Dear Walker,
I do not understand what you mean by " I get the identically zero
solution". Do you mean that D is zero ?
But if D is zero, then there is no chance that
"gf_compute(mfu,D,’interpolate on’,nodes);" to give other
result than zero.
May be if you attach the simplest program you can that does not work, it
could help.
Yves.
Le 08/02/2017 à 20:51, Walker, Ryan T. (GSFC-615.0)[UNIV OF MARYLAND] a
écrit :
> Hi all,
>
> I’m working on plate bending (i.e., bilaplacian) for a problem where I
> have observed data for the stiffness D.
>
> I’m setting D using gf_mesh_fem_get to evaluate the Matlab
> interpolation function interp2 on the lagrangian mesh.
> This produces an identically zero solution, as if D = 0 everywhere.
> However, when I use gf_compute to evaluate D on the solution nodes, I
> get the values I was expecting from the interpolation.
>
> The simplest thing I can do to get this problem is modifying
> demo_bilaplacian.m to include this:
>
> % create “data” on coarse grid
> [xx,yy] = meshgrid(0:0.1:0.4,0:0.1:1.2);
> foo = 1 + xx.^2 + yy.^2;
> % trying to interpolate onto the lagrangian mesh mfd
> getD = @(x,y,z) interp2(xx,yy,foo,x,y);
> D = gf_mesh_fem_get(mfd,'eval',{getD});
> gf_model_set(md, 'add initialized fem data', 'D', mfd, [D]);
>
> When I do this, I get the identically zero solution. But if I then do
> nodes = gf_mesh_get(mfu,’pts’);
> D_pts = gf_compute(mfu,D,’interpolate on’,nodes);
> I get the values of D I was expecting.
>
> If I use the same formula for D directly without interpolating like this:
> getD = @(x,y,z) 1 + x.^2 + y.^2;
> D = gf_mesh_fem_get(mfd,'eval',{getD});
> gf_model_set(md, 'add initialized fem data', 'D', mfd, [D]);
> I get the right solution (and the right values of D on the solution
> nodes).
>
> What am I doing wrong here?
>
> Thanks,
> Ryan
>
>
>
> **********************************************
> Dr. Ryan T. Walker
> Earth System Science Interdisciplinary Center
> University of Maryland at College Park
> Cryospheric Sciences Laboratory, Code 615
> NASA Goddard Space Flight Center
> 8800 Greenbelt Road
> Greenbelt, MD 20771 USA
>
>
>
>
>
>
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--
Yves Renard ([email protected]) tel : (33) 04.72.43.87.08
Pole de Mathematiques, INSA-Lyon fax : (33) 04.72.43.85.29
20, rue Albert Einstein
69621 Villeurbanne Cedex, FRANCE
http://math.univ-lyon1.fr/~renard
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