code: def _parse_tol(rtol,atol):
      
      #Process atol and rtol
      if rtol is None:
          rtol= -12.*nu.log(10.)
      else: #pragma: no cover
          rtol= nu.log(rtol)
      if atol is None:
          atol= -12.*nu.log(10.)
      else: #pragma: no cover
          atol= nu.log(atol)
      return (rtol,atol)
docs: Parse the tolerance keywords