Switched absolute to relative additional radius

[nicogno]

Larger virtual cell radii are currently considered when an interaction force is computed. This PR suggests switching to a virtual radius that is relative to the actual cell radius.
This might affect the demos where cell interaction is involved.

[nicogno]

WIP: adapt all the tests

[vasvav]

I agree with the approach you proposed @nicogno. I'd be in favour however setting the 'additional_radius_scaling' parameter as an input argument to the function. It can be let to take a default value (i.e., 1.03 as you propose in your code changes) yet permit a user to tailor the value to their needs - instead of restricting it to a fixed parameter value, isn't it?

[TobiasDuswald]

The force is a function so it would have to be a member variable together with some appropriate void Set[...](double val) and double Get[...](double val) functions. Optionally one could add this parameter to param.h. Either way, it would be nice if one could easily control these parameter via an interface that does not require rebuilding BDM. 👍

[nicogno]

Adapted tests and made the value adjustable by the user

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[TobiasDuswald]

Changes look all good to me. Just wondering, have you checked if/how it affects the demos?

[nicogno]

Changes look all good to me. Just wondering, have you checked if/how it affects the demos?

Very good point, I'm currently checking the demos.
Here's the usage of InteractionForce::ForceBetweenSpheres():

analytic_continuum: Force not involved
binding_cells: Check
cell_division: Force not involved
epidemiology: Force not involved
flocking: Force not involved
gene_regulation: Force not involved
makefile_project: Force not involved
monolayer_growth: Force not involved
multiple_simulations: Check
parameters: Force not involved
pyramidal_cells: Check
sbml_integration: Check
soma_clustering: Check
tumor_concept: Check