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