1 #define PETSCSNES_DLL 2 3 #include "src/mat/matimpl.h" /*I "petscmat.h" I*/ 4 #include "src/snes/snesimpl.h" /*I "petscsnes.h" I*/ 5 6 #undef __FUNCT__ 7 #define __FUNCT__ "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 PetscErrorCode PETSCSNES_DLLEXPORT SNESDefaultComputeJacobianColor(SNES snes,Vec x1,Mat *J,Mat *B,MatStructure *flag,void *ctx) 38 { 39 MatFDColoring color = (MatFDColoring) ctx; 40 PetscErrorCode ierr; 41 PetscInt freq,it; 42 Vec f; 43 PetscErrorCode (*ff)(void),(*fd)(void); 44 45 PetscFunctionBegin; 46 ierr = MatFDColoringGetFrequency(color,&freq);CHKERRQ(ierr); 47 ierr = SNESGetIterationNumber(snes,&it);CHKERRQ(ierr); 48 49 if ((freq > 1) && ((it % freq))) { 50 ierr = PetscLogInfo((color,"SNESDefaultComputeJacobianColor:Skipping Jacobian recomputation, it %D, freq %D\n",it,freq));CHKERRQ(ierr); 51 *flag = SAME_PRECONDITIONER; 52 } else { 53 ierr = PetscLogInfo((color,"SNESDefaultComputeJacobianColor:Computing Jacobian, it %D, freq %D\n",it,freq));CHKERRQ(ierr); 54 *flag = SAME_NONZERO_PATTERN; 55 ierr = SNESGetFunction(snes,&f,(PetscErrorCode (**)(SNES,Vec,Vec,void*))&ff,0);CHKERRQ(ierr); 56 ierr = MatFDColoringGetFunction(color,&fd,PETSC_NULL);CHKERRQ(ierr); 57 if (fd == ff) { /* reuse function value computed in SNES */ 58 ierr = MatFDColoringSetF(color,f);CHKERRQ(ierr); 59 } 60 ierr = MatFDColoringApply(*B,color,x1,flag,snes);CHKERRQ(ierr); 61 } 62 if (*J != *B) { 63 ierr = MatAssemblyBegin(*J,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 64 ierr = MatAssemblyEnd(*J,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 65 } 66 PetscFunctionReturn(0); 67 } 68 69 70 71