[aspect-devel] muparser and Floating point exception from divide by zero.
Magali Billen
mibillen at ucdavis.edu
Fri Jun 29 01:43:03 PDT 2018
Hello all,
I have small mystery I could use some help with.
I’m using a function to define the initial temperature field which is only defined for x (horizontal position)
greater than zero because x shows up in the denominator. At x=0 the temperature equals a constant value, TM
If I add a variable EPS=1e-12, and use (x+EPS), this fixes the problem.
However, if I instead use an if statement: if (x>0,..., TM), then I get a floating point exception, as I did in the case with no (x+EPS).
Any ideas why the if statement doesn’t work? This suggest to me that the equation is actually evaluated everywhere and then the if
condition is used, rather than the if condition being checked first (as it would be if written in a c program). Perhaps this is how
the muparser works, but this seems quite strange?
I’d like to use the if statement, because for my actual runs, I have a complicate temperature function, and it would be cleaner (easier to debug),
not to have a bunch of (x+EPS) in the equations.
I’ve pasted in the two different functions calls below. The errors are pasted in below that.
And, I’ve attached the prm-file (with the if statement).
Here are the actual function calls:
==> Option 1 - with eps = 1e-12 (this works, no floating point exception)
subsection Initial temperature model
set Model name = function
subsection Function
set Variable names = x,y
set Function constants = EPS=1e-12, YMAX=1e6, TS=0.000e+00, TM=1.400e+03, \
K=1.000e-06, VSUB=1.585e-09
set Function expression = TS+(TM-TS)*(1-erfc((YMAX-y)/(2*sqrt(K*(x+EPS)/VSUB))))
end
end
==> Option 2 with if statement. (this does not work, I get a floating point exception)
subsection Initial temperature model
set Model name = function
subsection Function
set Variable names = x,y
set Function constants = YMAX=1e6, TS=0.000e+00, TM=1.400e+03, \
K=1.000e-06, VSUB=1.585e-09
set Function expression = if(x>0, TS+(TM-TS)*(1-erfc((YMAX-y)/(2*sqrt(K*x/VSUB)))),TM)
end
end
> more *.output
-----------------------------------------------------------------------------
-- This is ASPECT, the Advanced Solver for Problems in Earth's ConvecTion.
-- . version 2.1.0-pre (master, f5e6a41d5)
-- . using deal.II 9.0.0
-- . using Trilinos 12.10.1
-- . using p4est 2.0.0
-- . running in DEBUG mode
-- . running with 8 MPI processes
-- How to cite ASPECT: https://aspect.geodynamics.org/cite.html
-----------------------------------------------------------------------------
Number of active cells: 1,280 (on 5 levels)
Number of degrees of freedom: 17,316 (10,626+1,377+5,313)
[c12-7:17151] *** Process received signal ***
SIGFPE received
[c12-7:17151] Signal: Floating point exception (8)
[c12-7:17151] Signal code: Floating point divide-by-zero (3)
[c12-7:17151] Failing at address: 0x7f37f5fc163a
[c12-7:17151] [ 0] /lib/x86_64-linux-gnu/libpthread.so.0(+0x12890)[0x7f37fac91890]
[c12-7:17151] [ 1] /usr/lib/x86_64-linux-gnu/libmuparser.so.2(_ZNK2mu10ParserBase16ParseCmdCodeBulkEii+0x24a)[0x7f37f5fc163a]
[c12-7:17151] [ 2] /usr/lib/x86_64-linux-gnu/libmuparser.so.2(_ZNK2mu10ParserBase11ParseStringEv+0x29)[0x7f37f5fc8999]
[c12-7:17151] [ 3] /share/apps/cig/dealii/dealii-9.0.0/install/deal.II-v9.0.0/lib/libdeal_II.g.so.9.0.0(_ZNK6dealii14FunctionParserILi2EE5valueERKNS_5PointILi2EdEEj+0x2c
2)[0x7f3803f1864c]
[c12-7:17151] [ 4] /share/apps/cig/dealii/dealii-9.0.0/install/deal.II-v9.0.0/lib/libdeal_II.g.so.9.0.0(_ZNK6dealii9Functions14ParsedFunctionILi2EE5valueERKNS_5PointILi2
EdEEj+0x10)[0x7f3803f85060]
[c12-7:17151] [ 5] /home/billen/AspectProjects/aspect/build/aspect(_ZNK6aspect18InitialTemperature8FunctionILi2EE19initial_temperatureERKN6dealii5PointILi2EdEE+0x6d)[0x5
5b227f7fe15]
[c12-7:17151] [ 6] /home/billen/AspectProjects/aspect/build/aspect(_ZNK6aspect18InitialTemperature7ManagerILi2EE19initial_temperatureERKN6dealii5PointILi2EdEE+0x47)[0x55
b227f83f33]
[c12-7:17151] [ 7] /home/billen/AspectProjects/aspect/build/aspect(_ZNSt17_Function_handlerIFdRKN6dealii5PointILi2EdEEESt5_BindIFMN6aspect18InitialTemperature7ManagerILi
2EEEKFdS4_ESt17reference_wrapperISA_ESt12_PlaceholderILi1EEEEE9_M_invokeERKSt9_Any_dataS4_+0x20)[0x55b228455ceb]
[c12-7:17151] [ 8] /share/apps/cig/dealii/dealii-9.0.0/install/deal.II-v9.0.0/lib/libdeal_II.g.so.9.0.0(_ZNKSt8functionIFdRKN6dealii5PointILi2EdEEEEclES4_+0xe)[0x7f3803e
b3b52]
[c12-7:17151] [ 9] /share/apps/cig/dealii/dealii-9.0.0/install/deal.II-v9.0.0/lib/libdeal_II.g.so.9.0.0(_ZNK6dealii38VectorFunctionFromScalarFunctionObjectILi2EdE12vecto
r_valueERKNS_5PointILi2EdEERNS_6VectorIdEE+0x4a)[0x7f3803ecee64]
[c12-7:17151] [10] /share/apps/cig/dealii/dealii-9.0.0/install/deal.II-v9.0.0/lib/libdeal_II.g.so.9.0.0(_ZNK6dealii8FunctionILi2EdE17vector_value_listERKSt6vectorINS_5Po
intILi2EdEESaIS4_EERS2_INS_6VectorIdEESaISA_EE+0xa4)[0x7f3803eb835c]
[c12-7:17151] [11] /share/apps/cig/dealii/dealii-9.0.0/install/deal.II-v9.0.0/lib/libdeal_II.g.so.9.0.0(+0x449bf22)[0x7f3800de3f22]
[c12-7:17151] [12] /share/apps/cig/dealii/dealii-9.0.0/install/deal.II-v9.0.0/lib/libdeal_II.g.so.9.0.0(_ZN6dealii11VectorTools11interpolateILi2ELi2ENS_16TrilinosWrapper
s3MPI11BlockVectorENS_10DoFHandlerEEEvRKNS_7MappingIXT_EXT0_EEERKT2_IXT_EXT0_EERKNS_8FunctionIXT0_ENT1_10value_typeEEERSF_RKNS_13ComponentMaskE+0x67)[0x7f3800de47b9]
[c12-7:17151] [13] /home/billen/AspectProjects/aspect/build/aspect(_ZN6aspect9SimulatorILi2EE48set_initial_temperature_and_compositional_fieldsEv+0x544)[0x55b228457f18]
[c12-7:17151] [14] /home/billen/AspectProjects/aspect/build/aspect(_ZN6aspect9SimulatorILi2EE3runEv+0xf3d)[0x55b2284028f7]
[c12-7:17151] [15] /home/billen/AspectProjects/aspect/build/aspect(_Z13run_simulatorILi2EEvRKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEbb+0x117)[0x55b227fda709
]
[c12-7:17151] [16] /home/billen/AspectProjects/aspect/build/aspect(main+0x4df)[0x55b227fb9b21]
[c12-7:17151] [17] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe7)[0x7f37f9f6bb97]
[c12-7:17151] [18] /home/billen/AspectProjects/aspect/build/aspect(_start+0x2a)[0x55b227e256ea]
[c12-7:17151] *** End of error message ***
srun: error: c12-7: task 0: Floating point exception
srun: error: c12-7: task 1: Exited with exit code 1
slurmstepd: error: c12-7 [0] pmixp_client_v2.c:203 [_errhandler] mpi/pmix: ERROR: Error handler invoked: status = -25: Interrupted system call (4)
srun: Job step aborted: Waiting up to 32 seconds for job step to finish.
slurmstepd: error: *** STEP 160.0 ON c12-7 CANCELLED AT 2018-06-29T01:20:19 ***
srun: error: c12-7: tasks 2-7: Killed
>
____________________________________________________________
Professor of Geophysics
Earth & Planetary Sciences Dept., UC Davis
Davis, CA 95616
2129 Earth & Physical Sciences Bldg.
Office Phone: (530) 752-4169
http://magalibillen.faculty.ucdavis.edu
Currently on Sabbatical at Munich University (LMU)
Department of Geophysics (PST + 9 hr)
Avoid implicit bias - check before you submit:
http://www.tomforth.co.uk/genderbias/
___________________________________________________________
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