2: #include <petsc-private/snesimpl.h>  /*I  "petscsnes.h" I*/
  3: #include <../src/mat/impls/mffd/mffdimpl.h>
  4: #include <petsc-private/matimpl.h>

  8: /*@C
  9:    MatMFFDComputeJacobian - Tells the matrix-free Jacobian object the new location at which
 10:        Jacobian matrix vector products will be computed at, i.e. J(x) * a. The x is obtained
 11:        from the SNES object (using SNESGetSolution()).

 13:    Logically Collective on SNES

 15:    Input Parameters:
 16: +   snes - the nonlinear solver context
 17: .   x - the point at which the Jacobian vector products will be performed
 18: .   jac - the matrix-free Jacobian object
 19: .   B - either the same as jac or another matrix type (ignored)
 20: .   flag - not relevent for matrix-free form
 21: -   dummy - the user context (ignored)

 23:    Level: developer

 25:    Warning: 
 26:       If MatMFFDSetBase() is ever called on jac then this routine will NO longer get 
 27:     the x from the SNES object and MatMFFDSetBase() must from that point on be used to
 28:     change the base vector x.

 30:    Notes:
 31:      This can be passed into SNESSetJacobian() as the Jacobian evaluation function argument
 32:      when using a completely matrix-free solver,
 33:      that is the B matrix is also the same matrix operator. This is used when you select
 34:      -snes_mf but rarely used directly by users. (All this routine does is call MatAssemblyBegin/End() on
 35:      the Mat jac.

 37: .seealso: MatMFFDGetH(), MatCreateSNESMF(), MatCreateMFFD(), MATMFFD,
 38:           MatMFFDSetHHistory(), MatMFFDSetFunctionError(), MatCreateMFFD(), SNESSetJacobian()

 40: @*/
 41: PetscErrorCode  MatMFFDComputeJacobian(SNES snes,Vec x,Mat *jac,Mat *B,MatStructure *flag,void *dummy)
 42: {
 45:   MatAssemblyBegin(*jac,MAT_FINAL_ASSEMBLY);
 46:   MatAssemblyEnd(*jac,MAT_FINAL_ASSEMBLY);
 47:   return(0);
 48: }

 50: PetscErrorCode MatAssemblyEnd_MFFD(Mat,MatAssemblyType);
 51: EXTERN_C_BEGIN
 52: PetscErrorCode MatMFFDSetBase_MFFD(Mat,Vec,Vec);
 53: EXTERN_C_END

 57: /*
 58:    MatAssemblyEnd_SNESMF - Calls MatAssemblyEnd_MFFD() and then sets the 
 59:     base from the SNES context

 61: */
 62: PetscErrorCode MatAssemblyEnd_SNESMF(Mat J,MatAssemblyType mt)
 63: {
 65:   MatMFFD        j = (MatMFFD)J->data;
 66:   SNES           snes = (SNES)j->funcctx;
 67:   Vec            u,f;

 70:   MatAssemblyEnd_MFFD(J,mt);

 72:   SNESGetSolution(snes,&u);
 73:   SNESGetFunction(snes,&f,PETSC_NULL,PETSC_NULL);
 74:   MatMFFDSetBase_MFFD(J,u,f);
 75:   return(0);
 76: }

 78: EXTERN_C_BEGIN
 79: /*
 80:     This routine resets the MatAssemblyEnd() for the MatMFFD created from MatCreateSNESMF() so that it NO longer
 81:   uses the solution in the SNES object to update the base. See the warning in MatCreateSNESMF().
 82: */
 85: PetscErrorCode  MatMFFDSetBase_SNESMF(Mat J,Vec U,Vec F)
 86: {

 90:   MatMFFDSetBase_MFFD(J,U,F);
 91:   J->ops->assemblyend = MatAssemblyEnd_MFFD;
 92:   return(0);
 93: }
 94: EXTERN_C_END

 98: /*@
 99:    MatCreateSNESMF - Creates a matrix-free matrix context for use with
100:    a SNES solver.  This matrix can be used as the Jacobian argument for
101:    the routine SNESSetJacobian(). See MatCreateMFFD() for details on how
102:    the finite difference computation is done.

104:    Collective on SNES and Vec

106:    Input Parameters:
107: .  snes - the SNES context

109:    Output Parameter:
110: .  J - the matrix-free matrix

112:    Level: advanced

114:    Warning: 
115:       If MatMFFDSetBase() is ever called on jac then this routine will NO longer get 
116:     the x from the SNES object and MatMFFDSetBase() must from that point on be used to
117:     change the base vector x.

119:    Notes: The difference between this routine and MatCreateMFFD() is that this matrix
120:      automatically gets the current base vector from the SNES object and not from an
121:      explicit call to MatMFFDSetBase().

123: .seealso: MatDestroy(), MatMFFDSetFunctionError(), MatMFFDDSSetUmin()
124:           MatMFFDSetHHistory(), MatMFFDResetHHistory(), MatCreateMFFD(),
125:           MatMFFDGetH(), MatMFFDRegisterDynamic), MatMFFDComputeJacobian()
126:  
127: @*/
128: PetscErrorCode  MatCreateSNESMF(SNES snes,Mat *J)
129: {
131:   PetscInt       n,N;

134:   if (snes->vec_func) {
135:     VecGetLocalSize(snes->vec_func,&n);
136:     VecGetSize(snes->vec_func,&N);
137:   } else if (snes->dm) {
138:     Vec tmp;
139:     DMGetGlobalVector(snes->dm,&tmp);
140:     VecGetLocalSize(tmp,&n);
141:     VecGetSize(tmp,&N);
142:     DMRestoreGlobalVector(snes->dm,&tmp);
143:   } else SETERRQ(((PetscObject)snes)->comm,PETSC_ERR_ARG_WRONGSTATE,"Must call SNESSetFunction() or SNESSetDM() first");
144:   MatCreateMFFD(((PetscObject)snes)->comm,n,n,N,N,J);
145:   MatMFFDSetFunction(*J,(PetscErrorCode (*)(void*,Vec,Vec))SNESComputeFunction,snes);
146:   (*J)->ops->assemblyend = MatAssemblyEnd_SNESMF;
147:   PetscObjectComposeFunctionDynamic((PetscObject)*J,"MatMFFDSetBase_C","MatMFFDSetBase_SNESMF",MatMFFDSetBase_SNESMF);
148:   return(0);
149: }