# KSPCheckNorm#

Checks if the result of a norm used by the corresponding KSP contains inf or NaN. These indicate that the previous application of the preconditioner generated an error. Sets a KSPConvergedReason and returns if the PC set a PCFailedReason. Collective

## Input Parameter#

• ksp - the linear solver KSP context.

## Output Parameter#

• beta - the result of the norm

## Developer Notes#

Used to manage returning from KSP solvers whose preconditioners have failed, possibly only a subset of MPI ranks, in some way.

It uses the fact that KSP piggy-backs the collectivity of certain error conditions on the results of norms and inner products.

PCFailedReason, KSPConvergedReason, PCGetFailedReasonRank(), KSP, KSPCreate(), KSPSetType(), KSP, KSPCheckDot(), KSPCheckSolve()