senting the Legendre series of their sum.

    See Also
    --------
    legsub, legmulx, legmul, legdiv, legpow

    Notes
    -----
    Unlike multiplication, division, etc., the sum of two Legendre series
    is a Legendre series (without having to "reproject" the result onto
    the basis set) so addition, just like that of "standard" polynomials,
    is simply "component-wise."

    Examples
    --------
    >>> from numpy.polynomial import legendre as L
    >>> c1 = (1,2,3)
    >>> c2 = (3,2,1)
    >>> L.legadd(c1,c2)
    array([4.,  4.,  4.])

    )