1 #ifdef PETSC_RCS_HEADER 2 static char vcid[] = "$Id: snesj2.c,v 1.19 1999/05/04 20:35:43 balay Exp bsmith $"; 3 #endif 4 5 #include "src/mat/matimpl.h" /*I "mat.h" I*/ 6 #include "src/snes/snesimpl.h" /*I "snes.h" I*/ 7 8 #undef __FUNC__ 9 #define __FUNC__ "SNESDefaultComputeJacobianColor" 10 /*@C 11 SNESDefaultComputeJacobianColor - Computes the Jacobian using 12 finite differences and coloring to exploit matrix sparsity. 13 14 Collective on SNES 15 16 Input Parameters: 17 + snes - nonlinear solver object 18 . x1 - location at which to evaluate Jacobian 19 - ctx - coloring context, where ctx must have type MatFDColoring, 20 as created via MatFDColoringCreate() 21 22 Output Parameters: 23 + J - Jacobian matrix (not altered in this routine) 24 . B - newly computed Jacobian matrix to use with preconditioner (generally the same as J) 25 - flag - flag indicating whether the matrix sparsity structure has changed 26 27 Options Database Keys: 28 . -mat_fd_coloring_freq <freq> - Activates SNESDefaultComputeJacobianColor() 29 30 Level: intermediate 31 32 .keywords: SNES, finite differences, Jacobian, coloring, sparse 33 34 .seealso: SNESSetJacobian(), SNESTestJacobian(), SNESDefaultComputeJacobian() 35 TSDefaultComputeJacobianColor(), MatFDColoringCreate(), 36 MatFDColoringSetFunction() 37 38 @*/ 39 int SNESDefaultComputeJacobianColor(SNES snes,Vec x1,Mat *J,Mat *B,MatStructure *flag,void *ctx) 40 { 41 MatFDColoring color = (MatFDColoring) ctx; 42 int ierr,freq,it; 43 44 PetscFunctionBegin; 45 ierr = MatFDColoringGetFrequency(color,&freq);CHKERRQ(ierr); 46 ierr = SNESGetIterationNumber(snes,&it);CHKERRQ(ierr); 47 48 if ((freq > 1) && ((it % freq) != 1)) { 49 PLogInfo(color,"SNESDefaultComputeJacobianColor:Skipping Jacobian, it %d, freq %d\n",it,freq); 50 *flag = SAME_PRECONDITIONER; 51 PetscFunctionReturn(0); 52 } else { 53 PLogInfo(color,"SNESDefaultComputeJacobianColor:Computing Jacobian, it %d, freq %d\n",it,freq); 54 *flag = SAME_NONZERO_PATTERN; 55 } 56 57 58 PLogEventBegin(SNES_FunctionEval,snes,x1,0,0); 59 PetscStackPush("SNES user function"); 60 ierr = MatFDColoringApply(*B,color,x1,flag,snes);CHKERRQ(ierr); 61 PetscStackPop; 62 snes->nfuncs++; 63 PLogEventEnd(SNES_FunctionEval,snes,x1,0,0); 64 PetscFunctionReturn(0); 65 } 66 67 68 69