# Nested NIntegrate problem

So I've been trying to evaluate the following integral in Mathematica 8.0 Student version:

opsnum[a_, \[Omega]_] := (c^5*(3*10^25))/\[HBar]*
NIntegrate[\[Rho][y, \[Omega]]/
Hubble[y, \[Omega]]*(1/Hubble[z, \[Omega]])^3, {y,
a, \[Infinity]}, {z, a, y}]

with

Hubble[z_, \[Omega]_] :=
H0 Sqrt[\[CapitalOmega]M (1 + z)^3 + \[CapitalOmega]\[Gamma] (1 +
z)^4 + \[CapitalOmega]\[CapitalLambda] ((1 +
z)^(3*(1 + \[Omega])))]

\[Chi][a_, \[Omega]_] :=
NIntegrate[c/Hubble[z, \[Omega]], {z, a, \[Infinity]}]
\[Rho][a_, \[Omega]_] := (3*Matter[a, \[Omega]])/(
4 \[Pi]*(\[Chi][a, \[Omega]])^3)

My problem is that this refuses to converge, and gives me an NIntegrate::inumr error, due to the nested integral nature of the function. Furthermore, I cannot think of another definition for the function as it relies on the cube of an integral which has limits different from the limits of the total integrand, of which it is a part.

Anyone got any ideas? I would be eternally grateful!

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You've got undefined terms, so NIntegrate can't evaluate; that's what inumr means. A simpler example is NIntegrate[a, {t, 0, 1}]. – Mark McClure Dec 10 '12 at 19:49
sorry, I meant to include that the variables are defined in my table, which is where the function's values are displayed. – Gokotai Dec 10 '12 at 20:01
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You get that error because some or all of your variables don't have a numerical value. I don't know what you mean by saying that they are defined in your table, but apparently they weren't defined at the time of execution of the NIntegrate. Please provide more details about what you were doing. – Sjoerd C. de Vries Dec 10 '12 at 21:25