egative, real)
    y : array_like
        Probability
    out : ndarray, optional
        Optional output array for the function results

    Returns
    -------
    scalar or ndarray
        Values of the shape parameter `m` such that ``pdtr(k, m) = p``

    See Also
    --------
    pdtr : Poisson cumulative distribution function
    pdtrc : Poisson survival function
    pdtrik : inverse of `pdtr` with respect to `k`

    Examples
    --------
    >>> import scipy.special as sc

    Compute the CDF for several values of `m`:

    >>> m = [0.5, 1, 1.5]
    >>> p = sc.pdtr(1, m)
    >>> p
    array([0.90979599, 0.73575888, 0.5578254 ])

    Compute the inverse. We recover the values of `m`, as expected:

    >>> sc.pdtri(1, p)
    array([0.5, 1. , 1.5])

    Ú