# cf.RTOL

`cf.``RTOL`(*arg)

  The value of relative tolerance for testing numerically tolerant equality.

  See also

  `cf.ATOL`

  Parameters: | arg : int, optional The new value of relative tolerance. The default is to not change the current value.
  Returns: | out: `float` The value prior to the change, or the current value if no new value was specified.
  Examples: |

      >>> cf.RTOL()
      1.0000000000000001e-05
      >>> old = cf.RTOL(1e-10)
      >>> cf.RTOL(old)
      1e-10
      >>> cf.RTOL()
      1.0000000000000001e-05