Hi, thanks for getting back to me.
I think for the project I'm doing converting to the laws that do not support inversion using the basal stress and velocity will do just fine! Thanks for the suggestion.
I do have a question about running inversions for the Weertman friction law, however. I am trying to adapt the tutorial .../examples/Inversion to the three friction laws that support inversion, and Budd and Schoof worked no problem. For the Weertman law, I am getting some weird outputs.
Each iteration of the inversion is of the form
f(x) = 4302.848 | maximum number of nonlinear iterations (100) exceeded
0.003398776 | 2496.586 1806.262 0.0002750466
,
and I can't seem to get rid of the warning "the maximum number of iterations (100) exceeded". My initial synthetic friction field is:
md.friction = frictionweertman();
md.friction.m = (1/3) * ones(md.mesh.numberofelements,1);
md.friction.C = 1e9 * ones(md.mesh.numberofvertices,1);
pos = find(md.mesh.x>400e3 & md.mesh.x<600e3);
md.friction.C(pos) = (1/4) * md.friction.C(pos);
,
which produces a velocity field similar to the original Budd inversion, with a maximum velocity of ~ 213 m/year. The only other changes that I've made are (1) using an initial guess of a uniform friction field of
md.friction.C = 5e8 * ones(md.mesh.numberofvertices,1);
,
and (2) my min and max parameters are
md.inversion.min_parameters = ones(md.mesh.numberofvertices,1);
md.inversion.max_parameters = 1e11 * ones(md.mesh.numberofvertices,1);
.
Other than that, I've kept all of the parameters the same as in the tutorial.
Any help would be appreciated, thanks!
Dylan