LAPACK is always linked with PETSc so you can always make direct calls to LAPACK routines from PETSc code..
Barry > On Apr 25, 2023, at 6:03 AM, 권승리 / 학생 / 항공우주공학과 <[email protected]> wrote: > > Thank you for your reply. > > I think I gave an example of an unrealistic problem. > > I just wanted to know how to compute the inverse matrix, so I was wondering > if there is an example of computing the inverse matrix in PETSc. > > Alternatively, I want to know how to link the LAPACK library. > > best, > > Seung Lee Kwon > > 2023년 4월 25일 (화) 오후 6:44, Matthew Knepley <[email protected] > <mailto:[email protected]>>님이 작성: >> On Mon, Apr 24, 2023 at 11:47 PM 권승리 / 학생 / 항공우주공학과 <[email protected] >> <mailto:[email protected]>> wrote: >>> Dear all >>> >>> It depends on the problem. It can have hundreds of thousands of degrees of >>> freedom. >> >> Suppose your matrix was dense and had 1e6 dofs. The work to invert a matrix >> is O(N^3) with a small >> constant, so it would take 1e18 = 1 exaflop to invert this matrix and about >> 10 Terabytes of RAM to store >> it. Is this available to you? PETSc's supports Elemental and SCALAPACK for >> this kind of calculation. >> >> If the system is sparse, you could invert it using MUMPS, SuperLU_dist, or >> Pardiso. Then the work and >> storage depend on the density. There are good estimates for connectivity >> based on regular grids of given >> dimension. The limiting resource here is usually memory, which motivates >> people to try iterative methods. >> The convergence of iterative methods depend on detailed properties of your >> system, like the operator spectrum. >> >> Thanks, >> >> Matt >> >>> best, >>> >>> Seung Lee Kwon >>> >>> 2023년 4월 25일 (화) 오후 12:32, Barry Smith <[email protected] >>> <mailto:[email protected]>>님이 작성: >>>> >>>> How large are the dense matrices you would like to invert? >>>> >>>>> On Apr 24, 2023, at 11:27 PM, 권승리 / 학생 / 항공우주공학과 <[email protected] >>>>> <mailto:[email protected]>> wrote: >>>>> >>>>> Dear all >>>>> >>>>> Hello. >>>>> I want to make an inverse matrix like inv(A) in MATLAB. >>>>> >>>>> Are there some methods to inverse matrix in petsc? >>>>> >>>>> If not, I want to use the inverse function in the LAPACK library. >>>>> >>>>> Then, how to use the LAPACK library in petsc? I use the C language. >>>>> >>>>> Best, >>>>> >>>>> Seung Lee Kwon >>>>> >>>>> -- >>>>> Seung Lee Kwon, Ph.D.Candidate >>>>> Aerospace Structures and Materials Laboratory >>>>> Department of Mechanical and Aerospace Engineering >>>>> Seoul National University >>>>> Building 300 Rm 503, Gwanak-ro 1, Gwanak-gu, Seoul, South Korea, 08826 >>>>> E-mail : [email protected] <mailto:[email protected]> >>>>> Office : +82-2-880-7389 >>>>> C. P : +82-10-4695-1062 >>>> >>> >>> >>> -- >>> Seung Lee Kwon, Ph.D.Candidate >>> Aerospace Structures and Materials Laboratory >>> Department of Mechanical and Aerospace Engineering >>> Seoul National University >>> Building 300 Rm 503, Gwanak-ro 1, Gwanak-gu, Seoul, South Korea, 08826 >>> E-mail : [email protected] <mailto:[email protected]> >>> Office : +82-2-880-7389 >>> C. P : +82-10-4695-1062 >> >> >> -- >> What most experimenters take for granted before they begin their experiments >> is infinitely more interesting than any results to which their experiments >> lead. >> -- Norbert Wiener >> >> https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/> > > > -- > Seung Lee Kwon, Ph.D.Candidate > Aerospace Structures and Materials Laboratory > Department of Mechanical and Aerospace Engineering > Seoul National University > Building 300 Rm 503, Gwanak-ro 1, Gwanak-gu, Seoul, South Korea, 08826 > E-mail : [email protected] <mailto:[email protected]> > Office : +82-2-880-7389 > C. P : +82-10-4695-1062
