def dup_neg(f, K):
    """
    Negate a polynomial in ``K[x]``.

    **Examples**

    >>> from sympy.polys.domains import ZZ
    >>> from sympy.polys.densearith import dup_neg

    >>> f = ZZ.map([1, 0, -1])

    >>> dup_neg(f, ZZ)
    [-1, 0, 1]

    """
    return [ -coeff for coeff in f ]