[petsc-users] SVD residual estimates with SLEPc

[Miguel Fosas]

Hi everyone,

I am using SLEPc to compute singular values from a shell matrix A (whose
matrix-vector product is very costly to evaluate). After the singular
value's are computed, I would like to obtain the error. For this purpose,
SLEPc provides the function SVDComputeResidualNorms. However, this function
needs to apply twice the operator A, which makes the calculation almost as
twice as long (for my case).

I know that the estimates that are printed by the monitors
(-svd_monitor_all) are pretty good. Is there a way to retrieve the value of
such estimates from the internal structures of SLEPc?

Thanks,

Miguel
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