Re: something funny!
- To: mathgroup at smc.vnet.net
- Subject: [mg78757] Re: [mg78696] something funny!
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Sun, 8 Jul 2007 06:19:21 -0400 (EDT)
- Reply-to: hanlonr at cox.net
$Version 5.2 for Mac OS X (June 20, 2005) (1/(2*#1^z - #1^z)& )[n]/.n->Range[10] {1, 2^(-z), 3^(-z), 4^(-z), 5^(-z), 6^(-z), 7^(-z), 8^(-z), 9^(-z), 10^(-z)} Same result for v6. Bob Hanlon ---- dimitris <dimmechan at yahoo.com> wrote: > The version is 5.2. > > Say > > In[125]:= > o = 1/(2*e^z - e^z) > > Out[125]= > e^(-z) > > Then > > In[126]:= > o = (1/(2*e^z - e^z) /. e -> #1 & ) /@ Range[2, 10] > > Out[126]= > {2^(-z), 3^(-z), 4^(-z), 5^(-z), 6^(-z), 7^(-z), 8^(-z), 9^(-z), 10^(- > z)} > > However, > > In[128]:= > FullSimplify[(1/(2*#1^z - #1^z) & ) /@ Range[10]] > > Out[128]= > {1, 2^(-z), 3^(-z), 1/(2^(1 + 2*z) - 4^z), 5^(-z), 1/(2^(1 + z)*3^z - > 6^z), 7^(-z), 1/(2^(1 + 3*z) - 8^z), 9^(-z), > 1/(2^(1 + z)*5^z - 10^z)} > > No matter what I tried I could not simplify the expressions with even > base of z above. > Any ideas? > > My query becomes bigger considering that as I was informed even in > version > 6 we get > > FullSimplify[(1/(2*#1^z - #1^z) & ) /@ Range[10]] > > {1, 2^(-z), 3^(-z), 4^(-z), 5^(-z), 1/(2^(1 + z)*3^z - 6^z), > 7^(-z), 8^(-z), 9^(-z), 1/(2^(1 + z)*5^z - 10^z)} > > What it is so exotic I can't figure out. It is so trivial! > > In[140]:= > FullSimplify[1/(2^(1 + 2*z) - 4^z) == 1/(2*4^z - 4^z)] > > Out[140]= > True > > In another CAS I took > > convert("(1/(2*#1^z - #1^z) & ) /@ Range[10]",FromMma);value(%); > > 1 > map(unapply(----, _Z1), [seq(i, i = 1 .. 10)]) > z > _Z1 > > > 1 1 1 1 1 1 1 1 1 > [1, ----, ----, ----, ----, ----, ----, ----, ----, ---] > z z z z z z z z z > 2 3 4 5 6 7 8 9 10 > > > Dimitris > >