
{{alias}}( x, λ )
    Evaluates the cumulative distribution function (CDF) for a Poisson
    distribution with mean parameter `λ` at a value `x`.

    If provided `NaN` as any argument, the function returns `NaN`.

    If provided a negative value for `λ`, the function returns `NaN`.

    Parameters
    ----------
    x: number
        Input value.

    λ: number
        Mean parameter.

    Returns
    -------
    out: number
        Evaluated CDF.

    Examples
    --------
    > var y = {{alias}}( 2.0, 0.5 )
    ~0.986
    > y = {{alias}}( 2.0, 10.0 )
    ~0.003
    > y = {{alias}}( -1.0, 4.0 )
    0.0
    > y = {{alias}}( NaN, 1.0 )
    NaN
    > y = {{alias}}( 0.0, NaN )
    NaN

    // Negative mean parameter:
    > y = {{alias}}( 2.0, -1.0 )
    NaN

    // Degenerate distribution at `λ = 0`:
    > y = {{alias}}( -2.0, 0.0 )
    0.0
    > y = {{alias}}( 0.0, 0.0 )
    1.0
    > y = {{alias}}( 10.0, 0.0 )
    1.0


{{alias}}.factory( λ )
    Returns a function for evaluating the cumulative distribution function (CDF)
    of a Poisson distribution with mean parameter `λ`.

    Parameters
    ----------
    λ: number
        Mean parameter.

    Returns
    -------
    cdf: Function
        Cumulative distribution function (CDF).

    Examples
    --------
    > var mycdf = {{alias}}.factory( 5.0 );
    > var y = mycdf( 3.0 )
    ~0.265
    > y = mycdf( 8.0 )
    ~0.932

    See Also
    --------

