Problems of HP prime with triple integrals?

[Nigel (UK)]

Strange. If I change variables to \(u=1/z\), then with exact mode ticked and approximate evaluation I get the correct answer to the triple integral at once, after a couple of messages.

With exact mode not ticked I get a message about using Romberg, then the calculator carries on calculating until interrupted.

With \(1/z\) in the exponent I can't get an answer to the triple integral at all, although the equivalent single integral evaluates with no problem.

Something's not right!

Nigel (UK)