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CliMA / ClimateMachine.jl

Climate Machine: an Earth System Model that automatically learns from data
https://clima.github.io/ClimateMachine.jl/latest/
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1D GMRES #513

Closed jkozdon closed 4 years ago

jkozdon commented 4 years ago

This has been brought up on slack, but figured an issue would be good so all are aware of the issues.

I was mistaken in PR #499 for the behavior of 1D IMEX with GMRES. Currently the GMRES solver with block diagonal systems does not actually do GMRES on each column but instead does global GMRES with a single norm and upper Hessenberg matrix.

To extend the GMRES solver to per-column behavior we need to:

simonbyrne commented 4 years ago

On the last point: is there a danger if we do keep iterating GMRES after it has converged? Is there a risk it might start to diverge?

jkozdon commented 4 years ago

Its possible to get NaNs with some iterative solvers, not sure about GMRES