106 lines
3.4 KiB
Matlab
106 lines
3.4 KiB
Matlab
% Square:
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% flatpak run org.octave.Octave <filename>
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% or
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% octave --no-window-system --no-gui -qf <filename>
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clear all
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clc
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% %% L-shape
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% g=[2 0 2 0 0 1 0; % #vertices,v_1x, v_2x, v_1y, v_2y, subdomain_left, subdomain_right
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% 2 2 2 0 1 1 0;
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% 2 2 1 1 0.5 1 0;
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% 2 1 1 0.5 2 1 0;
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% 2 1 0 2 2 1 0;
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% 2 0 0 2 0 1 0]';
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%% square
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% g=[2 0 1 0 0 1 0; % #vertices,v_1x, v_2x, v_1y, v_2y, subdomain_left, subdomain_right
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% 2 1 1 0 1 1 0;
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% 2 1 0 1 1 1 0;
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% 2 0 0 1 0 1 0]';
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% %% 2 squares
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% g=[2 0 1 0 0 1 0; % 1 #vertices,v_1x, v_2x, v_1y, v_2y, subdomain_left, subdomain_right
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% 2 1 1 0 1 1 2;
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% 2 1 0 1 1 1 0;
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% 2 0 0 1 0 1 0;
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% 2 1 2 0 0 2 0; % 2 #vertices,v_1x, v_2x, v_1y, v_2y, subdomain_left, subdomain_right
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% 2 2 2 0 1 2 0;
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% 2 2 1 1 1 2 0
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% ]';
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%% 4 squares
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g=[2 0 1 0 0 1 0; % 1 #vertices,v_1x, v_2x, v_1y, v_2y, subdomain_left, subdomain_right
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2 1 1 0 1 1 2;
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2 1 0 1 1 1 3;
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2 0 0 1 0 1 0;
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2 1 2 0 0 2 0; % 2 #vertices,v_1x, v_2x, v_1y, v_2y, subdomain_left, subdomain_right
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2 2 2 0 1 2 0;
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2 2 1 1 1 2 4;
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% 2 1 1 1 0 2 1;
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% 2 0 1 1 1 3 1; % 3 #vertices,v_1x, v_2x, v_1y, v_2y, subdomain_left, subdomain_right
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2 1 1 1 2 3 4;
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2 1 0 2 2 3 0;
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2 0 0 2 1 3 0;
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% 2 1 2 1 1 4 2; % 4 #vertices,v_1x, v_2x, v_1y, v_2y, subdomain_left, subdomain_right
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2 2 2 1 2 4 0;
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2 2 1 2 2 4 0
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% 2 1 1 2 1 4 3
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]';
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%% Generate mesh from geometry
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%
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[p,e,t] = initmesh(g,'hmax',1); % works correctly
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% p(1,15) = 1.51; %% angle in trangle > pi/2 ==> now the second refinement produces irregular meshes!
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% p(1,15) = 1.7; %% angle in trangle > pi/2 ==> now the second refinement produces irregular meshes!
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% ??
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% https://de.mathworks.com/help/pde/ug/mesh-data-pet-triples.html
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% generateMesh(...)
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% mesh2Pet(...)
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%
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% [p,e,t] = initmesh(g); % problems in solution after 2 refinements
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% [p,e,t] = initmesh(g,'hmax',0.5); % problems in solution after 2 refinements (peaks with h=0.5, oscillations in (1,1) for h=0.1
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% [p,e,t] = initmesh(g,'hmax',0.1/4); % no problems in solution with 0 refinemnet steps
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%% Show mesh
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pdemesh(p,e,t)
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% pdemesh(p,e,t,'NodeLabels','on')
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%% Improve mesh
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% min(pdetriq(p,t))
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% p = jigglemesh(p,e,t,'opt','minimum','iter',inf);
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% min(pdetriq(p,t))
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% pdemesh(p,e,t)
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%% Refine mesh, see comments in "Generate mesh from geometry"
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%
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% nrefine=8;
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nrefine=2; %
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for k=1:nrefine
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[p,e,t] = refinemesh(g,p,e,t);
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% p = jigglemesh(p,e,t,'opt','minimum','iter',inf); % improve mesh
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min(pdetriq(p,t))
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fprintf('refinement: %i nodes: %i triangles: %i \n', k, size(p,2), size(t,2))
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end
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% figure; pdemesh(p,e,t,'NodeLabels','on')
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%
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%% GH
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% output from <https://de.mathworks.com/help/pde/ug/initmesh.html initmesh>
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%
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% coordinates p: [2][nnode]
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% connectivity t: [4][nelem] with t(4,:) are the subdomain numbers
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% edges e: [7][nedges] boundary edges
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% e([1,2],:) - start/end vertex of edge
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% e([3,4],:) - start/end values
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% e(5,:) - segment number
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% e([6,7],:) - left/right subdomain
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ascii_write_mesh( p, t, e, mfilename);
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ascii_write_subdomains( p, t, e, mfilename);
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% tmp=t(1:3,:)
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