Re: Funny Limits
- To: mathgroup at yoda.physics.unc.edu, bugs
- Subject: Re: Funny Limits
- From: Steve Trainoff <steve at tweedledee.ucsb.edu>
- Date: Mon, 30 Sep 91 11:08:52 PDT
I wrote a message about problems with evaluating the limit:
Table[Limit[x^n/E^x, x->Infinity], {n, 0, 15}]
> To which I got the reply from From: Jack Seltzer <jack at chopin.udel.edu>
> The problem above is the order of evaluation...using Release eliminates the
> difficulty as shown below...
>
> In[15]:= Table[Release[Limit[x^n/E^x,x->Infinity]],{n,0,30}]
>
> Out[15]= {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
>
> > 0, 0, 0, 0, 0, 0, 0, 0, 0}
>
>
This indeed works under MMA 1.2 but not under MMA 2.0. I get:
Mathematica 2.0 for NeXT
Copyright 1988-91 Wolfram Research, Inc.
-- NeXT graphics initialized --
In[1]:= Table[Release[Limit[x^n/E^x,x->Infinity]],{n,0,5}]
4 5
x x
Out[1]= {0, 0, 0, 0, Limit[--, x -> Infinity], Limit[--, x -> Infinity]}
x x
E E
The real problem I wanted I had was with the limit,
Limit[x^n/E^x, x->Infinity]
for an UNSPECIFIED n. With Jack's suggestion MMA 1.2
correctly evaluates this as:
-----------------------------
Mathematica (NeXT) 1.2 (January 20, 1990) [With pre-loaded data]
by S. Wolfram, D. Grayson, R. Maeder, H. Cejtin,
S. Omohundro, D. Ballman and J. Keiper
with I. Rivin and D. Withoff
Copyright 1988,1989,1990 Wolfram Research Inc.
In[1]:= Release[Limit[x^n/E^x, x->Infinity]]
Out[1]= 0
whereas MMA 2.0 yields:
-----------------------------
Mathematica 2.0 for NeXT
Copyright 1988-91 Wolfram Research, Inc.
-- NeXT graphics initialized --
In[1]:= Release[Limit[x^n/E^x, x->Infinity]]
n
x
Out[1]= Limit[--, x -> Infinity]
x
E
...STeve
------------------------------------
Insert pithy maxim here...
steve at tweedledee.ucsb.edu (NeXT mail)