# A problem with parallelize

I am experimenting with Parallelize and ParallelTable

This is the code I am using:

K[a_, b_, r_] = a*Exp[-r/b]/r;

T = D[K[10^5, 10^9, s], s]/299792^2 /. s -> 7.6

R = Range[0, 7, 0.01];
\[Theta] = Range[0, 2*Pi, 0.05];

RcG[d_, t_] = Sqrt[7.6^2 + d^2 - 2*7.6*d*Cos[t]];
f[a_?NumberQ, b_?NumberQ] :=
1/299792^2*NIntegrate[K[10^5, 10^9, x], {x, 7.6 - a, b}];

tab = Parallelize[
Table[1/299792^2*
d*(K[10^5, 10^9, RcG[d, t]] - K[10^5, 10^9, 7.6] - d*T) +
f[d, RcG[d, t]], {d, R}, {t, \[Theta]}]];
p1 = ListPlot3D[tab, InterpolationOrder -> 4]


I want make a 3d plot using the complicated function defined in the table. When computing, Mathem. gives this error a lot of times:

NIntegrate::inumr: The integrand K[100000,1000000000,x] has evaluated to non-numerical values for all sampling points in the region with boundaries {{7.3,7.30039}}.


It doesn't happen without the Parallelize, so this means that I am using it wrongly, but I don't get where. I also used ParallelTable, with the same result.

  tab = ParallelTable[1/299792^2*d*(K[10^5, 10^9, RcG[d, t]] - K[10^5, 10^9, 7.6] - d*T) + f[d, RcG[d, t]], {d, R}, {t, \[Theta]}, DistributedContexts -> All];

• @mattiav27 DistributeContexts is in fact not necessary here and when set to All it can potentially cause problems ... the problem was (1), not (2). Commented May 22, 2014 at 16:36