How to increase the size of "s" using pdegeom?

I have written a pdegeom file which produce a sinusoidal edge. The standard amount of grid points (size(s)) is set to 50. This is not enough to reproduce approx. 50 periods of the sinus correctly.

The pdegeom file (you can check it with pdegplot('Geom') to see that the sinus is not correctly plotted):

function [ x,y ] = Geom(bs,s)

    nbs = 10;

    if nargin==0
      x=nbs;
      return
    end

    dl=[ 0  1  2  3  4  5  6  7  8   9;
         1  2  3  4  5  6  7  8  9  10;
         0  0  0  0  0  0  0  0  1   1; 
         1  1  1  1  2  2  2  1  2   2];

    if nargin==1
      x=dl(:,bs);
      return
    end

    x=zeros(size(s));
    y=zeros(size(s));
    [m,n]=size(bs);
    if m==1 && n==1,
      bs=bs*ones(size(s)); % expand bs
    elseif m~=size(s,1) || n~=size(s,2),
      error(message('pde:cardg:SizeBs'));
    end

    nn=size(bs,1)*size(bs,2);
    if nn==0
        x=[];
        y=[];
        return
    end

    for ibs=1:nn 
        switch bs(ibs)
        case 1 % Boundary-Tip down right
            xx=50 - (50-10)*s(ibs);
            yy=-50 +0*s(ibs);
        case 2 % Tip side right
            xx=10 - (10-5)*(s(ibs)-1);
            yy=-50*(1-(s(ibs)-1));
        case 3 % Tip apex half
            xx=5*cos(pi/2*(s(ibs)-2));
            yy=5*sin(pi/2*(s(ibs)-2));
        case 4 % Tip to resist
            xx=0*(s(ibs)-3);
            yy=5 + ((20-12)-5)*(s(ibs)-3);
        case 5 % resist to sample
            xx=0*(s(ibs)-4);
            yy=(20-12) + (12)*(s(ibs)-4);
        case 6 % Sample
            xx=50*(s(ibs)-5);
            yy=20 + 0*(s(ibs)-5);
        case 7 % Boundary right - Resist
            xx=50 + 0*(s(ibs)-6);
            yy=20 - (12)*(s(ibs)-6);
        case 8 % Boundary right
            xx=50 + 0*(s(ibs)-7);
            yy=(20-12) - ((20-12)-(-50))*(s(ibs)-7);
        case 9 % Layer right - Tip side
            xx=30*(s(ibs)-8);
            yy=(20-12)+3*sin(2*pi/1*xx);
        case 10
            xx=30-(30-50)*(s(ibs)-9);
            yy=20-12+0*(s(ibs)-9);
        end
    x(ibs)=xx;
    y(ibs)=yy;
    end
    end

Answer 1

[Bill Greene]

If your concern is about producing a nice looking plot from pdegplot, you will need to edit that function by changing the line:

n=50;

at around line 46 to make n something larger.

If your concern is about getting a sufficiently fine mesh near the sinusoid edge, you don't need to do anything but specify a sufficiently small value of hmax in the call to initmesh. initmesh will call your Geom function as often as needed to produce a mesh with an accurate boundary.

[Steve]

Thank you very much.

I tried to reduce hmax before and it seems to refine only the geometry produced by pdegplot. However now it works fine!