{{alias}}( x, y[, options] )
    Two-dimensional kernel density estimation.

    Parameters
    ----------
    x: Array<number>
        Array of x values.

    y: Array<number>
        Array of y values.

    options: Object (optional)
        Function options.

    options.h: number (optional)
        Array of length two containing the bandwidth values for x and y.

    options.n: number (optional)
        Number of partitions on the x- and y-axes. Default: `25`.

    options.xMin: number (optional)
        Lower limit of x.

    options.xMax: number (optional)
        Upper limit of x.

    options.yMin: number (optional)
        Lower limit of y.

    options.yMax: number (optional)
        Upper limit of y.

    options.kernel: string|Function
        A string or function to specifying the used kernel function. Default:
        `'gaussian'`.

    Returns
    -------
    out: Object
        Object containing the density estimates (`z`) along grid points (`x` and
        `y` values).

    Examples
    --------
    > var x = [ 1, 3, 5, 6, 21, 23, 16, 17, 20, 10 ];
    > var y = [ 0.40, 0.20, 0.20, 0.15, 0.05, 0.55, 0.6, 0.33, 0.8, 0.41 ];
    > var out = {{alias}}( x, y )
    { 'x': [1, ... ], 'y': [0.05, ...], 'z': ndarray{Float64Array[0.031, ...] }

    See Also
    --------