#include <petscts.h>

/* Simple C struct that allows us to access the two velocity (x and y directions) values easily in the code */
typedef struct {
  PetscScalar u, v;
} Field;

/* Data structure to store the model parameters */
typedef struct {
  PetscReal D1, D2, gamma, kappa;
  PetscBool aijpc;
  Vec       U;
  Mat       A;
  TS        ts;
} AppCtx;

/* User-supplied functions for TS */
PetscErrorCode RHSFunction(TS, PetscReal, Vec, Vec, void *);
PetscErrorCode RHSJacobian(TS, PetscReal, Vec, Mat, Mat, void *);
PetscErrorCode IFunction(TS, PetscReal, Vec, Vec, Vec, void *);
PetscErrorCode IJacobian(TS, PetscReal, Vec, Vec, PetscReal, Mat, Mat, void *);