KSP_DIVERGED_INDEFINITE_PC — PETSc 3.25.1 documentation

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# KSP_DIVERGED_INDEFINITE_PC

It appears the preconditioner is indefinite (has both positive and negative eigenvalues) and this Krylov method (`KSPCG`) requires it to be symmetric positive definite (SPD).

## Note

This can happen with the `PCICC` preconditioner, use the options database option `-pc_factor_shift_positive_definite` to force the `PCICC` preconditioner to generate a positive definite preconditioner

## See Also

KSP: Linear System Solvers, `KSPSolve()`, `KSPGetConvergedReason()`, `KSPConvergedReason`, `KSPSetTolerances()`

## Level

beginner

## Location

include/petscksp.h

## Examples

src/ksp/pc/tutorials/ex1.c
src/ksp/pc/tutorials/ex2.c

Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages