Can anyone help with forcing this to simplify

assume(x>0)

assum(y>0)

simplify(sqrt(-x^2-y^2))

I am looking for this to force the sqrt to return as the imaginary number multiplied by the square root of x^2+y^2

simplify(sqrt(-x^2)) does simplify as far as bringing in the imaginary number 

Many thanks

Hello. 

I would like to know if Maple can or cannot evaluate the integral below. It can be done analytically and also in Mathematica. It is not an uncommon type of integral being related to a Fourier transform of a Hankel function.

restart;
assume(alpha>0);assume(beta>0);assume(s>0);
gr:=(beta,r)->(1/8*I)*(-HankelH1(1, beta*r)-(2*I)*BesselK(1, beta*r)/Pi)/beta^2;
int(cos(alpha*s)*gr(beta,s),s=0..infinity);

Many thanks

Hello.

After using many versions of TA over many years on our own servers, we are considering paying for Maplesoft to host TA. Can anyone offer any experience of using TA hosted on Maplesoft servers? We can think of many good reasons to change but are there any downsides? Is remoteness a problem, speed of access? We have a fairly typical university central computing service dept.

I understand that the way the hosting system works is that more than one server...

1.I have been using TA for some years but we have only recently moved from version 4 to version 6. In versions up to version 5, when a question was edited there was a two stage saving process ie. the question was saved and the question bank was saved. Only after these two saves did assignements containing the question reflect the edits in the question. I have an assignment which depends on a question in TA6 and I have edited saved the question. The assignment does not reflect...

What has happened to the TA forum? Are questions now deliberately mixed with those for Maple? Is it possible to filter and somehow recover the TA forum?

Many thanks