7    User-defined application context
11   Vec       F;  /* right-hand side of PDE */
15 /* ------------------------------------------------------------------- */
17    FormInitialGuess - Computes initial guess.
20 .  x - the solution vector
31 /* ------------------------------------------------------------------- */
33    CpuFunction - Evaluates nonlinear function, F(x) on CPU
36 .  snes - the SNES context
37 .  x - input vector
38 .  ctx - optional user-defined context, as set by SNESSetFunction()
41 .  r - function vector
44    The user-defined context can contain any application-specific
50   DM              da   = user->da;  in CpuFunction()
60   PetscCall(DMDAVecGetArray(da, user->F, &F));  in CpuFunction()
68     xm--;  in CpuFunction()
71     R[xs + xm - 1] = X[xs + xm - 1] - 1.0;  in CpuFunction()
72     xm--;  in CpuFunction()
74   d = 1.0 / (user->h * user->h);  in CpuFunction()
75   for (i = xs; i < xs + xm; i++) R[i] = d * (X[i - 1] - 2.0 * X[i] + X[i + 1]) + X[i] * X[i] - F[i];  in CpuFunction()
79   PetscCall(DMDAVecRestoreArray(da, user->F, &F));  in CpuFunction()
86 using PetscScalarKokkosOffsetView      = Kokkos::Experimental::OffsetView<PetscScalar *, DefaultMem…
87 using ConstPetscScalarKokkosOffsetView = Kokkos::Experimental::OffsetView<const PetscScalar *, Defa…
92   DM                               da   = user->da;  in KokkosFunction()
102   d = 1.0 / (user->h * user->h);  in KokkosFunction()
106   PetscCall(DMDAVecGetKokkosOffsetView(da, user->F, &F)); /* read only */  in KokkosFunction()
110       else if (i == M - 1) R(i) = X(i) - 1.0;                                  /* right boundary */  in KokkosFunction()
111       else R(i) = d * (X(i - 1) - 2.0 * X(i) + X(i + 1)) + X(i) * X(i) - F(i); /* interior */  in KokkosFunction()
115   PetscCall(DMDAVecRestoreKokkosOffsetView(da, user->F, &F));  in KokkosFunction()
123   DM              da   = user->da;  in StubFunction()
131   PetscCall(VecAXPY(rk, -1.0, r));  in StubFunction()
134 …PetscCheck(norm <= 1e-6, PETSC_COMM_SELF, PETSC_ERR_PLIB, "KokkosFunction() different from CpuFunc…  in StubFunction()
137 /* ------------------------------------------------------------------- */
139    FormJacobian - Evaluates Jacobian matrix.
142 .  snes - the SNES context
143 .  x - input vector
144 .  dummy - optional user-defined context (not used here)
147 .  jac - Jacobian matrix
148 .  B - optionally different matrix used to construct the preconditioner
156   DM              da = user->da;  in FormJacobian()
181     xm--;  in FormJacobian()
184     i    = M - 1;  in FormJacobian()
187     xm--;  in FormJacobian()
192       - Note that in this case we set all elements for a particular  in FormJacobian()
195   d = 1.0 / (user->h * user->h);  in FormJacobian()
197     j[0] = i - 1;  in FormJacobian()
201     A[1]        = -2.0 * d + 2.0 * xx[i];  in FormJacobian()
206      Assemble matrix, using the 2-step process:  in FormJacobian()
224   ApplicationCtx ctx;        /* user-defined context */  in main()
226   PetscScalar    none = -1.0;  in main()
233   PetscCall(PetscOptionsGetInt(NULL, NULL, "-n", &N, NULL));  in main()
234   ctx.h = 1.0 / (N - 1);  in main()
235   PetscCall(PetscOptionsGetBool(NULL, NULL, "-view_initial", &viewinitial, NULL));  in main()
237   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  in main()
239      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */  in main()
266       - Note that the final routine argument is the user-defined  in main()
267         context that provides application-specific data for the  in main()
276   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  in main()
278      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */  in main()
285       - Note that the final routine argument is the user-defined  in main()
286         context that provides application-specific data for the  in main()
294   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  in main()
297    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */  in main()
305         FF(i)        = 6.0 * xp + pow(xp + 1.e-12, 6.0); /* +1.e-12 is to prevent 0^6 */  in main()
317   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  in main()
319    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */  in main()
332   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  in main()
334    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */  in main()
357 /*TEST
362    test:
365      args: -dm_vec_type kokkos -dm_mat_type aijkokkos -view_initial -snes_monitor
368 TEST*/