/*@
KSPSetDM - Sets the DM that may be used by some preconditioners
Logically Collective on KSP
Input Parameters:
+ ksp - the preconditioner context
- dm - the dm, cannot be NULL
Notes: If this is used then the KSP will attempt to use the DM to create the matrix and use the routine
set with DMKSPSetComputeOperators(). Use KSPSetDMActive(ksp,PETSC_FALSE) to instead use the matrix
you've provided with KSPSetOperators().
Level: intermediate
.seealso: KSPGetDM(), KSPSetDMActive(), KSPSetComputeOperators(), KSPSetComputeRHS(), KSPSetComputeInitialGuess(), DMKSPSetComputeOperators(), DMKSPSetComputeRHS(), DMKSPSetComputeInitialGuess()
@*/
PetscErrorCode KSPSetDM(KSP ksp,DM dm)
{
PetscErrorCode ierr;
PC pc;
PetscFunctionBegin;
PetscValidHeaderSpecific(ksp,KSP_CLASSID,1);
PetscValidHeaderSpecific(dm,DM_CLASSID,2);
ierr = PetscObjectReference((PetscObject)dm);
CHKERRQ(ierr);
if (ksp->dm) { /* Move the DMSNES context over to the new DM unless the new DM already has one */
if (ksp->dm->dmksp && !dm->dmksp) {
DMKSP kdm;
ierr = DMCopyDMKSP(ksp->dm,dm);
CHKERRQ(ierr);
ierr = DMGetDMKSP(ksp->dm,&kdm);
CHKERRQ(ierr);
if (kdm->originaldm == ksp->dm) kdm->originaldm = dm; /* Grant write privileges to the replacement DM */
}
ierr = DMDestroy(&ksp->dm);
CHKERRQ(ierr);
}
ksp->dm = dm;
ksp->dmAuto = PETSC_FALSE;
ierr = KSPGetPC(ksp,&pc);
CHKERRQ(ierr);
ierr = PCSetDM(pc,dm);
CHKERRQ(ierr);
ksp->dmActive = PETSC_TRUE;
PetscFunctionReturn(0);
}
PetscErrorCode PCSetUp_Exotic(PC pc)
{
PetscErrorCode ierr;
Mat A;
PC_MG *mg = (PC_MG*)pc->data;
PC_Exotic *ex = (PC_Exotic*) mg->innerctx;
MatReuse reuse = (ex->P) ? MAT_REUSE_MATRIX : MAT_INITIAL_MATRIX;
PetscFunctionBegin;
if (!pc->dm) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"Need to call PCSetDM() before using this PC");
ierr = PCGetOperators(pc,NULL,&A);
CHKERRQ(ierr);
if (ex->type == PC_EXOTIC_FACE) {
ierr = DMDAGetFaceInterpolation(pc->dm,ex,A,reuse,&ex->P);
CHKERRQ(ierr);
} else if (ex->type == PC_EXOTIC_WIREBASKET) {
ierr = DMDAGetWireBasketInterpolation(pc->dm,ex,A,reuse,&ex->P);
CHKERRQ(ierr);
} else SETERRQ1(PetscObjectComm((PetscObject)pc),PETSC_ERR_PLIB,"Unknown exotic coarse space %d",ex->type);
ierr = PCMGSetInterpolation(pc,1,ex->P);
CHKERRQ(ierr);
/* if PC has attached DM we must remove it or the PCMG will use it to compute incorrect sized vectors and interpolations */
ierr = PCSetDM(pc,NULL);
CHKERRQ(ierr);
ierr = PCSetUp_MG(pc);
CHKERRQ(ierr);
PetscFunctionReturn(0);
}
int main(int argc,char **argv)
{
PetscErrorCode ierr;
KSP ksp;
PC pc;
Vec x,b;
DM da;
Mat A;
PetscInt dof=1;
PetscBool flg;
PetscScalar zero=0.0;
PetscInitialize(&argc,&argv,(char *)0,help);
ierr = PetscOptionsGetInt(PETSC_NULL,"-dof",&dof,PETSC_NULL);CHKERRQ(ierr);
ierr = DMDACreate(PETSC_COMM_WORLD,&da);CHKERRQ(ierr);
ierr = DMDASetDim(da,3);CHKERRQ(ierr);
ierr = DMDASetBoundaryType(da,DMDA_BOUNDARY_NONE,DMDA_BOUNDARY_NONE,DMDA_BOUNDARY_NONE);CHKERRQ(ierr);
ierr = DMDASetStencilType(da,DMDA_STENCIL_STAR);CHKERRQ(ierr);
ierr = DMDASetSizes(da,3,3,3);CHKERRQ(ierr);
ierr = DMDASetNumProcs(da,PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE);CHKERRQ(ierr);
ierr = DMDASetDof(da,dof);CHKERRQ(ierr);
ierr = DMDASetStencilWidth(da,1);CHKERRQ(ierr);
ierr = DMDASetOwnershipRanges(da,PETSC_NULL,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
ierr = DMSetFromOptions(da);CHKERRQ(ierr);
ierr = DMSetUp(da);CHKERRQ(ierr);
ierr = DMCreateGlobalVector(da,&x);CHKERRQ(ierr);
ierr = DMCreateGlobalVector(da,&b);CHKERRQ(ierr);
ierr = DMCreateMatrix(da,MATAIJ,&A);CHKERRQ(ierr);
ierr = VecSet(b,zero);CHKERRQ(ierr);
/* Test sbaij matrix */
flg = PETSC_FALSE;
ierr = PetscOptionsGetBool(PETSC_NULL,"-test_sbaij",&flg,PETSC_NULL);CHKERRQ(ierr);
if (flg) {
Mat sA;
ierr = MatSetOption(A,MAT_SYMMETRIC,PETSC_TRUE);CHKERRQ(ierr);
ierr = MatConvert(A,MATSBAIJ,MAT_INITIAL_MATRIX,&sA);CHKERRQ(ierr);
ierr = MatDestroy(&A);CHKERRQ(ierr);
A = sA;
}
ierr = KSPCreate(PETSC_COMM_WORLD,&ksp);CHKERRQ(ierr);
ierr = KSPSetFromOptions(ksp);CHKERRQ(ierr);
ierr = KSPSetOperators(ksp,A,A,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);
ierr = PCSetDM(pc,(DM)da);CHKERRQ(ierr);
ierr = KSPSolve(ksp,b,x);CHKERRQ(ierr);
/* check final residual */
flg = PETSC_FALSE;
ierr = PetscOptionsGetBool(PETSC_NULL, "-check_final_residual", &flg,PETSC_NULL);CHKERRQ(ierr);
if (flg){
Vec b1;
PetscReal norm;
ierr = KSPGetSolution(ksp,&x);CHKERRQ(ierr);
ierr = VecDuplicate(b,&b1);CHKERRQ(ierr);
ierr = MatMult(A,x,b1);CHKERRQ(ierr);
ierr = VecAXPY(b1,-1.0,b);CHKERRQ(ierr);
ierr = VecNorm(b1,NORM_2,&norm);CHKERRQ(ierr);
ierr = PetscPrintf(PETSC_COMM_WORLD,"Final residual %g\n",norm);CHKERRQ(ierr);
ierr = VecDestroy(&b1);CHKERRQ(ierr);
}
ierr = KSPDestroy(&ksp);CHKERRQ(ierr);
ierr = VecDestroy(&x);CHKERRQ(ierr);
ierr = VecDestroy(&b);CHKERRQ(ierr);
ierr = MatDestroy(&A);CHKERRQ(ierr);
ierr = DMDestroy(&da);CHKERRQ(ierr);
ierr = PetscFinalize();
return 0;
}
int main(int argc,char **argv)
{
PetscErrorCode ierr;
KSP ksp;
PC pc;
Vec x,b;
DM da;
Mat A,Atrans;
PetscInt dof=1,M=8;
PetscBool flg,trans=PETSC_FALSE;
ierr = PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
ierr = PetscOptionsGetInt(NULL,NULL,"-dof",&dof,NULL);CHKERRQ(ierr);
ierr = PetscOptionsGetInt(NULL,NULL,"-M",&M,NULL);CHKERRQ(ierr);
ierr = PetscOptionsGetBool(NULL,NULL,"-trans",&trans,NULL);CHKERRQ(ierr);
ierr = DMDACreate(PETSC_COMM_WORLD,&da);CHKERRQ(ierr);
ierr = DMSetDimension(da,3);CHKERRQ(ierr);
ierr = DMDASetBoundaryType(da,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE);CHKERRQ(ierr);
ierr = DMDASetStencilType(da,DMDA_STENCIL_STAR);CHKERRQ(ierr);
ierr = DMDASetSizes(da,M,M,M);CHKERRQ(ierr);
ierr = DMDASetNumProcs(da,PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE);CHKERRQ(ierr);
ierr = DMDASetDof(da,dof);CHKERRQ(ierr);
ierr = DMDASetStencilWidth(da,1);CHKERRQ(ierr);
ierr = DMDASetOwnershipRanges(da,NULL,NULL,NULL);CHKERRQ(ierr);
ierr = DMSetFromOptions(da);CHKERRQ(ierr);
ierr = DMSetUp(da);CHKERRQ(ierr);
ierr = DMCreateGlobalVector(da,&x);CHKERRQ(ierr);
ierr = DMCreateGlobalVector(da,&b);CHKERRQ(ierr);
ierr = ComputeRHS(da,b);CHKERRQ(ierr);
ierr = DMSetMatType(da,MATBAIJ);CHKERRQ(ierr);
ierr = DMSetFromOptions(da);CHKERRQ(ierr);
ierr = DMCreateMatrix(da,&A);CHKERRQ(ierr);
ierr = ComputeMatrix(da,A);CHKERRQ(ierr);
/* A is non-symmetric. Make A = 0.5*(A + Atrans) symmetric for testing icc and cholesky */
ierr = MatTranspose(A,MAT_INITIAL_MATRIX,&Atrans);CHKERRQ(ierr);
ierr = MatAXPY(A,1.0,Atrans,DIFFERENT_NONZERO_PATTERN);CHKERRQ(ierr);
ierr = MatScale(A,0.5);CHKERRQ(ierr);
ierr = MatDestroy(&Atrans);CHKERRQ(ierr);
/* Test sbaij matrix */
flg = PETSC_FALSE;
ierr = PetscOptionsGetBool(NULL,NULL, "-test_sbaij1", &flg,NULL);CHKERRQ(ierr);
if (flg) {
Mat sA;
PetscBool issymm;
ierr = MatIsTranspose(A,A,0.0,&issymm);CHKERRQ(ierr);
if (issymm) {
ierr = MatSetOption(A,MAT_SYMMETRIC,PETSC_TRUE);CHKERRQ(ierr);
} else {ierr = PetscPrintf(PETSC_COMM_WORLD,"Warning: A is non-symmetric\n");CHKERRQ(ierr);}
ierr = MatConvert(A,MATSBAIJ,MAT_INITIAL_MATRIX,&sA);CHKERRQ(ierr);
ierr = MatDestroy(&A);CHKERRQ(ierr);
A = sA;
}
ierr = KSPCreate(PETSC_COMM_WORLD,&ksp);CHKERRQ(ierr);
ierr = KSPSetFromOptions(ksp);CHKERRQ(ierr);
ierr = KSPSetOperators(ksp,A,A);CHKERRQ(ierr);
ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);
ierr = PCSetDM(pc,(DM)da);CHKERRQ(ierr);
if (trans) {
ierr = KSPSolveTranspose(ksp,b,x);CHKERRQ(ierr);
} else {
ierr = KSPSolve(ksp,b,x);CHKERRQ(ierr);
}
/* check final residual */
flg = PETSC_FALSE;
ierr = PetscOptionsGetBool(NULL,NULL, "-check_final_residual", &flg,NULL);CHKERRQ(ierr);
if (flg) {
Vec b1;
PetscReal norm;
ierr = KSPGetSolution(ksp,&x);CHKERRQ(ierr);
ierr = VecDuplicate(b,&b1);CHKERRQ(ierr);
ierr = MatMult(A,x,b1);CHKERRQ(ierr);
ierr = VecAXPY(b1,-1.0,b);CHKERRQ(ierr);
ierr = VecNorm(b1,NORM_2,&norm);CHKERRQ(ierr);
ierr = PetscPrintf(PETSC_COMM_WORLD,"Final residual %g\n",norm);CHKERRQ(ierr);
ierr = VecDestroy(&b1);CHKERRQ(ierr);
}
ierr = KSPDestroy(&ksp);CHKERRQ(ierr);
ierr = VecDestroy(&x);CHKERRQ(ierr);
ierr = VecDestroy(&b);CHKERRQ(ierr);
ierr = MatDestroy(&A);CHKERRQ(ierr);
ierr = DMDestroy(&da);CHKERRQ(ierr);
ierr = PetscFinalize();
return ierr;
}
int main(int Argc,char **Args)
{
PetscBool flg;
PetscInt n = -6;
PetscScalar rho = 1.0;
PetscReal h;
PetscReal beta = 1.0;
DM da;
PetscRandom rctx;
PetscMPIInt comm_size;
Mat H,HtH;
PetscInt x, y, xs, ys, xm, ym;
PetscReal r1, r2;
PetscScalar uxy1, uxy2;
MatStencil sxy, sxy_m;
PetscScalar val, valconj;
Vec b, Htb,xvec;
KSP kspmg;
PC pcmg;
PetscErrorCode ierr;
PetscInt ix[1] = {0};
PetscScalar vals[1] = {1.0};
PetscInitialize(&Argc,&Args,(char*)0,help);
ierr = PetscOptionsGetInt(NULL,"-size",&n,&flg);CHKERRQ(ierr);
ierr = PetscOptionsGetReal(NULL,"-beta",&beta,&flg);CHKERRQ(ierr);
ierr = PetscOptionsGetScalar(NULL,"-rho",&rho,&flg);CHKERRQ(ierr);
/* Set the fudge parameters, we scale the whole thing by 1/(2*h) later */
h = 1.;
rho *= 1./(2.*h);
/* Geometry info */
ierr = DMDACreate2d(PETSC_COMM_WORLD, DMDA_BOUNDARY_PERIODIC,DMDA_BOUNDARY_PERIODIC, DMDA_STENCIL_STAR, n, n,
PETSC_DECIDE, PETSC_DECIDE, 2 /* this is the # of dof's */,
1, NULL, NULL, &da);CHKERRQ(ierr);
/* Random numbers */
ierr = PetscRandomCreate(PETSC_COMM_WORLD,&rctx);CHKERRQ(ierr);
ierr = PetscRandomSetFromOptions(rctx);CHKERRQ(ierr);
/* Single or multi processor ? */
ierr = MPI_Comm_size(PETSC_COMM_WORLD,&comm_size);CHKERRQ(ierr);
/* construct matrix */
ierr = DMSetMatType(da,MATAIJ);CHKERRQ(ierr);
ierr = DMCreateMatrix(da, &H);CHKERRQ(ierr);
/* get local corners for this processor */
ierr = DMDAGetCorners(da,&xs,&ys,0,&xm,&ym,0);CHKERRQ(ierr);
/* Assemble the matrix */
for (x=xs; x<xs+xm; x++) {
for (y=ys; y<ys+ym; y++) {
/* each lattice point sets only the *forward* pointing parameters (right, down),
i.e. Nabla_1^+ and Nabla_2^+.
In this way we can use only local random number creation. That means
we also have to set the corresponding backward pointing entries. */
/* Compute some normally distributed random numbers via Box-Muller */
ierr = PetscRandomGetValueReal(rctx, &r1);CHKERRQ(ierr);
r1 = 1.-r1; /* to change from [0,1) to (0,1], which we need for the log */
ierr = PetscRandomGetValueReal(rctx, &r2);CHKERRQ(ierr);
PetscReal R = PetscSqrtReal(-2.*PetscLogReal(r1));
PetscReal c = PetscCosReal(2.*PETSC_PI*r2);
PetscReal s = PetscSinReal(2.*PETSC_PI*r2);
/* use those to set the field */
uxy1 = PetscExpScalar(((PetscScalar) (R*c/beta))*PETSC_i);
uxy2 = PetscExpScalar(((PetscScalar) (R*s/beta))*PETSC_i);
sxy.i = x; sxy.j = y; /* the point where we are */
/* center action */
sxy.c = 0; /* spin 0, 0 */
ierr = MatSetValuesStencil(H, 1, &sxy, 1, &sxy, &rho, ADD_VALUES);CHKERRQ(ierr);
sxy.c = 1; /* spin 1, 1 */
val = -rho;
ierr = MatSetValuesStencil(H, 1, &sxy, 1, &sxy, &val, ADD_VALUES);CHKERRQ(ierr);
sxy_m.i = x+1; sxy_m.j = y; /* right action */
sxy.c = 0; sxy_m.c = 0; /* spin 0, 0 */
val = -uxy1; valconj = PetscConj(val);
ierr = MatSetValuesStencil(H, 1, &sxy_m, 1, &sxy, &val, ADD_VALUES);CHKERRQ(ierr);
ierr = MatSetValuesStencil(H, 1, &sxy, 1, &sxy_m, &valconj, ADD_VALUES);CHKERRQ(ierr);
sxy.c = 0; sxy_m.c = 1; /* spin 0, 1 */
val = -uxy1; valconj = PetscConj(val);
ierr = MatSetValuesStencil(H, 1, &sxy_m, 1, &sxy, &val, ADD_VALUES);CHKERRQ(ierr);
ierr = MatSetValuesStencil(H, 1, &sxy, 1, &sxy_m, &valconj, ADD_VALUES);CHKERRQ(ierr);
sxy.c = 1; sxy_m.c = 0; /* spin 1, 0 */
val = uxy1; valconj = PetscConj(val);
ierr = MatSetValuesStencil(H, 1, &sxy_m, 1, &sxy, &val, ADD_VALUES);CHKERRQ(ierr);
ierr = MatSetValuesStencil(H, 1, &sxy, 1, &sxy_m, &valconj, ADD_VALUES);CHKERRQ(ierr);
sxy.c = 1; sxy_m.c = 1; /* spin 1, 1 */
val = uxy1; valconj = PetscConj(val);
ierr = MatSetValuesStencil(H, 1, &sxy_m, 1, &sxy, &val, ADD_VALUES);CHKERRQ(ierr);
ierr = MatSetValuesStencil(H, 1, &sxy, 1, &sxy_m, &valconj, ADD_VALUES);CHKERRQ(ierr);
sxy_m.i = x; sxy_m.j = y+1; /* down action */
sxy.c = 0; sxy_m.c = 0; /* spin 0, 0 */
val = -uxy2; valconj = PetscConj(val);
ierr = MatSetValuesStencil(H, 1, &sxy_m, 1, &sxy, &val, ADD_VALUES);CHKERRQ(ierr);
ierr = MatSetValuesStencil(H, 1, &sxy, 1, &sxy_m, &valconj, ADD_VALUES);CHKERRQ(ierr);
sxy.c = 0; sxy_m.c = 1; /* spin 0, 1 */
val = -PETSC_i*uxy2; valconj = PetscConj(val);
ierr = MatSetValuesStencil(H, 1, &sxy_m, 1, &sxy, &val, ADD_VALUES);CHKERRQ(ierr);
ierr = MatSetValuesStencil(H, 1, &sxy, 1, &sxy_m, &valconj, ADD_VALUES);CHKERRQ(ierr);
sxy.c = 1; sxy_m.c = 0; /* spin 1, 0 */
val = -PETSC_i*uxy2; valconj = PetscConj(val);
ierr = MatSetValuesStencil(H, 1, &sxy_m, 1, &sxy, &val, ADD_VALUES);CHKERRQ(ierr);
ierr = MatSetValuesStencil(H, 1, &sxy, 1, &sxy_m, &valconj, ADD_VALUES);CHKERRQ(ierr);
sxy.c = 1; sxy_m.c = 1; /* spin 1, 1 */
val = PetscConj(uxy2); valconj = PetscConj(val);
ierr = MatSetValuesStencil(H, 1, &sxy_m, 1, &sxy, &val, ADD_VALUES);CHKERRQ(ierr);
ierr = MatSetValuesStencil(H, 1, &sxy, 1, &sxy_m, &valconj, ADD_VALUES);CHKERRQ(ierr);
}
}
ierr = MatAssemblyBegin(H, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
ierr = MatAssemblyEnd(H, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
/* scale H */
ierr = MatScale(H, 1./(2.*h));CHKERRQ(ierr);
/* it looks like H is Hermetian */
/* construct normal equations */
ierr = MatMatMult(H, H, MAT_INITIAL_MATRIX, 1., &HtH);CHKERRQ(ierr);
/* permutation matrix to check whether H and HtH are identical to the ones in the paper */
/* Mat perm; */
/* ierr = DMCreateMatrix(da, &perm);CHKERRQ(ierr); */
/* PetscInt row, col; */
/* PetscScalar one = 1.0; */
/* for (PetscInt i=0; i<n; i++) { */
/* for (PetscInt j=0; j<n; j++) { */
/* row = (i*n+j)*2; col = i*n+j; */
/* ierr = MatSetValues(perm, 1, &row, 1, &col, &one, INSERT_VALUES);CHKERRQ(ierr); */
/* row = (i*n+j)*2+1; col = i*n+j + n*n; */
/* ierr = MatSetValues(perm, 1, &row, 1, &col, &one, INSERT_VALUES);CHKERRQ(ierr); */
/* } */
/* } */
/* ierr = MatAssemblyBegin(perm, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); */
/* ierr = MatAssemblyEnd(perm, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); */
/* Mat Hperm; */
/* ierr = MatPtAP(H, perm, MAT_INITIAL_MATRIX, 1.0, &Hperm);CHKERRQ(ierr); */
/* ierr = PetscPrintf(PETSC_COMM_WORLD, "Matrix H after construction\n");CHKERRQ(ierr); */
/* ierr = MatView(Hperm, PETSC_VIEWER_STDOUT_(PETSC_COMM_WORLD));CHKERRQ(ierr); */
/* Mat HtHperm; */
/* ierr = MatPtAP(HtH, perm, MAT_INITIAL_MATRIX, 1.0, &HtHperm);CHKERRQ(ierr); */
/* ierr = PetscPrintf(PETSC_COMM_WORLD, "Matrix HtH:\n");CHKERRQ(ierr); */
/* ierr = MatView(HtHperm, PETSC_VIEWER_STDOUT_(PETSC_COMM_WORLD));CHKERRQ(ierr); */
/* right hand side */
ierr = DMCreateGlobalVector(da, &b);CHKERRQ(ierr);
ierr = VecSet(b,0.0);CHKERRQ(ierr);
ierr = VecSetValues(b, 1, ix, vals, INSERT_VALUES);CHKERRQ(ierr);
ierr = VecAssemblyBegin(b);CHKERRQ(ierr);
ierr = VecAssemblyEnd(b);CHKERRQ(ierr);
/* ierr = VecSetRandom(b, rctx);CHKERRQ(ierr); */
ierr = VecDuplicate(b, &Htb);CHKERRQ(ierr);
ierr = MatMultTranspose(H, b, Htb);CHKERRQ(ierr);
/* construct solver */
ierr = KSPCreate(PETSC_COMM_WORLD,&kspmg);CHKERRQ(ierr);
ierr = KSPSetType(kspmg, KSPCG);CHKERRQ(ierr);
ierr = KSPGetPC(kspmg,&pcmg);CHKERRQ(ierr);
ierr = PCSetType(pcmg,PCASA);CHKERRQ(ierr);
/* maybe user wants to override some of the choices */
ierr = KSPSetFromOptions(kspmg);CHKERRQ(ierr);
ierr = KSPSetOperators(kspmg, HtH, HtH, DIFFERENT_NONZERO_PATTERN);CHKERRQ(ierr);
ierr = DMDASetRefinementFactor(da, 3, 3, 3);CHKERRQ(ierr);
ierr = PCSetDM(pcmg,da);CHKERRQ(ierr);
ierr = PCASASetTolerances(pcmg, 1.e-6, 1.e-10,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
ierr = VecDuplicate(b, &xvec);CHKERRQ(ierr);
ierr = VecSet(xvec, 0.0);CHKERRQ(ierr);
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Solve the linear system
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
ierr = KSPSolve(kspmg, Htb, xvec);CHKERRQ(ierr);
/* ierr = VecView(xvec, PETSC_VIEWER_STDOUT_(PETSC_COMM_WORLD));CHKERRQ(ierr); */
ierr = KSPDestroy(&kspmg);CHKERRQ(ierr);
ierr = VecDestroy(&xvec);CHKERRQ(ierr);
/* seems to be destroyed by KSPDestroy */
ierr = VecDestroy(&b);CHKERRQ(ierr);
ierr = VecDestroy(&Htb);CHKERRQ(ierr);
ierr = MatDestroy(&HtH);CHKERRQ(ierr);
ierr = MatDestroy(&H);CHKERRQ(ierr);
ierr = DMDestroy(&da);CHKERRQ(ierr);
ierr = PetscRandomDestroy(&rctx);CHKERRQ(ierr);
ierr = PetscFinalize();
return 0;
}
