Dear Sir or Madam,
Recently, our research group try to use the PCfieldsplit method in Petsc to construct the preconditioner for the linear equation system. For example, if we have following system, K11, K12, K13 u1 f1 K21, K22, K23 u2 = f2 (1) K31, K32, K33 u3 f3 we construct the preconditioner as follows: K11, K12, K13 0, K22, K23 0, 0, K33. We also can reorder the system (1): K22, K21, K23 u2 f2 K12, K11, K13 u1 = f1 (2) K32, K31, K33 u3 f3 with the preconditioner K22, K21, K23 0, K11, K13 0, 0, K33 We use the same solver for Eq.(1) and Eq. (2) with corresponding preconditioner. The question is: is solving the Eq. (1) equivalent to solving Eq. (2) in Petsc? From our results, it seems not. Thank you so much. Best, Guoyi Note: This e-mail may contain PRIVILEGED and CONFIDENTIAL information intended only for the use of the specific individual or entity named above. If you or your employer is not the intended recipient of this e-mail or an employee or agent responsible for delivering it to the intended recipient, you are hereby notified that any unauthorized dissemination or copying of this e-mail is strictly prohibited. If you have received this transmission in error, please immediately delete the message.
