See ~petsc/src/mat/examples/tests/ex214.c on how to compute selected entries of inv(A) using mumps. Hong
On Fri, Sep 27, 2019 at 8:04 AM Smith, Barry F. via petsc-users <[email protected]<mailto:[email protected]>> wrote: MatMumpsGetInverse() maybe useful. Also simply using MatMatSolve() with the first 1000 columns of the identity and "throwing away" the part you don't need may be most effective. Barry > On Sep 27, 2019, at 3:34 AM, Jan Grießer via petsc-users > <[email protected]<mailto:[email protected]>> wrote: > > Hi all, > i am using petsc4py. I am dealing with rather large sparse matrices up to > 600kx600k and i am interested in calculating a part of the inverse of the > matrix(I know it will be a dense matrix). Due to the nature of my problem, I > am only interested in approximately the first 1000 rows and 1000 columns > (i.e. a large block in the upper left ofthe matrix). Before I start to play > around now, I wanted to ask if there is a clever way to tackle this kind of > problem in PETSc in principle. For any input I would be very grateful! > Greetings Jan
