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 = 3,n = 3,Ii,J; 13 PetscErrorCode ierr; 14 PetscScalar v,one = 1.0; 15 IS perm,iperm; 16 Vec x,u,b; 17 PetscReal norm; 18 MatFactorInfo luinfo; 19 20 ierr = PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr; 21 /* Create the matrix for the five point stencil, YET AGAIN */ 22 ierr = MatCreate(PETSC_COMM_SELF,&C);CHKERRQ(ierr); 23 ierr = MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n);CHKERRQ(ierr); 24 ierr = MatSetFromOptions(C);CHKERRQ(ierr); 25 ierr = MatSetUp(C);CHKERRQ(ierr); 26 for (i=0; i<m; i++) { 27 for (j=0; j<n; j++) { 28 v = -1.0; Ii = j + n*i; 29 if (i>0) {J = Ii - n; ierr = MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);CHKERRQ(ierr);} 30 if (i<m-1) {J = Ii + n; ierr = MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);CHKERRQ(ierr);} 31 if (j>0) {J = Ii - 1; ierr = MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);CHKERRQ(ierr);} 32 if (j<n-1) {J = Ii + 1; ierr = MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);CHKERRQ(ierr);} 33 v = 4.0; ierr = MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES);CHKERRQ(ierr); 34 } 35 } 36 ierr = MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 37 ierr = MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 38 ierr = MatGetOrdering(C,MATORDERINGRCM,&perm,&iperm);CHKERRQ(ierr); 39 ierr = MatView(C,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr); 40 ierr = ISView(perm,PETSC_VIEWER_STDOUT_SELF);CHKERRQ(ierr); 41 42 ierr = MatFactorInfoInitialize(&luinfo);CHKERRQ(ierr); 43 44 luinfo.fill = 2.0; 45 luinfo.dtcol = 0.0; 46 luinfo.zeropivot = 1.e-14; 47 luinfo.pivotinblocks = 1.0; 48 49 ierr = MatGetFactor(C,MATSOLVERPETSC,MAT_FACTOR_LU,&LU);CHKERRQ(ierr); 50 ierr = MatLUFactorSymbolic(LU,C,perm,iperm,&luinfo);CHKERRQ(ierr); 51 ierr = MatLUFactorNumeric(LU,C,&luinfo);CHKERRQ(ierr); 52 53 ierr = VecCreateSeq(PETSC_COMM_SELF,m*n,&u);CHKERRQ(ierr); 54 ierr = VecSet(u,one);CHKERRQ(ierr); 55 ierr = VecDuplicate(u,&x);CHKERRQ(ierr); 56 ierr = VecDuplicate(u,&b);CHKERRQ(ierr); 57 58 ierr = MatMult(C,u,b);CHKERRQ(ierr); 59 ierr = MatSolve(LU,b,x);CHKERRQ(ierr); 60 61 ierr = VecView(b,PETSC_VIEWER_STDOUT_SELF);CHKERRQ(ierr); 62 ierr = VecView(x,PETSC_VIEWER_STDOUT_SELF);CHKERRQ(ierr); 63 64 ierr = VecAXPY(x,-1.0,u);CHKERRQ(ierr); 65 ierr = VecNorm(x,NORM_2,&norm);CHKERRQ(ierr); 66 ierr = PetscPrintf(PETSC_COMM_SELF,"Norm of error %g\n",(double)norm);CHKERRQ(ierr); 67 68 ierr = MatGetInfo(C,MAT_LOCAL,&info);CHKERRQ(ierr); 69 ierr = PetscPrintf(PETSC_COMM_SELF,"original matrix nonzeros = %D\n",(PetscInt)info.nz_used);CHKERRQ(ierr); 70 ierr = MatGetInfo(LU,MAT_LOCAL,&info);CHKERRQ(ierr); 71 ierr = PetscPrintf(PETSC_COMM_SELF,"factored matrix nonzeros = %D\n",(PetscInt)info.nz_used);CHKERRQ(ierr); 72 73 ierr = VecDestroy(&u);CHKERRQ(ierr); 74 ierr = VecDestroy(&b);CHKERRQ(ierr); 75 ierr = VecDestroy(&x);CHKERRQ(ierr); 76 ierr = ISDestroy(&perm);CHKERRQ(ierr); 77 ierr = ISDestroy(&iperm);CHKERRQ(ierr); 78 ierr = MatDestroy(&C);CHKERRQ(ierr); 79 ierr = MatDestroy(&LU);CHKERRQ(ierr); 80 81 ierr = PetscFinalize(); 82 return ierr; 83 } 84 85 86 /*TEST 87 88 test: 89 filter: grep -v "MPI processes" 90 91 TEST*/ 92