diff --git a/src/sage/rings/lazy_laurent_series.py b/src/sage/rings/lazy_laurent_series.py index aa7684293c2..c32513c6201 100644 --- a/src/sage/rings/lazy_laurent_series.py +++ b/src/sage/rings/lazy_laurent_series.py @@ -1493,34 +1493,6 @@ def __call__(self, g): return P.element_class(P, CoefficientStream_composition(self._coeff_stream, g._coeff_stream)) - def revert(self): - r""" - Return the compositional inverse of ``self``. - - EXAMPLES:: - - sage: L. = LazyLaurentSeriesRing(ZZ) - sage: z.revert() - z + O(z^8) - sage: (1/z).revert() - z^-1 + O(z^6) - - sage: (z-z^2).revert() - z + z^2 + 2*z^3 + 5*z^4 + 14*z^5 + 42*z^6 + 132*z^7 + O(z^8) - """ - P = self.parent() - z = P.gen() - if self._coeff_stream._approximate_valuation == 1: - g = self - else: - g = self * z**(1 - self._coeff_stream._approximate_valuation) - f = P(None, valuation=1) - f.define(z/((g/z)(f))) - if self._coeff_stream._approximate_valuation == 1: - return f - else: - return f / z**(1 - self._coeff_stream._approximate_valuation) - def _div_(self, other): r""" Return ``self`` divided by ``other``.