task8

ex3/seq/generate_mesh/save_mesh2_mini.m

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+function save_mesh2_mini( xc, ia, e, basename)
+% Save the 3D triangular mesh in the minimal way (only coordinates and vertex connectivity)
+% in binary file.
+% The indexing in the connectivity is changed to C-style (starts with 0)
+%
+% coordinates  xc: [2][nnode]
+% connectivity ia: [4][nelem]   with  t(4,:) are the subdomain numbers
+% edges         e: [7][nedges]  boundary edges
+%                              e([1,2],:) - start/end vertex of edge
+%                              e([3,4],:) - start/end values
+%                              e(5,:)     - segment number
+%                              e([6,7],:) - left/right subdomain
+%        basename: file name without extension
+% data from
+% output from <https://de.mathworks.com/help/pde/ug/initmesh.html initmesh>
+%
+fname = [basename, '.bin'];
+offset = 1;         % index difference from C to Matlab
+
+nnode = size(xc,2);
+ndim  = size(xc,1);
+nelem = size(ia,2);
+nvert_e = 3;
+
+fileID = fopen(fname,'w');
+fwrite(fileID, nnode, 'int');          % number of nodes
+fwrite(fileID, ndim,  'int');          % space dimension
+fwrite(fileID, nelem, 'int');          % number of elements
+fwrite(fileID, nvert_e, 'int');        % number of vertices per element
+
+fwrite(fileID, xc(:), 'double');       % coordinates
+tmp=ia(1:3,:)-offset;
+fwrite(fileID, tmp(:), 'double');      % connectivity
+
+end