Arguments

ierr 		 Return value, negative value indicates theboundary condition was not successfully applied

cctkGH 		 Grid hierarchy pointer

finf 		 Scalar value at infinity

npow 		 Decay rate ($n$ in discussion above)

stencil_size 		 Array with dimension of the grid function, containing the stencil width to apply the boundary at

variable_name 		 Name of the variable

group_name 		 Name of the group

variable_index 		 Variable index

group_index 		 Group index