Re: convert an expression to an infinite series
- To: mathgroup at smc.vnet.net
- Subject: [mg29622] Re: [mg29618] convert an expression to an infinite series
- From: BobHanlon at aol.com
- Date: Fri, 29 Jun 2001 01:35:55 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
In a message dated 2001/6/28 5:42:56 AM, meshii at mech.fukui-u.ac.jp writes: >Does anyone know a way to convert an expression to an infinite series? >Let me show the idea by a concrete problem. > >In[29]:= >Sum[E^(-2*m*n*L), {n, 0, Infinity}] > >Out[29]= >E^(2*L*m)/(-1 + E^(2*L*m)) > >Yes, Mathematica 4.1 knows that the infinite sum converges to a specific >value. >Then, my question is that how can I expand the expression > E^(2*L*m)/(-1 + E^(2*L*m)) >in an infinite series on n, in this case > Sum[E^(-2*m*n*L), {n, 0, Infinity}] > >Is there any way or is it an one way path? > Solve[Sum[y^n, {n, 0, Infinity}] == E^(2*L*m)/(-1+E^(2*L*m)), y] {{y -> E^(-2*L*m)}} Bob Hanlon Chantilly, VA USA