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Re: Re: Sinh[y]/y as y->0?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg33514] Re: [mg33488] Re: Sinh[y]/y as y->0?
  • From: Andrzej Kozlowski <andrzej at tuins.ac.jp>
  • Date: Sun, 24 Mar 2002 01:44:36 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Rather than using Limit, which is not very reliable, I would recommend 
power series expansions. E.g.

In[5]:=
Normal[(Sin[x]/x) + (Sinh[y]/y)+O[x]+O[y]]

Out[5]=
2

etc.

Andrzej Kozlowski
Toyama International University
JAPAN
http://platon.c.u-tokyo.ac.jp/andrzej/

On Friday, March 22, 2002, at 09:08  AM, Chris Becker wrote:

> You have to use Limit when you want to take a limit, Mathematica won't
> immidiatly do this for you.
>
> Limit[(Sinh[y]/y), y -> 0]
>
> "aes" <siegman at stanford.edu> wrote in message
> news:a7csli$i0t$1 at smc.vnet.net...
>> A particular calculation produces at an early stage the intermediate
> result
>>
>>    p1 = (Sin[x]/x) + (Sinh[y]/y) ,        (x and y both real)
>>
>> and this result then feeds into further expressions in a lengthy 
>> symbolic
>> calculation.
>>
>> When I try to do any numerical evaluations of the final expressions 
>> with
> either
>> x or y = 0, I get "Indeterminate expression" or "infinity 1/0" error
> messages,
>> even though the expressions themselves, like the expression above, are
> perfectly
>> determinate and finite for those limits.
>>
>> Any simple way to make this expression behave as it should under 
>> numerical
>> evaluation?
>>
>
>
>
>
>



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