[Date Index]
[Thread Index]
[Author Index]
Re: Simplification with Integers assumption
*To*: mathgroup at smc.vnet.net
*Subject*: [mg74897] Re: Simplification with Integers assumption
*From*: "did" <didier.oslo at hotmail.com>
*Date*: Tue, 10 Apr 2007 05:20:00 -0400 (EDT)
*References*: <eunqc2$7ic$1@smc.vnet.net><euqnn4$89o$1@smc.vnet.net>
On Apr 2, 12:59 pm, "David W.Cantrell" <DWCantr... at sigmaxi.net> wrote:
> But your post did lead me to find something surprising. Suppose we fix n as
> a positive integer -- say, 3 for example:
>
> In[6]:= Sum[3/((2p)!(3 - 2p)!), {p, 1, Infinity}]
>
> results in nothing but warning messages and gibberish. OTOH, if we replace
> Infinity with a large integer -- say, 100 or 1000 -- Mathematica has no
> trouble giving the correct answer.
>
> In[7]:= Sum[3/((2p)!(3 - 2p)!), {p, 1, 1000}]
>
> Out[7]= 3/2
>
> Of course, that answer is _also_ the correct one for the infinite sum at
> which Mathematica balked. Why couldn't Mathematica do the infinite sum? Is
> this problem fixed in the development version perhaps?
Hi,
Thanks for the reply.
Actually it's not only infinite sums that have problems.
Try, for example,
Sum[3/((2p)!(3 - 2p)!), {p, 1, 10000000000000000000000}]
and you'll get some nonsensical answers too.
Did
Prev by Date:
**Re: Plot a simple function**
Next by Date:
**Re: NDSolve can't solve a complex ODE correctly?**
Previous by thread:
**Re: Simplification with Integers assumption**
Next by thread:
**Re: Re: Simplification with Integers assumption**
| |