1c4762a1bSJed Brown 2c4762a1bSJed Brown static char help[] = "Tests PC and KSP on a tridiagonal matrix. Note that most\n\ 3c4762a1bSJed Brown users should employ the KSP interface instead of using PC directly.\n\n"; 4c4762a1bSJed Brown 5c4762a1bSJed Brown #include <petscksp.h> 6c4762a1bSJed Brown 7c4762a1bSJed Brown int main(int argc,char **args) 8c4762a1bSJed Brown { 9c4762a1bSJed Brown Mat mat; /* matrix */ 10c4762a1bSJed Brown Vec b,ustar,u; /* vectors (RHS, exact solution, approx solution) */ 11c4762a1bSJed Brown PC pc; /* PC context */ 12c4762a1bSJed Brown KSP ksp; /* KSP context */ 13c4762a1bSJed Brown PetscInt n = 10,i,its,col[3]; 14c4762a1bSJed Brown PetscScalar value[3]; 15c4762a1bSJed Brown PCType pcname; 16c4762a1bSJed Brown KSPType kspname; 17c4762a1bSJed Brown PetscReal norm,tol=1000.*PETSC_MACHINE_EPSILON; 18c4762a1bSJed Brown 19*b122ec5aSJacob Faibussowitsch CHKERRQ(PetscInitialize(&argc,&args,(char*)0,help)); 20c4762a1bSJed Brown /* Create and initialize vectors */ 215f80ce2aSJacob Faibussowitsch CHKERRQ(VecCreateSeq(PETSC_COMM_SELF,n,&b)); 225f80ce2aSJacob Faibussowitsch CHKERRQ(VecCreateSeq(PETSC_COMM_SELF,n,&ustar)); 235f80ce2aSJacob Faibussowitsch CHKERRQ(VecCreateSeq(PETSC_COMM_SELF,n,&u)); 245f80ce2aSJacob Faibussowitsch CHKERRQ(VecSet(ustar,1.0)); 255f80ce2aSJacob Faibussowitsch CHKERRQ(VecSet(u,0.0)); 26c4762a1bSJed Brown 27c4762a1bSJed Brown /* Create and assemble matrix */ 285f80ce2aSJacob Faibussowitsch CHKERRQ(MatCreateSeqAIJ(PETSC_COMM_SELF,n,n,3,NULL,&mat)); 29c4762a1bSJed Brown value[0] = -1.0; value[1] = 2.0; value[2] = -1.0; 30c4762a1bSJed Brown for (i=1; i<n-1; i++) { 31c4762a1bSJed Brown col[0] = i-1; col[1] = i; col[2] = i+1; 325f80ce2aSJacob Faibussowitsch CHKERRQ(MatSetValues(mat,1,&i,3,col,value,INSERT_VALUES)); 33c4762a1bSJed Brown } 34c4762a1bSJed Brown i = n - 1; col[0] = n - 2; col[1] = n - 1; 355f80ce2aSJacob Faibussowitsch CHKERRQ(MatSetValues(mat,1,&i,2,col,value,INSERT_VALUES)); 36c4762a1bSJed Brown i = 0; col[0] = 0; col[1] = 1; value[0] = 2.0; value[1] = -1.0; 375f80ce2aSJacob Faibussowitsch CHKERRQ(MatSetValues(mat,1,&i,2,col,value,INSERT_VALUES)); 385f80ce2aSJacob Faibussowitsch CHKERRQ(MatAssemblyBegin(mat,MAT_FINAL_ASSEMBLY)); 395f80ce2aSJacob Faibussowitsch CHKERRQ(MatAssemblyEnd(mat,MAT_FINAL_ASSEMBLY)); 40c4762a1bSJed Brown 41c4762a1bSJed Brown /* Compute right-hand-side vector */ 425f80ce2aSJacob Faibussowitsch CHKERRQ(MatMult(mat,ustar,b)); 43c4762a1bSJed Brown 44c4762a1bSJed Brown /* Create PC context and set up data structures */ 455f80ce2aSJacob Faibussowitsch CHKERRQ(PCCreate(PETSC_COMM_WORLD,&pc)); 465f80ce2aSJacob Faibussowitsch CHKERRQ(PCSetType(pc,PCNONE)); 475f80ce2aSJacob Faibussowitsch CHKERRQ(PCSetFromOptions(pc)); 485f80ce2aSJacob Faibussowitsch CHKERRQ(PCSetOperators(pc,mat,mat)); 495f80ce2aSJacob Faibussowitsch CHKERRQ(PCSetUp(pc)); 50c4762a1bSJed Brown 51c4762a1bSJed Brown /* Create KSP context and set up data structures */ 525f80ce2aSJacob Faibussowitsch CHKERRQ(KSPCreate(PETSC_COMM_WORLD,&ksp)); 535f80ce2aSJacob Faibussowitsch CHKERRQ(KSPSetType(ksp,KSPRICHARDSON)); 545f80ce2aSJacob Faibussowitsch CHKERRQ(KSPSetFromOptions(ksp)); 555f80ce2aSJacob Faibussowitsch CHKERRQ(PCSetOperators(pc,mat,mat)); 565f80ce2aSJacob Faibussowitsch CHKERRQ(KSPSetPC(ksp,pc)); 575f80ce2aSJacob Faibussowitsch CHKERRQ(KSPSetUp(ksp)); 58c4762a1bSJed Brown 59c4762a1bSJed Brown /* Solve the problem */ 605f80ce2aSJacob Faibussowitsch CHKERRQ(KSPGetType(ksp,&kspname)); 615f80ce2aSJacob Faibussowitsch CHKERRQ(PCGetType(pc,&pcname)); 625f80ce2aSJacob Faibussowitsch CHKERRQ(PetscPrintf(PETSC_COMM_SELF,"Running %s with %s preconditioning\n",kspname,pcname)); 635f80ce2aSJacob Faibussowitsch CHKERRQ(KSPSolve(ksp,b,u)); 645f80ce2aSJacob Faibussowitsch CHKERRQ(VecAXPY(u,-1.0,ustar)); 655f80ce2aSJacob Faibussowitsch CHKERRQ(VecNorm(u,NORM_2,&norm)); 665f80ce2aSJacob Faibussowitsch CHKERRQ(KSPGetIterationNumber(ksp,&its)); 67c4762a1bSJed Brown if (norm > tol) { 685f80ce2aSJacob Faibussowitsch CHKERRQ(PetscPrintf(PETSC_COMM_SELF,"2 norm of error %g Number of iterations %D\n",(double)norm,its)); 69c4762a1bSJed Brown } 70c4762a1bSJed Brown 71c4762a1bSJed Brown /* Free data structures */ 725f80ce2aSJacob Faibussowitsch CHKERRQ(KSPDestroy(&ksp)); 735f80ce2aSJacob Faibussowitsch CHKERRQ(VecDestroy(&u)); 745f80ce2aSJacob Faibussowitsch CHKERRQ(VecDestroy(&ustar)); 755f80ce2aSJacob Faibussowitsch CHKERRQ(VecDestroy(&b)); 765f80ce2aSJacob Faibussowitsch CHKERRQ(MatDestroy(&mat)); 775f80ce2aSJacob Faibussowitsch CHKERRQ(PCDestroy(&pc)); 78c4762a1bSJed Brown 79*b122ec5aSJacob Faibussowitsch CHKERRQ(PetscFinalize()); 80*b122ec5aSJacob Faibussowitsch return 0; 81c4762a1bSJed Brown } 82c4762a1bSJed Brown 83c4762a1bSJed Brown /*TEST 84c4762a1bSJed Brown 85c4762a1bSJed Brown test: 86c4762a1bSJed Brown args: -ksp_type cg -ksp_monitor_short 87c4762a1bSJed Brown 88c4762a1bSJed Brown TEST*/ 89