#if !defined(_SNESNGMRES_H)
#define _SNESNGMRES_H

#include <petsc/private/snesimpl.h>

/*  Data structure for the Nonlinear GMRES method.  */
typedef struct {

  /* Solver parameters and counters */
  PetscInt    msize;            /* maximum size of krylov space */
  PetscInt    restart_it;       /* number of iterations the restart conditions persist before restart */
  PetscViewer monitor;          /* debugging output for NGMRES */
  PetscInt    restart_periodic; /* number of iterations to restart after */

  SNESNGMRESRestartType restart_type;
  SNESNGMRESSelectType  select_type;

  /* History and subspace data */
  Vec       *Fdot;             /* residual history -- length msize */
  Vec       *Xdot;             /* solution history -- length msize */
  PetscReal *fnorms;           /* the residual norm history  */
  PetscReal *xnorms;           /* the solution norm history */

  /* General minimization problem context */
  PetscScalar *h;              /* the constraint matrix */
  PetscScalar *beta;           /* rhs for the minimization problem */
  PetscScalar *xi;             /* the dot-product of the current and previous res. */

  /* Line searches */
  SNESLineSearch additive_linesearch;   /* Line search for the additive variant */

  /* Selection constants */
  PetscBool candidate;         /* use candidate storage approach */
  PetscBool approxfunc;        /* approximate the function rather than recomputing it */
  PetscBool singlereduction;   /* use a single reduction (with more local work) for tolerance selection */
  PetscReal gammaA;            /* Criterion A residual tolerance */
  PetscReal epsilonB;          /* Criterion B difference tolerance */
  PetscReal deltaB;            /* Criterion B residual tolerance */
  PetscReal gammaC;            /* Restart residual tolerance */

  PetscReal andersonBeta;      /* Relaxation parameter for Anderson Mixing */

  /* Least squares minimization solve context */
  PetscScalar  *q;             /* the matrix formed as q_ij = (rdot_i, rdot_j) */
  PetscBLASInt m;              /* matrix dimension */
  PetscBLASInt n;              /* matrix dimension */
  PetscBLASInt nrhs;           /* the number of right hand sides */
  PetscBLASInt lda;            /* the padded matrix dimension */
  PetscBLASInt ldb;            /* the padded vector dimension */
  PetscReal    *s;             /* the singular values */
  PetscReal    rcond;          /* the exit condition */
  PetscBLASInt rank;           /* the effective rank */
  PetscScalar  *work;          /* the work vector */
  PetscReal    *rwork;         /* the real work vector used for complex */
  PetscBLASInt lwork;          /* the size of the work vector */
  PetscBLASInt info;           /* the output condition */

  PetscBool setup_called;       /* indicates whether SNESSetUp_NGMRES() has been called  */
} SNES_NGMRES;

#define H(i,j)  ngmres->h[i*ngmres->msize + j]
#define Q(i,j)  ngmres->q[i*ngmres->msize + j]

/* private functions that are shared components of the methods */
PETSC_INTERN PetscErrorCode SNESNGMRESUpdateSubspace_Private(SNES,PetscInt,PetscInt,Vec,PetscReal,Vec);
PETSC_INTERN PetscErrorCode SNESNGMRESFormCombinedSolution_Private(SNES,PetscInt,PetscInt,Vec,Vec,PetscReal,Vec,Vec,Vec);
PETSC_INTERN PetscErrorCode SNESNGMRESNorms_Private(SNES,PetscInt,Vec,Vec,Vec,Vec,Vec,Vec,Vec,PetscReal*,PetscReal*, PetscReal*,PetscReal*,PetscReal*, PetscReal*,PetscReal*,PetscReal*);
PETSC_INTERN PetscErrorCode SNESNGMRESSelect_Private(SNES,PetscInt,Vec,Vec,PetscReal,PetscReal,PetscReal,Vec,Vec,PetscReal,PetscReal,PetscReal,PetscReal,PetscReal,PetscReal,Vec,Vec,Vec,PetscReal*,PetscReal*,PetscReal*);
PETSC_INTERN PetscErrorCode SNESNGMRESSelectRestart_Private(SNES,PetscInt,PetscReal,PetscReal,PetscReal,PetscReal,PetscBool*);

#endif