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 PetscErrorCode ierr; 14c4762a1bSJed Brown PetscInt n = 10,i,its,col[3]; 15c4762a1bSJed Brown PetscScalar value[3]; 16c4762a1bSJed Brown PCType pcname; 17c4762a1bSJed Brown KSPType kspname; 18c4762a1bSJed Brown PetscReal norm,tol=1000.*PETSC_MACHINE_EPSILON; 19c4762a1bSJed Brown 20c4762a1bSJed Brown ierr = PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr; 21c4762a1bSJed Brown /* Create and initialize vectors */ 22*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecCreateSeq(PETSC_COMM_SELF,n,&b)); 23*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecCreateSeq(PETSC_COMM_SELF,n,&ustar)); 24*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecCreateSeq(PETSC_COMM_SELF,n,&u)); 25*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecSet(ustar,1.0)); 26*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecSet(u,0.0)); 27c4762a1bSJed Brown 28c4762a1bSJed Brown /* Create and assemble matrix */ 29*5f80ce2aSJacob Faibussowitsch CHKERRQ(MatCreateSeqAIJ(PETSC_COMM_SELF,n,n,3,NULL,&mat)); 30c4762a1bSJed Brown value[0] = -1.0; value[1] = 2.0; value[2] = -1.0; 31c4762a1bSJed Brown for (i=1; i<n-1; i++) { 32c4762a1bSJed Brown col[0] = i-1; col[1] = i; col[2] = i+1; 33*5f80ce2aSJacob Faibussowitsch CHKERRQ(MatSetValues(mat,1,&i,3,col,value,INSERT_VALUES)); 34c4762a1bSJed Brown } 35c4762a1bSJed Brown i = n - 1; col[0] = n - 2; col[1] = n - 1; 36*5f80ce2aSJacob Faibussowitsch CHKERRQ(MatSetValues(mat,1,&i,2,col,value,INSERT_VALUES)); 37c4762a1bSJed Brown i = 0; col[0] = 0; col[1] = 1; value[0] = 2.0; value[1] = -1.0; 38*5f80ce2aSJacob Faibussowitsch CHKERRQ(MatSetValues(mat,1,&i,2,col,value,INSERT_VALUES)); 39*5f80ce2aSJacob Faibussowitsch CHKERRQ(MatAssemblyBegin(mat,MAT_FINAL_ASSEMBLY)); 40*5f80ce2aSJacob Faibussowitsch CHKERRQ(MatAssemblyEnd(mat,MAT_FINAL_ASSEMBLY)); 41c4762a1bSJed Brown 42c4762a1bSJed Brown /* Compute right-hand-side vector */ 43*5f80ce2aSJacob Faibussowitsch CHKERRQ(MatMult(mat,ustar,b)); 44c4762a1bSJed Brown 45c4762a1bSJed Brown /* Create PC context and set up data structures */ 46*5f80ce2aSJacob Faibussowitsch CHKERRQ(PCCreate(PETSC_COMM_WORLD,&pc)); 47*5f80ce2aSJacob Faibussowitsch CHKERRQ(PCSetType(pc,PCNONE)); 48*5f80ce2aSJacob Faibussowitsch CHKERRQ(PCSetFromOptions(pc)); 49*5f80ce2aSJacob Faibussowitsch CHKERRQ(PCSetOperators(pc,mat,mat)); 50*5f80ce2aSJacob Faibussowitsch CHKERRQ(PCSetUp(pc)); 51c4762a1bSJed Brown 52c4762a1bSJed Brown /* Create KSP context and set up data structures */ 53*5f80ce2aSJacob Faibussowitsch CHKERRQ(KSPCreate(PETSC_COMM_WORLD,&ksp)); 54*5f80ce2aSJacob Faibussowitsch CHKERRQ(KSPSetType(ksp,KSPRICHARDSON)); 55*5f80ce2aSJacob Faibussowitsch CHKERRQ(KSPSetFromOptions(ksp)); 56*5f80ce2aSJacob Faibussowitsch CHKERRQ(PCSetOperators(pc,mat,mat)); 57*5f80ce2aSJacob Faibussowitsch CHKERRQ(KSPSetPC(ksp,pc)); 58*5f80ce2aSJacob Faibussowitsch CHKERRQ(KSPSetUp(ksp)); 59c4762a1bSJed Brown 60c4762a1bSJed Brown /* Solve the problem */ 61*5f80ce2aSJacob Faibussowitsch CHKERRQ(KSPGetType(ksp,&kspname)); 62*5f80ce2aSJacob Faibussowitsch CHKERRQ(PCGetType(pc,&pcname)); 63*5f80ce2aSJacob Faibussowitsch CHKERRQ(PetscPrintf(PETSC_COMM_SELF,"Running %s with %s preconditioning\n",kspname,pcname)); 64*5f80ce2aSJacob Faibussowitsch CHKERRQ(KSPSolve(ksp,b,u)); 65*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecAXPY(u,-1.0,ustar)); 66*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecNorm(u,NORM_2,&norm)); 67*5f80ce2aSJacob Faibussowitsch CHKERRQ(KSPGetIterationNumber(ksp,&its)); 68c4762a1bSJed Brown if (norm > tol) { 69*5f80ce2aSJacob Faibussowitsch CHKERRQ(PetscPrintf(PETSC_COMM_SELF,"2 norm of error %g Number of iterations %D\n",(double)norm,its)); 70c4762a1bSJed Brown } 71c4762a1bSJed Brown 72c4762a1bSJed Brown /* Free data structures */ 73*5f80ce2aSJacob Faibussowitsch CHKERRQ(KSPDestroy(&ksp)); 74*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecDestroy(&u)); 75*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecDestroy(&ustar)); 76*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecDestroy(&b)); 77*5f80ce2aSJacob Faibussowitsch CHKERRQ(MatDestroy(&mat)); 78*5f80ce2aSJacob Faibussowitsch CHKERRQ(PCDestroy(&pc)); 79c4762a1bSJed Brown 80c4762a1bSJed Brown ierr = PetscFinalize(); 81c4762a1bSJed Brown return ierr; 82c4762a1bSJed Brown } 83c4762a1bSJed Brown 84c4762a1bSJed Brown /*TEST 85c4762a1bSJed Brown 86c4762a1bSJed Brown test: 87c4762a1bSJed Brown args: -ksp_type cg -ksp_monitor_short 88c4762a1bSJed Brown 89c4762a1bSJed Brown TEST*/ 90