Mathematica crashes after some iterations

Question

I wrote a Mathematica script, which calculates an integral value at a list of points and writes it to a file:

ϵ :=78.36;
z := 1;
bohr := 0.52917721;
boltzmann = 3.16681535*10^-6;
c := 10 * 6.02214129*10^23*1.0*10^-27*bohr^3;
κ := Sqrt[2.*4*π*c*z];
kBT := boltzmann * 300;

λ = κ/Sqrt[ϵ]*Sqrt[z/(kBT)]

funcin = 
  1/(ϵ*π)*Exp[-(2*r + λ*Sqrt[r^2 + ρ^2 - 2*r* ρ*Cos[θ]])]*
    r^2*Sin[θ]*1/Sqrt[ρ^2 + r^2 - 2*r*ρ*Cos[θ]]

intfuncinang = 
  Assuming[r > 0 && ρ > 0 && ϵ > 0 & &λ > 0, Integrate[funcin, {θ,0,π}, {ϕ,0, 2π}]]

Assuming[ρ > 0 && ϵ > 0 && λ > 0,
  funcins = 
    Integrate[intfuncinang, {r,0,ρ}] + Integrate[intfuncinang,{r, ρ, Infinity}]
  ]//Simplify

dataimport = Import["inputfile.dat", "Table"];
datatoint = dataimport[[1 ;;, 1]]

Print[Length[datatoint]]
int = Array[#&, Length[datatoint]];
Do[ρ = datatoint[[i]];
   int[[i]] = N[funcins];
   points = {datatoint[[i]], int[[i]]};
   points >>> "outputfile.dat"
   , {i, Length[datatoint]}]

I run this on the console with math -nopromt -run "<<script.m". This works always for some values, but crashes after some time. I am using Mathematica 8. Does anyone have an idea why I am getting crashes?

Answer 1

I have experienced kernel crashes like that of Mathematica 9.0.1 on OS X in scripts where there is a repeated output to text files during iterations over cycles. Curiously, same scripts run like a charm in Windows, so it is specifically the OS X issue.

Diagnosing this problem is hard, since the kernel just crashes, flushes all variables, and the only message appearing after choosing Why the Beep? from the Help menu is "kernel has quit during an evaluation". The crash is somewhat random, i.e. it does not happen at the same points in cycles or for the same data.

I managed to trace the problem (by naive Print debugging) to calls of Export. Specifically to the variant with Export["file.txt", data, "Table"]. Replacing this with Export["file.txt", data] fixes the problem. So it may be a bug in Export.

You get differently formatted output after the above mention change, with {} braces around lists - much like InputForm representation . When importing such files, you just do Import["file.txt", "List"] // ToExpression instead of Import["file.txt", "Table"].

I'm not sure what platform you working in, but if it is OS X you may be dealing with the same issue. Exporting with the file extension ".dat" produces "Table" format by default, I believe. Try using the extension ".txt" -- easiest of fixes, if it helps.