def chebmulx(c):
<EOL>[c] = pu.as_series([c])<EOL>if len(c) == <NUM_LIT:1> and c[<NUM_LIT:0>] == <NUM_LIT:0>:<EOL><INDENT>return c<EOL><DEDENT>prd = np.empty(len(c) + <NUM_LIT:1>, dtype=c.dtype)<EOL>prd[<NUM_LIT:0>] = c[<NUM_LIT:0>]*<NUM_LIT:0><EOL>prd[<NUM_LIT:1>] = c[<NUM_LIT:0>]<EOL>if len(c) > <NUM_LIT:1>:<EOL><INDENT>tmp = c[<NUM_LIT:1>:]/<NUM_LIT:2><EOL>prd[<NUM_LIT:2>:] = tmp<EOL>prd[<NUM_LIT:0>:-<NUM_LIT:2>] += tmp<EOL><DEDENT>return prd<EOL>
Multiply a Chebyshev series by x.

    Multiply the polynomial `c` by x, where x is the independent
    variable.


    Parameters
    ----------
    c : array_like
        1-D array of Chebyshev series coefficients ordered from low to
        high.

    Returns
    -------
    out : ndarray
        Array representing the result of the multiplication.

    Notes
    -----

    .. versionadded:: 1.5.0