Just an update: I ran with -info, and saw that the 186x6 matrix uses compressed rows routines, whereas 171x21 does not.
2013/10/9 Stefano Zampini <[email protected]> > I just noticed unexpected behaviour of MatMult_SeqBAIJ_3 in PCBDDC code > (on branch stefano_zampini/pcbddc-baijfixes) with rectangular matrices > having number of rows >> number of cols and number of cols =2*blocksize. I > guess this problem will show up for other values of block sizes. > > When some rows of the matrix are empty, the corresponding entry in the > resulting vector is not zero (as expected, mathematically speaking); > instead, the values are not overwritten at all. Is it the expected > behaviour? > > Attached are two matrices . The one with sizes 186x6 shows the problem on > my laptop (ubuntu, gnu compilers, --with-debugging, , CFLAGS -g -O0) > > I'm not familiar with PETSc low-level implementation of BAIJ, so I cannot > dig anymore into the problem apart saying that: > > A) if "converted" to SeqAIJ with a call > > MatConvert(Mymat,MATSEQAIJ,MAT_REUSE_MATRIX,&Mymat) > > the output of MatMult is always correct. > > B) the problem disappear by increasing the number of columns (the matrix > with sizes 171x21 does not show the problem). > > > Hope you can reproduce the problem, > -- > > Ph. D. Stefano Zampini > > > CINECA > SuperComputing Applications and Innovations Department - SCAI > Via dei Tizii, 6 00185 Roma - ITALY > ------------------------------------------------------------------------------------------------------------------------ > Email: [email protected] > SkypeID: stefano.zampini > GoogleTalk: [email protected] > Tel: +39 06.44486.707 > ------------------------------------------------------------------------------------------------------------------------ > > -- Ph. D. Stefano Zampini CINECA SuperComputing Applications and Innovations Department - SCAI Via dei Tizii, 6 00185 Roma - ITALY ------------------------------------------------------------------------------------------------------------------------ Email: [email protected] SkypeID: stefano.zampini GoogleTalk: [email protected] Tel: +39 06.44486.707 ------------------------------------------------------------------------------------------------------------------------
