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 TSDefaultComputeJacobianColor(), MatFDColoringCreate(), 29 MatFDColoringSetFunction() 30 31 @*/ 32 33 PetscErrorCode SNESDefaultComputeJacobianColor(SNES snes,Vec x1,Mat *J,Mat *B,MatStructure *flag,void *ctx) 34 { 35 MatFDColoring color = (MatFDColoring) ctx; 36 PetscErrorCode ierr; 37 Vec f; 38 PetscErrorCode (*ff)(void),(*fd)(void); 39 40 PetscFunctionBegin; 41 PetscValidHeaderSpecific(color,MAT_FDCOLORING_CLASSID,6); 42 *flag = SAME_NONZERO_PATTERN; 43 ierr = SNESGetFunction(snes,&f,(PetscErrorCode (**)(SNES,Vec,Vec,void*))&ff,0);CHKERRQ(ierr); 44 ierr = MatFDColoringGetFunction(color,&fd,PETSC_NULL);CHKERRQ(ierr); 45 if (fd == ff) { /* reuse function value computed in SNES */ 46 ierr = MatFDColoringSetF(color,f);CHKERRQ(ierr); 47 } 48 ierr = MatFDColoringApply(*B,color,x1,flag,snes);CHKERRQ(ierr); 49 if (*J != *B) { 50 ierr = MatAssemblyBegin(*J,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 51 ierr = MatAssemblyEnd(*J,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 52 } 53 PetscFunctionReturn(0); 54 } 55 56 57 58