On 6/17/07, Tim Stitt <timothy.stitt at ichec.ie> wrote: > Actually my sparse matrix has >2^32 rows and columns hence the global row and > column arguments need to be 64-bit.
Cool. What problem is that big? Matt > On Sunday 17 June 2007 17:36, Barry Smith wrote: > > If your problem is so big that you need integers that represent numbers > > more than about 2 billion then yes you will need to rebuild PETSc. > > > > Barry > > > > You'll be the first PETSc user who solves a problem with more than > > 2 billion unknowns. > > > > On Sun, 17 Jun 2007, Tim Stitt wrote: > > > Thanks for that Matt...will check it out. > > > > > > Incidentally, I need to pass a 64-bit integer to MatCreateMPIAIJ. Do I > > > need to rebuild PETSc using a 64-bit integer option switch? > > > > > > Tim. > > > > > > On Sunday 17 June 2007 17:07, Matthew Knepley wrote: > > > > On 6/17/07, Tim Stitt <timothy.stitt at ichec.ie> wrote: > > > > > Hi All, > > > > > > > > > > Currently I am using MatCreateMPIAIJ to create a distributed sparse > > > > > matrix for use in my parallel sparse eigensolver. If I understand > > > > > things correctly, it is important to specify the correct > > > > > pre-allocation values for (o_nz,d_nz) or (o_nnz, d_nnz) respectively > > > > > to obtain optimum memory usage per node. > > > > > > > > > > For information my matrix redistribution routine generates each row > > > > > in the sparse matrix (associated with a given node) "on-the-fly" and > > > > > then uses MatSetValues to apply the elements. > > > > > > > > > > My question is: does anyone have a standard code template for the > > > > > calculating the d_nz or d_nnz values (along with o_nz or o_nnz > > > > > respectively) so that optimum pre-allocation is obtained? Is there a > > > > > simple way of determining if a given non-zero value in a row is part > > > > > of the diagonal or off-diagonal regions for a given distributed > > > > > topology? > > > > > > > > > > Any assistance gratefully received. > > > > > > > > Basically, you run through the construction algorithm once to calculate > > > > d_nnz and o_nnz, and then again to set values. You can see my code for > > > > doing it in preallocateOperator() in src/dm/mesh/mesh.c. > > > > > > > > Matt > > > > > > > > > Thanks in advance, > > > > > > > > > > Tim. > > > > > > > > > > -- > > > > > Dr. Timothy Stitt <timothy_dot_stitt_at_ichec.ie> > > > > > HPC Application Consultant - ICHEC (www.ichec.ie) > > > > > > > > > > Dublin Institute for Advanced Studies > > > > > 5 Merrion Square - Dublin 2 - Ireland > > > > > > > > > > +353-1-6621333 (tel) / +353-1-6621477 (fax) / +353-874195427 (mobile) > > -- > Dr. Timothy Stitt <timothy_dot_stitt_at_ichec.ie> > HPC Application Consultant - ICHEC (www.ichec.ie) > > Dublin Institute for Advanced Studies > 5 Merrion Square - Dublin 2 - Ireland > > +353-1-6621333 (tel) / +353-1-6621477 (fax) / +353-874195427 (mobile) > > -- 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
