oefficient array `c` of shape
(xdeg + 1, ydeg + 1) in the order

.. math:: c_{00}, c_{01}, c_{02} ... , c_{10}, c_{11}, c_{12} ...

and ``np.dot(V, c.flat)`` and ``chebval2d(x, y, c)`` will be the same
up to roundoff. This equivalence is useful both for least squares
fitting and for the evaluation of a large number of 2-D Chebyshev
series of the same degrees and sample points.

Parameters
----------
x, y : array_like
    Arrays of point coordinates, all of the same shape. The dtypes
    will be converted to either float64 or complex128 depending on
    whether any of the elements are complex. Scalars are converted to
    1-D arrays.
deg : list of ints
    List of maximum degrees of the form [x_deg, y_deg].

Returns
-------
vander2d : ndarray
    The shape of the returned matrix is ``x.shape + (order,)``, where
    :math:`order = (deg[0]+1)*(deg[1]+1)`.  The dtype will be the same
    as the converted `x` and `y`.

See Also
--------
chebvander, chebvander3d, chebval2d, chebval3d
©