**-pc_ksp_true ** -use the matrix that defines the linear system as the matrix for the
inner solver, otherwise by default it uses the matrix used to construct
the preconditioner (see PCSetOperators())

Notes: Using a Krylov method inside another Krylov method can be dangerous (you get divergence or
the incorrect answer) unless you use KSPFGMRES as the other Krylov method

Developer Notes: PCApply_KSP() uses the flag set by PCSetInitialGuessNonzero(), I think this is totally wrong, because it is then not
using this inner KSP as a preconditioner (that is a linear operator applied to some vector), it is actually just using
the inner KSP just like the outer KSP.

### See Also

PCCreate(), PCSetType(), PCType (for list of available types), PC,

PCSHELL, PCCOMPOSITE, PCKSPUseTrue(), PCKSPGetKSP()

**Level:**intermediate

Location:src/ksp/pc/impls/ksp/pcksp.c

Index of all PC routines

Table of Contents for all manual pages

Index of all manual pages