thank you . but the matrix element has been changed in the third and fourth call. how to re calculate the preconditioner.
在 2013-08-24 18:18:17，"Matthew Knepley" <[email protected]> 写道： On Sat, Aug 24, 2013 at 4:57 AM, 丁老师 <[email protected]> wrote: in my code, i need to use kspsolve in the following way KSP ksp; KSPCreate(PETSC_COMM_WORLD,&ksp); KSPSetOperators(ksp,A,A,SAME_NONZERO_PATTERN); KSPSetOperators(ksp,A,A,SAME_PRECONDITIONER); KSPSetInitialGuessNonzero(ksp,PETSC_TRUE) KSPSetType(ksp,KSPBCGS); KSPSetFromOptions(ksp); set the matrix A value and right hand side bu and bv. kspsolve(A,bu); kspsolve(A,bv); change the value of matrix A and bu bv, kspsolve(A,bu); kspsolve(A,bv); the first and second call to the kspsolve use the same preconditioner. but which preconditoner does the third and fourth call to the kspsolve since the value of the matrix A has changed. The first call is redundant, and the subsequent solves use the same preconditioner, as you asked. Matt -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener
