1 #ifdef PETSC_RCS_HEADER 2 static char vcid[] = "$Id: snesj2.c,v 1.16 1998/09/25 03:16:01 bsmith Exp curfman $"; 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__ "SNESDefaultComputeJacobianWithColoring" 10 /*@C 11 SNESDefaultComputeJacobianWithColoring - 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 SNESDefaultComputeJacobianWithColoring() 29 30 Level: intermediate 31 32 .keywords: SNES, finite differences, Jacobian, coloring, sparse 33 34 .seealso: SNESSetJacobian(), SNESTestJacobian(), SNESDefaultComputeJacobian() 35 TSDefaultComputeJacobianWithColoring(), MatFDColoringCreate(), 36 MatFDColoringSetFunction() 37 38 @*/ 39 int SNESDefaultComputeJacobianWithColoring(SNES snes,Vec x1,Mat *J,Mat *B, 40 MatStructure *flag,void *ctx) 41 { 42 MatFDColoring color = (MatFDColoring) ctx; 43 int ierr,freq,it; 44 45 PetscFunctionBegin; 46 ierr = MatFDColoringGetFrequency(color,&freq);CHKERRQ(ierr); 47 ierr = SNESGetIterationNumber(snes,&it); CHKERRQ(ierr); 48 49 if ((freq > 1) && ((it % freq) != 1)) { 50 PLogInfo(color,"SNESDefaultComputeJacobianWithColoring:Skipping Jacobian, it %d, freq %d\n",it,freq); 51 *flag = SAME_PRECONDITIONER; 52 PetscFunctionReturn(0); 53 } else { 54 PLogInfo(color,"SNESDefaultComputeJacobianWithColoring:Computing Jacobian, it %d, freq %d\n",it,freq); 55 *flag = SAME_NONZERO_PATTERN; 56 } 57 58 59 PLogEventBegin(SNES_FunctionEval,snes,x1,0,0); 60 PetscStackPush("SNES user function"); 61 ierr = MatFDColoringApply(*B,color,x1,flag,snes); CHKERRQ(ierr); 62 PetscStackPop; 63 snes->nfuncs++; 64 PLogEventEnd(SNES_FunctionEval,snes,x1,0,0); 65 PetscFunctionReturn(0); 66 } 67 68 69 70