PETSC debug

[Barry Smith]

  These numbers are all garbage (tiny numbers like this very, very, very rarely
appear). It looks like the vector or the array you are using is not being 
initialized or is getting totally written over incorrectly.

   Barry


On Wed, 15 Nov 2006, billy at dem.uminho.pt wrote:

> 
> x has very small values and some zeros. Is this a problem?
> 
> 
> (gdb) p *x at 1710
> 
> {5.6661805945484757e-226, -1.1627609243420647e-234, 
>   -3.0191454638161275e-228, 4.9827910759046858e-233, -2.0736747864315411e-242, 
>   -6.2486892875076229e-236, 7.936938687044959e-240, -2.7194212807360601e-249, 
>   -8.588425549413817e-243, 2.3024631606271122e-243, -5.9846691224557681e-252, 
>   -2.2335202330567468e-245, 9.7831244726432479e-236, -1.3552548630405792e-244, 
>   -3.495520937088327e-238, 5.4989262786345397e-243, -1.3210098902792841e-252, 
>   -3.8682663837382384e-246, 8.8387035435575233e-250, -1.8090256621813952e-259, 
>   -5.4716023064278407e-253, 3.588000018861786e-253, -6.2458537296193104e-262, 
>   -2.3148026340361519e-255, 1.0977920182613153e-245, -1.0249411693868054e-254, 
>   -2.6419424389659324e-248, 3.9853740743647345e-253, -5.4255411897492446e-263, 
>   -1.5685468152877737e-256, 6.4972881272145346e-260, -7.7132606040774855e-270, 
>   -2.2883458301363077e-263, 3.7376905182602783e-263, -4.3589162441629927e-272, 
>   -1.6122153535564706e-265, 5.4679961341990742e-256, -3.4946761363871895e-265, 
>   -9.0506057005070676e-259, 1.2625051605987276e-263, -9.8127138874528815e-274, 
>   -2.8171459920204651e-267, 2.1144094764316537e-270, -1.4661783326174102e-280, 
>   -4.3021011674687748e-274, 1.7171839888390158e-273, -1.355360583021068e-282, 
>   -5.0256495711998189e-276, 2.3441225393534538e-275, -1.4167665839646082e-284, 
>   -9.5098664261506559e-276, 5.8664086258683721e-265, -5.2303663615699708e-274, 
>   -3.4638320353774473e-265, 7.1774245671418306e-255, -9.5315249514698032e-264, 
>   -6.22580454316614e-255, 4.3135135163622493e-245, -8.6106571400568118e-254, 
>   -5.54411948811998e-245, 1.2782302660591342e-235, -3.8700430138360975e-244, 
>   -2.4540088843175776e-235, 1.8714298666616161e-226, -8.667061714016371e-235, 
>   -5.4046157807505651e-226, 1.3558688389339507e-217, -9.6883371298320722e-226,
> ---Type <return> to continue, or q <return> to quit---
>  -5.9285856500623996e-217, 4.8468289723098665e-209, -5.3857466678811828e-217, 
>   -3.2242188218384035e-208, 8.4534293726532241e-201, -1.4738192384650725e-208, 
>   -8.5980759783639217e-200, 6.907091796675751e-193, -1.9033438119138147e-200, 
>   -1.0763770568701642e-191, 2.6478532383011193e-272, -1.4903005865209107e-282, 
>   -7.7998156143119667e-274, 9.305780800265163e-262, -8.8839704462246742e-272, 
>   -4.5901635372628567e-263, 1.6034530482636144e-251, -2.6131364216028464e-261, 
>   -1.3303679068670779e-252, 1.3592022238328847e-241, -3.7997620105273078e-251, 
>   -1.9017131279478928e-242, 5.6792247063849799e-232, -2.7364107576938111e-241, 
>   -1.3423648502867758e-232, 1.1692077782649843e-222, -9.7510387600061777e-232, 
>   -4.6696270174942923e-223, 1.1853783027581269e-213, -1.7218922665317482e-222, 
>   -8.0083000299810735e-214, 5.8785159049366656e-205, -1.495807982671848e-213, 
>   -6.7077377611273877e-205, 1.4070570606363661e-196, -6.3472382608798458e-205, 
>   -2.7230139900247648e-196, 1.5497123236581113e-188, -1.2485875796131097e-196, 
>   -5.0753617625768587e-188, 1.5434660362531493e-265, -9.6427364575548134e-276, 
>   -4.9469124048614407e-267, 5.5771128650726324e-255, -6.0715211415635001e-265, 
>   -3.0557860054339049e-256, 9.7596266862900188e-245, -1.8630746938040184e-254, 
>   -9.1835699478680429e-246, 8.400502948812723e-235, -2.8372007398618318e-244, 
>   -1.365943291479874e-235, 3.5683163152848973e-225, -2.1529642010355749e-234, 
>   -1.0086136614457182e-225, 7.470797689290204e-216, -8.1244038233290801e-225, 
>   -3.6841086790658924e-216, 7.6946486289534802e-207, -1.5231479988588442e-215, 
>   -6.6343355238597203e-207, 3.8658097394017472e-198, -1.4018784919234662e-206, 
>   -5.7883232195093694e-198, 9.3704091845606854e-190, -6.2833327107970169e-198, 
>   -2.4015591026235036e-189, 1.0604778036924017e-181, -1.3130129893123058e-189,
> ---Type <return> to continue, or q <return> to quit---
>   -4.3944520676710034e-181, 5.3191550180698584e-174, -1.2276467039908345e-181, 
>   6.582654853774009e-258, -3.6960150023175459e-267, -1.541051696004311e-258, 
>   1.5081568307026851e-247, -1.2291453940848028e-256, -5.045748607868979e-248, 
>   1.6985391993644289e-237, -2.0388029995970922e-246, -8.2307676982689932e-238, 
>   9.31882138782716e-228, -1.6611812318932581e-236, -6.5847692143411066e-228, 
>   2.4911590486436157e-218, -6.6411748999525368e-227, -2.578412473673239e-218, 
>   3.2461544324197385e-209, -1.3019895450678336e-217, -4.930407732106102e-209, 
>   2.0647053899839311e-200, -1.2536927838659388e-208, -4.5973820374997486e-200, 
>   6.3999453950640209e-192, -5.9162039831540975e-200, -2.0733460339667467e-191, 
>   9.6386220362933024e-184, -1.3685224770731774e-191, -4.468872196846956e-183, 
>   6.9383373250314803e-176, -1.5267617834505389e-183, -4.3847638022619328e-175, 
>   2.2993251811195029e-168, -8.018740019783814e-176, 8.0187312547169491e-280, 
>   -1.9681088822187587e-289, -8.6000837193564188e-281, 2.4418184153863893e-291, 
>   -3.6413466395574048e-301, -1.6520119055708723e-292, 6.2083711391797733e-303, 
>   0, -2.7166342721641981e-304, 0 <repeats 54 times>, 1.3382706765032754e-300, 
>   0, -3.7946354577853773e-304, 6.3527319749529548e-289, 
>   -1.0316342902978391e-298, -2.7857994540718757e-292, 1.3926426017545835e-277, 
>   -3.7119818003349503e-287, -9.8649586986765956e-281...}
> 
> 
> 
> Billy.
> 
> 
> Quoting Barry Smith <bsmith at mcs.anl.gov>:
> 
> > 
> >   Billy,
> > 
> >    The x array contains the vector entries. It is either that
> > 1) idx == 1710 is not a valid index or more likely
> > 2) x[] on input has garbage values in it.
> > 
> >    Can you call VecView() on x right before or after
> > it is passed into the MatMult? My guess is it has
> > garbage in it from earlier in the code.
> > 
> >    Barry
> > 
> > On Tue, 14 Nov 2006, billy at dem.uminho.pt wrote:
> > 
> > > 
> > > Hi,
> > > 
> > > I was running my code and I got FPE error on alpha machines.
> > > 
> > > Using gdb the output is the following. I am using 4 processors.
> > > 
> > > Program received signal SIGFPE, Arithmetic exception.
> > > 0x1202c4e1c in MatMult_SeqBAIJ_1 (A=0x120bbc7c0, xx=0x120be0770,
> > >     zz=0x120bc9fb0) at baij2.c:260
> > > 260         while (n--) sum += *v++ * x[*idx++];
> > > (gdb) print n
> > > $1 = 0
> > > (gdb) print idx
> > > $2 = (PetscInt *) 0x120c7aab8
> > > (gdb) print *idx
> > > $3 = 1710
> > > (gdb) print v
> > > $4 = (MatScalar *) 0x120c99190
> > > (gdb) print *v
> > > $5 = 4.0109832449655266e-12
> > > (gdb) print x
> > > $6 = (PetscScalar *) 0x120be1690
> > > (gdb) print x[*idx]
> > > $7 = 1.2349520920477556e-308
> > > (gdb) print sum
> > > $8 = 0
> > > 
> > > 
> > > Billy
> > > 
> > 
> > 
> 
> 
>