1 2 #include <petsc-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 - ignored context parameter 16 17 Output Parameters: 18 + J - Jacobian matrix (not altered in this routine) 19 . B - newly computed Jacobian matrix to use with preconditioner (generally the same as J) 20 - flag - flag indicating whether the matrix sparsity structure has changed 21 22 Level: intermediate 23 24 .notes: This will first try to get the coloring from the DM. If the DM type 25 has no coloring routine, then it will try to get the coloring from the matrix. This 26 requires that the matrix have nonzero entries precomputed, such as in 27 snes/examples/tutorials/ex45.c. 28 29 .keywords: SNES, finite differences, Jacobian, coloring, sparse 30 31 .seealso: SNESSetJacobian(), SNESTestJacobian(), SNESDefaultComputeJacobian() 32 MatFDColoringCreate(), MatFDColoringSetFunction() 33 34 @*/ 35 36 PetscErrorCode SNESDefaultComputeJacobianColor(SNES snes,Vec x1,Mat *J,Mat *B,MatStructure *flag,void *ctx) 37 { 38 MatFDColoring color = PETSC_NULL; 39 PetscErrorCode ierr; 40 DM dm; 41 PetscErrorCode (*func)(SNES,Vec,Vec,void*); 42 Vec F; 43 void *funcctx; 44 ISColoring iscoloring; 45 PetscBool hascolor; 46 47 PetscFunctionBegin; 48 ierr = PetscObjectQuery((PetscObject)*B,"SNESMatFDColoring",(PetscObject *)&color);CHKERRQ(ierr); 49 *flag = SAME_NONZERO_PATTERN; 50 ierr = SNESGetFunction(snes,&F,&func,&funcctx);CHKERRQ(ierr); 51 if (!color) { 52 ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr); 53 ierr = DMHasColoring(dm,&hascolor);CHKERRQ(ierr); 54 if (hascolor) { 55 ierr = DMCreateColoring(dm,IS_COLORING_GLOBAL,MATAIJ,&iscoloring);CHKERRQ(ierr); 56 ierr = MatFDColoringCreate(*B,iscoloring,&color);CHKERRQ(ierr); 57 ierr = ISColoringDestroy(&iscoloring);CHKERRQ(ierr); 58 ierr = MatFDColoringSetFunction(color,(PetscErrorCode (*)(void))func,funcctx);CHKERRQ(ierr); 59 ierr = MatFDColoringSetFromOptions(color);CHKERRQ(ierr); 60 } else { 61 ierr = MatGetColoring(*B,MATCOLORINGSL,&iscoloring);CHKERRQ(ierr); 62 ierr = MatFDColoringCreate(*B,iscoloring,&color);CHKERRQ(ierr); 63 ierr = ISColoringDestroy(&iscoloring);CHKERRQ(ierr); 64 ierr = MatFDColoringSetFunction(color,(PetscErrorCode (*)(void))func,(void*)funcctx);CHKERRQ(ierr); 65 ierr = MatFDColoringSetFromOptions(color);CHKERRQ(ierr); 66 } 67 ierr = PetscObjectCompose((PetscObject)*B,"SNESMatFDColoring",(PetscObject)color);CHKERRQ(ierr); 68 ierr = PetscObjectDereference((PetscObject)color);CHKERRQ(ierr); 69 } 70 71 /* F is only usable if there is no RHS on the SNES */ 72 if (!snes->vec_rhs) { 73 ierr = MatFDColoringSetF(color,F);CHKERRQ(ierr); 74 } 75 ierr = MatFDColoringApply(*B,color,x1,flag,snes);CHKERRQ(ierr); 76 if (*J != *B) { 77 ierr = MatAssemblyBegin(*J,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 78 ierr = MatAssemblyEnd(*J,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 79 } 80 PetscFunctionReturn(0); 81 } 82