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
