1 2 #include <private/snesimpl.h> /*I "petscsnes.h" I*/ 3 4 #undef __FUNCT__ 5 #define __FUNCT__ "SNESDefaultComputeJacobianColor" 6 /*@C 7 SNESDefaultComputeJacobianColor - Computes the Jacobian using 8 finite differences and coloring to exploit matrix sparsity. 9 10 Collective on SNES 11 12 Input Parameters: 13 + snes - nonlinear solver object 14 . x1 - location at which to evaluate Jacobian 15 - ctx - coloring context, where ctx must have type MatFDColoring, 16 as created via MatFDColoringCreate() 17 18 Output Parameters: 19 + J - Jacobian matrix (not altered in this routine) 20 . B - newly computed Jacobian matrix to use with preconditioner (generally the same as J) 21 - flag - flag indicating whether the matrix sparsity structure has changed 22 23 Level: intermediate 24 25 .keywords: SNES, finite differences, Jacobian, coloring, sparse 26 27 .seealso: SNESSetJacobian(), SNESTestJacobian(), SNESDefaultComputeJacobian() 28 MatFDColoringCreate(), MatFDColoringSetFunction() 29 30 @*/ 31 32 PetscErrorCode SNESDefaultComputeJacobianColor(SNES snes,Vec x1,Mat *J,Mat *B,MatStructure *flag,void *ctx) 33 { 34 MatFDColoring color = (MatFDColoring) ctx; 35 PetscErrorCode ierr; 36 Vec f; 37 PetscErrorCode (*ff)(void),(*fd)(void); 38 39 PetscFunctionBegin; 40 PetscValidHeaderSpecific(color,MAT_FDCOLORING_CLASSID,6); 41 *flag = SAME_NONZERO_PATTERN; 42 ierr = SNESGetFunction(snes,&f,(PetscErrorCode (**)(SNES,Vec,Vec,void*))&ff,0);CHKERRQ(ierr); 43 ierr = MatFDColoringGetFunction(color,&fd,PETSC_NULL);CHKERRQ(ierr); 44 if (fd == ff && !snes->vec_rhs) { /* reuse function value computed in SNES */ 45 ierr = MatFDColoringSetF(color,f);CHKERRQ(ierr); 46 } 47 ierr = MatFDColoringApply(*B,color,x1,flag,snes);CHKERRQ(ierr); 48 if (*J != *B) { 49 ierr = MatAssemblyBegin(*J,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 50 ierr = MatAssemblyEnd(*J,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 51 } 52 PetscFunctionReturn(0); 53 } 54 55 56 57