Segfault With Single Energy Bin

[tjlaboss]

MCNPTools experiences a Segmentation Fault when processing a meshtal file with only a single energy bin. A MWE will be posted.

MCNPTools attempts to compare to the "Total" bin, regardless of whether it exists. This occurs both in meshtal2vtk...

std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::compare (this=0x0, __s=0x47379d "Total")

...and the Python API:

import mcnptools
>>> mt = mcnptools.Meshtal("example.mesht")
>>> mt.GetTally(4)
Segmentation fault (core dumped)

Temporary workaround: Use emesh=0,1 instead of emesh=1.

[tjlaboss]

MCNPTools Meshtal Bug MWE
C 
C Cell cards
c N  M  D      Out  In  +11 -12   Imp
  1  1 -10.713      -1  +11 -12   imp:n=1     $ Fuel
  2  0          +1  -2  +11 -12   imp:n=1     $ Gap
  3  3  -6.56   +2  -3  +11 -12   imp:n=1     $ Clad
  4  4  -0.726  +3  -4  +11 -12   imp:n=1     $ Water 
 11  0          +4      +11 -12   imp:n=0     $ Radial Graveyard
 12  0                  +12       imp:n=0     $ Upper Graveyard
 13  0                      -11   imp:n=0     $ Lower Graveyard
C End Cell Cards

C Surface Cards
C Radial surfaces
1 cz   0.41148  $ Fuel Pellets and Spacers
2 cz   0.41656  $ Inner Clad Radius
3 cz   0.47498  $ Outer Clad, End Cap, Bellows, LVDT
4 cz  10.5     $ water boundary
C
C Axial surfaces
11 pz -50
12 pz +50
C End Surface Cards

C Data Cards
C ----------
C Material Cards
C 
C UO2 @ 4.95 wt%
m1       8016.01c 4.585223e-2
        92235.01c 1.151431e-3
        92238.01c 2.183053e-2
C
c Zirconium
m3      40090.01c  2.18865E-02
        40091.01c  4.77292E-03
        40092.01c  7.29551E-03
        40094.01c  7.39335E-03
        40096.01c  1.19110E-03
C
C Water
m4     8016.01c 1
       1001.01c 2
mt4 h-h2o.53t
C
C End Material Cards
C ------------------
C Begin Tally Cards
fc4 mesh tally that causes error
fmesh4:n 
           geom=xyz  
           origin= -2.5 -2.5 -25
           imesh= 0  iints=5
           jmesh= 0  jints=5
           kmesh= 0  kints=10
C          v v v v v
           emesh=1   $ <-- This breaks MCNPTools.
C          ^ ^ ^ ^ ^
C
C End Tally Cards
C ---------------
C Source Cards
sdef   pos=1 1 0
       par=n
       erg=d1
sc1 Watt fission spectrum
sp1 -3
nps 4e4