Groups > comp.soft-sys.math.mathematica > #1935

Why Indeterminate?

From	Themis Matsoukas <tmatsoukas@me.com>
Newsgroups	comp.soft-sys.math.mathematica
Subject	Why Indeterminate?
Date	2011-04-30 09:54 +0000
Organization	Steven M. Christensen and Associates, Inc and MathTensor, Inc.
Message-ID	<ipgm80$8tb$1@smc.vnet.net> (permalink)

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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

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Why Indeterminate? Themis Matsoukas <tmatsoukas@me.com> - 2011-04-30 09:54 +0000
  Re: Why Indeterminate? David Bailey <dave@removedbailey.co.uk> - 2011-05-01 10:20 +0000
  Re: Why Indeterminate? Stefan <wutchamacallit27@gmail.com> - 2011-05-01 10:21 +0000

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