1 /*$Id: snesj2.c,v 1.20 1999/10/01 21:22:24 bsmith Exp bsmith $*/ 2 3 #include "src/mat/matimpl.h" /*I "mat.h" I*/ 4 #include "src/snes/snesimpl.h" /*I "snes.h" I*/ 5 6 #undef __FUNC__ 7 #define __FUNC__ "SNESDefaultComputeJacobianColor" 8 /*@C 9 SNESDefaultComputeJacobianColor - Computes the Jacobian using 10 finite differences and coloring to exploit matrix sparsity. 11 12 Collective on SNES 13 14 Input Parameters: 15 + snes - nonlinear solver object 16 . x1 - location at which to evaluate Jacobian 17 - ctx - coloring context, where ctx must have type MatFDColoring, 18 as created via MatFDColoringCreate() 19 20 Output Parameters: 21 + J - Jacobian matrix (not altered in this routine) 22 . B - newly computed Jacobian matrix to use with preconditioner (generally the same as J) 23 - flag - flag indicating whether the matrix sparsity structure has changed 24 25 Options Database Keys: 26 . -mat_fd_coloring_freq <freq> - Activates SNESDefaultComputeJacobianColor() 27 28 Level: intermediate 29 30 .keywords: SNES, finite differences, Jacobian, coloring, sparse 31 32 .seealso: SNESSetJacobian(), SNESTestJacobian(), SNESDefaultComputeJacobian() 33 TSDefaultComputeJacobianColor(), MatFDColoringCreate(), 34 MatFDColoringSetFunction() 35 36 @*/ 37 int SNESDefaultComputeJacobianColor(SNES snes,Vec x1,Mat *J,Mat *B,MatStructure *flag,void *ctx) 38 { 39 MatFDColoring color = (MatFDColoring) ctx; 40 int ierr,freq,it; 41 42 PetscFunctionBegin; 43 ierr = MatFDColoringGetFrequency(color,&freq);CHKERRQ(ierr); 44 ierr = SNESGetIterationNumber(snes,&it);CHKERRQ(ierr); 45 46 if ((freq > 1) && ((it % freq) != 1)) { 47 PLogInfo(color,"SNESDefaultComputeJacobianColor:Skipping Jacobian, it %d, freq %d\n",it,freq); 48 *flag = SAME_PRECONDITIONER; 49 PetscFunctionReturn(0); 50 } else { 51 PLogInfo(color,"SNESDefaultComputeJacobianColor:Computing Jacobian, it %d, freq %d\n",it,freq); 52 *flag = SAME_NONZERO_PATTERN; 53 } 54 55 56 PLogEventBegin(SNES_FunctionEval,snes,x1,0,0); 57 PetscStackPush("SNES user function"); 58 ierr = MatFDColoringApply(*B,color,x1,flag,snes);CHKERRQ(ierr); 59 PetscStackPop; 60 snes->nfuncs++; 61 PLogEventEnd(SNES_FunctionEval,snes,x1,0,0); 62 PetscFunctionReturn(0); 63 } 64 65 66 67