r"""Highest max temperature

    The maximum value of daily maximum temperature.

    Parameters
    ----------
    tasmax : xarray.DataArray
      Maximum daily temperature [℃] or [K]
    freq : str, optional
      Resampling frequency

    Returns
    -------
    xarray.DataArray
      Maximum value of daily maximum temperature.

    Notes
    -----
    Let :math:`TX_{ij}` be the maximum temperature at day :math:`i` of period :math:`j`. Then the maximum
    daily maximum temperature for period :math:`j` is:

    .. math::

        TXx_j = max(TX_{ij})

def tx_max(tasmax, freq='YS'):
    r"""Highest max temperature

    The maximum value of daily maximum temperature.

    Parameters
    ----------
    tasmax : xarray.DataArray
      Maximum daily temperature [℃] or [K]
    freq : str, optional
      Resampling frequency

    Returns
    -------
    xarray.DataArray
      Maximum value of daily maximum temperature.

    Notes
    -----
    Let :math:`TX_{ij}` be the maximum temperature at day :math:`i` of period :math:`j`. Then the maximum
    daily maximum temperature for period :math:`j` is:

    .. math::

        TXx_j = max(TX_{ij})
    """

    return tasmax.resample(time=freq).max(dim='time', keep_attrs=True)