Actual source code: snesj2.c
1: /*$Id: snesj2.c,v 1.31 2001/06/21 21:18:37 bsmith Exp $*/
3: #include src/mat/matimpl.h
4: #include src/snes/snesimpl.h
6: /*@C
7: SNESDefaultComputeJacobianColor - Computes the Jacobian using
8: finite differences and coloring to exploit matrix sparsity.
9:
10: Collective on SNES
12: Input Parameters:
13: + snes - nonlinear solver object
14: . x1 - location at which to evaluate Jacobian
15: - ctx - coloring context, where ctx must have type MatFDColoring,
16: as created via MatFDColoringCreate()
18: Output Parameters:
19: + J - Jacobian matrix (not altered in this routine)
20: . B - newly computed Jacobian matrix to use with preconditioner (generally the same as J)
21: - flag - flag indicating whether the matrix sparsity structure has changed
23: Options Database Keys:
24: . -mat_fd_coloring_freq <freq> - Activates SNESDefaultComputeJacobianColor()
26: Level: intermediate
28: .keywords: SNES, finite differences, Jacobian, coloring, sparse
30: .seealso: SNESSetJacobian(), SNESTestJacobian(), SNESDefaultComputeJacobian()
31: TSDefaultComputeJacobianColor(), MatFDColoringCreate(),
32: MatFDColoringSetFunction()
34: @*/
35: int SNESDefaultComputeJacobianColor(SNES snes,Vec x1,Mat *J,Mat *B,MatStructure *flag,void *ctx)
36: {
37: MatFDColoring color = (MatFDColoring) ctx;
38: int ierr,freq,it;
39: Vec f;
42: MatFDColoringGetFrequency(color,&freq);
43: SNESGetIterationNumber(snes,&it);
45: if ((freq > 1) && ((it % freq))) {
46: PetscLogInfo(color,"SNESDefaultComputeJacobianColor:Skippingsnesj2.c and Jacobian, it %d, freq %dn",it,freq);
47: *flag = SAME_PRECONDITIONER;
48: } else {
49: PetscLogInfo(color,"SNESDefaultComputeJacobianColor:Computing Jacobian, it %d, freq %dn",it,freq);
50: *flag = SAME_NONZERO_PATTERN;
51: ierr = SNESGetFunction(snes,&f,0,0);
52: ierr = MatFDColoringSetF(color,f);
53: ierr = PetscLogEventBegin(SNES_FunctionEval,snes,x1,0,0);
54: PetscStackPush("SNES user function");
55: ierr = MatFDColoringApply(*B,color,x1,flag,snes);
56: PetscStackPop;
57: snes->nfuncs++;
58: PetscLogEventEnd(SNES_FunctionEval,snes,x1,0,0);
59: }
60: if (J != B) {
61: MatAssemblyBegin(*J,MAT_FINAL_ASSEMBLY);
62: MatAssemblyEnd(*J,MAT_FINAL_ASSEMBLY);
63: }
64: return(0);
65: }