So documentation here, "The composite of two permutations p*q means first apply p, then q" should read "...apply q, then p", right? This would be an easy issue to open and fix if there is consensus that it is wrong as written. But note that using the composition of function syntax reverses the order, "One can use also the notation p(i) = i^p, but then the composition rule is (p*q)(i) = q(p(i)), not p(q(i)):"
/c On Thursday, March 11, 2021 at 8:37:25 PM UTC-6 Chris Smith wrote: > Given elements `0,1,2,3`, `Permutation(1,2)(2,3)` interpreting R to L > gives `0123->0132->0312`; interpreting L to R gives `0123->0213->0231` > > If you let `p = Permutation(1,2)(2,3)` then `p.list()` gives `[0, 3, 1, > 2]` which is consistent with R to L interpretation. So the assumption that > spelling it `Permutation(1,2)*Permutation(2,3)` means left to right must be > wrong? > > /c > > On Monday, February 22, 2021 at 3:51:02 PM UTC-6 [email protected] wrote: > >> Hi everyone, >> >> I've been experimenting with the "Permutations" module, trying to follow >> the examples in the documentation here: >> >> https://docs.sympy.org/latest/modules/combinatorics/permutations.html >> >> As expected, >> >> Permutation(1, 2)(2, 3) == Permutation(1, 2) * Permutation(2, 3) >> >> But doesn't this mean that the permutations are applied from left to >> right, since (as described in the docs) left-to-right permutation >> multiplication p*q is equivalent to composition q o p? >> >> If so, this contradicts the documentation's claim that "The convention is >> that the permutations are applied from *right to left*". >> >> If not, I must be confused about something, and would appreciate any >> corrections. >> >> Thanks for your help, >> Alex >> >> -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/7556df78-eb14-408c-bf38-326dafaa1318n%40googlegroups.com.
