);
  ql(i)=fscanf(fid,'%d',1);
end
for i=1:n(2)
  i_tmp=fscanf(fid,'%d',4);
  me(1,i)=i_tmp(1);
  me(2,i)=i_tmp(2);
  me(3,i)=i_tmp(3);
  mel(i)=i_tmp(4);
end

for i=1:n(3)
  i_tmp=fscanf(fid,'%d',3);
  be(1,i)=i_tmp(1);
  be(2,i)=i_tmp(2);
  bel(i) =i_tmp(3);
end

fclose(fid);

Mesh=struct('q',q,'me',me,'ql',ql,'mel',mel,'be',be,'bel',bel, ...
            'nq',size(q,2), ...
            'nme',size(me,2), ...
            'nbe',size(be,2), ...
            'areas',ComputeArea(q,me),...
            'lbe',EdgeLength(be,q));