1 2 static char help[] = "Tests matrix factorization. Note that most users should\n\ 3 employ the KSP interface to the linear solvers instead of using the factorization\n\ 4 routines directly.\n\n"; 5 6 #include <petscmat.h> 7 8 int main(int argc,char **args) 9 { 10 Mat C,LU; 11 MatInfo info; 12 PetscInt i,j,m,n,Ii,J; 13 PetscErrorCode ierr; 14 PetscScalar v,one = 1.0; 15 IS perm,iperm; 16 Vec x,u,b; 17 PetscReal norm,fill; 18 MatFactorInfo luinfo; 19 20 ierr = PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr; 21 22 ierr = PetscOptionsBegin(PETSC_COMM_WORLD,NULL,"Mat test ex7 options","Mat");CHKERRQ(ierr); 23 m = 3; n = 3; fill = 2.0; 24 CHKERRQ(PetscOptionsInt("-m","Number of rows in grid",NULL,m,&m,NULL)); 25 CHKERRQ(PetscOptionsInt("-n","Number of columns in grid",NULL,n,&n,NULL)); 26 CHKERRQ(PetscOptionsReal("-fill","Expected fill ratio for factorization",NULL,fill,&fill,NULL)); 27 28 ierr = PetscOptionsEnd();CHKERRQ(ierr); 29 30 /* Create the matrix for the five point stencil, YET AGAIN */ 31 CHKERRQ(MatCreate(PETSC_COMM_SELF,&C)); 32 CHKERRQ(MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n)); 33 CHKERRQ(MatSetFromOptions(C)); 34 CHKERRQ(MatSetUp(C)); 35 for (i=0; i<m; i++) { 36 for (j=0; j<n; j++) { 37 v = -1.0; Ii = j + n*i; 38 if (i>0) {J = Ii - n; CHKERRQ(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));} 39 if (i<m-1) {J = Ii + n; CHKERRQ(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));} 40 if (j>0) {J = Ii - 1; CHKERRQ(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));} 41 if (j<n-1) {J = Ii + 1; CHKERRQ(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));} 42 v = 4.0; CHKERRQ(MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES)); 43 } 44 } 45 CHKERRQ(MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY)); 46 CHKERRQ(MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY)); 47 CHKERRQ(MatGetOrdering(C,MATORDERINGRCM,&perm,&iperm)); 48 CHKERRQ(MatView(C,PETSC_VIEWER_STDOUT_WORLD)); 49 CHKERRQ(ISView(perm,PETSC_VIEWER_STDOUT_SELF)); 50 51 CHKERRQ(MatFactorInfoInitialize(&luinfo)); 52 53 luinfo.fill = fill; 54 luinfo.dtcol = 0.0; 55 luinfo.zeropivot = 1.e-14; 56 luinfo.pivotinblocks = 1.0; 57 58 CHKERRQ(MatGetFactor(C,MATSOLVERPETSC,MAT_FACTOR_LU,&LU)); 59 CHKERRQ(MatLUFactorSymbolic(LU,C,perm,iperm,&luinfo)); 60 CHKERRQ(MatLUFactorNumeric(LU,C,&luinfo)); 61 62 CHKERRQ(VecCreateSeq(PETSC_COMM_SELF,m*n,&u)); 63 CHKERRQ(VecSet(u,one)); 64 CHKERRQ(VecDuplicate(u,&x)); 65 CHKERRQ(VecDuplicate(u,&b)); 66 67 CHKERRQ(MatMult(C,u,b)); 68 CHKERRQ(MatSolve(LU,b,x)); 69 70 CHKERRQ(VecView(b,PETSC_VIEWER_STDOUT_SELF)); 71 CHKERRQ(VecView(x,PETSC_VIEWER_STDOUT_SELF)); 72 73 CHKERRQ(VecAXPY(x,-1.0,u)); 74 CHKERRQ(VecNorm(x,NORM_2,&norm)); 75 CHKERRQ(PetscPrintf(PETSC_COMM_SELF,"Norm of error %g\n",(double)norm)); 76 77 CHKERRQ(MatGetInfo(C,MAT_LOCAL,&info)); 78 CHKERRQ(PetscPrintf(PETSC_COMM_SELF,"original matrix nonzeros = %" PetscInt_FMT "\n",(PetscInt)info.nz_used)); 79 CHKERRQ(MatGetInfo(LU,MAT_LOCAL,&info)); 80 CHKERRQ(PetscPrintf(PETSC_COMM_SELF,"factored matrix nonzeros = %" PetscInt_FMT "\n",(PetscInt)info.nz_used)); 81 82 CHKERRQ(VecDestroy(&u)); 83 CHKERRQ(VecDestroy(&b)); 84 CHKERRQ(VecDestroy(&x)); 85 CHKERRQ(ISDestroy(&perm)); 86 CHKERRQ(ISDestroy(&iperm)); 87 CHKERRQ(MatDestroy(&C)); 88 CHKERRQ(MatDestroy(&LU)); 89 90 ierr = PetscFinalize(); 91 return ierr; 92 } 93 94 /*TEST 95 96 test: 97 suffix: 1 98 filter: grep -v "MPI processes" 99 100 test: 101 suffix: 2 102 args: -m 1 -n 1 -fill 0.49 103 filter: grep -v "MPI processes" 104 105 TEST*/ 106