int main(int argc,char **args)
{
Vec x, b, u; /* approx solution, RHS, exact solution */
Mat A; /* linear system matrix */
KSP ksp; /* linear solver context */
PC pc; /* preconditioner context */
PetscReal norm; /* norm of solution error */
PetscErrorCode ierr;
PetscInt i,n = 10,col[3],its,rstart,rend,nlocal;
PetscScalar neg_one = -1.0,one = 1.0,value[3];
PetscBool TEST_PROCEDURAL=PETSC_FALSE;
PetscInitialize(&argc,&args,(char*)0,help);
ierr = PetscOptionsGetInt(NULL,"-n",&n,NULL);CHKERRQ(ierr);
ierr = PetscOptionsGetBool(NULL,"-procedural",&TEST_PROCEDURAL,NULL);CHKERRQ(ierr);
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Compute the matrix and right-hand-side vector that define
the linear system, Ax = b.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/*
Create vectors. Note that we form 1 vector from scratch and
then duplicate as needed. For this simple case let PETSc decide how
many elements of the vector are stored on each processor. The second
argument to VecSetSizes() below causes PETSc to decide.
*/
ierr = VecCreate(PETSC_COMM_WORLD,&x);CHKERRQ(ierr);
ierr = VecSetSizes(x,PETSC_DECIDE,n);CHKERRQ(ierr);
ierr = VecSetFromOptions(x);CHKERRQ(ierr);
ierr = VecDuplicate(x,&b);CHKERRQ(ierr);
ierr = VecDuplicate(x,&u);CHKERRQ(ierr);
/* Identify the starting and ending mesh points on each
processor for the interior part of the mesh. We let PETSc decide
above. */
ierr = VecGetOwnershipRange(x,&rstart,&rend);CHKERRQ(ierr);
ierr = VecGetLocalSize(x,&nlocal);CHKERRQ(ierr);
/* Create a tridiagonal matrix. See ../tutorials/ex23.c */
ierr = MatCreate(PETSC_COMM_WORLD,&A);CHKERRQ(ierr);
ierr = MatSetSizes(A,nlocal,nlocal,n,n);CHKERRQ(ierr);
ierr = MatSetFromOptions(A);CHKERRQ(ierr);
ierr = MatSetUp(A);CHKERRQ(ierr);
/* Assemble matrix */
if (!rstart) {
rstart = 1;
i = 0; col[0] = 0; col[1] = 1; value[0] = 2.0; value[1] = -1.0;
ierr = MatSetValues(A,1,&i,2,col,value,INSERT_VALUES);CHKERRQ(ierr);
}
if (rend == n) {
rend = n-1;
i = n-1; col[0] = n-2; col[1] = n-1; value[0] = -1.0; value[1] = 2.0;
ierr = MatSetValues(A,1,&i,2,col,value,INSERT_VALUES);CHKERRQ(ierr);
}
/* Set entries corresponding to the mesh interior */
value[0] = -1.0; value[1] = 2.0; value[2] = -1.0;
for (i=rstart; i<rend; i++) {
col[0] = i-1; col[1] = i; col[2] = i+1;
ierr = MatSetValues(A,1,&i,3,col,value,INSERT_VALUES);CHKERRQ(ierr);
}
ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
/* Set exact solution; then compute right-hand-side vector. */
ierr = VecSet(u,one);CHKERRQ(ierr);
ierr = MatMult(A,u,b);CHKERRQ(ierr);
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Create the linear solver and set various options
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
ierr = KSPCreate(PETSC_COMM_WORLD,&ksp);CHKERRQ(ierr);
ierr = KSPSetOperators(ksp,A,A);CHKERRQ(ierr);
/*
Set linear solver defaults for this problem (optional).
- By extracting the KSP and PC contexts from the KSP context,
we can then directly call any KSP and PC routines to set
various options.
- The following statements are optional; all of these
parameters could alternatively be specified at runtime via
KSPSetFromOptions();
*/
if (TEST_PROCEDURAL) {
/* Example of runtime options: '-pc_redundant_number 3 -redundant_ksp_type gmres -redundant_pc_type bjacobi' */
PetscMPIInt size,rank,subsize;
Mat A_redundant;
KSP innerksp;
PC innerpc;
MPI_Comm subcomm;
ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);
ierr = PCSetType(pc,PCREDUNDANT);CHKERRQ(ierr);
ierr = MPI_Comm_size(PETSC_COMM_WORLD,&size);CHKERRQ(ierr);
ierr = MPI_Comm_rank(PETSC_COMM_WORLD,&rank);CHKERRQ(ierr);
if (size < 3) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ, "Num of processes %d must greater than 2",size);
ierr = PCRedundantSetNumber(pc,size-2);CHKERRQ(ierr);
ierr = KSPSetFromOptions(ksp);CHKERRQ(ierr);
/* Get subcommunicator and redundant matrix */
ierr = KSPSetUp(ksp);CHKERRQ(ierr);
ierr = PCRedundantGetKSP(pc,&innerksp);CHKERRQ(ierr);
ierr = KSPGetPC(innerksp,&innerpc);CHKERRQ(ierr);
ierr = PCGetOperators(innerpc,NULL,&A_redundant);CHKERRQ(ierr);
ierr = PetscObjectGetComm((PetscObject)A_redundant,&subcomm);CHKERRQ(ierr);
ierr = MPI_Comm_size(subcomm,&subsize);CHKERRQ(ierr);
if (subsize==1 && !rank) {
printf("A_redundant:\n");
ierr = MatView(A_redundant,PETSC_VIEWER_STDOUT_SELF);CHKERRQ(ierr);
}
} else {
ierr = KSPSetFromOptions(ksp);CHKERRQ(ierr);
}
/* Solve linear system */
ierr = KSPSolve(ksp,b,x);CHKERRQ(ierr);
/* Check the error */
ierr = VecAXPY(x,neg_one,u);CHKERRQ(ierr);
ierr = VecNorm(x,NORM_2,&norm);CHKERRQ(ierr);
ierr = KSPGetIterationNumber(ksp,&its);CHKERRQ(ierr);
if (norm > 1.e-14) {
ierr = PetscPrintf(PETSC_COMM_WORLD,"Norm of error %g, Iterations %D\n",(double)norm,its);CHKERRQ(ierr);
}
/* Free work space. */
ierr = VecDestroy(&x);CHKERRQ(ierr); ierr = VecDestroy(&u);CHKERRQ(ierr);
ierr = VecDestroy(&b);CHKERRQ(ierr); ierr = MatDestroy(&A);CHKERRQ(ierr);
ierr = KSPDestroy(&ksp);CHKERRQ(ierr);
ierr = PetscFinalize();
return 0;
}
void PETSC_STDCALL pcredundantsetnumber_(PC pc,PetscInt *nredundant, int *__ierr ){
*__ierr = PCRedundantSetNumber(
(PC)PetscToPointer((pc) ),*nredundant);
}
