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 ierr = PetscOptionsInt("-m","Number of rows in grid",NULL,m,&m,NULL);CHKERRQ(ierr); 25 ierr = PetscOptionsInt("-n","Number of columns in grid",NULL,n,&n,NULL);CHKERRQ(ierr); 26 ierr = PetscOptionsReal("-fill","Expected fill ratio for factorization",NULL,fill,&fill,NULL);CHKERRQ(ierr); 27 28 ierr = PetscOptionsEnd();CHKERRQ(ierr); 29 30 /* Create the matrix for the five point stencil, YET AGAIN */ 31 ierr = MatCreate(PETSC_COMM_SELF,&C);CHKERRQ(ierr); 32 ierr = MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n);CHKERRQ(ierr); 33 ierr = MatSetFromOptions(C);CHKERRQ(ierr); 34 ierr = MatSetUp(C);CHKERRQ(ierr); 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; ierr = MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);CHKERRQ(ierr);} 39 if (i<m-1) {J = Ii + n; ierr = MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);CHKERRQ(ierr);} 40 if (j>0) {J = Ii - 1; ierr = MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);CHKERRQ(ierr);} 41 if (j<n-1) {J = Ii + 1; ierr = MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);CHKERRQ(ierr);} 42 v = 4.0; ierr = MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES);CHKERRQ(ierr); 43 } 44 } 45 ierr = MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 46 ierr = MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 47 ierr = MatGetOrdering(C,MATORDERINGRCM,&perm,&iperm);CHKERRQ(ierr); 48 ierr = MatView(C,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr); 49 ierr = ISView(perm,PETSC_VIEWER_STDOUT_SELF);CHKERRQ(ierr); 50 51 ierr = MatFactorInfoInitialize(&luinfo);CHKERRQ(ierr); 52 53 luinfo.fill = fill; 54 luinfo.dtcol = 0.0; 55 luinfo.zeropivot = 1.e-14; 56 luinfo.pivotinblocks = 1.0; 57 58 ierr = MatGetFactor(C,MATSOLVERPETSC,MAT_FACTOR_LU,&LU);CHKERRQ(ierr); 59 ierr = MatLUFactorSymbolic(LU,C,perm,iperm,&luinfo);CHKERRQ(ierr); 60 ierr = MatLUFactorNumeric(LU,C,&luinfo);CHKERRQ(ierr); 61 62 ierr = VecCreateSeq(PETSC_COMM_SELF,m*n,&u);CHKERRQ(ierr); 63 ierr = VecSet(u,one);CHKERRQ(ierr); 64 ierr = VecDuplicate(u,&x);CHKERRQ(ierr); 65 ierr = VecDuplicate(u,&b);CHKERRQ(ierr); 66 67 ierr = MatMult(C,u,b);CHKERRQ(ierr); 68 ierr = MatSolve(LU,b,x);CHKERRQ(ierr); 69 70 ierr = VecView(b,PETSC_VIEWER_STDOUT_SELF);CHKERRQ(ierr); 71 ierr = VecView(x,PETSC_VIEWER_STDOUT_SELF);CHKERRQ(ierr); 72 73 ierr = VecAXPY(x,-1.0,u);CHKERRQ(ierr); 74 ierr = VecNorm(x,NORM_2,&norm);CHKERRQ(ierr); 75 ierr = PetscPrintf(PETSC_COMM_SELF,"Norm of error %g\n",(double)norm);CHKERRQ(ierr); 76 77 ierr = MatGetInfo(C,MAT_LOCAL,&info);CHKERRQ(ierr); 78 ierr = PetscPrintf(PETSC_COMM_SELF,"original matrix nonzeros = %D\n",(PetscInt)info.nz_used);CHKERRQ(ierr); 79 ierr = MatGetInfo(LU,MAT_LOCAL,&info);CHKERRQ(ierr); 80 ierr = PetscPrintf(PETSC_COMM_SELF,"factored matrix nonzeros = %D\n",(PetscInt)info.nz_used);CHKERRQ(ierr); 81 82 ierr = VecDestroy(&u);CHKERRQ(ierr); 83 ierr = VecDestroy(&b);CHKERRQ(ierr); 84 ierr = VecDestroy(&x);CHKERRQ(ierr); 85 ierr = ISDestroy(&perm);CHKERRQ(ierr); 86 ierr = ISDestroy(&iperm);CHKERRQ(ierr); 87 ierr = MatDestroy(&C);CHKERRQ(ierr); 88 ierr = MatDestroy(&LU);CHKERRQ(ierr); 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