void setCompositePC(Type* A, PC pc) {
PetscInt nsplits;
KSP* subksp;
PCFieldSplitGetSubKSP(pc, &nsplits, &subksp);
if(A->_S.size() == 1)
KSPSetOperators(subksp[nsplits - 1], A->_S[0], A->_S[0]);
else {
PC pcS;
KSPGetPC(subksp[nsplits - 1], &pcS);
for(int i = 0; i < A->_S.size(); ++i)
PCCompositeAddPC(pcS, PCNONE);
PCSetUp(pcS);
for(int i = 0; i < A->_S.size(); ++i) {
PC subpc;
PCCompositeGetPC(pcS, i, &subpc);
PCSetOperators(subpc, A->_S[i], A->_S[i]);
PCSetFromOptions(subpc);
}
}
PetscFree(subksp);
}
int main(int argc, char **argv)
{
PetscErrorCode ierr;
PetscInt n=10000,its,dfid=1;
Vec x,b,u;
Mat A;
KSP ksp;
PC pc,pcnoise;
PCNoise_Ctx ctx={0,NULL};
PetscReal eta=0.1,norm;
PetscScalar(*diagfunc)(PetscInt,PetscInt);
ierr = PetscInitialize(&argc,&argv,(char*)0,help);CHKERRQ(ierr);
/* Process command line options */
ierr = PetscOptionsGetInt(NULL,"-n",&n,NULL);CHKERRQ(ierr);
ierr = PetscOptionsGetReal(NULL,"-eta",&eta,NULL);CHKERRQ(ierr);
ierr = PetscOptionsGetInt(NULL,"-diagfunc",&dfid,NULL);CHKERRQ(ierr);
switch(dfid){
case 1:
diagfunc = diagFunc1;
break;
case 2:
diagfunc = diagFunc2;
break;
case 3:
diagfunc = diagFunc3;
break;
default:
SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Unrecognized diagfunc option");
}
/* Create a diagonal matrix with a given distribution of diagonal elements */
ierr = MatCreate(PETSC_COMM_WORLD,&A);CHKERRQ(ierr);
ierr = MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);CHKERRQ(ierr);
ierr = MatSetFromOptions(A);CHKERRQ(ierr);
ierr = MatSetUp(A);CHKERRQ(ierr);
ierr = AssembleDiagonalMatrix(A,diagfunc);CHKERRQ(ierr);
/* Allocate vectors and manufacture an exact solution and rhs */
ierr = MatCreateVecs(A,&x,NULL);CHKERRQ(ierr);
ierr = PetscObjectSetName((PetscObject)x,"Computed Solution");CHKERRQ(ierr);
ierr = MatCreateVecs(A,&b,NULL);CHKERRQ(ierr);
ierr = PetscObjectSetName((PetscObject)b,"RHS");CHKERRQ(ierr);
ierr = MatCreateVecs(A,&u,NULL);CHKERRQ(ierr);
ierr = PetscObjectSetName((PetscObject)u,"Reference Solution");CHKERRQ(ierr);
ierr = VecSet(u,1.0);CHKERRQ(ierr);
ierr = MatMult(A,u,b);CHKERRQ(ierr);
/* Create a KSP object */
ierr = KSPCreate(PETSC_COMM_WORLD,&ksp);CHKERRQ(ierr);
ierr = KSPSetOperators(ksp,A,A);CHKERRQ(ierr);
/* Set up a composite preconditioner */
ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);
ierr = PCSetType(pc,PCCOMPOSITE);CHKERRQ(ierr); /* default composite with single Identity PC */
ierr = PCCompositeSetType(pc,PC_COMPOSITE_ADDITIVE);CHKERRQ(ierr);
ierr = PCCompositeAddPC(pc,PCNONE);CHKERRQ(ierr);
if(eta > 0){
ierr = PCCompositeAddPC(pc,PCSHELL);CHKERRQ(ierr);
ierr = PCCompositeGetPC(pc,1,&pcnoise);CHKERRQ(ierr);
ctx.eta = eta;
ierr = PCShellSetContext(pcnoise,&ctx);CHKERRQ(ierr);
ierr = PCShellSetApply(pcnoise,PCApply_Noise);CHKERRQ(ierr);
ierr = PCShellSetSetUp(pcnoise,PCSetup_Noise);CHKERRQ(ierr);
ierr = PCShellSetDestroy(pcnoise,PCDestroy_Noise);CHKERRQ(ierr);
ierr = PCShellSetName(pcnoise,"Noise PC");CHKERRQ(ierr);
}
/* Set KSP from options (this can override the PC just defined) */
ierr = KSPSetFromOptions(ksp);CHKERRQ(ierr);
/* Solve */
ierr = KSPSolve(ksp,b,x);CHKERRQ(ierr);
/* Compute error */
ierr = VecAXPY(x,-1.0,u);CHKERRQ(ierr);
ierr = PetscObjectSetName((PetscObject)x,"Error");CHKERRQ(ierr);
ierr = VecNorm(x,NORM_2,&norm);CHKERRQ(ierr);
ierr = KSPGetIterationNumber(ksp,&its);CHKERRQ(ierr);
ierr = PetscPrintf(PETSC_COMM_WORLD,"Norm of error %g, Iterations %D\n",(double)norm,its);CHKERRQ(ierr);
/* Destroy objects and finalize */
ierr = KSPDestroy(&ksp);CHKERRQ(ierr);
ierr = MatDestroy(&A);CHKERRQ(ierr);
ierr = VecDestroy(&x);CHKERRQ(ierr);
ierr = VecDestroy(&b);CHKERRQ(ierr);
ierr = VecDestroy(&u);CHKERRQ(ierr);
PetscFinalize();
return 0;
}
void PETSC_STDCALL pccompositegetpc_(PC pc,PetscInt *n,PC *subpc, int *__ierr ){
*__ierr = PCCompositeGetPC(
(PC)PetscToPointer((pc) ),*n,subpc);
}
