Can I manipulate boundery conditions in the pdetoolbox

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Florian Baumgartner 2015-7-7

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/228941-can-i-manipulate-boundery-conditions-in-the-pdetoolbox

Hello, let´s say I specify with the pdetoolbox an elliptic (skalar) partial differential equation with only Dirichlet boundery conditions on a rectangle and plot it. 3 of the boundery conditions are h=1 and r=0 but the 4th is h=1 and r=5. If i save it i get following code created by the toolbox.

if true
  % code function pdemodel 
[pde_fig,ax]=pdeinit; 
pdetool('appl_cb',1); 
set(ax,'DataAspectRatio',[1 1 1]); 
set(ax,'PlotBoxAspectRatio',[1.5 1 1]); 
set(ax,'XLim',[-1.5 1.5]); 
set(ax,'YLim',[-1 1]); 
set(ax,'XTickMode','auto'); 
set(ax,'YTickMode','auto'); 
pdetool('gridon','on'); 
%
% Geometry description: 
pderect([0 1 0.40000000000000002 0],'R1'); 
set(findobj(get(pde_fig,'Children'),'Tag','PDEEval'),'String','R1') 
%
% Boundary conditions: 
pdetool('changemode',0) 
pdesetbd(4,... 
'dir',... 
1,... 
'1',... 
'0') 
pdesetbd(3,... 
'dir',... 
1,... 
'1',... 
'5')         % <---------  hier manipulieren !!
pdesetbd(2,... 
'dir',... 
1,... 
'1',... 
'0') 
pdesetbd(1,... 
'dir',... 
1,... 
'1',... 
'0') 
%
% Mesh generation: 
setappdata(pde_fig,'Hgrad',1.3); 
setappdata(pde_fig,'refinemethod','regular'); 
setappdata(pde_fig,'jiggle',char('on','mean','')); 
setappdata(pde_fig,'MesherVersion','preR2013a'); 
pdetool('initmesh') 
%
% PDE coefficients: 
pdeseteq(1,... 
'1.0',... 
'0.0',... 
'10.0',... 
'1.0',... 
'0:10',... 
'0.0',... 
'0.0',... 
'[0 100]') 
setappdata(pde_fig,'currparam',... 
['1.0 ';... 
'0.0 ';... 
'10.0';... 
'1.0 ']) 
%
% Solve parameters: 
setappdata(pde_fig,'solveparam',... 
char('0','1000','10','pdeadworst',... 
'0.5','longest','0','1E-4','','fixed','Inf')) 
%
% Plotflags and user data strings: 
setappdata(pde_fig,'plotflags',[1 1 1 1 1 1 1 1 1 1 0 1 1 0 1 0 0 1]); 
setappdata(pde_fig,'colstring',''); 
setappdata(pde_fig,'arrowstring',''); 
setappdata(pde_fig,'deformstring',''); 
setappdata(pde_fig,'heightstring',''); 
%
% Solve PDE: 
pdetool('solve')
end

Can I manipulate the code at "pdesetbd(3,'dir',1,'1','5')" where the arrow in the code is? For example can I include in the boundary condition a variable. Let´s say I want to include a variable called "Factor_1", where Factor_1 = 5 for example. In the code it would look like this now.

if true
%
% same code as in the top example
%
  pdesetbd(3,... 
'dir',... 
1,... 
'1',... 
'5*Factor_1') 
%
% same code as in the top example
%
end

Now the pdetoolbox should read the code, where the one boundary condition is now h=1 and r=5*Factor_1=25. I tried a few ways but it didn´t work. Is there even a way to do that?