       Re: HELP!

• To: mathgroup at smc.vnet.net
• Subject: [mg81192] Re: HELP!
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Sat, 15 Sep 2007 04:09:44 -0400 (EDT)
• Organization: The Open University, Milton Keynes, UK
• References: <fcdfdj\$pnr\$1@smc.vnet.net>

```conoverm at vt.edu wrote:

> How do i put a code in Mathematica 6.0 lab worksheet 2 of calculus I where I
> need to use sigma notation of (1/n!)
> I tried doing it but when i make a table it does not add the products of 1-3 if
> i put in as n goes to 3. Please help me with the code. Thank You
>
> \[ExponentialE]=\!\(
> \*UnderoverscriptBox[\(\[Sum]\), \(n = 0\), \(\[Infinity]\)]
> \*FractionBox[\(1\), \(n!\)]\)=1+1/1!+1/2!+1/3!+1/4!+...

I am pretty sure I have not correctly understood what the problem is
(i.e. typesetting or evaluating the sum expressed in sigma notation),
illustrate some of the feature of function such as Table, HoldForm, N, etc.)

In:= Sum[1/n!, {n, 0, 3}]

Out=
8
-
3

In:= Plus @@ FoldList[1/HoldForm[#2]! &, 1, Range]

Out=
1    1    1    1    1
1 + -- + -- + -- + -- + --
1!   2!   3!   4!   5!

In:= HoldForm@Sum[1/n!, {n, 0, 5}] ==
Plus @@ FoldList[1/HoldForm[#2]! &, 1, Range]

Out=
1                     1    1    1    1    1
Sum[--, {n, 0, 5}] == 1 + -- + -- + -- + -- + --
n!                    1!   2!   3!   4!   5!

In:= Limit[Sum[1/n!, {n, 0, x}], x -> Infinity]

Out= E

In:= Table[N@Sum[1/n!, {n, 0, x}], {x, 1, 5}]

Out= {2., 2.5, 2.66667, 2.70833, 2.71667}

HTH,
--
Jean-Marc

```

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