FGMRES refinement for Primal Dual System #773
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This PR implements the flexible generalized minimal residual method for refinement of the solution of the primal-dual system.
The main changes/additions in this PR are:
ComputeResidualRatio
method is modified to now compute the Infinity norm-wise relative backward error, which is used in the stopping criterion for FGMRES and iterative refinement.PDFullSpaceSolver::NrmInf
to compute the Inf-norm of the primal-dual system, which is used to compute the relative backward error.ComputeRowA1
andComputeColA1
inIpMatrix
to compute the 1-norm of the rows/columns in the matrix. This is implemented in the derived classes.PDFullSpaceSolver::ComputeResiduals
to use thealpha
andbeta
parameters so it can be used to compute a matrix vector product (or the residual).Our tests show improvements in convergence when using FGMRES compared to iterative refinement, for select problems, with minimal runtime overhead.
@bknueven @k1nshuk