Sorry, ignore my previous email. You are not solving eigenvalue problem. Hong
On Mon, Apr 21, 2014 at 9:59 AM, Hong Zhang <[email protected]> wrote: > Umut, > Have you tried slepc for eigenvalue problems? > Why do you need mumps in your eigensolver? Shift-and-invert? > > Hong > > On Mon, Apr 21, 2014 at 9:39 AM, Matthew Knepley <[email protected]> wrote: >> On Sat, Apr 19, 2014 at 2:13 PM, Umut Tabak <[email protected]> wrote: >>> >>> Dear all, >> >> >> For any timing question, we need to see the output f -log_summary. Also, if >> you have significant >> time in routines you wrote, we need you to create PETSc events for these. >> >> Matt >> >>> >>> I am experiencing lately some issues with a symmetric Lanczos eigensolver >>> in FORTRAN. Basically, I have test code in MATLAB where I am using >>> HSL_MA97(MATLAB interface) at the moment >>> >>> When I program Lanczos iterations in blocks in MATLAB by using HSL_MA97, >>> as expected my overall solution time decreases meaning that block solution >>> improves the solution efficiency. >>> >>> Then, to apply the same algorithm on problems on the orders of millions, I >>> am transferring the same algorithm to a FORTRAN code but this time with >>> MUMPS as the solver then I was expecting the solution time to decrease as >>> well, but my overall solution times are increasing when I increase the block >>> size. >>> >>> For a check with MUMPS, I only tried the block solution phase and compared >>> 120 single solutions to >>> >>> 60 solutions by blocks of 2 >>> 30 solutions by blocks of 4 >>> 20 solutions by blocks of 6 >>> 15 solutions by blocks of 8 >>> >>> and saw that the total solution time in comparison to single solves are >>> decreasing so I am thinking this is not the source of the problem, I >>> believe. >>> >>> What I am doing is that I am performing a full reorthogonalization in the >>> Lanczos loop, which includes some dgemm calls and moreover there are some >>> other calls for sparse symmetric matrix vector multiplications from Intel >>> MKL. >>> >>> I could not really understand why the overall solution time is increasing >>> with the increase of the block sizes in FORTRAN whereas I was expecting even >>> an improvement over my MATLAB code. >>> >>> Any ideas on what could be going wrong. >>> >>> Best regards and thanks in advance, >>> >>> Umut >> >> >> >> >> -- >> 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
