1*c4762a1bSJed Brown 2*c4762a1bSJed Brown static char help[] = "Tests PC and KSP on a tridiagonal matrix. Note that most\n\ 3*c4762a1bSJed Brown users should employ the KSP interface instead of using PC directly.\n\n"; 4*c4762a1bSJed Brown 5*c4762a1bSJed Brown 6*c4762a1bSJed Brown #include <petscksp.h> 7*c4762a1bSJed Brown 8*c4762a1bSJed Brown int main(int argc,char **args) 9*c4762a1bSJed Brown { 10*c4762a1bSJed Brown Mat mat; /* matrix */ 11*c4762a1bSJed Brown Vec b,ustar,u; /* vectors (RHS, exact solution, approx solution) */ 12*c4762a1bSJed Brown PC pc; /* PC context */ 13*c4762a1bSJed Brown KSP ksp; /* KSP context */ 14*c4762a1bSJed Brown PetscErrorCode ierr; 15*c4762a1bSJed Brown PetscInt n = 10,i,its,col[3]; 16*c4762a1bSJed Brown PetscScalar value[3]; 17*c4762a1bSJed Brown PCType pcname; 18*c4762a1bSJed Brown KSPType kspname; 19*c4762a1bSJed Brown PetscReal norm,tol=1000.*PETSC_MACHINE_EPSILON; 20*c4762a1bSJed Brown 21*c4762a1bSJed Brown ierr = PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr; 22*c4762a1bSJed Brown /* Create and initialize vectors */ 23*c4762a1bSJed Brown ierr = VecCreateSeq(PETSC_COMM_SELF,n,&b);CHKERRQ(ierr); 24*c4762a1bSJed Brown ierr = VecCreateSeq(PETSC_COMM_SELF,n,&ustar);CHKERRQ(ierr); 25*c4762a1bSJed Brown ierr = VecCreateSeq(PETSC_COMM_SELF,n,&u);CHKERRQ(ierr); 26*c4762a1bSJed Brown ierr = VecSet(ustar,1.0);CHKERRQ(ierr); 27*c4762a1bSJed Brown ierr = VecSet(u,0.0);CHKERRQ(ierr); 28*c4762a1bSJed Brown 29*c4762a1bSJed Brown /* Create and assemble matrix */ 30*c4762a1bSJed Brown ierr = MatCreateSeqAIJ(PETSC_COMM_SELF,n,n,3,NULL,&mat);CHKERRQ(ierr); 31*c4762a1bSJed Brown value[0] = -1.0; value[1] = 2.0; value[2] = -1.0; 32*c4762a1bSJed Brown for (i=1; i<n-1; i++) { 33*c4762a1bSJed Brown col[0] = i-1; col[1] = i; col[2] = i+1; 34*c4762a1bSJed Brown ierr = MatSetValues(mat,1,&i,3,col,value,INSERT_VALUES);CHKERRQ(ierr); 35*c4762a1bSJed Brown } 36*c4762a1bSJed Brown i = n - 1; col[0] = n - 2; col[1] = n - 1; 37*c4762a1bSJed Brown ierr = MatSetValues(mat,1,&i,2,col,value,INSERT_VALUES);CHKERRQ(ierr); 38*c4762a1bSJed Brown i = 0; col[0] = 0; col[1] = 1; value[0] = 2.0; value[1] = -1.0; 39*c4762a1bSJed Brown ierr = MatSetValues(mat,1,&i,2,col,value,INSERT_VALUES);CHKERRQ(ierr); 40*c4762a1bSJed Brown ierr = MatAssemblyBegin(mat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 41*c4762a1bSJed Brown ierr = MatAssemblyEnd(mat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 42*c4762a1bSJed Brown 43*c4762a1bSJed Brown /* Compute right-hand-side vector */ 44*c4762a1bSJed Brown ierr = MatMult(mat,ustar,b);CHKERRQ(ierr); 45*c4762a1bSJed Brown 46*c4762a1bSJed Brown /* Create PC context and set up data structures */ 47*c4762a1bSJed Brown ierr = PCCreate(PETSC_COMM_WORLD,&pc);CHKERRQ(ierr); 48*c4762a1bSJed Brown ierr = PCSetType(pc,PCNONE);CHKERRQ(ierr); 49*c4762a1bSJed Brown ierr = PCSetFromOptions(pc);CHKERRQ(ierr); 50*c4762a1bSJed Brown ierr = PCSetOperators(pc,mat,mat);CHKERRQ(ierr); 51*c4762a1bSJed Brown ierr = PCSetUp(pc);CHKERRQ(ierr); 52*c4762a1bSJed Brown 53*c4762a1bSJed Brown /* Create KSP context and set up data structures */ 54*c4762a1bSJed Brown ierr = KSPCreate(PETSC_COMM_WORLD,&ksp);CHKERRQ(ierr); 55*c4762a1bSJed Brown ierr = KSPSetType(ksp,KSPRICHARDSON);CHKERRQ(ierr); 56*c4762a1bSJed Brown ierr = KSPSetFromOptions(ksp);CHKERRQ(ierr); 57*c4762a1bSJed Brown ierr = PCSetOperators(pc,mat,mat);CHKERRQ(ierr); 58*c4762a1bSJed Brown ierr = KSPSetPC(ksp,pc);CHKERRQ(ierr); 59*c4762a1bSJed Brown ierr = KSPSetUp(ksp);CHKERRQ(ierr); 60*c4762a1bSJed Brown 61*c4762a1bSJed Brown /* Solve the problem */ 62*c4762a1bSJed Brown ierr = KSPGetType(ksp,&kspname);CHKERRQ(ierr); 63*c4762a1bSJed Brown ierr = PCGetType(pc,&pcname);CHKERRQ(ierr); 64*c4762a1bSJed Brown ierr = PetscPrintf(PETSC_COMM_SELF,"Running %s with %s preconditioning\n",kspname,pcname);CHKERRQ(ierr); 65*c4762a1bSJed Brown ierr = KSPSolve(ksp,b,u);CHKERRQ(ierr); 66*c4762a1bSJed Brown ierr = VecAXPY(u,-1.0,ustar);CHKERRQ(ierr); 67*c4762a1bSJed Brown ierr = VecNorm(u,NORM_2,&norm);CHKERRQ(ierr); 68*c4762a1bSJed Brown ierr = KSPGetIterationNumber(ksp,&its);CHKERRQ(ierr); 69*c4762a1bSJed Brown if (norm > tol) { 70*c4762a1bSJed Brown ierr = PetscPrintf(PETSC_COMM_SELF,"2 norm of error %g Number of iterations %D\n",(double)norm,its);CHKERRQ(ierr); 71*c4762a1bSJed Brown } 72*c4762a1bSJed Brown 73*c4762a1bSJed Brown /* Free data structures */ 74*c4762a1bSJed Brown ierr = KSPDestroy(&ksp);CHKERRQ(ierr); 75*c4762a1bSJed Brown ierr = VecDestroy(&u);CHKERRQ(ierr); 76*c4762a1bSJed Brown ierr = VecDestroy(&ustar);CHKERRQ(ierr); 77*c4762a1bSJed Brown ierr = VecDestroy(&b);CHKERRQ(ierr); 78*c4762a1bSJed Brown ierr = MatDestroy(&mat);CHKERRQ(ierr); 79*c4762a1bSJed Brown ierr = PCDestroy(&pc);CHKERRQ(ierr); 80*c4762a1bSJed Brown 81*c4762a1bSJed Brown ierr = PetscFinalize(); 82*c4762a1bSJed Brown return ierr; 83*c4762a1bSJed Brown } 84*c4762a1bSJed Brown 85*c4762a1bSJed Brown 86*c4762a1bSJed Brown 87*c4762a1bSJed Brown 88*c4762a1bSJed Brown 89*c4762a1bSJed Brown /*TEST 90*c4762a1bSJed Brown 91*c4762a1bSJed Brown test: 92*c4762a1bSJed Brown args: -ksp_type cg -ksp_monitor_short 93*c4762a1bSJed Brown 94*c4762a1bSJed Brown TEST*/ 95