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Topic: pdenonlin "Stepsize too small"
Replies: 2   Last Post: Jul 9, 2013 10:18 AM

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Steven Finch

Posts: 9
Registered: 7/17/08
pdenonlin "Stepsize too small"
Posted: Jul 8, 2013 10:47 AM
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Please download two files ellipseb2.m & ellipseg.m from

and execute the following code:



axis equal tight;

format long

tArea = pdetrg(p,t);
surfaceArea = sqrt(1 + ux.^2 + uy.^2)*tArea';

tArea = pdetrg(p,t);
surfaceArea = sqrt(1 + ux.^2 + uy.^2)*tArea';

Everything works fine up to this point. The graph shows the minimal surface spanning a folded circular loop (with sharp corners at two boundary points). A good numerical estimate 2.48201... is found (the true value is 2.48228...). If, however, we attempt to improve upon the estimate via


then the following message appears:

??? Error using ==> pdenonlin at 251
Stepsize too small.

Does anyone have suggestions for how to avoid this problem? Thank you,

Steve Finch

P.S. The two files were created using the command:


then specifying u = abs(y) using the Boundary Mode menu, and finally using the commands:

fid = wgeom(g, 'ellipseg');
fid = wbound(b, 'ellipseb2');

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