# Integrate boundaries defined as equations

Have you guys ever needed to define Integrate boundaries as equations?

I tried to submit the equation as was written in original text but it seems that mathematica can't understand it.

kb = 0.001872041; Na =  6.02214129*10^23;
ep = 10.22; p = 2.56;

pot2[r_] := 4 ep ((p/r)^12 - (p/r)^6)

f[r_, T_] := Exp[-pot2[r]/(kb T)] - 1
B3[T_] := -8 \[Pi]^2/3  Na^2 \!$$\*UnderoverscriptBox[\(\[Integral]$$, $$0$$, $$\[Infinity]$$]$$\*UnderoverscriptBox[\(\[Integral]$$, $$0$$, $$\[Infinity]$$]$$\*UnderoverscriptBox[\(\[Integral]$$, $$Abs[r12 - r13]$$, $$r12 + r13$$]f[r12, T]\ f[r13, T]\ f[r23,
T]\ r12\ r13\ r23\ \[DifferentialD]r12 \[DifferentialD]r13 \
\[DifferentialD]r23\)\)\)


Original Text

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Perhaps you should try to find the real culprit Integrate[ x y z, {x, 1, 2}, {y, -x, x^2}, {z, x - y, x + y}] –  belisarius Jul 2 '13 at 12:44