That solved the problem, thank you very much! Afterall, it ocurred that I don't need this procedure since I will only use diagonal matrices and inverse of such are trivial.
It will come in handy someday though, I am sure. Thanks again. --- 30.3.11 (?r), Hong Zhang <hzhang at mcs.anl.gov> napisa?(a): Od: Hong Zhang <hzhang at mcs.anl.gov> Temat: Re: [petsc-users] Matrix inverse and LU decomposition Do: "PETSc users list" <petsc-users at mcs.anl.gov> Data: 30 Marzec 2011 (?roda), 15:07 You need call MatSetType(I,MATDENSE);MatSetType(Dinv,MATDENSE); See?petsc-dev/src/mat/examples/tests/ex1.c (attached) on how to useMatMatSolve().Can you send me your complete code so I can check why Dinv is empty? Hong On Wed, Mar 30, 2011 at 8:31 AM, Bart?omiej W <bartlomiej.wach at yahoo.pl> wrote: Hello, I want to obtain the inverse of a matrix, even though it's not advised by the FAQ ;-) and I have a problem that earlier responses didn't solve for me. Simply speaking : the inverse matrix that is a result of? DI=Dinv as told by the FAQ, is empty for me. Here is my code(the significant part) : ? ierr = MatCreate(PETSC_COMM_WORLD,&D);CHKERRQ(ierr); ? ierr = MatSetSizes(D,PETSC_DECIDE,PETSC_DECIDE,n,n);CHKERRQ(ierr); ? ierr = MatSetFromOptions(D);CHKERRQ(ierr); ? ierr = MatCreate(PETSC_COMM_WORLD,&Dinv);CHKERRQ(ierr); ? ierr = MatSetSizes(Dinv,PETSC_DECIDE,PETSC_DECIDE,n,n);CHKERRQ(ierr); ? ierr = MatSetFromOptions(Dinv);CHKERRQ(ierr); ? ierr = MatCreate(PETSC_COMM_WORLD,&I);CHKERRQ(ierr); ? ierr = MatSetSizes(I,PETSC_DECIDE,PETSC_DECIDE,n,n);CHKERRQ(ierr); ? ierr = MatSetFromOptions(I);CHKERRQ(ierr); (...) ? ierr = MatAssemblyEnd(D,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); ? ierr = MatAssemblyEnd(I,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); ? ierr = MatAssemblyEnd(Dinv,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); ? MatView(D,PETSC_VIEWER_STDOUT_SELF); ??? ? ierr = MatGetOrdering(D,? MATORDERING_NATURAL,? &perm,? &iperm); CHKERRQ(ierr); ??? ? ierr = MatFactorInfoInitialize(&info); CHKERRQ(ierr); ? ierr = MatLUFactor(D, perm, iperm, &info); CHKERRQ(ierr); ? MatView(D,PETSC_VIEWER_STDOUT_SELF); ? MatView(I,PETSC_VIEWER_STDOUT_SELF); ??? ? ierr = MatMatSolve(D,I,Dinv); CHKERRQ(ierr); ? MatView(Dinv,PETSC_VIEWER_STDOUT_SELF); // Results in such output: //==== MATRIX D row 0: (0, 2) row 1: (1, 1) row 2: (2, 1) row 3: (3, 1) //==== MATRIX D after LU decomposition row 0: (0, 0.5) row 1: (1, 1) row 2: (2, 1) row 3: (3, 1) //==== Identity matrix row 0: (0, 1) row 1: (1, 1) row 2: (2, 1) row 3: (3, 1) //==== inverse of D? (result of MatMatSolve(D,I,Dinv)) row 0: row 1: row 2: row 3: The approach with : ??? ierr = MatGetOrdering(D,? MATORDERING_NATURAL,? &perm,? &iperm); CHKERRQ(ierr); ??? ??? ierr = MatGetFactor(D, MAT_SOLVER_PETSC, MAT_FACTOR_LU,&F); ??? ierr = MatFactorInfoInitialize(&info); CHKERRQ(ierr); ??? ierr = MatLUFactorSymbolic(F,D,perm,iperm,&info);CHKERRQ(ierr); ??? ierr = MatLUFactorNumeric(F,D,&info);CHKERRQ(ierr); ??? ierr = MatLUFactor(D, perm, iperm, &info); CHKERRQ(ierr); Provides same output Thank You for Your help. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20110330/f00750a0/attachment.htm>
