Hi there!

I was wondering if it is possible to integrate a FESpace variable over a subregion of the original mesh.

Let’s suppose `Th3D`

in my example is a cylinder with a height of 0.0 to 100 cm. I want to integrate the `Pow`

FESpace variable over just the axial region where z≥10.0z \geq 10.0z≥10.0 and z≤20.0z \leq 20.0z≤20.0. I tried the following approach, but it only generates a vector composed entirely of zeros.

Thank you in advance!

Christian

```
ofstream fffout("power_density_results/PowerDensity_levelset_testing.txt");
real[int] PowerDensityRegionsLevelsetTest(64);
// Defintion of the function that has to be used in levelset
func flevelset = (z>= 10.0 && z<=20.0);
//
for (int i=0; i<64; i++)
{
real xc =vecCenters(i,0);
real yc =vecCenters(i,1);
int thisregion = Th3D(xc,yc,10.0).region;
PowerDensityRegionsLevelsetTest[i] = int3d(Th3D,levelset=flevelset)(PowerDensityFespaceVariable)/int3d(Th3D,levelset=flevelset)(1.0);
fffout.scientific<<PowerDensityRegionsLevelsetTest[i]<<endl;
}
```