int main(int argc,char **argv) {
PetscErrorCode ierr;
SNES snes;
Vec u;
DMDALocalInfo info;
Ctx user;
PetscInitialize(&argc,&argv,(char*)0,help);
ierr = configureCtx(&user); CHKERRQ(ierr);
ierr = DMDACreate2d(PETSC_COMM_WORLD,
DM_BOUNDARY_NONE, DM_BOUNDARY_NONE,
DMDA_STENCIL_STAR,
-3,-3,
PETSC_DECIDE,PETSC_DECIDE,
1,1,
NULL,NULL,
&user.da); CHKERRQ(ierr);
ierr = DMDASetUniformCoordinates(user.da,-1.0,1.0,-1.0,1.0,0.0,1.0); CHKERRQ(ierr);
ierr = DMSetApplicationContext(user.da,&user); CHKERRQ(ierr);
ierr = DMDAGetLocalInfo(user.da,&info); CHKERRQ(ierr);
if ((info.mx < 2) || (info.my < 2)) {
SETERRQ(PETSC_COMM_WORLD,1,"grid too coarse ... require (mx,my) > (2,2)");
}
ierr = DMCreateGlobalVector(user.da,&u); CHKERRQ(ierr);
ierr = PetscObjectSetName((PetscObject)u,"u_vec");CHKERRQ(ierr);
ierr = formInitial(&info,&user,u); CHKERRQ(ierr);
ierr = SNESCreate(PETSC_COMM_WORLD,&snes);CHKERRQ(ierr);
ierr = SNESSetDM(snes,user.da);CHKERRQ(ierr);
ierr = DMDASNESSetFunctionLocal(user.da,INSERT_VALUES,
(DMDASNESFunction)FormFunctionLocal,&user);CHKERRQ(ierr);
ierr = DMDASNESSetJacobianLocal(user.da,
(DMDASNESJacobian)FormJacobianLocal,&user);CHKERRQ(ierr);
ierr = SNESSetFromOptions(snes);CHKERRQ(ierr);
ierr = SNESSolve(snes,NULL,u); CHKERRQ(ierr);
ierr = PetscPrintf(PETSC_COMM_WORLD,
"done on %d x %d x %d grid with eps=%g ...\n",
info.mx,info.my,info.mz,user.eps); CHKERRQ(ierr);
VecDestroy(&u);
SNESDestroy(&snes); DMDestroy(&user.da);
ierr = PetscFinalize(); CHKERRQ(ierr);
return 0;
}
int main(int argc,char **argv) {
PetscErrorCode ierr;
SNES snes;
Vec u, uexact;
double err, uexnorm;
DMDALocalInfo info;
Ctx user;
PetscInitialize(&argc,&argv,(char*)0,help);
ierr = configureCtx(&user);
CHKERRQ(ierr);
//STARTDMDA
ierr = DMDACreate3d(PETSC_COMM_WORLD,
DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, DM_BOUNDARY_PERIODIC,
DMDA_STENCIL_STAR, 3,3,3, PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE,
1, 1, NULL,NULL,NULL,
&user.da);
CHKERRQ(ierr);
//ENDDMDA
ierr = DMSetFromOptions(user.da);
CHKERRQ(ierr);
ierr = DMSetUp(user.da);
CHKERRQ(ierr);
ierr = DMDASetUniformCoordinates(user.da,-1.0,1.0,-1.0,1.0,-1.0,1.0);
CHKERRQ(ierr);
ierr = DMSetApplicationContext(user.da,&user);
CHKERRQ(ierr);
ierr = DMDAGetLocalInfo(user.da,&info);
CHKERRQ(ierr);
if ((info.mx < 2) || (info.my < 2) || (info.mz < 3)) {
SETERRQ(PETSC_COMM_WORLD,1,"grid too coarse: require (mx,my,mz) > (2,2,3)");
}
ierr = DMCreateGlobalVector(user.da,&uexact);
CHKERRQ(ierr);
ierr = VecDuplicate(uexact,&user.f);
CHKERRQ(ierr);
ierr = VecDuplicate(uexact,&user.g);
CHKERRQ(ierr);
ierr = formUexFG(&info,&user,uexact);
CHKERRQ(ierr);
ierr = SNESCreate(PETSC_COMM_WORLD,&snes);
CHKERRQ(ierr);
ierr = SNESSetDM(snes,user.da);
CHKERRQ(ierr);
ierr = DMDASNESSetFunctionLocal(user.da,INSERT_VALUES,
(DMDASNESFunction)FormFunctionLocal,&user);
CHKERRQ(ierr);
ierr = DMDASNESSetJacobianLocal(user.da,
(DMDASNESJacobian)FormJacobianLocal,&user);
CHKERRQ(ierr);
ierr = SNESSetFromOptions(snes);
CHKERRQ(ierr);
ierr = VecDuplicate(uexact,&u);
CHKERRQ(ierr);
ierr = VecCopy(user.g,u);
CHKERRQ(ierr); // g has zeros except at bdry
ierr = SNESSolve(snes,NULL,u);
CHKERRQ(ierr);
ierr = VecAXPY(u,-1.0,uexact);
CHKERRQ(ierr); // u <- u + (-1.0) uxact
ierr = VecNorm(u,NORM_2,&err);
CHKERRQ(ierr);
ierr = VecNorm(uexact,NORM_2,&uexnorm);
CHKERRQ(ierr);
ierr = PetscPrintf(PETSC_COMM_WORLD,
"done on %d x %d x %d grid with eps=%g: error |u-uexact|_2/|uexact|_2 = %g\n",
info.mx,info.my,info.mz,user.eps,err/uexnorm);
CHKERRQ(ierr);
VecDestroy(&u);
VecDestroy(&uexact);
VecDestroy(&user.f);
VecDestroy(&user.g);
SNESDestroy(&snes);
DMDestroy(&user.da);
ierr = PetscFinalize();
CHKERRQ(ierr);
return 0;
}
