1 #ifdef PETSC_RCS_HEADER 2 static char vcid[] = "$Id: snesj2.c,v 1.11 1997/10/12 21:45:52 bsmith 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__ "SNESDefaultComputeJacobianWithColoring" 10 /*@C 11 SNESDefaultComputeJacobianWithColoring - Computes the Jacobian using 12 finite differences and coloring to exploit matrix sparsity. 13 14 Input Parameters: 15 . snes - nonlinear solver object 16 . x1 - location at which to evaluate Jacobian 17 . ctx - coloring context, where 18 $ ctx must have type MatFDColoring, 19 $ as created via MatFDColoringCreate() 20 21 Output Parameters: 22 . J - Jacobian matrix (not altered in this routine) 23 . B - newly computed Jacobian matrix to use with preconditioner (generally the same as J) 24 . flag - flag indicating whether the matrix sparsity structure has changed 25 26 Options Database Keys: 27 $ -mat_fd_coloring_freq <freq> 28 29 .keywords: SNES, finite differences, Jacobian, coloring, sparse 30 31 .seealso: SNESSetJacobian(), SNESTestJacobian(), SNESDefaultComputeJacobian() 32 @*/ 33 int SNESDefaultComputeJacobianWithColoring(SNES snes,Vec x1,Mat *J,Mat *B,MatStructure *flag,void *ctx) 34 { 35 MatFDColoring color = (MatFDColoring) ctx; 36 int ierr,freq,it; 37 38 PetscFunctionBegin; 39 ierr = MatFDColoringGetFrequency(color,&freq);CHKERRQ(ierr); 40 ierr = SNESGetIterationNumber(snes,&it); CHKERRQ(ierr); 41 42 if ((freq > 1) && ((it % freq) != 1)) { 43 PLogInfo(color,"SNESDefaultComputeJacobianWithColoring:Skipping Jacobian, it %d, freq %d\n",it,freq); 44 *flag = SAME_PRECONDITIONER; 45 PetscFunctionReturn(0); 46 } else { 47 PLogInfo(color,"SNESDefaultComputeJacobianWithColoring:Computing Jacobian, it %d, freq %d\n",it,freq); 48 *flag = SAME_NONZERO_PATTERN; 49 } 50 51 ierr = MatFDColoringApply(*B,color,x1,flag,snes); CHKERRQ(ierr); 52 PetscFunctionReturn(0); 53 } 54 55 56 57