[ENHANCEMENT] Rework the examples to reduce code duplication and warnings

**Describe the enhancement**
The examples should be reworked at some point in time to reduce code duplication and especially to make it easier to fix the warnings.

E.g. `using ft = double` and partially templated code in combination with float inputs for the geometry leads to some type conversion warnings which are tedious to fix.

**Expected behavior**
I think there are two options:
1. remove templates and use `float` for everything
2. templatize everything and use static_casts where appropriate.

The end goal would be to get rid of all warnings during the compilation of the code.