Additional arguments

A table passed to the radiative boundary condition may contain the following additional arguments:

key	variable type	description	default value
LIMIT	CCTK_REAL	$f_0$	0.0
PREVIOUS_TIME_LEVEL	CCTK_INT or CCTK_STRING	GV which holds the	Cactus previous time level
		previous time level
SPEED	CCTK_REAL	wave speed $v$	1.0
BOUNDARY_WIDTH	CCTK_INT array	stencil width for each face	n/a

The default behavior is to use the Cactus previous time level, as defined in the interface.ccl file, for the grid variable requested for the radiative boundary condition. The ``PREVIOUS_TIME_LEVEL'' key is provided for backward compatibility only, and will be deprecated in the future. The corresponding value may be either a CCTK_INT, which will be interpreted as the index of a grid variable holding the previous time level, or a CCTK_STRING, interpreted as holding the name. Note that this will not work when selecting an entire variable group (with more than one member) with one call to Boundary_SelectGroupForBC*, as each member will have a separate previous time level, and thus require a separate table. Please make your life easier by using Cactus time levels...