(self, x, y=None, lonlat=False, direct=False)
From position in the projection plane to angular direction (%s).

        Input:
          - x : if y is None, x[0], x[1] define the position in %s plane.
          - y : if defined, x,y define the position in projection plane.
          - lonlat: if True, angle are assumed in degree, and longitude, latitude
          - flipconv is either 'astro' or 'geo'. None will be default.

        Return:
          - theta, phi : angular direction.
From position in the projection plane to angular direction (%s).
From position in the projection plane to angular direction ( %s ) .
def xy2ang(self, x, y=None, lonlat=False, direct=False):
        """From position in the projection plane to angular direction (%s).

        Input:
          - x : if y is None, x[0], x[1] define the position in %s plane.
          - y : if defined, x,y define the position in projection plane.
          - lonlat: if True, angle are assumed in degree, and longitude, latitude
          - flipconv is either 'astro' or 'geo'. None will be default.

        Return:
          - theta, phi : angular direction.
        """
        pass
def xy2ang ( self , x , y = None , lonlat = False , direct = False ) : pass