Cactus Code Thorn RotatingSymmetry90 Author(s) : Erik Schnetter Maintainer(s): Erik Schnetter Licence : GPL -------------------------------------------------------------------------- 1. Purpose Provide a 90 degree rotational symmetry boundary condition. This is the kind of symmetry that exists e.g. in a single black hole evolution when the black hole has spin. The same setup also admits an additional bitant symmetry. Currently the symmetry is fixed to be located at the lower x and y boundaries, so that there is a rotation about the z axis. The coordinate thorn does not know about this symmetry. You will have to set up the domain such that you have an upper quadrant in the x and y directions. This symmetry boundary condition can be mixed with arbitrary symmetry conditions in the z direction, e.g. bitant or periodicity. ================================================================================ R90: operator that rotates points (counter-clockwise) by 90 degrees f(x) = f(R90 x) = f(R180 x) = f(R270 ) symmetry about x=0: f (-x) = f (+x) vx (-x) = vx (+x) vy (-x) = -vy (+x) vz: same as scalar