2009/12/7 Matt Bainbridge <bainbridge.m...@gmail.com>: > Hi there, > > Does anyone know if Sage has a function for computing the composition > inverse of a power series (not the reciprocal)?
Yep, we have that: sage: R.<x> = QQ[[]] sage: f = 1/(1-x) - 1; f x + x^2 + x^3 + x^4 + x^5 + x^6 + x^7 + x^8 + x^9 + x^10 + x^11 + x^12 + x^13 + x^14 + x^15 + x^16 + x^17 + x^18 + x^19 + O(x^20) sage: g = f.reversion(); g x - x^2 + x^3 - x^4 + x^5 - x^6 + x^7 - x^8 + x^9 - x^10 + x^11 - x^12 + x^13 - x^14 + x^15 - x^16 + x^17 - x^18 + x^19 + O(x^20) sage: f(g) x + O(x^20) > --Matt > > P.S. Just started using sage and finding it very useful. Thanks for > developing it. > > -- > To post to this group, send email to sage-support@googlegroups.com > To unsubscribe from this group, send email to > sage-support-unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/sage-support > URL: http://www.sagemath.org -- William Stein Associate Professor of Mathematics University of Washington http://wstein.org -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
