def _sh_negate(sh, order):
 assert (order >= 0)
 return (sh.conj() * ((-1.0) if (order % 2) else 1.0))

def _sh_negate ( sh , order ) : assert ( order >= 0 ) return ( sh . conj ( ) * ( ( - 1.0 ) if ( order % 2 ) else 1.0 ) )
helper to get the negative spherical harmonic from a positive one .