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Re: Re: Bug with Hypergeometric2F1?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg99449] Re: [mg99406] Re: Bug with Hypergeometric2F1?
  • From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
  • Date: Wed, 6 May 2009 05:21:42 -0400 (EDT)
  • References: <200905050940.FAA20697@smc.vnet.net>

On 5 May 2009, at 18:40, Bill Rowe wrote:

>  If
> you want to use machine precision numbers you should be using
> NSum rather than Sum. That is:
>
> In[4]:= f[n_, k_] := NSum[Binomial[n, i], {i, 0, k}]
>
> In[5]:= f[1000, 1.]
>
> Out[5]= 1001.


The supposed advantage of NSUm over Sum in this particular case is a  
mere illusion.

g[n_, k_] := Sum[Binomial[n, i], {i, 0, k}]
g[1000, 1.]
1001

Note that you are using SetDelayed while the original post has Set;  
hence the difference.

Andrzej Kozlowski


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