On Feb 1, 8:20�pm, casevh <cas...@gmail.com> wrote: > On Feb 1, 1:04�pm, Mensanator <mensana...@aol.com> wrote: > > > > > On Feb 1, 2:27�am, casevh <cas...@gmail.com> wrote: > > > > On Jan 31, 9:36�pm, "Tim Roberts" <t.robe...@cqu.edu.au> wrote: > > > > > Actually, all I'm interested in is whether the 100 digit numbers have > > > > an exact integral root, or not. �At the moment, because of accuracy > > > > concerns, I'm doing something like > > > > > � � � � � � � � � � for root in powersp: > > > > � � � � � � � � � � � � � � nroot = round(bignum**(1.0/root)) > > > > � � � � � � � � � � � � � � if bignum==long(nroot)**root: > > > > � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �......... > > > > which is probably very inefficient, but I can't see anything better..... > > > > > Tim > > > > Take a look at gmpy and the is_power function. I think it will do > > > exactly what you want. > > > And the root function will give you the root AND tell you whether > > it was an integral root: > > > >>> gmpy.root(a,13) > > > (mpz(3221), 0) > > > In this case, it wasn't. > > I think the original poster wants to know if a large number has an > exact integral root for any exponent. is_power will give you an answer > to that question but won't tell you what the root or exponent is. Once > you know that the number is a perfect power, you can root to find the > root.
But how do you know what exponent to use? > > > > > > > >http://code.google.com/p/gmpy/ > > > > casevh -- http://mail.python.org/mailman/listinfo/python-list
