I have an expression of a vector field ##\vec J = J_r \hat r + J_\theta \hat \theta## in polar coordinates, in a region that's a quarter of an annulus, where theta ranges between 0 and pi/2 and r goes from ri to ro.
I need to compute ##-\int _\Omega T(S_{xx}-S_{yy}) \frac{\partial J_x}{\partial...