petsc-3.14.5 2021-03-03
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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 positive definite

### Notes

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

### See Also

KSPSolve(), KSPGetConvergedReason(), KSPConvergedReason, KSPSetTolerances()

### Level

beginner

### Location

src/ksp/ksp/guess/../../../../include/petscksp.h

### Examples

src/ksp/pc/tutorials/ex1.c.html
src/ksp/pc/tutorials/ex2.c.html
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages