def c2max(f, c1, c2):
    """Take the maximum value between two columns in a dataframe.

    Parameters
    ----------
    f : pandas.DataFrame
        Dataframe containing the two columns ``c1`` and ``c2``.
    c1 : str
        Name of the first column in the dataframe ``f``.
    c2 : str
        Name of the second column in the dataframe ``f``.

    Returns
    -------
    max_val : float
        The maximum value of the two columns.

    """
    max_val = max(f[c1], f[c2])
    return max_val
