PETSC debug

[billy at dem.uminho.pt]

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
> > 
> 
>