Converts input arguments x and y to a 2d meshgrid,
    suitable for calling Means, Covariances and Realizations.

def vecs_to_datmesh(x, y):
    """
    Converts input arguments x and y to a 2d meshgrid,
    suitable for calling Means, Covariances and Realizations.
    """
    x, y = meshgrid(x, y)
    out = zeros(x.shape + (2,), dtype=float)
    out[:, :, 0] = x
    out[:, :, 1] = y
    return out