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Re: Hypergeometric2F1 gives wrong complex infinities

  • To: mathgroup at smc.vnet.net
  • Subject: [mg100881] Re: Hypergeometric2F1 gives wrong complex infinities
  • From: pfalloon <pfalloon at gmail.com>
  • Date: Wed, 17 Jun 2009 04:36:59 -0400 (EDT)
  • References: <h19i96$p8o$1@smc.vnet.net>

On Jun 17, 11:52 am, Wieland Brendel <wielandbren... at gmx.net> wrote:
> Dear all!
> I currently have a problem with the hypergeometric function: Consider
>
> Hypergeometric2F1[1, I, I + 1, -Exp[a]]
>
> Whenever I set a > 36 I only get "complex infinity" as a result although
> it should be perfectly finite (take 10 as a scale). Is there any way to
> expand the range of a to higher values?
>
> I would be very thankful for a solution! A big thanks in advance and
> best greetings from germany!
>
> Wieland Brendel
>
> PS: I use Mathematica 7.

Hi Wieland,

I don't see the problem you report:

In[260]:= $Version

Out[260]= 7.0 for Microsoft Windows (32-bit) (February 18, 2009)

In[262]:= Hypergeometric2F1[1, I, I+1, -Exp[#]] & /@ {35,36,37,100} //
N

Out[262]= {-0.245831+0.116478 I, -0.0348098+0.269793 I,
0.208215+0.175061 I, 0.234576+0.137746 I}

Can you reproduce the problem, showing the exact input?

Cheers,
Peter.


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