Q: Taking integration of a forward problem in a region of interest which is disretized-Microwave Imaging I am trying to implemented the below formula in order to find the integration in matlab. However, I do not know how to do change of variables. The formula is 
$E=\int_{\Omega}H_{0}^{1}(k\sqrt|r_{s}-r'|)H_{0}^{1}(k\sqrt|r_{r}-r'|)\chi(r')dr'$ 
where $H_{0}^{1}$ is Hankel function, $r_{s}$ and $r_{r}$ are positions of receivers and sources respectively and $r'$ is positions of cells. $\chi$ is a known matrix. $\Omega$ has dimensions as [x -x, y -y] and I want to take this integral according to the dimension of $\Omega$. However, I do not how to do change of variables or in other way to take integral of this function. I would be quite pleased if you can able help me in any way
thanks in advance
