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Re: Why Indeterminate?

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  Re: Why Indeterminate? Andrzej Kozlowski <akoz@mimuw.edu.pl> - 2011-05-01 10:21 +0000

#2019 — Re: Why Indeterminate?

On 30 Apr 2011, at 11:53, Themis Matsoukas wrote:

> Consider this expression:
>
> A[a_List, x_] := x (1 - x)  \!\(
> \*UnderoverscriptBox[\(\[Sum]\), \(j = 1\), \(2\)]
> \*FractionBox[\(a[[j]]
> \*SuperscriptBox[\((1 - 2\ x)\), \(j - 1\)]\), \(1 -
>     a[[3]] \((1 - 2  x)\)\)]\)
> a = Range[3];
>
> Evaluation at x=0.5 gives
>
> A[a, 0.5]
>
> Indeterminate
>
> ..but I can get the right answer if I use
>
> A[a, x] /. x -> 0.5
>
> 0.25
>
> What puzzles me is that there is no obvious indeterminacy in the original expression at x=0.5.
>
> Thanks
>
> Themis
>


Actually, there is. Note that, in Mathematica,  x^0  is 1 but 0^0 is Indeterminate.

Andrzej Kozlowski

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