I failed to have a look at the wright function. So of couse this answers my first question.
I measure the times in release mode. -Simon Am Mi., 2. Juni 2021 um 16:33 Uhr schrieb Praveen C <[email protected]>: > The initialize function does the LU factorization which is the most > expensive part > > > https://www.dealii.org/developer/doxygen/deal.II/classSparseDirectUMFPACK.html#af23a74dd9cac006c9d87c18e5d638076 > > The solution part should be faster than initialize. > > Did you measure the time in “release” mode or “debug” ? > > best > praveen > > On 02-Jun-2021, at 7:56 PM, Simon <[email protected]> wrote: > > Dear all, > > I use the SparseDirectUMFPACK solver for doing some post-processing steps. > I also measure some cpu_times in my program in order to compare different > methods regarding efficiency. For my question only the following three > lines of code from my program are relevant: > --------------------------------------------------- > timer.enter_section("Initialize Direct Solver"); > sparse_direct_solver.initialize(global_matrix); > timer.leave_subsection("Initialize Direct Solver"); > --------------------------------------------------- > So I only measure the time which is neeed for executing the member > function "initialize": > ->Solving a scalar problem with *dim=2* and *263425 DoFs* the above call > takes about 1.3 seconds, whereas solving the linear system takes only 0.8 > seconds. > ->Solving the same scalar problem with *dim=3* and only *72369 DoFs* the > above call takes about 4.4 seconds and solving the linear system about 3.2 > seconds. > > -My first question is what this function actually does since it takes > longer than assembling and solving the system together? > The documentation says: "This function does nothing. It is only here to > provide a interface consistent with other sparse direct solvers." > By having a look in the function body I´ve seen that this function > acutally does nothing, i.e. the function body is empty. > > -My second question is why for my dim=3 case the function call takes much > longer as in the dim=2 case? In the latter I have much more DoFs. > My guess was that the number of DoFs is the essential quantity but this is > obviously not the case. > > Any input would be greatly appreciated! > > Best > Simon > > > -- > The deal.II project is located at http://www.dealii.org/ > For mailing list/forum options, see > https://groups.google.com/d/forum/dealii?hl=en > --- > You received this message because you are subscribed to the Google Groups > "deal.II User Group" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/5B31FFA2-C446-41CD-A43E-9196A73B8269%40gmail.com > <https://groups.google.com/d/msgid/dealii/5B31FFA2-C446-41CD-A43E-9196A73B8269%40gmail.com?utm_medium=email&utm_source=footer> > . > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/CAM50jEsKUQitCRov1RuM8%2BEoRMvJjCCsZ8Q%2BGXYDpQe-ooauZw%40mail.gmail.com.
