[petsc-users] Regarding the conjugate gradient method

[Matt Baker]

Hello,


just a quick question:

The CG method is generally derived for spd matrices. However, the PETSc man page states


Notes: The PCG method requires both the matrix and preconditioner to be symmetric positive (or negative) (semi) definite Only left preconditioning is supported.


Does this mean CG works for semi-definite problems as well? Is that guaranteed then?


Thanks.
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