SpECTRE
v2023.09.07

Holds the constant coefficient of the regular field inside the worldtube. More...
#include <Tags.hpp>
Public Types  
using  type = Scalar< DataVector > 
Holds the constant coefficient of the regular field inside the worldtube.
At orders n = 0 or 1 this is just equal to the monopole, but at n = 2, the monopole gets an additional contribution from the trace of the second order coefficient. At this point, this tag is used to solve an ODE based on the expanded KleinGordon equation. It is implemented as a Scalar
of size 1 because the evolution system does not work with doubles.