From: David Knezevic <dknezevic@se...>  20111215 15:57:23

John's right that there are random numbers in general, but in that example the training sets are not randomly generated. But the way the algorithm chooses the next parameter is by finding the one with the maximum error bound, and as you can see this problem has the same error bound at two different parameter values, so rounding error would determine which one you end up with. So I think the "early" difference is not surprising. I don't see where the NULL pointer is coming from though in the failure case though... On 12/15/2011 09:35 AM, Roy Stogner wrote: > > I can't seem to reproduce it easily, myself! BuildBot is showing a > failure every time with my default build: > > loadmodules intel tbb mpich2/1.2.1 mklpecos petsc slepc trilinos glpk > vtk &&./configure enableeverything > > but it's showing success with literally every other build I've > configured it to try. They're all being run with "LIBMESH_RUN='mpirun > np 2'", even. > > The failing build and the success build seem to differ starting early: > > FAILURE: > >  Basis dimension: 5  > Performing RB solves on training set > Maximum (absolute) error bound is 0.946406 > > Performing truth solve at parameter: > mu[0] = 0 > mu[1] = 1 > > SUCCESS: > >  Basis dimension: 5  > Performing RB solves on training set > Maximum (absolute) error bound is 0.946406 > > Performing truth solve at parameter: > mu[0] = 1 > mu[1] = 0 > > but I've no idea what causes the difference. >  > Roy > > On Thu, 15 Dec 2011, David Knezevic wrote: > >> hmm, I can't seem to reproduce this error...? >> >> >> >> On 12/14/2011 10:38 PM, Roy Stogner wrote: >>> >>> We're hitting this with my plain standard enableeverything build, >>> too: >>> >>> ... >>> >>>  Basis dimension: 19  >>> Performing RB solves on training set >>> Maximum (absolute) error bound is 0.199127 >>> >>> Performing truth solve at parameter: >>> mu[0] = 0.5 >>> mu[1] = 1 >>> >>> Enriching the RB space >>> Updating RB matrices >>> >>>  Basis dimension: 20  >>> Performing RB solves on training set >>> Maximum (absolute) error bound is 0.198364 >>> >>> Maximum number of basis functions reached: Nmax = 20. >>> Perform one more Greedy iteration for error bounds. >>> Performing truth solve at parameter: >>> mu[0] = 1 >>> mu[1] = 0.5 >>> >>> Enriching the RB space >>> Updating RB matrices >>> >>>  Basis dimension: 20  >>> Performing RB solves on training set >>> Maximum (absolute) error bound is 0.198364 >>> >>> Extra Greedy iteration finished. >>> In RBEvaluation::write_offline_data_to_files, directory eim_data >>> already exists, overwriting contents. >>> Assertion `theta_q_f[i] != NULL' failed. >>> [0] src/reduced_basis/rb_theta_expansion.C, line 89, compiled Dec 14 >>> 2011 at 20:58:16 >>> terminate called after throwing an instance of 'libMesh::LogicError' >>> what(): Error in libMesh internal logic >>> make[2]: *** [run] Aborted >>> make[2]: Leaving directory >>> `/workspace/buildbot/slave/libmeshtrunk/build/examples/reduced_basis/reduced_basis_ex4' >> >> >> 