def _eps_cast(dtyp):
 dt = dtyp
 if (dt == np.longdouble):
  dt = np.float64
 elif (dt == np.clongdouble):
  dt = np.complex128
 return np.finfo(dt).eps

def _eps_cast ( dtyp ) : dt = dtyp if ( dt == np . longdouble ) : dt = np . float64 elif ( dt == np . clongdouble ) : dt = np . complex128 return np . finfo ( dt ) . eps
get the epsilon for dtype .