Yes both the formula are not equal as

1/sqrt(beta) not equal sqrt(1/beta) when beta<0

Thanks

And this one which is equal

(sqrt(1/beta)+1)*beta/(beta+sqrt(beta))

@ecterrab Thanks for your response. I ask if my company is ready to fund it.

My problem is related to Birkhoff-Gustavson Normal Form transformation of Hamiltonian when the Hamiltonian is in integral form. I have found packages when Hamiltonian is in discrete sums, but not in integral form. So I work on it.

Regards

@ecterrab Thanks for your answer. In fact I have Maple 13 and the answer to Fundiff(t,phi(-k)) is:

Int(Int(delta(k2+k3-k)*phi(k2)*phi(k3)+phi(-k2-k3)*delta(k2+k)*phi(k3)+phi(-k2-k3)*phi(k2)*delta(k3+k),k2 = -infinity .. infinity),k3 = -infinity .. infinity)

and simplify or combine applied on it do not change anything.

Concerning your curiosity:

In my more complicated problem, I will integrate after on k and I need to keep an expression in k,k2,k3, to use some properties of commutativity between them.

Regards